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 SBAS and GPS Accuracy - Side by Side Testing

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T O P I C    R E V I E W
gpspassion Posted - 22 avr. 2006 : 02:58:25
May/June/July 2006 SBAS Poll Results:
Useful and use it : 48% - Useful but don't use it : 18% - Not useful don't use it : 34%


SBAS (WAAS/EGNOS) - Side by Side Testing



http://www.gpspassion.com/fr/articles.asp?id=185


This article started out as an attempt to come up with some real life data to answer the recurring questions about SBAS (Satellite Based Augmentation System - known in various parts of the world as WAAS, EGNOS, MSAS) with everyone being logically convinced they need it after reading the technical specs of GPS systems where SBAS accuracy is generally shown as being much better than non-SBAS accuracy, typically 10 meters down to 5 meters or even 2 meters...For some fair testing, I had to find a way to measure a reference point with the best possible accuracy and that's where the Delorme GPSPostPro suite comes in, so I added a page in this article describing how I used it.

[/center]

Questions, comments ?
_________________________________________________________________________
Discounts and Assistance/Réductions et Assistance (Club GpsPasSion) / Où commencer?
149   L A T E S T    R E P L I E S    (Newest First)
pyxis Posted - 25 déc. 2007 : 17:59:11
An additional comment pertaining to the Elevation Mask is that DGPS corrections were constrained to apply only to Satellite Elevations above 10.0 degrees. The default Elevation Mask value for the SIRF II chipset was 7.5 degrees. The default value for the SIRF III chipset is 5.0 degrees.
pyxis Posted - 25 déc. 2007 : 17:52:59
I would not be concerned with the grayed out Tracking Parameter.From all indications the TRACKING parameter under Power Mask is not implemented. However, the NAV parameter is implemented and adjustable. It can be set somewhere around 12 to 15 dBs for the SIRF III since the principal characteristic of this generation chipset is its ability to correlate inputs with much lower signal to noise ratio than previous chipsets. The SIRF II operating value was around 24 to 28 dBs. In SIRF Protocol mode watch the C/No value. You will notice that many of the satellites being used in the Fix are lower than 28 dB. Experiment with the Power Mask NAV and the Elevation Mask to find your optimum operating setup.
musky Posted - 25 déc. 2007 : 15:03:59
If SirfDemo won't modify the mask, I don't know any alternative way to do it. Maybe another piece of "tweaker" software out there?

It could be SirfDemo does not implement that function correctly, or maybe the GPS is blocking the power mask command.

You might want to check out this thread on this forum:
http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=54188&whichpage=6

This is back when we were trying to solve the SirfIII WAAS issues. aaronprez was trying to mess with the power mask.....
zjdcjyj Posted - 25 déc. 2007 : 04:36:51
I found satellites signal often near 20db,but power mask for tracking is 28db default,So GPS FFTT is very long.
I want to modify power mask for tracking to 20db.
Can you tell me how to do it?
musky Posted - 24 déc. 2007 : 14:10:53
Respectfully asking, why do you want to modify the power mask for "tracking" ??
zjdcjyj Posted - 24 déc. 2007 : 04:07:58
My GPS is Nokia LD-3W(Sirf StarIII inside)
when I use Sirfdemo,I found I couldn't modify power mask for tracking
musky Posted - 23 déc. 2007 : 14:38:11
Are you referring to Sirf or MTK?? If it's Sirf, SirfDemo may be able to do that. If it's MTK, then probably no. MTK does not have a binary mode with all kinds of parameter tweaking available like Sirf does. They do have some NMEA extensions available. See the Transystem document for these extensions. I just looked through the document and did not see any power mask commands.
zjdcjyj Posted - 22 déc. 2007 : 17:04:00
Now,Can anyone tell me how to modify power mask for tracking?Thank you!!!
Zigster Posted - 11 mars 2007 : 00:08:38
@musky,
yes I'm in for testing!

@gpspassion,
thanks for the new thread, I'll post there from now !
Zigster
gpspassion Posted - 11 mars 2007 : 00:02:53
CE version would be great yes and you can use this method and I started this * Discussing MTK receivers and Tips and Tweaks * thread where you can post it as well as your previous MTK comments.
musky Posted - 10 mars 2007 : 23:36:22
Ok, I've got the MTKTweak app ready here. I've got a Windows version, I can also do a CE version if anyone's interested. All it does now is turn WAAS on and off.
GPSPassion, is there a place on your server I can upload this app?
Zigster, you want to test it?
gpspassion Posted - 10 mars 2007 : 23:03:02
I see, a 737 clone, best for you to post in the 737 thread then.
Zigster Posted - 10 mars 2007 : 22:52:44
@gpspassion,
sure can: http://www.polaris-gps.com/4.html

bought it @ebay from a shop in London.
It calls itself iBT-GPS, and has the same packaging as seen on http://www.transystem.com.tw/p-gps-iblue737.htm .

I just mailed polaris on information on three points:
1. WAAS/EGNOS support enabled ?
2. USB bridge available (for now I can use the miniUSB for charging only?
3. 5Hz update enabled or or can it be turned on?

I wonder, if I will receive an answer. I will keep you updated.

Greetings

Zigster
gpspassion Posted - 10 mars 2007 : 21:44:34
Musky, again interesting MTK research but largely OT here, and people missing on it, you should start a new MTK thread with some cutting and pasting of your previous messages.

@Zigster - only Polaris I've seen was a Sony chip, got a link for the MTK version ?
Zigster Posted - 10 mars 2007 : 20:04:26
@musky,
thank you for your information.
My unit is Polaris iBT-GPS. It has a USB port, but, as it seems, it is only meant for charging the battery (no device is being recognized, when plugged into the USB port of my computer. I actually tried to communicate via Bluetooth to the device with HyperTerminal already, but to no prevail.
I'm also a software developer...perhaps I can chip in with some help on clearing the fog on the MTKs. I'm looking forward to hearing from you and if you don't mind, I would like to check out your tool ... :-)

Greetings

Zigster
musky Posted - 10 mars 2007 : 19:54:44
I have a USB unit, but it's probably the same core GPS chip if you have the MTK "32 channel" unit. I sent the commands with my own C++ software. (I'm a software developer) You can probably use the built in Windows program called HyperTerminal, although I've never tried that. Trouble is, you have to calculate the checksum for each command.

Really, the support for this chipset is lacking right now. There is no equivalent of Sirf's "SirfDemo". I think there's some software out there for the MTK, but they don't support the tweaks you can do with SirfDemo. I really don't know how anyone can possibly put this unit into WAAS mode without knowing the "tricks". I suppose if some people twist my arm, I could write a little tweaker app for this. I know how to turn WAAS off and on, and change the update rate to SLOWER than 1 HZ, but that's about it.... Would be nice to be able to change baud rate too, but I need help on that one!!
Zigster Posted - 10 mars 2007 : 17:49:00
First Post ;-)
@musky: Is the receiver you are talking about a bluetooth GPS receiver? Sounds to me like it is just like these iblue 737 or my Polaris iBT-GPS :-).
My question: How do you connect to the device for posting the commands (eg. $PMTK301,2) and with which utility ?
Thank you so much for your information.

Greetings
Zigster
GTBecker Posted - 09 mars 2007 : 19:52:25
Watching, yes.

Just yesterday, I got my other iTrek M5 back from a job so I can finally do the simultaneous 2-pair (2x GlobalSat BT359C SS3 v3.2.2 vs. 2x Nemerix NJ-1039) WAAS comparisons.

The work the M5 did over a month, though, already suggests the SS3 will win this pretty easily, but we'll see shortly.

musky Posted - 09 mars 2007 : 18:04:07
MTK Update:
Here's another update on my mini evaluation. (Anybody reading this thread?) I've now got 228,338 seconds of acquisition on my MTK GPS, in the same location, all with WAAS enabled. 2D RMS error is 13.0 feet.

I've noticed another somewhat odd thing about this chipset. Cold starts seem to include a lot of initial wandering about. You really need to wait a couple of minutes for a good fix. Some of this may be due to the "static navigation" finally kicking in, I'm not sure. Like I said before, I don't really like evaluating precision with static navigation on, and wish I could turn it off. I had one incident of turn on wandering that lasted 5 minutes, that degraded the 2D RMS from 9 feet to the above mentioned 13 feet. The nature of the 2D RMS calculation is that a few incidents of gross wandering can really slam the precision. That is why you need to do hundreds of thousands of acquisitions over the course of a week or so to get a good estimate.

I still have been unable to increase the baud rate. The $PMTK251 command doesn't do it. Anybody found out the key to this yet???
musky Posted - 28 févr. 2007 : 03:44:01
MTK Update:
Well, I've succeeded in coaxing the MTK into WAAS mode. It takes 2 special commands, $PMTK301,2 and $PMTK313,1. After sending these commands, the unit locks onto WAAS sat ID 48 (PanAm PRN 135) and stays locked pretty much all the time. I've completed 47,000 1 second acquisitions (in fixed location), and my standard deviation is 8 feet! This seems outstanding, however, my excitement is tempered by the continual "static navigation" feature that I fear is affecting my precision study results.

I am kind of amazed that the unit doesn't default to WAAS on, and the user has to find an obscure pdf on an obscure website (transystem) to turn the unit's WAAS on, using hand entered $PMTK commands. Sheesh!!! What gives???

I did take the unit out on the road and try some tracking. Went a couple of miles, and laid down a track, then went back and forth over the track to see how reproducible the track was. It was excellent. My second tracks were within a couple of feet of the first track all along the length of the track.

Doing this experiment brought up an interesting thing though. If you get above a certain speed, the unit "wakes up" out of its static mode, and then you can slow down to sub-MPH speeds and have the unit report a valid bearing and speed. Then if you come to a complete stop, it finally says , "I am stopped" and gets back into static mode, and then it takes a >3 MPH or so move to wake it up again.... etc. This is very annoying, but if you do keep moving it seems to behave pretty well.

The hot topic on other threads in this forum is the 5HZ capability. This is the $PMTK300 command. This command works from the standpoint that I can slow down the position update rate to 2 seconds or 3 seconds. I cannot increase the rate to <1 second however.

I thought that the problem COULD be baud rate. Perhaps the firmware recognizes that it can't do higher updates without having the baud rate set to higher than the default of 9600 baud. So I tried the $PMTK251 command to set the baud rate higher. I have been unsuccessful.

So, in summary, looks like a good start, but PLEASE MTK, help me get rid of the static nav, and give me some better documentation and tools!
musky Posted - 27 févr. 2007 : 02:45:59
Well, I finally lucked out on a Google search and found the MTK specific command set!!! I am now able to switch WAAS on and off, and change the update rate. There are a bunch of other commands I will experiment with in the near future. The baud rate can be changed now I hope. I am proceeding with the precision experiment, and Sirf still leads. My biggest gripe right now is this "static navigation" or "pinning" or whatever you want to call it. The MTK command set does not seem to have a command for turning this off! Dang!
tomlouie Posted - 25 févr. 2007 : 04:25:43
quote:
Originally posted by musky

MTK update:
I've noticed another peculiar thing about the MTK. The bearing field of RMC and VTG seems to have a certain threshold, below which it freezes. I haven't determined exactly what this threshold value is, but it is around 5 MPH. Under this speed, the bearing (or heading) value simply freezes. Sirf III units, on the other hand, will report a bearing for speeds down to a fraction of a MPH. I do wonder if this is related to the odd fix distribution. It may be that under a certain speed it changes into "fixed" mode. I am only speculating though.

One more thing. I did manage to find a brand name on the box, It is Xemics. What the model # is, I still don't know.




The BT338 SirfIII has a "static navigation" option that I think causes it reject movements below a certain speed (4mph?) as mere jitter, I think. Maybe your MTK unit is in a similar mode.
musky Posted - 23 févr. 2007 : 17:17:48
MTK update:
I've noticed another peculiar thing about the MTK. The bearing field of RMC and VTG seems to have a certain threshold, below which it freezes. I haven't determined exactly what this threshold value is, but it is around 5 MPH. Under this speed, the bearing (or heading) value simply freezes. Sirf III units, on the other hand, will report a bearing for speeds down to a fraction of a MPH. I do wonder if this is related to the odd fix distribution. It may be that under a certain speed it changes into "fixed" mode. I am only speculating though.

One more thing. I did manage to find a brand name on the box, It is Xemics. What the model # is, I still don't know.
musky Posted - 23 févr. 2007 : 02:15:27
I've got my MTK chipset GPS unit, and have some preliminary results. I bought the unit off of E-bay. It has the MTK 32 channel chipset and is a USB interface unit. It came directly from Hong Kong. I can't tell you the model #! For some reason it's like the seller is keeping the model # top secret! Anyway, I've some preliminary results.

This unit is advertised as having an accuracy of 2.5m! That is quite the claim. It is also advertised as having WAAS support, although I have yet to see the '2' in the GGA command, so I cannot verify that I am ever getting WAAS with this thing. The baud rate is advertised as being the usual series of typical baud rates, 4800,9600,19200, etc. but I have been unsuccessful at finding any MTK extended commands that support changing the baud rate. The default turns out to be 9600. (The only extended command that I know about is the cold reset command.

So here are preliminary results. I'll give the final when I get more data. I like to have a couple 100,000 data samples over a period of a week or so to get a good estimate of the standard deviation of the fix.

For the experiment I have my Sirf III running at exactly the same time as the MTK, approximately 1m away, indoors. (I live in Wisconsin, USA, BTW) I acquire continually, saving the data and plotting the results with my own software I wrote. I calculate the standard deviation of the distance of all the fixes from the average of all the fixes. Thus , this defines a circle of a particular radius, of which about 70% of the fixes should fall within.

First of all, the unit IS SENSITIVE. It is on par with the Sirf III in terms of its ability to pick up satellites. It is locked onto a sufficient number of satellites to perform a fix almost, if not all the time. I presently have 84,000 seconds of acquisitions, and this number is almost exact between the Sirf and the MTK. Average HDOP with the Sirf has been 1.1 over this period, and 1.1 with the MTK also.

On to standard deviation.... So far the Sirf III is at about 5 meters, the MTK is at about 8 meters. (I have performed many experiments with the Sirf, and long term accuracy is always around 5 meters.) So, so far, Sirf III "wins".

There is a very interesting thing going on with the MTK though! If you look at the distribution of the Sirf data, it is what you would expect, I guess, it is a 2 dimensional gaussian semi random distribution of points, with what I would call the "wandering tracks" which occur when one or more satellites are acting up. With the MTK, there is some kind of wierd processing going on. To me it looks like they are doing some kind of "algorithmic" processing of the data that MIGHT be something like trying to guess if the unit is stationary and then deciding not to allow a change in the position. If you follow the MTK track (stationary of course) it tends to wander in a very defined, but random manner, making very small increments. It's like it is constrianed to only move for smaller increments. A picture is like a thousand words. I will try to post a JPG of this phenomena on my next report. It looks totally different than the Sirf! Anyway I will report back when I get up to 400,000 or so acquisitions.

So in summary so far, the claim of 2.5m accuracy is not real by my experience, I can't verify WAAS, Sirf III still is better, but the MTK IS a sensitive unit.
musky Posted - 13 févr. 2007 : 13:32:17
No apology needed.... It's not like you are getting paid to do this, right?

Meanwhile, I have a new unit with an MTK chipset in it ordered. When I get this in a week or so, I will be doing a side by side comparison with my SirfStarIII. This should be interesting....
GTBecker Posted - 12 févr. 2007 : 14:32:21
Yes, my apologies. Life has interceded but I'll make the time to collect more WAAS/noWAAS data here over the next few days.


Tom
musky Posted - 10 févr. 2007 : 14:42:05
GTBecker:
Are you still working on gathering the data? I anxiously await your results!
gpspassion Posted - 28 janv. 2007 : 14:52:07
Well it's based on Globalsat unit ;-) If they can I'm sure they will do it, but OT here, keep us posted in the Semsons forums.

@GTbecker - looking forward to the "pair" testing :
musky Posted - 28 janv. 2007 : 05:40:08
GPSPassion:
No, GlobalSat is not the only one who has done firmware upgrades. Semsons updated my Trek S3 (Sirf III, USB) from 3.0 to 3.1 to help fix the WAAS problem, but it didn't work. They were very cooperative with the upgrade though. I just don't know how cooperative they are going to be a third time if I ask for 3.2.2 !!
GTBecker Posted - 28 janv. 2007 : 02:27:12
quote:
... the average position bewteen your two test runs if off by about 5 meters, with standard deviation being low in both cases.


Yes, that's puzzling. They are from the same point, about a day apart. I'll have the second iTrek later this week. I'll take more data with both pairs.

gpspassion Posted - 28 janv. 2007 : 02:17:54
As you can see in the "SiRF firmware Version" thread, firmware updates are seldom made available, only known exceptions are Globalsat who have updated and swapped units in the past and Fortuna back in the Xtrack days.

@GTBecker - Thanks for the info about that spot, what's strange is that the average position bewteen your two test runs if off by about 5 meters, with standard deviation being low in both cases.

Good point about the altitude, I ran some numbers on your 20070121 recording and got a standard deviation of 3 meters Non-WAAS and 0.75 meters WAAS, the next day 2 and 2.59 respectively and 1.5 for the iTrek.
MikeMc Posted - 28 janv. 2007 : 00:38:53
Has anybody heard from Holux lately? I have sent 3 e-mails within the last month asking about Sirf 3.2.2 firmware for the GPSlim without any reply.
musky Posted - 27 janv. 2007 : 17:13:36
Great! Glad to see WAAS works on Sirf III finally! How can I get the .zip you uploaded?

Another question.... Anybody know where to get a Sirf III with 3.2.2 firmware in a USB unit?????
GTBecker Posted - 23 janv. 2007 : 23:11:32
The corners of the lot have been surveyed twice in recent years so I picked a convenient pair of coordinates and measured my way to that intersection from each corner. I believe the stake is no more than 20cm from where it should be, and the top of it is 9 feet AMSL.

Come to think of it, it would be interesting to see a 3D cloud of points, not just Lat/Long. While it is said to, and appears to, improve horizontal position, WAAS's focus is altitude improvement, I believe. I'd be interesting to see a vertical axis, too.
gpspassion Posted - 23 janv. 2007 : 22:31:10
Thanks for the pics, it looks like an ideal setting for accuray testing ;-) Out of curiosity how was the position of the stake determined ? A cheap way to get excellent sub-meter accuracy is with Delorme's Post-Processing kit I described in my article.
GTBecker Posted - 23 janv. 2007 : 18:39:39

This is my test site. The stake is believed to be at 26.555710 -82.025780; the work surface is exactly 3m AMSL. I place the inverted box over the receivers to block Florida sun.





Tom
GTBecker Posted - 23 janv. 2007 : 00:25:08
Yes, I have a matching iTrek that I can use to simultaneously test two NS1030s, but it is 150 miles from here at the moment. I'll do that test when I have both in hand soon.

gpspassion Posted - 22 janv. 2007 : 23:14:36
Thanks, let me retrieve these files from the server, do you know the "true" position of the spot where you had placed the receivers (seems to have moved about 5 meters between v1 and v2 ?) and maybe a picture of your setup to illustrate the article I'll update.

Had a quick look, the 3 GPS test run is very impressive indeed for WAAS, 95, 1.8m - you don't happen to have a non-WAAS Nemerix receiver do you? I'd seen some degradation due to EGNOS in my testing.
GTBecker Posted - 22 janv. 2007 : 17:10:07
I had an opportunity last night to collect an hour of simultaneous data from two identical GlobalSat BT-359C (SS3 v3.2.2) receivers, one with WAAS corrections (forced to PRN138) and one without WAAS corrections. WAAS easily wins this contest.

Where do you want the data uploaded?

More data to come...

...I've also uploaded a zip of three files, each an hour of data taken this afternoon from the same two BT359Cs as yesterday (one WAAS'd, one not), and from an NS1030-based iTrek (I have a second iTrek that's unavailable at the moment, but I'll run two of them against each other soon).

Although not as convincing as last night's comparison, the WAAS-corrected BT359C outperformed it's non-WAAS twin, and the solo iTrek was, unfortunately, not a contender.

North_BT359CaNoWAAS_BT359CbWAAS_iTrek_WAAS_20070122_01.zip
vettedude00 Posted - 13 janv. 2007 : 21:30:32
As a Sirf Evaluaion kit owner, I can download new versions of F/W for the eval kit. I don't know if this would run on any other receiver.
aaronprez Posted - 10 janv. 2007 : 23:38:15
[SNIP]
Did you get that firmware and do it yourself, or did you have to send it back to Taiwan or wherever it was manufactured?
vettedude00 Posted - 07 janv. 2007 : 23:10:11
I just loaded 3.2.4 firmware onto my SSIII eval unit and now have access to 3 WAAS sources here in California! With version 3.2.0 I could get an occasional glimpse of SV 122, but could never lock; now I can lock onto 135 and 138, both high in the sky (elevations > 40).

In addition, now 122 is now high in the sky and I can now lock it too sometimes !!! It seems to come and go (?)

135 Az = 205, El = 47, C/No = 38
138 Az = 162, El = 49, C/No = 37
122 Az = 219, El = 45, C/No = 30

When I allow Sirf Demo to scan, 138 is preferred.


So I conclude that the firmware is critical to enabling access to WAAS SV's
GTBecker Posted - 30 déc. 2006 : 19:39:11
Meaningful testing, specifically for my needs, is a pair of identical receivers at the ends of a 20m N-S line, 3m above sea level. I'll send an hour of those data from each of the BT-359C and iTrek-M5, with and without WAAS, after testing next week.

gpspassion Posted - 30 déc. 2006 : 19:22:38
Depends what you mean by "meaningful", but any side by side logging that looks like that http://www.gpspassion.com/fr/articles.asp?id=185&page=5 would be fine by me.
GTBecker Posted - 30 déc. 2006 : 18:37:28
quote:
If GTBecker can send me some his logs...


I assumed you meant after I do some meaningful testing. Do you want something before that?

gpspassion Posted - 30 déc. 2006 : 15:58:01
...hence the pain I went though to sort through the "noise" with some side by side testing -> http://www.gpspassion.com/fr/articles.asp?id=185 - EGNOS so far, but there's no reason to believe the results will be any different with WAAS. If GTBecker can send me some his logs I'll update the article, if not it will have to wait until next summer when I go across the "pond" ;-)
musky Posted - 29 déc. 2006 : 13:37:45
Thanks Tom. So what you are saying is that they really mean "Broken WAAS enabled by default" ! Anyway, I guess I need to go back to Semsons for my second firmware upgrade. It just kind of blows my mind that Semsons didn't recognize that the last firmware upgrade to 3.1 wasn't going to work either. I assume the company sells enough units to know what's going on. They could have just said, "Well, Sirf is having this trouble with WAAS and they still don't have it fixed in 3.1" , but whatever....

The reason I want WAAS is because I am map making and would like the potential additional precision. I have some Sirf-II units and they have WAAS support. I have done precision tests by taking fixes (Sirf II) at my computer here for a couple hundred thousand acquisitions over days, where I have sorted my fix data according to whether it was acquired with or without WAAS. With the Sirf II, WAAS doesn't help very much. With or without WAAS I get a fairly consistant 1 sigma radius of about 6 meters. (Rejecting fixes where HDOP is over 10)

The Sirf III units are much better at pulling in every satellite in the sky, and basically the 1 sigma radius is about 5 meters, which is not THAT great of an improvement, BUT, HDOP is lower, and there are very very few times when I have to reject fixes due to high HDOP.

I suspect that WAAS may not help much on Sirf III, but I really want to find this out for myself. There is so much "noise" on the internet on this subject. Some say it doesn't help, some say it does!
GTBecker Posted - 29 déc. 2006 : 04:26:53
quote:
the advertising stated clearly, "WAAS supported".



GlobalSat, too, clearly states "WAAS enabled default unit" and they sell them on that basis. Unfortunately, that is true - but what is enabled with v3.1.1 firmware is a process that does not work. v3.2.2 works, finding WAAS without difficulty.
musky Posted - 29 déc. 2006 : 00:00:28
One of the units I am talking about is a Trek S3 from Semsons. I already have had one firmware upgrade . I had ver. 3.0, and supposedly ver. 3.1 was going to be the magic for all my WAAS woes. Semsons was really nice about upgrading the unit to 3.1, so I have to give them credit. But, unfortunately, 3.1 didn't do the trick. My newest unit is a Holux GR-213, and that also doesn't do WAAS. Bear in mind that when I bought both these units the advertising stated clearly, "WAAS supported".
gpspassion Posted - 28 déc. 2006 : 22:24:56
Based on GTBecker's recent testing with the BT359 you need firmware v3.2.2.
musky Posted - 28 déc. 2006 : 22:22:40
I've also been trying unsuccessfully for some time now to get WAAS to work on my SirfIII. My conclusion:

SirfIII = NO WAAS Support

I've even resorted to buying another SirfIII GPS to see if that one works, but no.....

I wish this issue would resolve itself somehow. All the vendors are claiming WAAS support, but I hear all this talk on how it doesn't work, and I've come to that conclusion myself.
aaronprez Posted - 17 nov. 2006 : 18:00:21
I may be sending mine back also to get the 3.2 firmware. Below is a link to the entire email thread of dealing with Holux to see if a new firmware will help me.

http://www.boccebowl.com/holux.htm
GTBecker Posted - 14 nov. 2006 : 14:00:15
One of the BT-359Ws is on its way to GlobalSat. We'll see what I get back.
aaronprez Posted - 12 nov. 2006 : 00:15:38
Well I guess I give up trying to make the Sirfstar III work with WAAS. I don't think there is any reason that it shouldn't get a big enough consistent signal to see PRN 138 (at an elevation of about 39 degrees) using an external antenna. I also tested my identical Holux unit, and it behaves the same way. However, I am not going to give up complaining to Holux and Sirf to address the issue. They shouldn't advertise WAAS like they do if their implementation can't be expected to work. If I would have known it had no chance of working, there is no way I would have bought it in the first place. It is obvious that other chipsets have this working, but Sirf has failed. This is probably my last Sirf and/or Holux product, and I intend to give bad word of mouth of them whenever I can, unless they finally do provide a solution. I am going to put together a web page in the near future summarizing the entire issue so that others can also learn about this deceptive marketing practice, because I find it aggravating.
GTBecker Posted - 11 nov. 2006 : 03:41:48
Ah, the confusion. Surely the iTrek M5 has Nemerix inside, but you wouldn't know that from the companion CD:



The small poorly-screened text says "Powered by SiRF Star III".

My initial test of four receivers (two pairs of BT-359W and M5) suggests that the M5 isn't as nervous as the -359W, at least; and WAAS, at least here and now, helps. The M5s needed to be started outdoors but, once initialized, could still see four satellites indoors; still, SiRFStar-IIIs are clearly more sensitive.

The M5s selected PRN 138 for WAAS within maybe five minutes of first position. Oddly, PRN 138 appears as "129" in VisualGPS (verfied as 138 in $GPGSV), but as I write this PRN 120 EGNOS is popping up, as "120"; strange. In this stationary test, the M5 WAAS position is significantly more stable than the non-WAAS BT-359W, and each M5 remained within nicely a ~5' radius; the uncorrected -359W positions wandered faster and farther, perhaps to a ~15' radius.

I was not critical in this first test and did not plot, but my impression is that the WAAS'd M5s seem more tame - and accurate, at least when static. M5 speed is zero; -359W speed dithers nervously, like all of my SiRFStar-IIIs. The calculated baselines between the receivers' positions (actually 20 meters) was relatively accurate and constant for the M5s, and the vector they drew (actually 180 degrees) was within 10 degrees; I am pleased. The -359Ws can't do that.

One M5 receiver is on a window ledge right now, and is doing quite well, with WAAS. BTW, the WAAS source (PRN 138) appears to be as strong as the strongest GPS satellite. Though shown in different color in VisualGPS, if the scale is the same, there is no WAAS signal strength concern; it's hot.

More later as I learn it.
aaronprez Posted - 10 nov. 2006 : 20:33:01
I think that's a BS answer from them. I have access to another Holux 236 GPSlim just like mine that I am going to try tonight. I bet I get the same results. I don't think we both coincidentally have faulty units, I think there is a problem with the current WAAS implementation in Sirfstar III chipsets, at least with 3.1.1 firmware.

I got my Gilsson external antenna. While it did pick up slightly better signals for the rest of the ranging satellites than the other external antenna that I had, it hasn't really changed the reception of the WAAS ones.

Tom, I would be curious to hear your results with the i.Trek M5.
GTBecker Posted - 10 nov. 2006 : 20:23:56
Well, without any discussion beyond my problem description on their support site, USGlobalSat has "... determined that your product needs to be returned for further examination", and gave me an RMA number.

Simultaneously, the i.Trek M5s arrived at the door.
aaronprez Posted - 10 nov. 2006 : 18:08:08
Based on this image, which shows where PRN 122 (AOR-W) used to be before it moved, above Brazil, could be why the receiver is showing it there, which happens to be where PRN 121 Inmarsat 4F2 is currently located.



I think Sirf needs to release a firmware upgrade to it's customers such as Holux and Globalsat, who in turn need to release that firmware to their customers. It appears they need to update the factory almanac possibly, and maybe the power mask issue. I have read mentions of a 3.2 firmware being released to Sirf's customers, but it seems that Holux and Globalsat have stuck with 3.1.1. I wonder if 3.2 addresses any of these issues. I sent an email to Holux, and someone from Taiwan finally replied, a week and a half later, wanting a screenshot showing to show what version I was running exactly. I did that a couple of days ago, but based on the response time of the first one, it could be a while until I get a response from him.

Here is the email he sent me on 11/08/06:

"Dear Sir:

Would you tell us how do you identify the version you are using is Ver.3.1?

Would you please use attached program to see the version that you are using now?

It would be great if you can send us the screenshot.
So that we can help to provide instruction for the next step.
Thanks and Best Regards,

Anthony

www.holux.com.tw"


Here was my original email from 10/28/2006:

"I am using a Holux 236 GPSlim, and I've enabled WAAS. I occasionally see satellite #35, but the signal is not strong enough to get a lock on it. The two new WAAS satellites, #48 and #51 never show up, even though they should be much higher in the sky from my location in the Midwest United States. I've been reading that some people say the Holux needs to supply updated firmware to see the new WAAS satellites. My firmware is version 3.1, but I've read that there is a version 3.2 that might correct this WAAS issue."
GTBecker Posted - 10 nov. 2006 : 04:01:41
Well, I've had no success with either of our propositions. I have one more idea to try to see PRN 135. PRN 138 seemed to not be carrying any data this afternoon, BTW, while 135 was fine.

GTBecker Posted - 10 nov. 2006 : 01:55:55
The PowerMask value in the SiRFStar-II is the same, 28dBHz, but it looks like that parameter does not affect the WAAS data channel; no value changed the SBAS processing. Perhaps it would apply to ranging in the -III, though.

You're a step ahead of me if you get to see PRN 135 or 138 at all. I'm still working on it - and waiting for an answer from USGlobal.


Tom
aaronprez Posted - 09 nov. 2006 : 23:50:41
I forced PRN 138, and I was able to see it like I did PRN 135, where it disappears just as fast as it appears. Since this is the one that is highest in the sky to the United States, I don't think a Sirfstar III chipset will ever be able to use WAAS from northwest Indiana on the ground, unless that tracking power mask is able to be set lower or disabled. Maybe the Gilsson antenna that I am getting may help, but I doubt it will be enough to make that signal consistently receive a signal above 28 dBHz. At least today I proved to myself that a satellite can be tracked when it is in test mode using a Sirfstar III.

Here is the definition of the power mask:

"Power Mask
GPS satellites that have a low signal strength are not easily tracked by a GPS receiver
and may result in using signals that are either noisy or have been effected by multipath
or other interference source.
The power mask parameter allows a user to prevent the use of satellites with a low
signal strength being used in the position solution. This will result in a potentially
higher accuracy position. However, as the number of satellites available will be
decreased, the fix density will be decreased."


BTBecker (Tom), can you look in Sirfdemo for on your Sirfstar II receiver, and see what the tracking power mask is set to? Do you have any other conclusions?
aaronprez Posted - 09 nov. 2006 : 22:46:13
I think I have come to a conclusion on why WAAS isn't working on SirfstarIII.

I can't explain why it is misidentifying PRN 122. But what I did was force PRN 135 under "SBAS Control" using Sirfdemo, which made it stop attempting to track that "false PRN 122" satellite, and PRN 135 came up for a split second for me maybe about 3 times in 20 minutes (disappears too fast to get a screenshot), in an area that has a great view of the southwest, and using an external antenna. The reason that it is so hard for the receiver to track it is because the power mask for tracking is set to 28 dBHz, so it will only attempt to track that satellite if the signal for it gets above that, which apparently won't really happen here in northwest Indiana for more than a split second. I think if we were allowed to disable or change the tracking power mask to something lower, it would be able to be tracked. Whether or not we would be able to download the almanac and receive corrections from it would be the next question.

I am not impressed by this limitation of the Sirfstar III, and if I don't get an answer from Holux or maybe even attempt to contact Sirf, this will be my last Sirf product, and I am going to give them bad word of mouth. I think the only way you are going to be able to change the tracking power mask is by a firmware upgrade. I believe the tracking power mask is hard coded in. Evidence is as follows:

Here is from the Sirf Binary reference:



Notice how it says it defaults to 28 dBHz, and then lower down it says "not implemented." I have been able to send Sirf binary to my receiver using Sirfdemo (and be able to change the navigation power mask (which it does only allow to be between 20 and 50) but changing the value of the tracking power mask does not set in the receiver.

I would venture a guess the reason that they don't want the receiver using satellites with signals less than 28 dBHz because of multipath and may make the receiver less accurate. This is bad implementation, and they should have a separate power mask for the WAAS satellites or disable it for WAAS ones, since we just want to use them to get the correction data, and really don't care about ranging from them. But I am no expert, I just play one on TV.

If any experts have any analysis of my analysis, feel free to chime in. Later on I am going to try forcing PRN 138 and see if it will find it at all. I don't think it will, but what the heck. I have a Gilsson antenna being shipped to me, because the external antenna I am using is a cheapy. We'll see if that makes a difference too. I will report any other findings.
aaronprez Posted - 09 nov. 2006 : 20:33:52
According to this, PRN 135 (48) is now out of test mode and is operational since 2:00 CST this morning:

http://www.nstb.tc.faa.gov/incoming/New_WAAS_Geo_Status.pdf

New WAAS GEO Status as of 11/9/06
INTELSAT(PanAmSat), Galaxy-15, W133 deg, PRN -135 (48)
PRN-135 was taken out of "Test Mode" and placed in normal mode at 08:00 UTC
on 11/9.
PRN-135 will operate for about the first 6 to 9 months as a data link of correction
and integrity information only. That is, the UDRE will be set to "not monitored".
This will result in it being displayed with a "hollow bar" on some receiver displays.
The ranging control loop for PRN-135 will be running, but the WAAS ground system
will not provide UDREs smaller than Not Monitored until the FAA's verification of
the integrity analyses for the ranging function have been completed as part of the
PRN-138 testing. (Data link only operation allowed the PRN-135 deployment to be
accelerated to compensate for the loss of PRN-122 in the North East)
GTBecker Posted - 09 nov. 2006 : 14:21:02
I am assuming that SiRF (and all that use them) has not released a product that simply does not and cannot work; if they have, they've got a legal problem. But assuming that is not so, perhaps something has put these receivers in a WAAS mode that they cannot escape from.

Here's a guess:

When PRN 122 was moved to 142W, my understanding is that ranging was disabled; that is, the satellite is sending WAAS corrections but is not acting as an stationary GPS position reference.

SiRFStar-IIIs first see the satellite after a cold start but perhaps unnecessarily reject it as a WAAS source because is isn't ranging - but they still get the WAAS almanac from it. PRN 122's WAAS almanac does not yet list the two new WAAS birds, PRN 135 and PRN 138; they are both functioning and sending corrections, but are not yet officially operational - set to Do Not Use for airmen. So, SiRFStar-IIIs don't know about the new WAAS sources but don't look for them, either, since the PRN 122 almanac lacks them. That leaves the receiver with one apparently bad WAAS source that it won't use (but SiRFStar-IIs will).

My proposal is to cold start the receiver and prevent it from seeing PRN122 until it has discovered another WAAS source. I propose we try a cold start and place the receiver in a position that sees the new birds _but which blocks PRN 122 at 143W_. This isn't easy for me since all of them are southwest of me, but PRN 122 is low and the other two are high in the sky. I can use my metal garage door to block the low one, I think.

With the BT-359W, we must either connect Bluetooth to the receiver or power it via USB to make certain it does not auto-power-off before it finds either PRN 135 or PRN 138, and hope it doesn't see PRN 122 first. This might be accelerated by forcing the receiver to look for PRN 135 or PRN 138 after the cold start while blocking PRN 122.

Report later.
GTBecker Posted - 09 nov. 2006 : 03:04:08
quote:
Originally posted by GTBecker

... It also points to but can't see PRN 126 and PRN 134.



Those two satellites are on the other side of the planet from me, so their existence can only be known via an almanac that the BU-303 collected. Also, AOR-W moved from 53W to 142W earlier this year and kept the PRN 122 designation; its position at 53W was then taken by 4F2, a new satellite that appears to not carry PSAS. So, my guess is that the SiRFStar-III isn't getting the WAAS almanac and is showing old, apparently preloaded, position data for PRN 122.

I admit to being confused about just where PRN 122 was and have tended to try to provide a perfect view of a non-WAAS bird (at 53W) to the BT-359W, unproductively. In the morning I'll find a good view point for 142W, where PRN 122 really is, and try to get a WAAS almanac into it. Maybe then it will be able to find the others that are higher in the sky for me.


aaronprez Posted - 09 nov. 2006 : 01:20:48
quote:
Originally posted by GTBecker

The left window is the BU-303, and the right window is the BT-359W.
http://images.rightime.com/WAAS/SiRF2vs3.GIF

It looks like SiRFStar-IIIs are looking at PRN 121 and calling it PRN 122. The SiRFStar-II can't find a PRN 121.




Using the satellite tracker here http://www.lyngsat.com/tracker/inmar4f2.html
The azimith and elevation angles completely agree that it is the satellite based on when you click on our respective locations in Indiana and Florida. Now that we've identified that this the happening, we just need to figure out why. Since it's not even a WAAS satellite, the receiver tracking it is doing us no good.
aaronprez Posted - 09 nov. 2006 : 00:25:55
quote:
Originally posted by GTBecker

The left window is the BU-303, and the right window is the BT-359W.
http://images.rightime.com/WAAS/SiRF2vs3.GIF

It looks like SiRFStar-IIIs are looking at PRN 121 and calling it PRN 122. The SiRFStar-II can't find a PRN 121.




I agree. Here is my screenshot:

GTBecker Posted - 08 nov. 2006 : 23:54:26
The left window is the BU-303, and the right window is the BT-359W.
http://images.rightime.com/WAAS/SiRF2vs3.GIF

It looks like SiRFStar-IIIs are looking at PRN 121 and calling it PRN 122. The SiRFStar-II can't find a PRN 121.
aaronprez Posted - 08 nov. 2006 : 23:03:36
quote:
Originally posted by GTBecker
Oddly, the two receivers think that PRN 122 is a different satellite. The BT-359W points to 4F2 at 53W, while the BU-303 points to 3F4 at 142W. If the BU-303 eventually recognizes 4F2, it would have access to five PSAS sources from here.
I have a Holux 236 GPSlim (Sirfstar III) I have experienced exactly what you are talking about, where it sees PRN 122, but it shows it in the Southeast sky on all the satellite views of all my software, but I darn well know that it is in the Southwest over the Pacific Ocean. I am located in Northwest Indiana. Like you said, it is showing a #35 (PRN 122), but it is showing it being in the location of Inmarsat 4F2. I think something is screwy with Sirfstar III.
gpspassion Posted - 08 nov. 2006 : 22:55:10
What you've found seems to indicate that some internal "tables" in the firmwares are "problematic" and would explain the mixed results, you could try going to www.n2yo.com to see which one's right, based on the better SBAS handling in the SS2 GPS I think we have the answer.
GTBecker Posted - 08 nov. 2006 : 22:41:03
Please excuse the dupe post.

I just concluded a simultaneous comparison of the SBAS channel function of a new SiRFStarIII chipset in a GlobalSat BT-359W (said to be WAAS-enabled) and a SiRFStarII chipset in an older BU-303 (WAAS-capable but not enabled by default).

From southwest Florida, the new BT-359W recognizes a signal from geostationary PRN 122 (Inmarsat 4F2), but it does not decode the corrections despite an apparently excellent signal. That is the only SBAS signal that this receiver indicates.

Conversely, once enabled the BU-303 gets EGNOS corrections from PRN 120 (Inmarsat 4F2), and WAAS corrections from PRN 122 (3F4), PRN 135 (Galaxy 15) and PRN 138 (Anik F1R). It also points to but can't see PRN 126 and PRN 134.

Oddly, the two receivers think that PRN 122 is a different satellite. The BT-359W points to 4F2 at 53W, while the BU-303 points to 3F4 at 142W. If the BU-303 eventually recognizes 4F2, it would have access to five PSAS sources from here.

Still, of course, the -III outperforms the -II. Why, though, can the two receivers not see the same PSAS sources?
aaronprez Posted - 06 nov. 2006 : 21:58:41
quote:
Originally posted by daberti

quote:
Originally posted by frder
No, the EGNOS satellites are always the last satellite reported in the column/line (since in the GSV sentences they are always reported as the last satellite). The numbers are 33,37,39.
I dont't know what's the meaning of the number in the last line in AFTrack's satellite view that is slightly on the right.

francesco


Such a number is just on the right, last line. I guess it shows the WAAS/EGNOS satellite scanning status, and in fact it scans. But does not manage to get any of them.

Ciao



I think that number is the average signal strength of all satellites that the receiver is currently locked on to. That's why it gets higher when you go to open areas, even higher using an external antenna, and lower when you go inside, and really low when you put your hand over the receiver.
zpintar Posted - 22 sept. 2006 : 07:54:27
quote:
Originally posted by lperez

Hello.
I have a FS n560, which FW is GSW3.1.1HTC_3.1.00.07-C23P1.00a.
As I saw previously on the forum, with this fw version I should be able to use DGPS, but I can't.


Anybody knows how to set up SBAS?




I have same problem on my n560. Today I'll try to forcing PRN 126, this is only what I didn't try yet!
daberti Posted - 20 août 2006 : 22:38:24
quote:
Originally posted by frder

I don't think so. Because the number ranges below 33, and the first SBAS satellite number is 33, and also because in the NMEA sentences there is'nt any information of what the receiver is scanning. If an EGNOS satellite is tracked, even for a second, it appears in the first available line after the GPS satellites and on the satellite map, with azimuth, elevation and signal power data.

francesco



That's what I'm trying to say: there I read satellites above 32.....

EDIT August 22th: starting from yesterday and confirmed today: I got some stable EGNOS mode hooking on sat. 39
frder Posted - 20 août 2006 : 22:18:35
quote:
Originally posted by daberti

Such a number is just on the right, last line. I guess it shows the WAAS/EGNOS satellite scanning status, and in fact it scans. But does not manage to get any of them.

Ciao


I don't think so. Because the number ranges below 33, and the first SBAS satellite number is 33, and also because in the NMEA sentences there is'nt any information of what the receiver is scanning. If an EGNOS satellite is tracked, even for a second, it appears in the first available line after the GPS satellites and on the satellite map, with azimuth, elevation and signal power data.

francesco
daberti Posted - 20 août 2006 : 18:57:02
quote:
Originally posted by frder
No, the EGNOS satellites are always the last satellite reported in the column/line (since in the GSV sentences they are always reported as the last satellite). The numbers are 33,37,39.
I dont't know what's the meaning of the number in the last line in AFTrack's satellite view that is slightly on the right.

francesco


Such a number is just on the right, last line. I guess it shows the WAAS/EGNOS satellite scanning status, and in fact it scans. But does not manage to get any of them.

Ciao
frder Posted - 20 août 2006 : 11:45:07
quote:
Originally posted by daberti

Yes, I'm registered to this proggie. In Satellite view there is the last line with a number which is changing (slightly more on the right than the others). Is this the EGNOS sat. scanning?

Thanks


No, the EGNOS satellites are always the last satellite reported in the column/line (since in the GSV sentences they are always reported as the last satellite). The numbers are 33,37,39.
I dont't know what's the meaning of the number in the last line in AFTrack's satellite view that is slightly on the right.

francesco
daberti Posted - 20 août 2006 : 01:37:51
quote:
Originally posted by frder
AFTrack:
http://www.afischer-online.de/sos/AFTrack/index.html

MapviewGPS and SmartcomGPS show EGNOS satellites but not the DGPS fix.

francesco



Yes, I'm registered to this proggie. In Satellite view there is the last line with a number which is changing (slightly more on the right than the others). Is this the EGNOS sat. scanning?

Thanks
frder Posted - 20 août 2006 : 00:01:39
quote:
Originally posted by daberti
Huge thanks. Do you know of any Symbian proggie capable of showing EGNOS satellites besides the nromal ones and if the DGPS is applied or not?

Thanks again


AFTrack:
http://www.afischer-online.de/sos/AFTrack/index.html

MapviewGPS and SmartcomGPS show EGNOS satellites but not the DGPS fix.

francesco
Leif Posted - 19 août 2006 : 23:12:11
quote:
Originally posted by lperez
3.- under "SBAS", I try to get the info, but I get "Get SBAS parameter not accepted. A likely reason is that it is not supported on XTrac or GSW3 firmware".



It's only the 'Get' command that is not supported on GSW3.

If the 'Set' command is accepted by SirfTech without 'NAcknowledgment' message it is really accepted.

If you settle for setting 'Testing', also satellites working in 'Integrity' mode will be accepted.

Best Regards
Dennis Gröning
daberti Posted - 19 août 2006 : 21:53:07
quote:
Originally posted by frder

quote:
Originally posted by daberti
I've the same equipment of yours and I live in Lecco, but I cannnot lock any EGNOS satellite at all!
Could you please help me to tune the Royaltek so that I can bring it to work?

Thanks


The easyest and safest way:
download BTGPS x-mini laptop utility 1.4.9.41 from the Royaltek's site:
http://www.royaltek.com/index.php/component/option,com_weblinks/catid,46/Itemid,82/
Launch GPSDemo, connect to the receiver and select "Enable SBAS".
That's all.

francesco



Huge thanks. Do you know of any Symbian proggie capable of showing EGNOS satellites besides the nromal ones and if the DGPS is applied or not?

Thanks again
frder Posted - 19 août 2006 : 19:44:35
quote:
Originally posted by daberti
I've the same equipment of yours and I live in Lecco, but I cannnot lock any EGNOS satellite at all!
Could you please help me to tune the Royaltek so that I can bring it to work?

Thanks


The easyest and safest way:
download BTGPS x-mini laptop utility 1.4.9.41 from the Royaltek's site:
http://www.royaltek.com/index.php/component/option,com_weblinks/catid,46/Itemid,82/
Launch GPSDemo, connect to the receiver and select "Enable SBAS".
That's all.

francesco
daberti Posted - 19 août 2006 : 15:55:12
quote:
Originally posted by frder


The HDOP is related to the GPS satellites position, it does'nt change with SBAS corrections.
Anyway I think that we should wait the EGNOS gets the full operational capability and then we can test if it's useful or not.
While I'm writing my royaltek 2001 locks for some seconds to the satellite n.39 and then the signal disappears.

francesco




I've the same equipment of yours and I live in Lecco, but I cannnot lock any EGNOS satellite at all!
Could you please help me to tune the Royaltek so that I can bring it to work?

Thanks
lperez Posted - 17 août 2006 : 14:17:49
Hello.
I have a FS n560, which FW is GSW3.1.1HTC_3.1.00.07-C23P1.00a.
As I saw previously on the forum, with this fw version I should be able to use DGPS, but I can't.
I use SirfTech 1.18 to activate DGPS:
1.- under "DGPS Source", I select SBAS
2.- under "DGPS Mode", I select Auto & 18s
3.- under "SBAS", I try to select Auto, Integrity & Default, & once I click the set button, I try to get the info, but I get "Get SBAS parameter not accepted. A likely reason is that it is not supported on XTrac or GSW3 firmware".

Anybody knows how to set up SBAS?
frder Posted - 13 août 2006 : 17:35:58
I have read a lot in the forum, and I have'nt seen the link before.
Anyway, repetita iuvant :-)
I just wanted to give a link where to check the EGNOS availability, since as you could have seen there have been many planned and unplanned SIS outages in the last days, and people could waste their time trying to use or test EGNOS when actually the EGNOS satellites are not transmitting.

francesco
gpspassion Posted - 13 août 2006 : 11:20:57
I think we've given that link before, anything new there ? Warnings maybe ?
frder Posted - 10 août 2006 : 10:39:35
For those who want to play with EGNOS, have a look at this site before playing:
http://asqf-gnss.com/mambo/index.php

francesco
frder Posted - 10 août 2006 : 00:16:18
@pgmunzi

non ho ancora capito come fare per vedere i file che hai linkato, che programma occorre usare?

translation:
I did'nt understand how to read the files in the above links, which program should I use?

francesco
mike99 Posted - 09 août 2006 : 17:50:08
quote:
Originally posted by gpspassion

I got a lock with the Holux GR240 running FW3.2 on PRN39 last week so it's likely back up. Maybe you need a firmware upgrade to be able to use the way EGNOS works now although you'd thing that this is a standard...
My machine and similar ones are still not picking up EGNOS here in central England although the same type of machine does seem to be working with EGNOS in other parts of europe. Might be useful to hear if other people can get EGNOS in their area now that the system has changed.
pgmunzi Posted - 09 août 2006 : 13:33:57
try to use with sirfdemo. they show that the BT338 is capable to lock EGNOS satellites and use DGPS, and then you can try to lock this satellite for an updated "Side by Side Testing" article.

This files are for all people that said: BT338 after july is not capaple to lock EGNOS signal.
gpspassion Posted - 09 août 2006 : 13:06:03
I got a lock with the Holux GR240 running FW3.2 on PRN39 last week so it's likely back up. Maybe you need a firmware upgrade to be able to use the way EGNOS works now although you'd thing that this is a standard...

@pgmunzi - thanks will look up the files, but I'm not sure I can do much with .srf files, binary ?
mike99 Posted - 09 août 2006 : 12:16:20
Earlier in the thread someone said that EGNOS was unavailable, has anyone found it again yet?
I tried yesterday with a leica gps and it could not find any of the EGNOS satellites whereas a garmin60cx gave an accuracy of 4m with egnos enabled which i assume means it was somehow finding and using the system. The Leica machine worked perfectly well with EGNOS earlier in the year before the EGNOS system was changed.
pgmunzi Posted - 08 août 2006 : 16:54:39
The system permit to upload only images, then
download this files and change the extension to ".srf"

http://www.gpspassion.com/upload/060807191506.gif
http://www.gpspassion.com/upload/060807192114.gif

To lock PRN126 i have used the sirftech and force to use this satellite and SBAS Mode =Integrity.
Use the last version and remember to ser the message ID 29 to view the satellite correction.

The sky must be clear, only with a signal level > 30 the BT338 is able to use DGPS.
gpspassion Posted - 08 août 2006 : 11:49:06
You can use this method -> http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=14251
pgmunzi Posted - 08 août 2006 : 09:50:43
hello, i'm returned, and I have carried the files of log with the use of the DGPS 126 with BT338. How I make to upload?
frder Posted - 01 août 2006 : 17:40:19
" Still nervous ? ;-)

May/June/July 2006 SBAS Poll Results:
Useful and use it : 48% - Useful but don't use it : 18% - Not useful don't use it : 34%"

Yes, still nervous. I'll let you know when I will be more calm. Maybe in the next 1 or 2 years :-).

francesco
igalan Posted - 01 août 2006 : 10:35:20
I've verified that the i.Trek M5 (Nemerix) does use corrections, this weekend it has been picking PRN 124 and VisualGPSCe showed "Differential GPS"; I even logged some traces. But I don't find it useful, I've yet to see improvements in accuracy.

___
Qtek 9100, F-S Loox 720, GlobalSat BT338, i.Trek M5, TomTom Navigator 5
gpspassion Posted - 01 août 2006 : 02:09:04
Too late but I can reopen it after the current one. What you have voted ? "useful" ? You have to tell us why then ;-)

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bviator Posted - 01 août 2006 : 02:05:41
I guess I'll have to call some friends to vote.

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________________________
gpspassion Posted - 01 août 2006 : 01:25:55
Still nervous ? ;-)

May/June/July 2006 SBAS Poll Results:
Useful and use it : 48% - Useful but don't use it : 18% - Not useful don't use it : 34%

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frder Posted - 22 juil. 2006 : 13:02:41
"Ok, that's the original link, but other than the interruptions, I can't see any indication that it isn't the "real deal" though."

For what is concerning differential corrections yes, when it works it's "real deal".
But during the last hour my etrex vista did'nt get any correction data and my royaltek was locking and unlocking continually on the PRN126.
I get nervous :-) when a system sometimes works and sometimes does'nt.

francesco
bviator Posted - 22 juil. 2006 : 04:02:27
Yep,

PRN 122, Satellite #35
gpspassion Posted - 22 juil. 2006 : 03:05:57
Sure, let us know how it's doing with SBAS in the US, PRN122 is it ?

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bviator Posted - 22 juil. 2006 : 02:54:43
It could be you all are having the same issues I had in the US with WAAS and SirfIII. Maybe or maybe not, but I have given up on was and PRN 122. See my plethora of postings regarding my struggles. There is just something not right with SBAS and SirfIII.

Love my I-Trek M5 with Nemerix. Dead lock every time, little wandering, and WAAS is consistent and reliable. Thanks GPSPassion for leaning me towards Nemerix!
gpspassion Posted - 22 juil. 2006 : 02:22:37
Ok, that's the original link, but other than the interruptions, I can't see any indication that it isn't the "real deal" though.

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frder Posted - 22 juil. 2006 : 02:20:23
" Well it's supposed to be fully operational since June, have you seed any indication that it might still not be ?"

It's supposed to start "Initial Operations" in June/July with PRN120 and PRN126 satellites as reported here:
http://esamultimedia.esa.int/docs/egnos/estb/egnos_pro.htm
As a matter of fact yesterday I have noticed interruptions in EGNOS signal broadcast (as reported in the link above).

francesco
gpspassion Posted - 22 juil. 2006 : 00:06:35
Well it's supposed to be fully operational since June, have you seed any indication that it might still not be ?

Generally spearking I wouldn't pay too much attention to HDOP, see if you can track the data on a chart like I did in the article to see how stable the position is.

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frder Posted - 21 juil. 2006 : 16:56:03
"The result is strange: into te program and reading the nmea log the receiver use a DGPS with the satellite PRN126, the estimated error in meter is better with DGPS (0,65mt instead 1,8mt) but:
1)the HDOP is fixed to 0,8 with 8 satellites with or without correction"

The HDOP is related to the GPS satellites position, it does'nt change with SBAS corrections.
Anyway I think that we should wait the EGNOS gets the full operational capability and then we can test if it's useful or not.
While I'm writing my royaltek 2001 locks for some seconds to the satellite n.39 and then the signal disappears.

francesco
pgmunzi Posted - 21 juil. 2006 : 11:53:43
Ok another day, another test, another fix

The result is strange: into te program and reading the nmea log the receiver use a DGPS with the satellite PRN126, the estimated error in meter is better with DGPS (0,65mt instead 1,8mt) but:
1)the HDOP is fixed to 0,8 with 8 satellites with or without correction
2)the receiver doesnt apply any correction.

I have recorded the log but i have stopped it before the correction

PS
With SBAS set to auto the receiver do not lock the satellite 126
gpspassion Posted - 20 juil. 2006 : 21:53:16
Thanks for clarifying, I'll try again then,I had forced 126 with SiRFdemo the other day, they may have changed a few things since. I'm surprised they were able to provide a specific answer ! The Garmin receivers with the old Garmin chipset don't have a problem locking on two SBAS satellites, only the SiRFstarIII Garmin's have that limitation.

You can use MagicSS for screenshots.
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pgmunzi Posted - 20 juil. 2006 : 17:03:09
i live in italy near Rome

i have used sirftech and forced to use PRN126 and the integrity signal (not testing).
I will made more test this afternoon.
Ii you can suggest to me a program to make screenshots from my pocketpc i can send to you an image with all information.

I asked also to EGNOS TEAM why i have problem with my BT338, this is the e-mail:

Dear Madam/Sir,

Thank you very much for contacting us. Your question has been recorded as Call nr. xxxxx.

EGNOS system is not fully operational yet and is going through a transitional period in which the transmission of EGNOS on certain satellites is being changed. In particular, PRN120 and 126 have started broadcasting EGNOS SIS with MT02.
Garmin receivers will receive and use PRN126 as it has been tested before by ESA, but there is no way of forcing Garmin receivers to use this GEO nor 124 or 120. BT338 seems to be the same. As a result it may be that the receiver is trying to use a satellite temporarily not transmitting messages.

This situation is temporary and by the end of the month things should have settled down as the system fine tuning comes to and end and a solid EGNOS signal should be transmitted.
gpspassion Posted - 20 juil. 2006 : 15:22:32
Interesting, but tell us more, which location ? Did you you force any specific settings with SiRFdemo ?

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pgmunzi Posted - 20 juil. 2006 : 12:23:47
Yesterday 19/07/2006 i'm able to use SBAS with my Globalsat BT338 with the PRN126 (39)
HDOP 0,8 with 6 satellites
HDOP 0,6 with 8 satellites
gpspassion Posted - 11 juil. 2006 : 01:23:29
Not that I know of, no. I have started a new thread here for proprietary commands http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=60637

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Waylo Posted - 11 juil. 2006 : 00:08:55
I apologize if this may be slightly OT, but back to the Nemerix commands, is there a way to find out what version firmware one has on a Nemerix unit?
gpspassion Posted - 06 juil. 2006 : 15:45:57
33 is the Garmin number, that would be PRN120, the only I've been able to pick up with a SiRFstarIII receiver. The "production" one is PRN126/#39. Yes the Haicom's are often difficult to switch around. Why don't you activate SBAS on your 338 ?

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igalan Posted - 06 juil. 2006 : 11:48:28
I've been able to get corrections with my Haicom 303III, but I don't remember which satellite was the source; if memory serves, in VisualGPSCe it was 33, is this possible? On a side by side comparison with the BT338 and 303III, the BT338 gets about 10% more signal and usually 1 satellite more. I've disabled SBAS/WAAS because it seems that either this Haicom is less sensible than my GlobalSat BT338, or DGPS causes this degraded performance.

Today I will enable again SBAS/WAAS and see if it can pick up EGNOS corrections, just for the hell of it . BTW I'm having problems trying to set the Haicom into SiRF mode and back in NMEA to do all those tests.

___
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gpspassion Posted - 06 juil. 2006 : 01:09:02
Article has been updated for the official launche of EGNOS and the use of PRN126 for the full range of corrections - http://www.gpspassion.com/fr/articles.asp?id=185&page=6 - Still no measurable impact unfortuately.

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gpspassion Posted - 04 juil. 2006 : 16:16:09
Sounds good, this is rather OT here, but do you a list of commands that work for NemeriX chipsets, say cold/warm/hot resets ? If you do feel free to start a new thread ;-)

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Leif Posted - 04 juil. 2006 : 16:01:18
You don't have to. SirfTech and SiRFDemo calculates it for you. Just enter the NMEA data that should go between the $ and * and the $, * and checksum is added before transmission.
bitslizer Posted - 25 juin 2006 : 19:40:32
so how to go about calculating the checksum? i assume the *xx is the checksum?
Leif Posted - 24 juin 2006 : 13:15:56
quote:
What software does one use to disable SBAS on a Nemerix chipset?

From NS1030 GPS Software, Datasheet, NS1030-GPS-SW-ds15 – Rev. 1.5 – November 2005.

$PNMRX114,0,0*xx : disable SBAS functions
$PNMRX114,1,1*xx : enable SBAS functions with normal handling of type 0 messages
(to be used on WAAS satellites, for example).
$PNMRX114,1,0*xx : enable SBAS functions and ignore type 0 messages
(to be used on EGNOS satellites, for example).

So any software that can transmit a user defined NMEA message and add a calculated checksum. SiRFDemo, menu Action, Transmit Serial Message. SirfTech, NMEA, Set.

gpspassion Posted - 24 juin 2006 : 03:23:52
Thanks for keeping us posted. No software I'm aware of to turn SBAS on/off on a Nemerix bsaed receiver.

Good to hear you're getting some good accuray results. Not sure how they do it, but there must be some astute filtering going on to have so little wandering, nothing like SN though that just freezes the position completely. Navigation accuracy on foot is good too, so again no SN.

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bviator Posted - 24 juin 2006 : 03:11:30
By the way,

The GPSPassion testing article indicated that the Nemerix chipset was actually somewhat more accurate without SBAS enabled. What software does one use to disable SBAS on a Nemerix chipset?

________________________
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Holux GM-270
Ipaq 2200 Series
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bviator Posted - 24 juin 2006 : 03:09:10
Received my M5 a week ago and love it. First, it got WAAS correction right away. Still no WAAS from my two SirfIII units. My SirfII Globalsat unit is getting WAAS everytime. I have about given up on my Haicom 303III and BT-338. I have done every possible tweak with GPSTweak, SirfDemo, MMSirf, etc.

Back to M5, comparing it to my arc view maps underlayed on the location marker of the gps location, I find it is dead on. As GPSPassion saw in the testing, much less jumping around and wandering of the calculated location. But is this a "true" phenomena or some sort of "static navigation" processing?

The shape file fields boundries I am using as an underlay of my gps postion was measured using a sub-meter gps. It seems darned close. I am looking forward to the fall when I will have time to some testing. I just wish I could get WAAS to work on those SirfIII units for the testing.

________________________
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Globalsat BC-307 (SirfII)
I-Trek M5 (Nemerix)
Holux GM-270
Ipaq 2200 Series
________________________
gpspassion Posted - 14 juin 2006 : 10:07:23
Are you already noticing some increased accuracy with the M5 ? I Used SA Watch see 5 here http://www.gpspassion.com/fr/articles.asp?id=185

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bviator Posted - 14 juin 2006 : 03:42:32
What software (especially inexpensive)can be used to calculate average deviation from a fixed point? I am not too concerned about logging over a period of time nor getting an accurate reference point. But how was GPSPassion able to calculate the average deviation from the fixed point?

I am excited about doing a little more accuracy testing in the field of precision agriculture, and especially encouraged about GPSPassions intitial results on the Nemerix chipset. Great job!

________________________
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________________________
gpspassion Posted - 10 juin 2006 : 23:25:40
Oh that sounds like it would do the job fine, if you have an accurate geodetical marker in your area you can make sure it is working properly but I suppose it has some kind of error checking built-in ;-)

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bviator Posted - 10 juin 2006 : 03:42:53
I will have an i-trek M5 with Nemerix chipset by next week. I also own a SirfII and and a SirfIII gps unit. I would like to do some testing for accuracy, especially repeatability of accuracy on different days with different satellite orientations. I would also like to see what WAAS is doing over here in the U.S. as far as improving accuracy. Of course, I stil have not been able to get WAAS on my Sirf III unit, so that may be a limitation.

Question: I have access to an RTK system, a very high end system (costs over 24,000 US dollars) used in precision agriculture that has accuracy of less than one inch. It utilizes a base station to generate localized correction signals to the mobile unit mounted on farm equipment.
I imagine I could use this equipment to get a somewhat "true" reference point to compare accuracy to the consumer gps units. Would I still need Delorme's GPSPostPro or is there some free software I could use. I do have some aricultural software on my IPAQ that can log points every few seconds over a given amount of time, and can export these points into standard arc shape files. Any suggestions on how best to do this in order to measure accuracy in comparison to the reference point?
bviator Posted - 07 juin 2006 : 20:13:13
Interesting quote from the article:



"Please be aware that although some of the marketed GPS receivers can process the MSAS test signals, test signals are NOT necessarily valid as GPS augmentation information for some of the marketed GPS receivers."

gpspassion Posted - 07 juin 2006 : 15:35:15
Interesting link about MSAS http://www.kasc.go.jp/MSAS/index_e.html

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gpspassion Posted - 05 juin 2006 : 22:58:01
In case you missed it, it is now available - http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=57401 ;-)

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gpspassion Posted - 28 mai 2006 : 01:23:22
Correct the SBAS enable M5 I used will be available for purchase in June it seems. The current iBlue is the one I used as the other part of the "Nemerix pair" for non-SBAS, but it's 3.2.7, not 3.8 ? Is there a mention of 3.8 somewhere, if yes that would be a typo I need to fix ;-)

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bviator Posted - 28 mai 2006 : 01:14:46
So, the unit you tested is not for sale yet to the general public?

If that is the case, how do you think the current i-blue with Nemerix chipset and version 3.8 will compare as far as accuracy?
gpspassion Posted - 28 mai 2006 : 00:22:30
You'll have to wait for their branded version, the M5 (black/gray finish), I checked with them last week and it seems like it should be available in June.

Thanks for the kind words, yes I think that these three pairs of receivers were a good way of getting some facts. Let us know how your testing goes, would be happy to include your findings in an updated article.

As a side note and following up on a comment in the other thread, I was surprised to find more "wandering" with the SiRFII receivers as I thought the SiRFIII receivers would have more of that due to the higher sensitivity, not so.

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bviator Posted - 27 mai 2006 : 22:18:55
Great!

I just received a replacement SIRFIII Haicom 303III unit. In clear view of the sky, I got WAAS correction for four seconds, then gone. In two weeks, I have had not received WAAS correction, even after factory resetting, etc.

By SirfII BC-307 is getting it consistently.

Question about the excellent testing in your article:

After reading it, and I am more interested in accuracy than am sensitivity, I am really looking at getting the i-blue from Semsons with the Nemerix chipset. However, I have read some specs on the unit at Semsons, and it does not indicate that it is WAAS/SBAS capable. It seems from your testing, you could get SBAS on the nemerix chipset, although it seemed to degrade performance of the Nemerix chipset. Other websites indicate the i-blue is not WAAS capable.

Can you clarify?

And, btw, excellent article and testing procedures. I may try the same over here if I could ever get WAAS to work on my SIRFIII unit.
gpspassion Posted - 27 mai 2006 : 22:10:20
Yes, the power of marketing, eh ;-) BTW, I've saved your updates on your SBAS problems, will read them tonight.

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bviator Posted - 27 mai 2006 : 22:06:34
In looking at the SBAS poll results, as of today, those who use and find SBAS useful are well in the lead. Hmmmmm...
gpspassion Posted - 25 mai 2006 : 00:30:14
Thanks for the kind words. It seems to me that the Nemerix firmware doesn't make a lot of difference since it was upgraded to v3.1 last year, v3.2, v3.2.7 and you saw what v4 does in the narrow streets of Paris, quite amazing really. Not sure what performance would be under a hardwood forest canopy, but the conditions can't be worse than bounced urban signals. I'm not sure how they do it, I understand Nemerix's "forte" is the RF chip so maybe getting an extra clean signal upfront helps them achieve that.

Your experience with dynamic post-processing is interesting, haven't had a chance to try it myself as I was concerned I wouldn't really be able to measure the difference before/after as the raw data probably isn't readable with other software than GPSPostPro. It's

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jrdwyer Posted - 25 mai 2006 : 00:18:41
Thanks for doing the side-by-side comparison. It was very insightful and I believe I learned a few things.

I mostly use GPS (Blue Logger) off-road with topo (raster) maps that don't snap position, so I am very interested in the iBlue v3.2.7 as it appears to do the best for overall accuracy and precision.

I like the Blue Logger for its ability to post-process static positions with relatively good accuracy at a low cost. It's dynamic post-processed accuracy is quite poor, based on my experience.

I often verify property corners using a tri-pod and the Blue-Logger with PostPro 2.0 and mapping software. I typically get horizontal RMS values of 80-300 cm (95% CI) with the higher numbers coming under a hardwood forest canopy. I usually log 30-45 minutes per point.

Do you think the iBlue firmware version makes any difference on accuracy or precision?
gpspassion Posted - 10 mai 2006 : 01:44:48
Hope you took part in the new SBSA poll : http://www.gpspassion.com/fr/polls.asp ;-)

Article has been updated http://www.gpspassion.com/fr/articles.asp?id=185 with a part about post-processing for improved accuracy.



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btlen Posted - 08 mai 2006 : 08:50:51
I'm also in Melbourne, Australia and have a SiRF StarII based Holux GR-230 Bluetooth GPS. This isn't a very sensitive unit, but with an external antenna it gets SBAS PRN134 at Azimuth 46degrees, Altitude 34degrees. (Is this the WAAS INMARSAT Pacific Ocean Satellite?)

With the improved sensitivity of SS3 you shouldn't need an extenal antenna - but the forum suggests that there are other issues for SS3 users.

It seems I'm not the ony one unenthusiastic about SBAS though. If we ran a poll about SBAS, I'm not sure if I'd respond:
1) "Yes, I can get a SBAS signal, but I just ignore it."
or 2) "SBAS? ... Yawn"
monobeg Posted - 02 mai 2006 : 19:54:00
I've been doing a lot of reading into SBAS in Australia to help choose a bluetooth GPS for my PPC. It looks like Japan is working on setting something up in the region, but its unlikely to be any good in my area (Melbourne - in the South (ie: further from the equator)).

2 questions I was hoping people could help me with:

- Will having WAAS/MSAS/SBAS turned on in Australia cause me any problems (longer fix times, decreased accuracy etc). It seems people are turning it off even in the USA for these reasons, so I think it might. (I think you have to turn it off every time you turn on the unit, which sounds really annoying.) Any comments? Do you think its something to avoid in a GPS, especially in Australia?

- Does anyone know enough about the Australia SBAS situation to make any additional comments there? (The best info I've found is www.casa.gov.au/fsa/2005/aug/54-55.pdf)

Thanks for any help!!!
gpspassion Posted - 27 avr. 2006 : 10:07:06
Thanks for the kind words. Actually I got PRN120 to work again the next day and ran 6 receivers simultaneously SS2, SS3 and NX. SS3 did show some improvements with SBAS but was still more inaccurate than NX without SBAS, will have it up next week hopefulle ;-)

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dcrochet Posted - 27 avr. 2006 : 06:09:21
Wow, I just want to thank you gpspassion for this testing and report. A report like this contributes to our ability to discern the theoretical from what we can expect in our real world experience. I'll be interested to hear more about the SS3 quirks and SBAS reception reliability if you pursue that angle in any future testing/experience.


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gpspassion Posted - 23 avr. 2006 : 00:19:50
The trick of course if knowing you're off by 2/3 meters, depends on the map accuracy and whether your position is being "snapped to the road" or not. The plan here was to start form a post-processed position to get have something to compare the measurements to.

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Mercenary Posted - 22 avr. 2006 : 23:01:07
on or off ive never noticed my position being off by more than 2-3 meters. I use mine for walking a bit (can never park next to the building in London) and thats the only time you will notice accuracy issues but even then it puts me in the right place, just gets confused with my direction.

Dont think i mentioned but SBAS is now off and will remain off. Faster and more reliable fixes with my RBT-1000. Seems to be when it cant get a deffinate SBAS lock it starts running slow.



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gpspassion Posted - 22 avr. 2006 : 21:40:51
All fair points, the problem is that people read the specs showing 10 meters for standard GPS and 2 meters for SBAS and naturally will want it and are not happy if you tell them they don't need it ;-) That's why I've started this article to hopefully figure out what the bottom line is so we can stop worrying about SBAS.
Still no joy with SS3, but I've got some new data with SS2 to post, even worse impact than with the Nemerix chip.

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Mercenary Posted - 22 avr. 2006 : 21:29:06
I turned SBAS on for my Royaltek RBT-1000 and i must say, its bad.

Fixes took about 1 minutes longer before it was even usable for navigating then it would loose a lock in london a lot more than with it off.

Accuracy... couldnt tell the difference, no better, no worse and considering nav snaps to road anyway there was no problems. going around roundabouts with SBAS on or off it would alwyas say "Exit... here" bang on que.

Needed?? I would say no. Turn it on?? No, makes things slower if anything.

I think its not something for the home user, just those with all the other hardware to really make use of it and as the article above says, if SA was still on then yes, it would be of use but as its not whats the point.




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