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Russel
Australia
49 Posts |
 Posted - 13 mai 2006 : 18:41:32
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I bought a bluetooth gps reciever - the Arkon BT339. I chose it mostly because it was the cheapest I could find  And also, partly thanks to the review on this site of the Sirf III chipset. Anyhow, I was very pleased to find that this unit lets me get Sirf III MID 28 psuedorange data.
Ok, that was fun. But now I'd love to know which other receiver's will let you obtain raw pseudorange data this easily? I am aware also of the somewhat hacky means of getting this sort of data from (some) Garmin units.
I've been googling for a week over this issue. There are so many products out there. Lots of bluetooth units. Lots with Sirf III chipsets. But is there a definitive list of those I can get raw data from?
And do the usb connected units dump the sirf binary data, or keep it?
And what about all those 'self contained portable' units out there with screens and maps. You know hiking units, car units. Are any units from this category useful for getting raw data (and I don't mean NMEA) ?
And as an ancillary question, how hard is it to find the Sirf chipset based units with older firmware (without the Carrier Phase data switched off)?
my brain hurts... my brain hurts..
(with apologies to those who never heard of Monty Python) |
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gpspassion
93402 Posts |
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Russel
Australia
49 Posts |
Posted - 14 mai 2006 : 09:31:57
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So far as I can tell, the Delorme comes bundled with their software? Or did I read their site wrongly? I think what they've done is cool as far as it goes. Am I wrong in thinking that they are using a SirfStar II and relying on its carrier phase data. Part of my interest is in figuring the tradeoff between having the carrier phase data and extra time spent making the observation.
Still looking to compile a proper list. Found a few Sirf II units out there but that raises the question, is Sirf continuing to make them for the likes of Delorme or are they 'end of life' ing them? Hmm
Ok.. here's some urls off topic
http://www.ibras.dk/montypython/finalripoff.htm
http://www.wickedcoolstuff.com/mopymybrhut.html
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gpspassion
93402 Posts |
Posted - 14 mai 2006 : 19:02:45
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Yes, clearly it's their own software, but they're logging raw SiRF data I believe. That's the thing, I'm not sure whether ANY SiRFstarII GPS can log raw data, maybe it's as simple as switching it to SiRF mode and logging.
PS - So that was the "Cherry Orchard" don't remember that one. I love this one ;-)
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Discounts and Assistance/Réductions et Assistance (Club GpsPasSion) / Où commencer? |
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Russel
Australia
49 Posts |
Posted - 15 mai 2006 : 04:37:01
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My gut feeling is pretty much any Sirf II/III chipset device in a box with a serial port (usb or bluetooth) should by default be able to go into Sirf binary mode. (Unless someone has broken this feature.) I'm going to see if I can find a Sirf II blueooth unit to test this. If you have one lurking around, let me know what it does for you?
---
You were lucky. We had to used FORTRAN.
Luxury! We used to have to enter octal addresses on a PDP front panel.
And you try and tell the young people today that.. and they won't believe ya! |
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btlen
27 Posts |
Posted - 15 mai 2006 : 09:38:50
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I haven't used the software, but these people sell utilities to convert raw GPS data into RINEX format for a number of different chipsets/protocols. The table they provide may help you decide what chipsets are suitable:
http://www.helenav.nl/rinex.htm
Octapc in Western Australia (www.octapc.com.au) still advertise some SiRF II units for sale. Prices look a bit high ...
My Holux GR-230 (SiRF II) fills in carrier phase data in MID28. The helenav link says that (all?) SiRF II units provide "Integrated Carrier" into the observation file. |
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Russel
Australia
49 Posts |
Posted - 15 mai 2006 : 13:06:31
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Thanks for the tips btlen. The table has some useful info. What I'm trying to do is to understand the physics/timing of the receiver(s). And just as I have issues with potentially lost information in the raw data stream, so is there a potential lost information issue in the raw data to RINEX converter programs. Since the TECQ people are commercial, it's not easy to talk to them about algorithms, so I can only guess at the assumptions they are making about the internals of the recievers themselves.
I'm most familiar with the Sirf binary protocol. I've looked over the TSIP protocol and again, on the surface it appears to be well documented but when you dig deep, it doesn't seem to say much about how the numbers were derived.
To give you a feeling for this issue, the GPS Software Time variable in the Sirf binary MID 28 is (gut feeling and screenfuls of numbers) fairly 'processed'. Which means it contains not only corrections for the receiver's crystal but accidental contributions from the sattelite's clock. Now, what information gets lost when a converter program tries to create a RINEX file with uniform epoch spacings.
But back to the original topic. It simplifies things to consider only the chipsets used on garden variety receivers (forget anything over $1000 or with a 'survey' sticker on it - I'm not rich either :) ). So which chipsets does that leave?
Ok.. The U-Blox people seem pretty keen to have a wide market. Who is putting them into 'serial-output' type boxes?
The Canadian Marconi Corporation seems to be mostly interested in fully-integrated products.
Garmins own products have sometimes accidentally been useful. But, who uses the Garmin OEM products in anything but 'serious gear'.
Didn't Connexants GPS get eaten by Sirf?
The Oncore receiver - now this looks promising. It mentions motorola binary protocol. Now, they claim to be targeting it at high volume markets. Has someone seen one in the wild? Was it a 'smart phone' or a standalone unit.. or?
Fastrax. Now is there an issue with some of their boards doing binary and some not? I haven't seen a Fastrax based gizmo in the wild yet.
Geotracer.. all I can say is what is the price tag on these things?
And the others on that list... Zeiss.. Trimble.. etc. Seem to be deep-pocket items. Someone correct me if I've stuffed up.
As for the Holux. Im considering the GlobalSat BT-318 from the same site. Mostly because of it's claimed range and the fact that I'd like to set it up as my base receiver. (My BT339 hardly goes 10m in open air). The BT-318 says it uses a Sirf II/LP and I'm going to take the punt that it uses a 2.x version of the firmware. Now all I gotta do is shop around.. yay! |
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gpspassion
93402 Posts |
Posted - 15 mai 2006 : 15:55:13
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A few things.
The BT-318 was the short-lived successor to the BT-308, bigger battery and GPRS cradle, if memory serves, BT range was about 10 meters too, if you want range ge the Emtac, 80 meters if memory serves, check out the olf Bluetooth Comparison article on the site, #54 if memory serves.
I just received a Fastrax unit for testing purposes, Wintec BT-100, I think Fastrax might somehow be related to uNav, but don't quote me on that ;-)
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Discounts and Assistance/Réductions et Assistance (Club GpsPasSion) / Où commencer? |
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Russel
Australia
49 Posts |
Posted - 15 mai 2006 : 17:44:06
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I'm going by this page, among others. All claiming long range. Presumably bluetooth Class 1: http://www.ow.com.au/shop/product_info.php/products_id/1147 .
I went looking for emtac crux II and can't seem to find much of it in oz. It also claims to have a bluetooth Class 2 radio. Nominally 10m or so.
Hopefully the BT-318 will serve as a base station. Which is to say it'll get left in the field outside while my PC logs it inside. |
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Russel
Australia
49 Posts |
Posted - 15 mai 2006 : 18:07:46
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Just a few more notes on chipsets...
If only hardware makers believed in thorough documentation and open standards :/
I found info on the motorola binary protocol hard to track down down. The nearest I seem to have gotten is this: http://www.axman.com/support/CMD-2003%20GPS/GPSBIT.PDF .
If you read carefully, there are binary messages, but none that include pseudorange data, which is really interesting because the TECQ people claim to be able to make use of the Motorola Encore VP. Perhaps the VP is special? Or perhaps Motorola regard pseudorange data as 'test' data. Hmm..
From the nemerix site it's very hard to get much of an idea of whether they are more interested in selling blank chips or if they provide chips with firmware. If there is a 'nemerix protocol' out there, I've not caught a whiff of it :)
uBlox seem to be in the same boat. Some firmware might do it. Well, some obviously does, but I get the feeling they too want to promote individualistic firmware.
And finally, sony, who seem to be quite inscrutible :)
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andymarr
3 Posts |
Posted - 13 juin 2006 : 16:35:32
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| This website seems to give the sort of list you're looking for; it's about 4 years old though |
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Russel
Australia
49 Posts |
Posted - 14 juin 2006 : 02:44:54
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Yes, it's been around for a while. The problem is, which if any of these chipsets ends up in an inexpensive unit where the raw data is still available via a bluetooth/serial port. Most of these chips seem to end up in survey gear I'm afraid.
At this point it seems to boil down to the Sirf chips. Some please correct me if I'm wrong :-/ |
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HS
3 Posts |
Posted - 16 août 2006 : 01:02:50
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The receivers on my list for carrier phase and pseudorange data are mainly the iTrax03 from Fastrax and uBlox LEA-4T.
I don't have personal experience with either though. I have used the iTrax02 but that's not really relevant here I think.
iTrax03 series from Fastrax http://www.fastrax.fi/
iTalk binary protocol messages TRACK and PSEUDO look interesting:
http://isuite.fastrax.fi/sdk/331/Protocols/PRO_MsgFormats.html#TRACK
http://isuite.fastrax.fi/sdk/331/Protocols/PRO_MsgFormats.html#PSEUDO
Of the uBlox LEA-4 series you want the LEA-4T version which provides the raw measurements. http://www.u-blox.com/products/lea_4t.html
uBlox sells an evaluation kit with this module in their webshop but it's naturally more expensive than the mass produced gps receivers.
quote:
Originally posted by gpspassion
I just received a Fastrax unit for testing purposes, Wintec BT-100, I think Fastrax might somehow be related to uNav, but don't quote me on that ;-)
AFAIK the first Fastrax products all used u-Nav chipsets. Now Fastrax also has products using some other gps chipsets but the most interesting to me still seems to be the u-Nav based modules.
Also u-Nav was launched by Finnish company VLSI Solution Oy (someone might recognise them from the VS1001 MP3 decoder IC) http://www.vlsi.fi/company/company.shtml and Fastrax is also from Finland.
I'm not totally sure how the whole software side with the u-Nav goes but I remember (based on what I've read) that u-Nav has offered software solution to use with their chipset from either Fastrax or SigNav. I have also seen some press release from Trimble that they should also offer a software for the u-Nav chipset.
Ok that was just some information how Fastrax and u-Nav are related.
Yes looks like the Wintec WBT-100 / WBT-200 Bluetooth GPS receivers are based on the u-Nav/Fastrax combo. Now would be interesting to know if the software is similar as in the iTrax03 modules from Fastrax and if these Wintec receivers can be made speak iTalk.
EDIT:
Hmm looks like the http://isuite.fastrax.fi/ is not working at the moment.
Also found this. Want 100Hz update rate ? ;)
High raw measurement data rate is implemented by routing TRACK
and SUBFRAME message directly out from iTrax. Consequently,
navigation is not performed in iTrax. However, navigation solution can
be calculated off-line or in real-time on another processor from the
TRACK and SUBFRAME messages.
iTrax03 is able to produce 100Hz raw data rate with 12 tracked
satellites. Because of big raw data output from iTrax03, the iTalk
serial port speed must be 921600 bps.
From: http://66.249.93.104/search?q=cache:1zGzSlDh5ccJ:isuite.fastrax.fi/sdk/331/Common/AppNotes/APP_HighDataRate.pdf
EDIT2:
http://isuite.fastrax.fi/ is working now and also fixed some links. |
Edited by - HS on 17 août 2006 11:10:27 |
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HS
3 Posts |
Posted - 17 août 2006 : 01:25:02
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gpspassion, do you still have the Wintec unit ?
Looks like it should be based on the iTrax03 so if you'd like to help here you could test if that can be made to communicate with the iTalk binary protocol.
The $PFST,ITALK command should work for changing to iTalk from NMEA:
http://isuite.fastrax.fi/sdk/331/Protocols/PRO_NMEA.html#mozTocId110626
And this change is restored when powering off the unit so there shouldn't be any harm trying.
If the command changes the unit out of NMEA mode you could try the GPS Workbench utility if you wish:
http://isuite.fastrax.fi/downloads.html |
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HS
3 Posts |
Posted - 17 août 2006 : 11:04:40
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I was just exchanging couple emails with Wintec support and they told that the iTalk protocol has been disabled in the firmware using the iSuite SDK. Apparently to save some space in the flash to have more room for the logging function.
As I was the first person to ask for iTalk support they aren't interested in enabling iTalk at this time in their firmware. I suppose that maybe if there was demand they could provide alternative firmware version (as the firmware in the unit is user upgradeable) with iTalk enabled. |
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gpspassion
93402 Posts |
Posted - 17 août 2006 : 13:14:20
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| Catching up, I was going to fire up the BT100 but it seems we have our answer. I rememer trying some iTrax tools with an old Royaltek uNav based mouse GPS, loks like it's been discontinued. It seems most of the uNav based units out there "went through" fastrax first, not that that there are that many consumer systems, FWD sport systems and the Wintec come to mind. |
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Which receivers provide raw data (pseudorange) ?
