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gpspassion
93400 Posts |
 Posted - 11 mars 2007 : 00:00:39
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 UPDATED MARCH 2011 : MTK chipset MT3328 (host-based version o MT3329à used on Garmin nuvi 3790.
UPDATED SEPTEMBER 2008 : MTK chipset v2 (MTK 3329) is available on the Qstarz Nano Q1300 datalogger, see details below.
1. INTRODUCTION
The MTK chipset took the GPS world by surprise in the fall of 2006 with the arrival of Transystem's iBlue 737 when many of us had been anticipating the NemeriX NJ2020/Nx3 based iBlue 727 that remains unavailable to this day.
A quick summary for the MTK chipset would be "powerful and lean", powerful because rated and perceived sensitiviy is on par with SiRFstarIII and lean because the battery life of MTK based receivers was 3x that of SiRFstarIII receivers. However the SiRFstarIII-LT chipset has become available (on the Garmin GPS10x) and battery life is now equivalent.
Compared to the SiRFstarIII receiver it provides more accurate tracks when driving, with better resistance to multipath problems (bounced signals in urban environments), but it appears to have been tuned for driving and not pedestrian use where it has issuss getting back on track in some situations. (UPDATED 200707 : low speed tracking, not to be confused with SiRF's Static Navigation setting, fixed starting with FW1.92, now performs on par with SiRFstarIII and Skytraq, see this comparison). On average it also has a longer time to first fix in the morning on average.
2. MTK BASED RECEIVERS
MTK v2 BASED RECEIVERS > 08/2008
- Qstarz BT-Q1300 logger with AXN_0.3-B_1.3_C01, see more
MTK v1 BASED RECEIVERS > 09/2006
In order of appearance :
- iBlue 737/Qstarz 810
- Qstarz 815 Solar GPS
- Qstarz 818
- iBlue 747/757 Bluetooth loggers
- Holux M-1000
- Qstarz BT-Q1000 logger
- Garmin nüvi 2x0 AIO - more
- Garmin eTrex Vista HCx - more
- Qstarz Q1200 logger with v2.0 - more
- Qstarz BT-Q1000P logger with Bcore 1.1, see more
- Semsons M7 BT GPS with Bcore 1.1, see more
Please use the thread dedicated to each of these receivers to discuss their specific features.
3. FIRMWARE VERSIONS
V2 CHIPSET - MTK3329
- Q1300 (08/2008) : AXN_0.3-B_1.3_C01
V1 CHIPSET - MTK3318
- 737 (sample - 09/2006) : M-core_1.5,0000 - 1.902_23_1102_0000,0609_m0247,0001
- 737 (shipping) : Mcore_1.62,0001 - 1.902 28 1102 0001,0609
- 737 (shipping-c300k) : M-core_1.8,0001 - 1.902_0__1102_0001,0609_m0279,0001
- Qstarz 810 : Mcore_1.62,0001 - 1.902_28_1102_0001,0609_mA254,0001
- Qstarz 815 : M-core_1.51,0002 - 1.902_23_1102_0002,0609_m0247,0001
- 747 : M-core_1.8 0011 - 1.902_40_LOG1.3_1102_0017,0609_m0279,0001
- 757/ZI v1 : M-core_1.8 1388 - 1.902_40_LOG1.3_1102_5000,0609_m0279,0001
- 757/ZI v2 (>06/2007) : M-core_1.94,5202
- Polaris iBT-GPS : M-core_1.8,0001 - 1.902_40_1102_0001,0609_m0279,001
- USB GPS : 1.902_34A_1102_0006, 0609_m0269 Mcore_1.72
- Holux M1000 : Mcore_1.8,0001 - 1.902_38_B09_1100_0001,0609_m0297,0001
- Qstarz BT-Q1000 : Mcore 1.94001
- Qstarz BT-Q1200 : M-core_2.0,8300,QST1000,*64, see see review
- Gisteq Phototrackr Lite : M-core 2.0, see topic
- Qstarz BT-Q1000P : Bcore 1.1, see topic
4. USEFUL LINKS
- MTK Proprietary commands : link
- MTK chipset operating at 5hz : link
- Logging > 1Hz : link
5. COMMENTS, TIPS AND TWEAKS - INDEX- BT747 Configuration , Log downloading, Google Maps creator - BT747
- PC Configuration utility on the TS site - GPSview 1.0.3
- PC Configuration utility on the Sparkfun site - MiniGPS 1.32
- Activating SBAS from a PC or PPC with MTKTweak, see below
- Sending commands over Bluetooth, seebelow
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Discounts and Assistance/Réductions et Assistance (Club GpsPasSion) / Où commencer? |
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jm_araujo
12 Posts |
Posted - 11 mars 2007 : 13:57:08
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I think this classifies as a Tweak.
The IBlue 737 and clones (I have a Qstarz 810) will not accept commands sent via bluetooth because the manufacturer disconnected the serial output of the bluetooth module from the GPS Chipset.
To solve this situation adding a simple resistor will be enough.
After removing the battery, open the GPS using a blade or sharp screwdriver on the crack on the top of the utit and twist. Pay atention to the power switch because it will probably fall off.
Now you will have to solder a resistor as pictured next(shown aligned before soldering). I've used an 1Kohm and it works fine. Be carefull and make sure it doesn't make contact with anything else.
It's a job for someone with some previous soldering experience.
The place of the actual missing resistor is on this picture where i've made my soldering (had some SMD resistor), but I think the way described above is easier:
Now my unit accepts commands, and I've been able to make it work at 5Hz.
Regards to everyone,
José Araújo
(I've not added any disclaimer, but pretend they are all there) |
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Zigster
27 Posts |
Posted - 11 mars 2007 : 14:09:33
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@jm_araujo
That's awesome... I might try that, once I get my fingers on a 1kOhm resistor.
So, you send the commands via bluetooth after aplying this tweak?
Nice work !
Zigster
BTW: Is there any chance to get the USB Port working for sending commands ? |
Polaris iBT-GPS |
Edited by - Zigster on 11 mars 2007 15:11:04 |
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jm_araujo
12 Posts |
Posted - 11 mars 2007 : 14:59:45
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Yes, I do send the commands via bluetooth.
I use SirfTech (Menu NMEA-Development Data) to send the commands on my PPC as it will automaticaly generate the checksum for the messages and I still haven't got my USB-Bluetooth adapter for the PC.
José Araújo
New question edit:
On the second picture you can see next to the mini-USB connector a lot of components are missing. Those where the ones that provided USB data connection. You whould have to find which parts they where and replace all of them. Very difficult, if not impossible to do.
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Edited by - jm_araujo on 11 mars 2007 15:24:21 |
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musky
USA
226 Posts |
Posted - 11 mars 2007 : 16:11:38
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I have written a little app that turns WAAS on and off for the MTK chipset. I have tested it with my MTK (32 channel) USB unit, and it works quite well. The app sends the unit the $PMTK301 and $PMTK313 commands via serial comm port. I use a default baud rate of 9600. I believe all the MTK units default to 9600. (FWIW I have been unsuccessful in setting the baud rate to other than 9600.)
The zip file has 2 versions of the app. MTKTweak.exe is a Windows app, and MTKTweakCE.exe is a Windows CE app.
To use: You need to choose a COM port, I write the result to the registry so the app will remember it. Click on the button with the GPS hooked up, and the app will connect to the GPS and set the WAAS state, and then close the COM port. That's it! If you don't get an error dialog, then the operation should have completed.
As far as telling whether the unit really is in WAAS mode or not, the way I do it is monitor the GPS commands with my other apps, and look at the GGA command. The presence of a "W,2" in the string indicates WAAS is on. Also, with WAAS on, I get a consistant lock on PRN135 here in the USA.
The only testing other than myself was done by an individual in Germany, and it didn't seem to work for him. He has a different GPS unit than I do, and, of course, it's EGNOS over there, so I'm not sure what the deal is, but, anybody let me know how it works.
If anyone finds this useful I might be willing to add some more tweaks.
Here is my first attempt at a file posting in this site. Hope this link works. If it doesn't I'm sure you will let me know.
http://www.gpspassion.com/upload/MTKTweak.zip
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Zigster
27 Posts |
Posted - 11 mars 2007 : 16:49:42
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Even though it didn't work for me now (perhaps after applying the above tweak) I recommend musky's tool and I'm looking forward to it's progress in adding more tweaks.
Zigster
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Polaris iBT-GPS |
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musky
USA
226 Posts |
Posted - 11 mars 2007 : 16:57:35
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MTK review (edited summary from other thread):
I've purchased an MTK chipset GPS unit, and have some 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 to turn it on, you need to send a special NMEA command sequence, or use my MTKTweak utility. (see other post in this thread) 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 is 9600.
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.
2D RMS: WITHOUT WAAS on the MTK is at about 8 meters. (I have performed many experiments with the Sirf III, and long term accuracy is always around 5 meters.)
There is a very interesting thing going on with the MTK though! If you look at the distribution of the Sirf III 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.
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.
To send 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 >330,000 1 second acquisitions (in fixed location), and my standard deviation is about 4.5 meters. 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 speed (but not bearing). 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 >5 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!
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 3 meters to the above mentioned 4 meters. 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.
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Edited by - musky on 23 mars 2007 18:01:53 |
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musky
USA
226 Posts |
Posted - 11 mars 2007 : 17:24:09
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MTK Evaluation:
Here is the distribution of 230,000 fixes with the MTK GPS. Notice the "constraining" of the tracks. I believe this is due to the "static navigation" feature.
Here is a Sirf III precision study for comparison. Notice the much more "gaussian" appearance of the fixes.
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gpspassion
93400 Posts |
Posted - 11 mars 2007 : 19:39:49
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Thanks for sharing, will try your apps. I haven't really seen the SN problem you describe in good reception environments, with minute speed increments, but clearly in challenging environments where it gets confused when it goes off track. I'll compile my various tests above.
Woukd you say you have a 737 clone ? |
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musky
USA
226 Posts |
Posted - 12 mars 2007 : 03:07:17
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| No, it's not a 737 clone. It's USB, not bluetooth. Brand name is unknown. BTW, firmware is ver. 1.902 |
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gpspassion
93400 Posts |
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musky
USA
226 Posts |
Posted - 12 mars 2007 : 12:08:57
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| Just go onto EBay and search for "MTK USB" |
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gpspassion
93400 Posts |
Posted - 12 mars 2007 : 12:15:08
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Thansk, got it, wow, looks like they will soon be giving away GPS receivers...Back to the SN discussion, walked around with the 757 this morning and with good signals it does indeed reflect movements at slow speeds, 1/2kph. I did see it lagging at some point, but nothing like this in very bad signal conditions :
More here http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=81290
I wonder if your USB receiver hasn't been "tuned" differently, how did you see the FM version, is there a commande for that ? |
Discounts and Assistance/Réductions et Assistance (Club GpsPasSion) / Où commencer? |
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musky
USA
226 Posts |
Posted - 12 mars 2007 : 12:19:52
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Yeah, they may be giving them away pretty soon, but I'd be nice if they asked for $1 more and gave some software utilities with it!
The query for firmware version is $PMTK604 |
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jm_araujo
12 Posts |
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gpspassion
93400 Posts |
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* Discussing MTK receivers and Tips and Tweaks *
