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bkspero
6 Posts |
 Posted - 21 oct. 2011 : 16:46:20
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I would like to use a non-gps tablet for some offroad navigation. I have 2 BT gps receivers that have been in a drawer for 4 years since my last Palm PDA died. One, a Delorme BlueLogger GPS (Googling it says it is a Sirf IIe receiver) connects and works with the navigation software, but its elevation output is too innacurate and variable, even with a wide-open sky view (-200 to -10 ft relative).
The other is a GoPass GPT-600 Sirf III receiver that I remember as being faster, more sensitive, and more accurate. Plus it is listed as WAAS capable. Based on the LEDs on the receiver, it is getting both bluetooth connection with either the navigation software or SirfDemo, and satellite lock. Specifically, the connection LED changes from steady blinking blue to 2 quick blinks per second blue, and the satellite LED changes from solid orange to blinking orange. But there is no gps data coming from the receiver.
SirfDemo seems to believe that it is taking commands. I tell it to enter NMEA mode and the menu entry for NMEA mode grays out and the SIRF mode menu item turns black. Same with the reverse. But I've tried doing a reset with SirfDemo and it did not get it working.
I've tried unsuccessfully to leave the battery out of the receiver for a week on the hope of discharging the internal backup battery and getting a factory reset. The 2nd time I tried that I put the receiver in the freezer over the last night in an last effort to insure its power was depleted. I also have tried holding down the power button for a couple of minutes (that reset my BlueLogger receiver).
This was a great little receiver and I'd hate to needlessly throw it away without trying everything I can to get it working. What have I missed?
Thanks in advance for your help. Barry |
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bkspero
6 Posts |
Posted - 21 oct. 2011 : 23:04:00
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I tried one more thing. I disassembled the case and shorted out what appeared to be the leads to a button cell battery. When I started to test it I was initially encouraged because it took several minutes to get satellite lock compared to the 15-30 seconds for all the times previously...I was hopeful that this meant that I had finally succeeded in producing a factory reset.
It connected to my tablet normally. The bluetooth symbol on the tablet showed the connection and the blue LED on the receiver showed two rapid blinks per second.
But none of the other software on the tablet was able to get position information from the gps! I still need to test it with SirfDemo, but I'm not optimistic.
Could the problem be related to the Comm ports? Specifically that one comm port is connecting allowing commands to flow from the computer/tablet to the receiver, but the other comm port that should be sending data from the receiver to the computer/tablet is not connecting properly? |
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gpspassion
93402 Posts |
Posted - 23 oct. 2011 : 02:02:42
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| Nice efforts! Hard to tell what's wrong and how to fix it, but it could be a lost synch between the baudrate of the GPS module and the Bluetooth module. That can happen when commands are issued by SiRFDemo but it seems the problem started before that so it could be hardware related. |
Discounts and Assistance/Réductions et Assistance (Club GpsPasSion) / Où commencer? |
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bkspero
6 Posts |
Posted - 23 oct. 2011 : 15:47:18
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| Thanks for the reply. Any suggestions as to what I can try to resynch the GPS and Bluetooth modules? I haven't found anything in my searching, but that is getting "deep" enough in the electronics and jargon that I could well have missed it. |
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bkspero
6 Posts |
Posted - 25 oct. 2011 : 03:11:15
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I'm getting closer. I tried the factory reset again, but this time went to the GPS reading software that came with the GPS receiver (GPS Viewer). Set the rate to 4800, and it worked!. Was collecting data and eventually got a multi-satellite position with what seems to be an altitude that makes sense and is steady. Shut everything down, restarted, and worked again. Did it a 3rd time just to be sure.
I then tried my tablet and no luck. Symptoms same as before. Went back to the computer and GPS Viewer no longer was getting data from the receiver. Bluetooth connected and it gave a "GPS Open" messsage, but no data. Did another hard reset shorting out the battery, and it worked again.
Next I tried SirfDemo. Sirfdemo defaulted to 38400 so I gave it a shot. Told it to connect, and it worked there too. It started out in NMEA mode. I thought I'd next test Sirf mode. Checked that the rate was still 38400, and tried that. Nothing. Rate had switched to 57600. Tried every rate from 4800 to 38400. No improvement. Went back to GPS Viewer and again nothing more than the message "GPS Open" when I try to open communication with the receiver. Factory reset and it worked again with GPS Viewer.
So it doesn't look like a hardware problem. But I don't understand enough about the protocols to recognize what these symptoms represent. Any ideas based on the new info?
Thanks, Barry |
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bkspero
6 Posts |
Posted - 25 oct. 2011 : 13:33:44
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It works! Functional solution should have been obvious to me once the issue with Sirf mode showed up. The software on my tablet that allows it to access an external GPS receiver has a setting for Sirf GPS. I naturally had that turned on...not thinking that it might try to put the receiver into Sirf mode. I disabled the Sirf GPS setting on the tablet and it worked.
Only issue that I can see is that WAAS is under the Sirf GPS menu. So presumably I can't utilize that feature.
Anyone have thoughts on why this Sirf III GPS can't output satellite information in Sirf mode?
Barry |
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gpspassion
93402 Posts |
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bkspero
6 Posts |
Posted - 26 oct. 2011 : 01:39:13
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It is an Android tablet and i'm using a program called BlueGPS to handle the link between the GPS receiver and the navigation software (for example Google Maps).
I also have an issue trying to switch to Sirf mode in Sirfdrmo.
Barry |
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Revive GPT-600 BT GPS receiver
