April 26, 2007
about 6 years ago
Update: I found a USB->UART converter from another project of mine, and the GPS works fantastically on 5v USB power! It was able to track 7 Satellites from indoors, a couple of meters away from any windows.
I must be getting some sort of interference on the power supply of my dev board. Just wanted to set the record straight, it’s not the GPS’s fault :)
I’m having a pretty nasty problem with this receiver: I can’t seem to get a decent satellite fix.
Unfortunately I don’t have an RS232->Uart cable so I can’t run the Mini GPS software. Instead I’m receiving NMEA messages with a microcontroller. I receive fully parse-able messages at 5hz at the default 38400bps, and have no trouble extracting data (no parse failures, no missing/bad characters, no bad checksum errors).
However, the receiver usually doesn’t obtain a fix. I was able to get Lat/Long information ONCE (3 satellites) after standing in completely open skies for 5 straight minutes.
Sometimes I can get just the time signal but no position fix after standing outside for several minutes.
I can’t get any kind of fix by an open window with a view of half of the sky.
I’ve tried running the unit from my microcontroller power source 3.3V, as well as an external power source at 4.8V. There is no difference. Both the GPS and microcontroller share the same ground.
Have I forgotten something glaring? Do I need to ground the case? Do I need to set some sort of settings on the unit via explicit commands? If so, how was I able to get a fix at all?
Any help is much appreciated!
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