I hope the detailed description of the erratic behaviour, recorded below,
will give an indication to someone of the cause.
My Trimble Jupiter modules refused to register [both of them]. So did my
Sure Evaluation kit. Even though they all work perfectly with several GPS
evaluation programmes. An EM-406a arrived from Germany this morning, and I
have tried everything I have seen suggested in the past week or so. This is
how it goes:
I have Frame set to 10
I have Start set to 04
GPS Baud is 04800,01,1,8
Use GPS On
Inv GPS On -- yes, I know, but nothing works with it off
Frq set to 10.140.198
Locator is rubbish
Set Time is rubbish
Switch on at 16:00:04
Locator sets correctly to IO91, time sets correctly to 16:00:04, Sys Frq
remains un-modified;
Time them increments in two-second steps every second -- 06, 08, 10, etc --
until it reads 16:03:50, when it resets itself to the correct time
(16:01:26, say). Then count up at double speed until it gets to 16:03:50,
when it resets itself to the correct time, and starts counting up at double
speed again. This happens over and over until the time really is 16:03:50,
when it counts on up to 16:04:00 and starts transmitting. Of course, it
counted at double speed, so the transmission starts at about 3 seconds
before the start of the even minute. But the transmission itself is at
normal speed, so I can decode it on another rig.
After the transmission, we go through the double speed until the clock reads
16:13:50, then the reset etc cycle goes on until the transmission at a
couple of seconds before 16:14:00.
Does that seem reasonable?
OK, so how do I cure it? I have the RX data pin of the module tied to Vcc,
and both ground pins are connected to 0v. Beyond that, I have tried pull-up
resistors (10k ohm) and pull-down resistors on the pps line and/or the TX
data line. No change.
?help?
David G8XBZ
