Jupiter-T GPSDO Communication - Page 1
Forum section: electronics / projects

author: davorin
author_rank: Unknown
timestamp: July 11, 2014, 10:14:13 am
content: Have now all components together to build a GPSDO 10MHz reference oscillator..When I power up the GPS module I receive the standard 0xFF, 0x81 start sequence in the reply...Though when I try to communicate with it there seems to be no reply at all....For example the command "@@Cj" should return model, version and serial number...but doesn nothing...

author: davorin
author_rank: Unknown
timestamp: July 11, 2014, 11:22:43 am
content: Found some documentation and examples here....but still no luck with it....for example just how to find out if the GPS has a lock...http://www.casde.iitb.ac.in/IMSL/motion/gps/Connecting my HP5335A display for the first 5 - 10 minutes a value of 10000.360 Hz...then goes down to 10000.177 Hz...which is reproducible when power-cycling the Jupiter-T GPS module...

author: davorin
author_rank: Unknown
timestamp: July 11, 2014, 12:36:55 pm
content: As per example in the Word document in the link above....getting the pinning status should be possible with:Code:echo -ne '\xFF\x81\xF4\x03\x00\x00\x00\x48\x0D\x32' > /dev/ttyUSB0Still no output....only during power-up...

author: jpb
author_rank: Super Contributor
timestamp: July 11, 2014, 12:54:43 pm
content: It sounds as if the Jupiter is not receiving your signals - perhaps there is a fault on pin J1-9. You may even have a faulty cable - have you double checked it with a DMM for continuity?

author: davorin
author_rank: Unknown
timestamp: July 11, 2014, 01:07:31 pm
content: I see the signal going to pin 9...Also..happens with both of my TU60-D001 modules...Bitrate is also correct when sending...just checked with a simple '\xAA' > /dev/ttyUSB0 and my DSO...

author: davorin
author_rank: Unknown
timestamp: July 11, 2014, 01:17:12 pm
content: Hmm...should work with a regular USB2TTL serial adapter, right?Not that the Jupiter expects RXD to be inverted.....

author: Andy Watson
author_rank: Super Contributor
timestamp: July 11, 2014, 01:36:33 pm
content: Quote from: davorin on July 11, 2014, 01:17:12 pmAre you sure about that? The jupiter GPS that I've used required its serial output converting to RS232 level (including inversion). Also, check the mode that it boots-up in. I think it defaults to the NMEA message mode.

author: davorin
author_rank: Unknown
timestamp: July 11, 2014, 01:43:13 pm
content: They default to binary mode...as it sends after reset this message with the regular 0xFF81 flag:Code:\0xff\0x81\0x9c\0x04\0x01\0x00\0x00\0x00dy\0x00\0x00\0x00\0x00

author: davorin
author_rank: Unknown
timestamp: July 11, 2014, 03:28:04 pm
content: Just stumbled upon this thread:http://en.it-usenet.org/thread/16759/1388/And tried myself with the Motorola WinOncore 12 software, and it is indeed sending information back when asked for the receiver id:Also it sends data continuously when opening the command monitor...

author: davorin
author_rank: Unknown
timestamp: July 11, 2014, 04:16:06 pm
content: Some step forward (o;Sending this:Code:echo -ne '@@Cj)\x0D\x0A' > /dev/ttyUSB0returns the module information:Code:@@CjCOPYRIGHT 1995-2004 NAVMAN LTD.SFTW P/N # 0000SOFTWARE VER # 93SOFTWARE REV # 07SOFTWARE DATE 01/16/2004MODEL # R01HDWR P/N # TU60-D125SERIAL # 407132508MANUFACTUR DATE 401//12070OPTIONS LIST 5843 Sending:Code:echo -ne '@@Ea\x01\x25\x0D\x0A' > /dev/ttyUSB0initiates the sending of the status/position information every 1 second...

author: davorin
author_rank: Unknown
timestamp: July 11, 2014, 05:08:03 pm
content: Seems to be plain Motorola binary format it accepts after power-on:https://www.febo.com/pages/hardware/VPCommands.pdf