[time-nuts] Jupiter GPS questions

Mike Seguin N1JEZ n1jez at burlingtontelecom.net
Fri Oct 19 10:08:24 EDT 2012

Hi TJ,

I recently ran into a similar issue with a Jupiter T. No NMEA output. What I 
found was the unit came up in Motorola Binary @ 9600 and sent only an 
initial string out.

The solution here was to use a PIC. (I was actually working with a PIC done 
by Tommy Sullivan called "3DFIXLED")

Here are the HEX commands to send to the unit to make it do 9600 baud NMEA.

1.) 0x40 0x40 0x57 0x62 0x01 0x34 0x0D 0x0A

This is the @@Wb1 command - switch from Motorola Binary to Zodiac Binary

2.) 0xFF 0x81 0x33 0x05 0x03 0x00 0x00 0x07 0xCB 0x71 0x00 0x00 0x00 0x00
0x01 0x00 0xFF 0xFF

This switches to NMEA. There are three additional strings that can be sent 
assure sentence output. I'm not sure they are needed, but here they are:

1.) 0xFF 0x81 0x4E 0x04 0x03 0x00 0x00 0x67 0xB0 0x12 0x00 0x00 0x01 0x00
0x00 0x00 0xFF 0xFF
2.) 0xFF 0x81 0xEB 0x03 0x03 0x00 0x00 0x67 0x13 0x13 0x00 0x00 0x01 0x00
0x00 0x00 0xFF 0xFF
3.) 0xFF 0x81 0xF4 0x03 0x03 0x00 0x00 0x67 0x0A 0x13 0x00 0x00 0x01 0x00
0x00 0x00 0xFF 0xFF

There is no ACK that I see. I'd power up and wait a few seconds, then send
the first string, then wait a couple more secs and send at least the second

After doing this, my unit now sends out GPGGA, GPRMC and GPGSA sentences @ 
9600 baud.

Mike, N1JEZ
"A closed mouth gathers no feet"

> -----Original Message-----
> From: TJ Fiel <zulutime at yahoo.com>
> Subject: Contact: Jupiter GPS questions

> Message: Hello KO4BB,
> Many thanks for making so many resources available through your
> website.  I'd never seen Labmon 7 before and it cured several
> problems with previous versions.
> I'm attempting to use a Jupiter serial GPS receiver with APRS.  This
> is an OEM version made for Etak/Sony about 1999, p.n. TU40-D310-011.
> It uses the Rockwell Scorpio DSP (11577-11) but implements few
> features.  I've never found a datasheet or even a pinout for this
> chip.  Conexant stopped producing this chip about ten years ago and
> now they don't appear to answer their phones.  Apparently they never
> released chip level data to the public for this DSP, only for
> built-up GPS modules.
> My biggest issues are automatically forcing NMEA out at startup and
> possibly adding an RTC.  Any insights you can give will be greatly
> appreciated.
> Best wishes and thanks,
> TJ Fiel 

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