[time-nuts] Z3801A - notes on the hp58533a GPSDO

paul@wireless kontakt at corallinks.com
Fri Jan 12 11:02:11 EST 2007


to: John,KE5FX

Hi John
I read your question on the THUNDERBOLT look-alike sold by 'accelium'. Since
I have bought this unit (for 500$!!!), I can answer some of it:

The hp58533a has a similar form factor as the Thunderbolt but it's an
entirely different design. I made the following notes when trying it out:

- simplified version of hp58540a where data sheet is available. (missing
power supply board and cheaper TCXO by TOYOCOM). Separate 5V and 15VDC (for
TCXO) have to be supplied instead of 18...32 VDC is the '540a.
- while the data sheet boasts SCPI on the rs-232 interface, this unit pours
out NMEA messages every second (no SCPI prompt could be effected):

$GPGGA,135308,4656.5706,N,00723.4843,E,0,04,00.50,000562.6,M,0049.4,M,,
$GPZDA,135308,10,01,2007,-04,00
$GPGSV,3,1,09,03,79,152,54,08,06,309,00,11,14,264,29,14,10,129,33
$GPGSV,3,2,09,16,18,183,40,18,33,051,43,19,66,304,31,21,07,071,29
$GPGSV,3,3,09,22,60,091,55
$GPVTG,,T,,M,,N,,K
$PFEC,GPtps,070110135308,3,1,2,060101000000,00,14,070110023110,1409,309202
...the last line made me suspicious because it's a proprietary code used by
FURUNO!

- inspection of the board brought the proof, because one IC is from FURUNO.
- data are displayed in any NMEA compatible GPS program like TAC32 or
Trimble's GPDDS:EXE for DOS. 
- missing of course any information on timing, since PFEC is not decoded.
- 10 MHz and 1PPS outputs operate always, so no integrity check seems to be
performed.
- quality of 10 MHz was fair: r.m.s 3.6e-11 with tau 60s
- 1PPS was found within expectations but no long-term observation has been
made  so far
- processor seems to work real slow; TOF was one hour or so woth

Conclusion: unit is useful but in no way as interesting for research as
TRIMBLE's Thunderbolt or its derivative, LUCENt'S GPSTM. 
 
	QUESTION: does anybody know mire about the FURUNO code mentioned
above?????

Regards
Paul
TM-Brokers of Switzerland




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