[time-nuts] KS-24361 REF-0 standalone

Bill Hawkins bill at iaxs.net
Fri Oct 2 22:44:49 EDT 2015

Actually, the Lucent software uses RAIM, and reports the value in its
status message. If the position appears to have drifted off, or there
aren't enough satellites to calculate the position, the software
declares the oscillators to be free-wheeling, an expression meaning that
the oscillators are free from discipline and are now drifting.

So yes, the positioning aspects matter.

Disclaimer: I haven't studied RAIM (or TRAIM) enough to know exactly
what goes on, but that's the behavior I've observed.

Bill Hawkins

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Gregory
Sent: Friday, October 02, 2015 6:07 PM
To: time-nuts at febo.com
Subject: Re: [time-nuts] KS-24361 REF-0 standalone

Dan -

I have been following your experimentation with the surplus Lucent
KS-24361 REF-0 module, to transform it into a standalone GPSDO.

The original usage of the classic Oncore UT+ GPS receiver for KS-24361
REF-1, by Symmetricom / Datum for Lucent, was deliberate.  
For usage at a cellular data/telecom site, the focus was on the timing
and frequency discipline from the GPS satellite transmission, rather
than the position or dead reckoning aspects -- used by smartphones,
automobiles, and other GPS applications on the market.
A couple of comments.
While I can appreciate being economical (main criteria) and selecting
the NEO-6M receiver, I believe that a u-Blox timing specific module
(like LEA-6T) would be more desirable in this application.

In addition, the u-Blox 6-series is the trailing edge of product support
(market demand dictates its continuance), while the 7 and 8-series are
their current modules (largely for the cellular / mobile industry
(smartphones or cell sites themselves)

u-Blox 6-series Timing Application Note (using the LEA-6T)

IF you successfully adopt the u-Blox module to correctly "mimic" the
Oncore UT+ GPS receiver command suite, THEN you open up a larger
audience of "time-nuts" and Frequency Standard users (HP Z3801A
frequency standard universe) as a receiver alternative.

These users may desire a "newer" GPS receiver that has more channels
(8-channel); latest generation receiver; access to the newest GPS
TAPR might be interested in sponsoring, as a kit/module, if a wider
audience existed.

The Heol Designs N024 receiver (France) accomplished this replacement
role for the Trimble ACE II/III GPS receiver used in the
Symmetricom/Datum TymServe TS2100.  
Their solution resolved shortcomings in the mid-1990 Trimble receiver
design and giving this Symmetricom NTP server, time IRIG-B time code
generator, and 10 MHz reference appliance a new lease on life (no longer
a door stop).


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