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

[Daniel Watson]

Gregory,

Thanks for your comments. You are absolutely right that a timing GPS module
is required to make this a proper Time-Nuts solution. I know that many on
the list have been thinking the same thing when they read my posts. Cost
alone is what has prevented me from going directly to that approach. Even
at eBay or Ali Express prices, 6T modules are six to seven times more
expensive than the 6M modules. I have decided to develop this in an
iterative fashion using lower-cost modules for testing. This way I can get
the bulk of the development done at a low cost, and then add in a higher
grade module when the time is right.

I am already working on a version of the board that uses the LEA-6T module.
The footprint on the board would be upwards-compatible with the LEA-M8T
module, with it's GNSS all-in-view features. That would surely interest a
lot of folks. Of course, that would come at a significantly increased cost,
but at least the option will be there.

I also agree that translating the GPS strings to the Oncore format would
open up the usage of this board to more applications. This is one of the
reasons I have had a microcontroller between the GPS and REF-0 from the
very beginning. Early on this enabled the quick fix of sending canned
strings. But newer versions of my code instead translate important
information such as fix status and sawtooth correction. This can easily be
extended to correctly populate all of the messages. And with even more time
invested, the micro can be programmed to translate two-way messages and
commands to fully replicate an Oncore. The hardware will soon be done to
enable all of that.

What you see in the Denuo GPS board is just one more step forward in the
project. I hope I can eventually bring it to a very satisfying and
Time-Nutty conclusion.


Best regards,

Dan W.

On Fri, Oct 2, 2015 at 7:06 PM, Gregory Beat <w9gb at icloud.com> wrote:

> 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)
>
> https://www.u-blox.com/sites/default/files/products/documents/Timing_AppNote_%28GPS.G6-X-11007%29.pdf
>
> 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.
> http://www.realhamradio.com/GPS_Frequency_Standard.htm
>
> These users may desire a "newer" GPS receiver that has more channels
> (8-channel); latest generation receiver; access to the newest GPS
> constellations.
> 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).
>
> http://www.heoldesign.com/index.php?module=products&action=catalog&cat=14&id=54
>
> w9gb
>
> Sent from iPad Air
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