[time-nuts] GPS time module

[John C. Westmoreland, P.E.]

Thanks for the comparison Said.  I am glad I have an LC_XO.  ;)

Regards,
John Westmoreland



On Tue, Oct 29, 2013 at 4:35 PM, <SAIDJACK at aol.com> wrote:

> Sorry in advance guys,
>
> I could not resist doing a short comparison between our LC_XO module and
> this new Selig/RF-Suisse 1x1 module. Please excuse this blatantly biased
> comparison:
>
> The Selig module is slightly larger, and consumes about the same amount of
> power as the LC_XO (TCXO version), and basically provides a similar set of
> signals. It is however about twice as expensive, has an 8-week lead-time
> versus  from-stock delivery, and there are other differences:
>
> * 20 channel GPS without WAAS/SBAS (Selig) versus 50 channels with
> WAAS/SBAS (LC_XO)
>
> * 1us time pulse accuracy (Selig) versus +/-25ns time pulse accuracy typ.
> (LC_XO)
>
> * Washing not approved (Selig) versus washing approved (LC_XO)
>
> * Selig requires an antenna cable to be plugged into the bottom of the PCB,
>  then the module is soldered onto a customer PCB. Thus if the antenna cable
>  becomes loose, it cannot be plugged back into the connector. LC_XO:
> antenna feed  via the solder pins from carrier PCB
>
> * Selig I/O: Status LED and requirement to program for an I2C slave
> register, no NMEA or control command interface for GPSCon, GPSD, or Z38xx
>  etc
> versus LC_XO: two NMEA outputs (RAW NMEA and Binary from uBlox GPS), JLT
>  NMEA
> commands with custom commands, and SCPI control interface for third-party
> software
>
> * Selig 60,000 feet altitude limit versus 164,000 feet for LC_XO
>
> * Power requirement: Selig: 5V versus LC_XO 3.3V (LC_XO will provide 5V
> from internal DC switcher that can be used externally on carrier PCB)
>
> * Phase Noise: about the same between both units
>
> * ADEV: Selig slightly better at around 20s, LC_XO better above 1000s
> (LC_XO short-term ADEV can be significantly improved in stable
> environments by
> setting the time-constant of the loop to longer time frames)
>
> * Selig module options: GPS or no GPS versus LC_XO module options: TCXO,
> OCXO, and external 1PPS input with auto-switchover to internal GPS
>  receiver
>
> * Firmware updates: Selig does not provide customer update mechanism versus
>  LC_XO can be easily updated with various firmware versions available for
> customer download from the website without any website log-in etc.
>
> * Selig TCXO stability: +/-100ppb from -20C to +70C versus +/-75ppb from 0C
>  to 60C or +/-25ppb from 0C to +60C (OCXO version)
>
> Selig/RF-Suisse offering this form factor is a welcome event as it
> validates the form factor in itself.
>
> I am however not seeing too many advantages for the Selig part in
> comparison especially at about twice the cost, am I missing something?
>
> bye,
> Said
>
>
> In a message dated 10/29/2013 14:54:51 Pacific Daylight Time,
> lstoskopf at cox.net writes:
>
> Sorry if  already  posted:
>
> http://www.saelig.com/COMCR/COMCR002.htm
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>