[App_rpt-users] Trouble with RTCM and Garmin GPS (18x LVC)

[Chuck Henderson]

I only use this Garmin (GPS18x LVC, 5m) and have no problem with the RTCM.
I got most of them many years ago but the last one I bought in 2016 and it
worked fine also. I just hook them up and they work.  I have not looked at
the pulse with a scope.  I recall there is a JP4 that can be changed in the
RTCM.  In one position, (1-2), it has thresholds of less than  0.8v and
greater than 2.0V and is +-25v tolerant and in the other default position
(2-3) it should be standard TTL input and 0 to 5 volt tolerant.
Chuck

On Thu, Nov 16, 2017 at 9:58 AM, Lee Woldanski <ve7fet at tparc.org> wrote:

> Have you looked at:
>
> http://wiki.allstarlink.org/wiki/RTCM_Client#GPS
>
> Specifically, does this Garmin use 5V or 3.3V logic?
>
> I believe the RTCM uses 5V logic only (the VOTER) will do either.
>
> If your Garmin is 3.3V, it may have issues.
>
> Also, make sure the baud rate is correct, and it is configured to send the
> required NMEA sentences.
>
>
> Lee
>
> On Nov 16, 2017 12:40 AM, "Doug Kingston" <dpk at randomnotes.org> wrote:
>
> I can't get the RTCM to recognize the attached GPS unit.
> Reference: http://static.garmincdn.com/pumac/GPS_18x_Tech_Specs.pdf
>
> I have determined that pin6 on the DB15 of the RTCM is transmit data to
> the GPS (using an oscilloscope) and that's hooked to the RxData line of the
> Garmin (green).  Will the Garmin respond if it does not have lock?
>
> RTCM diagnostics complain:
> Running Diagnostics...
>
> Warning!! VF Diode NOT calibrated!!!
>
> Testing PTT/External CTCSS
> Error - Failed to read PTT/CTCSS in asserted state
> Testing GPS UART
> Error - Failed to read data from GPS UART
>
> Any hints? or ways to get more diagnostics?
>
> -Doug-
>
>
>
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