Trouble with RTCM and Garmin GPS (18x LVC)

App_rpt-users
1

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-

2

For the Garmin GPS18x LVC, 5m to the RTCM, the following works for me:

I have green on 6, yellow on 7, shield and 1-small black and large black on 8, white on 14, red on 13, 1-small black n/c.
You need to do the diode calibration procedure and then set the levels.

Hope this helps.

Chuck

···

On Thu, Nov 16, 2017 at 2:39 AM, Doug Kingston dpk@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-

3

Did you need to do the calibration before the GPS would show functioning? I have not tackled the RF side yet.

-Doug-

···

On Thu, Nov 16, 2017 at 2:42 AM, Chuck Henderson rpt2@chuck.midlandsnetworking.com wrote:

For the Garmin GPS18x LVC, 5m to the RTCM, the following works for me:

I have green on 6, yellow on 7, shield and 1-small black and large black on 8, white on 14, red on 13, 1-small black n/c.
You need to do the diode calibration procedure and then set the levels.

Hope this helps.

Chuck

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On Thu, Nov 16, 2017 at 2:39 AM, Doug Kingston dpk@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-

4

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@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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5

Thanks for the pointer to the GPS writeup. I had missed this. Will review and see where I get.

···

On Thu, Nov 16, 2017 at 7:58 AM, Lee Woldanski ve7fet@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

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On Nov 16, 2017 12:40 AM, “Doug Kingston” dpk@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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6

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@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@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-

7

Thanks to the advice above, my problems are resolved. Thanks all!

-Doug-

···

On Thu, Nov 16, 2017 at 6:44 PM, Chuck Henderson rpt2@chuck.midlandsnetworking.com wrote:

Chuck

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.

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On Thu, Nov 16, 2017 at 9:58 AM, Lee Woldanski ve7fet@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@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-