SL871 – NMEA messages for Short/Open antenna detection

5 thoughts on “SL871 – NMEA messages for Short/Open antenna detection

  1. Hello,

    In the page 40 of SL871 Family Product User Guide says:

    ANT-OC
    This signal is a high true input. When the input is at logic 1, the receiver will output a
    special NMEA message indicating the antenna line is open.

    ANT-SC-N

    This signal is a low true input. When the input is at logic 0, the receiver will output a special
    NMEA message indicating the antenna line is shorted.

    But I cannot find in any Telit document that I have which are those NMEA messages, so if you could help me…

    Thank you very much in advance.

    Best regards.

    1. Hello,

      In the page 40 of SL871 Family Product User Guide says:

      ANT-OC
      This signal is a high true input. When the input is at logic 1, the receiver will output a
      special NMEA message indicating the antenna line is open.

      ANT-SC-N

      This signal is a low true input. When the input is at logic 0, the receiver will output a special
      NMEA message indicating the antenna line is shorted.

      But I cannot find in any Telit document that I have which are those NMEA messages, so if you could help me…

      Thank you very much in advance.

      Best regards.

      Hello,

      the antenna sensing feature reports the output of the detection through $GPTXT sentences in this way:

      • GPTXT,01,01,02,ANTSTATUS=SHORT*6D
      • GPTXT,01,01,02,ANTSTATUS=OK*3B
      • GPTXT,01,01,02,ANTSTATUS=OPEN*2B

      those messages rely on ANT-OC, ANT-SC-N signals so to have a correct behaviour you must first develop a correct sensing circuit that feeds those two signals.

      Best regards,

      Simone Andrea Muscas
      Technical Support – EMEA Application Engineering

      Telit Communications S.p.A.

      1. Hello.

        We have implented the sensing circuit and we can measure with the oscilloscope that the ANT-OC and ANT-SC-N signals are changing properly when forcing an OC or an SC in the anthena, so at this point we assume that the HW is well implemented.

        The problem is that no NMEA $GPTXT messages are sended by the module.

        Maybe, are we missing some initialization/configuration in the module?

        Thanks and regards!

        1. Hello.

          We have implented the sensing circuit and we can measure with the oscilloscope that the ANT-OC and ANT-SC-N signals are changing properly when forcing an OC or an SC in the anthena, so at this point we assume that the HW is well implemented.

          The problem is that no NMEA $GPTXT messages are sended by the module.

          Maybe, are we missing some initialization/configuration in the module?

          Thanks and regards!

          Hello,

          we have verified that in the last release of the firmware the antenna sense related messages are not being sended by the module. We are waiting for a beta version of the firmware that will enable those $GPTXT messages.

          For a better tracking of your request, please send a mail to ts-emea@telit.com.

          Best Regards,

          Simone Andrea Muscas
          Technical Support – EMEA Application Engineering

          Telit Communications S.p.A.

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