FM Analysis > P175 FM Analyzer

RDS not showing phase angle or data


My P175 seems to work perfectly except that it usually fails to show RDS data or subcarrier phase angle. It has shown these on one occasion but not since then.

I have a good clean signal, 54dBuV, and the RDS is working perfectly well on other receivers. I have also tested it on other local signals such as the BBC, and it shows no RDS data or phase for those either.

Is there a setting I have failed to make, or what could be the reason?


For showing RDS data, disable the Measuring in the menu and select RDS mode. You may need better signal for stations which do not comply with the standards (especially RDS level below 1 kHz or no RDS and pilot synchronization) - this is maybe 1/3 of all stations, depending on location. The decoder is limited by preceding measurement module characteristics and it's sensitivity is usually worse compared to consumer radio.

Pilot-to-RDS subcarrier phase difference can only be showed on station whose RDS encoder is synchronized with pilot tone. If the pilot and RDS subcarrier oscillators are leaved free-running, no stable phase difference exists for most of time and thus there's nothing to show.

Okay, thank you for your quick reply. Disabling the measurement option has activated the RDS readout.

However, I still don't get a phase measurement although the RDS carrier is good at 2.7-3.8kHz on various stations. I am surprised if the BBC stations do not use a synchronized subcarrier, but there is no phase readout with them.

The local FM station is under my control, and I was under the impression that its RDS encoder automatically synchronizes with the stereo pilot tone in the MPX signal that passes through it, but I will try taking a direct pilot tone feed from the stereo encoder to the RDS unit to see if that produces a better result.


You're not the first who is surprised but all transmitters are installed and administered by people and all people sometimes do mistake or forget something or simply do not have time to solve what most listeners cannot recognize.
"I cannot believe the values, my P175 is probably bad, please help!" - This reaction is adequate natural. Well, it is not the R&S, nevertheless the measurement is reliable if the device is used in accordance with the instructions.
We have a station here with almost national coverage which does not synchronize RDS and pilot anywhere on their transmitters. Confirmed by their technician...


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