Foreign format on 67kHz and Retirement home format aka Silver Memories radio (https://silvermemories.com.au/) on 92kHz
Was turned back off due to potential interference to/from the 67kHz Sub Carrier Audio and the RDS been jumbled up cause of it
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Ive never heard of sub carrier audio before on FM, do any other stations around australia use it or only 4MBS?
I donāt believe so, only 4MBS around my area (Toowoomba/Brisbane), maybe someone else can chime in if they know of any others
Used to be pretty popular. A good way to deliver in-store radio or foreign-language services. Youād usually get a thousand custom radios manufactured, locked to your specific frequency and subcarrier.
Not sure of anyone doing it now aside from 4MBS. The internet and DAB have largely made this irrelevant.
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Franklins radio was distributed in a bunch of places around the country back in the day via this method
Thanks for filling in the missing piece of the jigsaw puzzle re 92kHz 
Next time Iām up in Brisbane Iāll try to record some audio of 67kHz & ask a friend to confirm itās definitely in the Vietnamese language or not.
Are you positive the 67kHz ACS was scrambling the RDS RT? I suspected it could be. A video capture of MPX spectrum of 4MBS would have likely have proven it. 4MBS could reduce the modulation of 67kHz to reduce the bandwidth or intrusion into the 57kHz RDS subcarrier. Iām just thinkingā¦
2MBS used to run an SCA service back in 2009-10; this was an Indian language service. It could be faintly heard on my Sony XDR-F1HD by tuning to 102.4 or 102.6; the audio was mixed with heavy splash from the main 2MBS service.
The fact that the subcarrier was audible at all is a testament to the selectivity of the XDR series tuners. With the TEFs offering a similar level of selectivity, it might be possible to hear one (or both) SCA services by this detuning method.
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How does one tune into or decode the subcarriers?
Normally youād manufacture specially locked radios. But you could also use an SDR.
Yes, this was Indian Link Radio. Now an online-only service, but it was on 2MBSās subcarrier for many years.
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4MBS has historically been one of the more poorly behaved stations in Brisbane in terms of overspill onto adjacent frequencies - even on an excellent radio there is splash on 103.5 and 103.9, which might not help things.
My Sony canāt hear anything other than spill when tuned to 103.8, but the TEF can hear the Vietnamese language program under the noise if I lower the bandwidth and tune to 103.78 or there abouts. No sign of the other program from my quick check though.
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From memory, 2CBA/Hope ran this in Sydney. It was well before my time, though.
It wasnt interference from the SCās as the corruption in the RT never changedā¦ If it was corruption of the RDS it would be random and changing
I suspect a hardware problem in the encoder itself.. its a Harris gates TX
Thatās what I also presumed. I doubt even if the 67kHz SC was unmodulated it would consistently show the same corruption. But certainly one would expect that the BW between 57kHz & 67kHz would need to be tightly set to avoid interference to each subcarrier.
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Agreeā¦ RDS is pretty robust
the greatest threat to its integrity is the stereo pilot 3rd harmonic, thats why 90deg phase angle is super important to listeners decoding it properly.
RDS SC isnt that wide (should be 3kHz with 4% injection) and even taking to account the side bands it shouldnt interfer with SC @ 67kHz
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Easy FM Gosford 93.3 has RDS back on.. Still nothing from 94.1 Todayās Country on normal radios.
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Iāll confirm when Iāve got time
Must be the Mondo Rock relay of Sky Sports Radio