Radio Data System (RDS)

[dxnerd]

@mcpaton

A duplication between Sydney and Albury or Cairns and Maryborough is unlikely to affect many people so it’s not a high priority to change these.

I live in Bungendore where both 2MMM Sydney and hit 104.9 can be received, with RDS on occasion.

[Moe]

I dunno if it is TP or TA - but Triple M Melbourne light up that flag on my car radio - and occasionally it will get into a mode where no matter what I do, it will jump from any station I tune to back to Triple M.

I find myself, if I don’t switch to a different input, switching over to listen to Magic on AM just because it won’t change bands to flip to it.

[ozbark]

@Moe

I dunno if it is TP or TA - but Triple M Melbourne light up that flag on my car radio - and occasionally it will get into a mode where no matter what I do, it will jump from any station I tune to back to Triple M.

If TP & TA flag is set from a station & your in local reception range, it would definitely cause issue from what I’ve seen demonstrated if unintentionally sent from station. TA should only be on for the duration of the Traffic Announcement. Difficult to imagine Triple M having the TA flag set permanently.

Consider downloading the RDS Spy software program if you have suitable tuner/SDR etc. One can easy fault find with this software & with sufficient study of the RDS standards etc.

[Moe]

@ozbark

Consider downloading the RDS Spy software program if you have suitable tuner/SDR etc. One can easy fault find with this software & with sufficient study of the RDS standards etc.

I think I had it all set up right - but I can’t get enough FM signal strength to get it to decode anything - in SDR# it was reading around 30, and occasionally barely decoding the RDS info - so I’m not sure if I had RDS Spy set up right and it just didn’t have enough signal, or I had it broken.

Is anyone else in Melbourne better set up?

[tvcl]

@Dingus

If I’m not mistaken, and Wikipedia is to be believed, TA should only be sent when an actual traffic report is being broadcast, and receivers can be set to change station to the station with that flag set, so as listeners can theoretically receive the latest traffic info.

Yes, TA should only be on when an actual announcement is being broadcast. I mentioned before that when I was driving around in Europe, there was a religious station that had TA on all the time and the car radio kept switching itself to that station (until I turned off TA/TP on the car radio). This switching happened even when listening to the Bluetooth source (as it’s supposed to).

If there’s no regulation of RDS in Australia by the ACMA, what’s to stop a station from just setting TA on all the time to get/force more people to listen? (At least for those who can’t figure out how to turn off TA/TP on their car radios)

[ozbark]

@Moe

so I’m not sure if I had RDS Spy set up right and it just didn’t have enough signal, or I had it broken.

A couple of notes follow from this:-

1. On the SDR# with ‘FM MPX Spectrum’ showing (Enable MPX checked). Is the RDS subcarrier at 57kHz clearly showing, as it should with a strong signal.
2. What program are you using as the audio pipeline/link between SDR# & RDS Spy?
3. If using a cheapo RTL-SDR dongle ensure gain is altered to get the best SNR & just before it starts to overload.
4. Very important & this follows from point 1, ensure your bandwidth is at least 135kHz wide, if narrower RDS decoding will either be unreliable or won’t occur.

@tvcl

If there’s no regulation of RDS in Australia by the ACMA, what’s to stop a station from just setting TA on all the time to get/force more people to listen? (At least for those who can’t figure out how to turn off TA/TP on their car radios)

EXACTLY. A good point. I can only imagine if a high powered FM station was doing this in a metro city there would be a tonne of complaints by both listeners & other radio stations directed at the culprit broadcast station.

[Moe]

@ozbark

• On the SDR# with ‘FM MPX Spectrum’ showing (Enable MPX checked). Is the RDS subcarrier at 57kHz clearly showing, as it should with a strong signal.
• What program are you using as the audio pipeline/link between SDR# & RDS Spy?
• If using a cheapo RTL-SDR dongle ensure gain is altered to get the best SNR & just before it starts to overload.
• Very important & this follows from point 1, ensure your bandwidth is at least 135kHz wide, if narrower RDS decoding will either be unreliable or won’t occur.

Used ABC Classic here as it’s the one I have the strongest signal of, Triple M is weaker still. I don’t see anything obviously showing as the RDS subcarrier, but then I’m not 100% sure what I’m looking for here

It is however showing some RDS info on the top bar, so seems like something is getting through?

Using VB-CABLE as the connection - it looks like something is getting through to RDS Spy because it’s showing there is an input signal - but clearly not enough for it to do anything with.

Using a very cheap RTL-SDR dongle, not sure exactly where I should be putting the gain though, I assume it’d just too weak of a signal in the first place.

[ozbark]

@Moe,

Okay something wrong with the config, probably with RDS Spy.
Your ‘Relative RDS Signal Level’ should be around -25 to -35dB (not -107dB).
Check in the RDS Spy config. Go to Configure --> Sound Card & ensure
that it points to VB Cable O/P.
Soundcard Input Mode: Direct RDS/MPX 192kHz.

Also ensure control panel VB Cable setup per RDS Spy instructions etc.

BTW Use VB Cable “HiFi” version. There are RDS decode problems with the standard version. Delete old version, restart PC & instal HiFi version (is free) & restart PC.

Bandwidth is fine.

In SDR# in menus open ZOOM FFT & tick the MPX display option. Nice to see the RDS subcarrier.

If SDR# is showing RDS internally as it is, then your signal level is fine/sufficient.

Try those tips for now

[Moe]

@ozbark

BTW Use VB Cable “HiFi” version. There are RDS decode problems with the standard version. Delete old version, restart PC & instal HiFi version (is free) & restart PC.

Thanks! This seemed to be the main issue - swapping to the hifi version and then ensuring it was all 192kHz seems to have made it all work.

So no sign of the TA flag - but I’ll try and check it occasionally and see if it does ever come on.

[RFBurns]

@Moe that MPX Spectrum looks very strange, what do the other stations look like?

[ozbark]

@Moe

Thanks! This seemed to be the main issue - swapping to the hifi version and then ensuring it was all 192kHz seems to have made it all work.

Excellent. Pleased to have helped. I’ve actually found the HiFi version of VB cable with RDS Spy slightly more sensitive or better at RDS decodes than the inbuilt SDR# RDS decoder.
Anyway hope you have some fun with it.

Have a look at the other Melb & Geelong stations with RDS.
You might find you can help fill in some blanks to the Aust RDS List

Australian RDS List

eg PTY & PI codes for 88.3, 97.7 Melb. Determine if JOY FM has reactivated their RDS
PTY & PI for 96.3 Geelong & other stuff etc

@Moe

So no sign of the TA flag - but I’ll try and check it occasionally and see if it does ever come on.

Sounds like a good idea

Have fun with RDS Spy.

[Moe]

@RFBurns

that MPX Spectrum looks very strange, what do the other stations look like?

Not sure what I’m looking at/for, but here’s a few:

Summary

@ozbark

eg PTY & PI codes for 88.3, 97.7 Melb. Determine if JOY FM has reactivated their RDS
PTY & PI for 96.3 Geelong & other stuff etc

No joy except for Joy, most of those I’m not getting enough of a signal from.

[ozbark]

@Moe

No joy except for Joy, most of those I’m not getting enough of a signal from.

Thanks for that. Good to see RDS back on JOY & I see their changed PS.

The low powered FMers can be a tough ask for the SDR dongles. The dongle SDRs are usually an 8 bit encoder/decoder & hence have limited dynamic range etc.

What’s the story with 3MBS? Their PS used to be 3MBS FM. Now showing as ‘Listen’ or are they now using Dynamic PS?

[Moe]

@ozbark

What’s the story with 3MBS? Their PS used to be 3MBS FM. Now showing as ‘Listen’ or are they now using Dynamic PS?

Yeah, dynamic

[Mechsta]

Triple M’s RDS in Coffs Harbour now says “Rock’s Greatest Hits”. I’m guessing this means a permanent change in format for the regional network.

[ozbark]

Listening to Mike Jeffreys on Hawksbury Gold 89.9: RDS has AF set as 91.3MHz, 91.9MHz (Method A)
I wonder where this RDS encoder came from?

[RFBurns]

@Moe

Not sure what I’m looking at/for, but here’s a few:

The Triple M one the mono frequency drops off quite significantly, but I don’t know what the audio was at the time? It also looks like there’s no Stereo sub-carrier, it’s levels are not much different to what I’d say is the general noise floor above the 57KHz RDS sub-carrier, but again I don’t know what the audio was at the time?

If you’re looking at the MPX Spectrum, from 0Hz to roughly 16KHz is the mono audio sub-carrier, the spike at 19KHz is the Stereo Pilot, centered at 38KHz & working back towards 19KHz & up towards 57KHz is the Stereo L-R sub-carrier (with the Bass frequency at 38KHz & the high frequencies on the outsides), 57KHz is the RDS sub-carriers (should normally be 2 peaks), going further up there’s normally nothing just noise, though sometimes there’s another sub-carrier here for other data, such as another audio program, etc.

[NDY]

94.3 Gippsland finally has RDS.

PS “HitFM”

No RT as far as I can tell.

I’m not sure if 97.9 has it or not, but I would imagine so. @mcpaton Do you have any insight into that?

[ozbark]

TCBL FM station; WHCR FM, 89.9 Hawkesbury, NSW now has RDS.

PI: 264C
PTY: Easy Listening
PS: WHCR89.9
RT: Windsor Hawkesbury Community Radio

Also has AF of 91.3, 95.1 MHz.

PI & AF programming/data almost a clone of TCBL Hawksbury Gold.
Maybe RDS encoder or PC feeding TX came from same supplier/tech ?

LATE NOTE Think station might also be using RT+, not sure if configured correctly, someone closer to transmitter might be able to determine.

[stilesykenny]

I wonder if 92.5 Triple M Gold Coast will change their format as well.