With RDS system on FM, the station broadcasts a 4-digit PI (Programme Identification) code as a unique identification. Relays of the station have the same code.
Each digit is a hexadecimal number 0-9 plus up A-F.
This station has PI of 42A4 - the same on the main station 91.1 and its relay 97.9. Radios can use this to switch to the strongest signal automatically.
Like a radio version of LCNs on TV?
And it’s not a number that consumer end tuners/receivers would normally show & not something that a user needs to know, but it’s a code that needs to be unique & carefully selected amongst broadcasters in same area to prevent incorrect frequency switching & other problems - that’s another tangent one can follow on the RDS thread.
It’s a code that techs & engineers need to carefully select & really only needed to be known to them & other radio techs of FM RDS stations in the local & surrounding broadcast areas. DAB+ has a similar code called SId, again not needed to be known by user & not normally displayed on radios.
Not quite, because TVs usually are in a fixed location and have a fixed antenna, but the code can be used by car radios to determine the strongest signal based on current location and can switch between the main and relay signals as the car moves around.
As in the case above, Hot FM Sunshine Coast has two frequencies - 91.1 for most of the Sunshine Coast, but 97.9 to fill in black spots around Noosa.
As a car drives up the coast, this feature enables a car radio to auto switch from 91.1 to 97.9 as the Noosa signal becomes more dominant.
Thats what the AF (Alternative frequency) is for.
Radio dont need to to see the same PI code to change to the strongest signal if the AF flag is set
The reason Hot91’s PI codes are the same between frequencies is because Tewantin is feed off-air with the baseband being re-transmitted
Though we have seen some car radios switch frequency bsed on either the last two digits of the PI code (sometimes if the first digit is the same as well as the last two).
For instance, when Nova 96.9 Sydney had 2969 and Hit106.9 Newcastle had 2069, my car radio switched between the two around Kariong on the Central Coast. I know another member here had a similar experience.
That could be debated as to whether that is a design fault however.
An explanation of the Bridge 99.7 FM antenna move has been written up in a local Redcliffe publication. They uploaded this screenshot to their Facebook today.
Thanks @Radiohead I’ll follow it up
I’m struggling to see how the relocation of a two-bay array costs $120,000?
Bridge is better but still nowhere near the reception it used to be where I am in Morningside
One week on from the end of Daylight Saving Time there’s still some radio stations with RDS Clock Time (CT) switched on., showing DST.
Its is strongly advised for stations to switch off CT from your RDS Encoder if you don’t have the manpower or resources or means to easily check or change this. I’ve seen some stations go for several Daylight Saving /Standard Time seasonal changes without altering their RDS CT settings.
Simply put, if radio stations don’t change this setting manually or to have the means to do this automatically, then the wrong time (one hour fast or slow) will be displayed on some users radios or vehicle RDS radio tuners for ~ half the year - annoying! 
I post this message in the community forum as usually a minority of the community radio stations are the worst offenders here (but certainly not limited to them), and as a community announcement. 
4AAA is broken again. This time with too narrow a bandwidth. RDS is gone and signal is mono. Volume is very low.
Callsigns need to be 10 letters long so they can change theirs to 4AAAARRGGHH!
They should swap call signs with 4DDD Dalby, to better reflect their credit rating in the world of radio.
4AAA should swap frequencies with Switch 1197AM! Dance/Pop music should be on FM not AM but country can go on AM 
The station is back to normal today - bandwidth and RDS. But it would have been a difficult listen yesterday when the audio level was very low.
We should get 4EB off FM first! Ethnic talk shouldn’t be wasting FM spectrum. It belongs on AM
@gordo92 said the 4AAA over-modulation issue was due to backup tape & they’ve turned it down, you guys never mentioned before it was on backup tape, just normal programming, was the backup tape really the issue & why was it on backup tape so often, seems they have more issues than just over-modulation if it was a backup tape issue?
You can thank the ABA for that one. Such a dumb idea giving 4EB the 98.1 FM slot and Switch the 1197AM slot.
Yes clearly done to protect the commercial FM stations.
