About RDS...

[TimmyWA]

Folks,

I recently relocated to the Salt Lake City area. Apparently radio here is very unique as there are a number of 100kw stations but in order to cover the area, they require a number of repeaters/translators. My question is does this pose a problem with getting the rds data to be sync'd correctly? Do the stations in this kind of scenario have to put in RDS systems on all or the most powerful of translators and then somehow time-sync them to get the correct text info to be streamed out? Forgive me if the vocabulary and usage is incorrect.

Thanks,

-Timmy<P ID="signature">______________
Perfection is overrated...
www.marinifamily.org</P>

 

[tpt]

Depends on how the translators are fed.

"Traditional" translators were a receiver and low power transmitter in one box, receiving the main signal off air and "translating" it to another frequency. They would pass stereo, but not necessarily subcarriers. However, RDS is a 57 khz subcarrier, so it might pass through OK.

New translators are often fed by microwave, which can eaisily handle an additional feed of the rDS data.

Either way, if the RDS shows up on the translator, it should not be delayed enough to make any difference.

Incidentally, the RDS signal can also be used to switch radios to the translator signal if it is stronger than the main signal. This system is used a lot in Europe on car radios, but there aren't very many radios in the US that would have this feature.

 

[PhilJSmith67]

> Incidentally, the RDS signal can also be used to switch
> radios to the translator signal if it is stronger than the
> main signal. This system is used a lot in Europe on car
> radios, but there aren't very many radios in the US that
> would have this feature.

The RDS-capable radios in GM cars do this (the AF feature), but they do it very discreetly. As long as the station you wish to follow has the AF feature enabled and you store the station in a preset button, the receiver will "follow" the station from frequency to frequency. If you're in an area where the station+frequency stored in the preset is not present, the radio will immediately search the dial for the station.

There was a station in the Chicago area using it until about six months ago. I'm not quite sure why they disabled it... It worked very nicely on my Blaupunkt, and frequency hops were many times unnoticeable.

 

[tpt]

Thanks for the info!

Our one station is on 4 translators, gives me some incentive to pick up another little Inovonics RDS geni. Using one on our Class A with good results--indeed, I have a Blaupunkt Heidelberg in a rack as a monitor.

 

[PhilJSmith67]

> Thanks for the info!
>
> Our one station is on 4 translators, gives me some incentive
> to pick up another little Inovonics RDS geni. Using one on
> our Class A with good results--indeed, I have a Blaupunkt
> Heidelberg in a rack as a monitor.

That Heidelberg is a great receiver... A bit more sensitive than my Alaska-II but doesn't overload/desense. The DigiCeivers do a great job of "hiding" the AF frequency hop. There were times with 91.5 WBEZ Chicago and 89.5 WBEW Chesterton that I could see the frequency change on the display but not hear a dropout.

Nine-FM tried to get AF working on two of their three "trimulcast" stations in the Chicagoland area, but their bitstream was apparently botched. From my observation, I believe the radio would hop to the other freq, detect that it wasn't the "same" station, then hop back, wait a few seconds, then begin searching the entire dial, after which it cancelled the search and resumed the original frequency. The cycle would soon repeat itself because, obviously, the signal was already too weak on that freq.

The key is getting the AF and PI data programmed properly. Nine-FM apparently had different PI's, or perhaps was using EON with AF which should work fine if, again, it is programmed correctly.