720 WGN AM Chicago...

[2M Guy]

on VHF?

That's what I hear when I tune to 161.745 FM. :?:

 

[Highlander_821]

Probably a remote broadcast pickup.

 

[Captain Kilowatt]

on VHF?

That's what I hear when I tune to 161.745 FM. :?:

How close to them do you live? It may be an STL or Studio-Transmitter Link. That is how most stations get the audio from the studio to the TX site.Some use special telephone lines and some use radio links. My stations were fed on 164.940,164.250,455.200,455.4875.450.2125,and a couple up around 960 MHz.

You sure it's not 161.760 MHz? It is a wideband signal.

 

[2M Guy]

The link doesn't work.

I don't know how far I am from the transmitter, but I'm about 40 miles (air) from Chicago across the lake.

 

[Highlander_821]

I don't know where their transmitter is, but I'm pretty sure the studio is in the Tribune Building, which is pretty close to Wacker and Michigan.

 

[Captain Kilowatt]

The link doesn't work.

I don't know how far I am from the transmitter, but I'm about 40 miles (air) from Chicago across the lake.

CRAP! Thats what I get for trying to link to an FCC database. The link had all the freqs used by WGN starting at 720 on air and included all their V/UHF STL and remote broadcast freqs. It worked for me right after posting it but I see it no longer works. :evil:

 

[2M Guy]

It must be a feed, it's about 5 to 10 seconds ahead of the broadcast on 720 khz. Downtown Chicago is about 50 air miles ( Google Earth) from me. Must have a good transmitter, I get it at S9.

 

[Master Chief]

It's not a feed. What you hear on 720 is after a required 7 to 10 second delay. The VHF/UHF transmissions are live.

Most radio stations are using T-1 digital lines to feed audio to the transmitter.

You can listen to KFI here in Los Angeles on 450.725. You can also hear the remote stations talking back to the studio.

 

[2M Guy]

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It's not a feed. What you hear on 720 is after a required 7 to 10 second delay. The VHF/UHF transmissions are live.

I meant "feed" as in a live feed to the station and Xmiter.

Is that what you are referring to, or am I lost again?

I understand why a delay is requied ( I think), to cut out anything that would offend the FCC and cost a station money in fines.

 

[Captain Kilowatt]

It definately sounds like an STL feed to me.The delay may be caused by one of two things.Either an intentional delay to ensure something does not go to air that shouldn't or, depending where the audio processing gear is located, something called propagation delay. It has nothing to do with radio wave propagation but rather the time lag in converting from analog audio to digital and back again if a digital optimod is used at the TX site.When I put a station on 94.9 a couple years ago the announcers were complaining about the echo they were hearing.The problem was that they were hearing themselves in real time and then the slightly delayed off air feed. Some propagation delays in some Orban optimods could be over 10 seconds long which is totally unacceptable in my boos. Ours was about a second.All in all my guess is that the delay is intentional.The long delay periods were pretty much confined to the really old optimods.