CTA is Simulcasting!!

[That_Radio_Geek]

As I write this, I'm sitting at the Quincy CTA station with three radios on three different CTA frequencies: Blue/Pink, Brown/Purple/Yellow, and Green/Orange.

I'm noticing that everytime CTA Control or a train Operator keys up to give traffic, the exact same traffic comes over all the CTA train frequencies. That means it's an analog simulcast system. No matter what line you're listening to, you're hearing all the lines no matter what.

I didn't know this until today because I never had the opportunity to monitor all the lines at the same time.

The only line I don't hear simulcasting is the Red Line.

 

[wtp]

multicasting.
yes it fits both, but if different frequencies are used, it is multicasting.
and yes, you can't have enough radios !

 

[werinshades]

Each line(s) are on their assigned channel only from what I'm hearing, no multicasting.

 

[That_Radio_Geek]

Each line(s) are on their assigned channel only from what I'm hearing, no multicasting.

Maybe they only did it for a portion of the day? Or it was a mistake they caught? I was certainly observing and hearing them multicast.

My radios were: SDS-100, Kayotom D-10 rebranded as the Optimus (Hybrid POC/UHF and VHF), and Bridgecom Maverick.

 

[werinshades]

Maybe they only did it for a portion of the day? Or it was a mistake they caught? I was certainly observing and hearing them multicast.

My radios were: SDS-100, Kayotom D-10 rebranded as the Optimus (Hybrid POC/UHF and VHF), and Bridgecom Maverick.

Anything is possible, but was listening shortly after you posted and wasn't hearing any multicasting.

 

[ChicagoRadio736]

Anything is possible, but was listening shortly after you posted and wasn't hearing any multicasting.

Same here heard everything normal.

 

[werinshades]

Same here heard everything normal.

Yes, might have jumped the gun in a moment of jubilation.

As I write this, I'm sitting at the Quincy CTA station with three radios on three different CTA frequencies: Blue/Pink, Brown/Purple/Yellow, and Green/Orange.

I'm noticing that everytime CTA Control or a train Operator keys up to give traffic, the exact same traffic comes over all the CTA train frequencies. That means it's an analog simulcast system. No matter what line you're listening to, you're hearing all the lines no matter what.

I didn't know this until today because I never had the opportunity to monitor all the lines at the same time.

The only line I don't hear simulcasting is the Red Line.

Give it a little time to confirm before you post updates.

 

[ChicagoRadio736]

Yes, might have jumped the gun in a moment of jubilation.


Give it a little time to confirm before you post updates.

I wonder if it was a programming issue that's happened to me at times. Where I had frequencies mislabeled.

 

[Premises2972]

As a pretty regular CTA listener, this is a common thing, and the rail controllers have the ability to multicast on different channels. For example, when Power control sends out a message for power cut/restore, it goes out over al the rail channels. Many times, ch7 (brown/purple/yellow) and ch8 (red) are multicast because they share many of the same tracks. You'll often hear these 2 channels multicast in the mornings when the signal maintainers are out on the tracks, and Control needs a way to notify all Brown/Red/Purple/Yellow line operators of personnel on or near the right of way.

 

[That_Radio_Geek]

I wonder if it was a programming issue that's happened to me at times. Where I had frequencies mislabeled.

When I program, I double and triple check to make sure everything is correct. I had a second person on the platform with me who was also seeing it happen....they were also hearing traffic from other CTA train lines on the freq they were on. So, there was indeed multi-casting goin g-n on. So there are two people now saying they witnessed it on their own radio as well. The only other thing I can think of that would explain it is because we were downtown, maybe we were close to a CTA repeater and we were getting images from other CTA freqs?