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AM Stereo STL

C

chriscollins

Hi guys... I post here some, but I am an IT Guy.

Is there an STL available that allows you to transmit AM Stereo with the Optimod at the Studio? We currently use a Digital STL to send two channel uncompressed audio to the transmitter with the Optimod located there.

I am trying to get that STL repurposed to my FM, so I can keep it's path digital all the way to the transmitter (On that station, I have digital board and an 8300 Optimod).

I need to find a relatively cheap way to get the am stereo out to the transmitter.

Can I get a suggestion from the guru's? I promise to help you in return on your next Radio Automation questions.... :)
 
Does the audio need to be full quality like your current setup, or just AM bandwidth? You could encode the audio using a high rate MP3 feed at 12KHz, and save a big bunch of bandwidth. Something like STL-IP might do the trick for you, or even a basic set of computers with decent sound cards, and streaming software like SHOUTCast.

I forgot to ask, does this need to be delivered aurally as your current setup is?
 
If you choose analog for your STL system, you'll need a pair of STL's.
You'll need to feed L+R into one of them and L-R into the other.
Even so, you may run into problems with the phase response between the two systems.
At the transmitter end, you will need some way of controlling the L+R level and the L-R level into your AM stereo exciter.
I the past, I have used an analog composite STL to get the AM audio to the transmitter.
I used an AGC feeding an FM stereo generator at the studio and an FM modulation monitor at the AM transmitter to recover the stereo audio.
I fed the output of the FM modulation monitor into the AM Optimod. It worked out nicely.
All in all, it may be less costly to purchase another digital STL for the FM. There is really no cheap way to accomplish the task.
 
Marti STL-10's are available cheap on the used market. Workhorse units, very reliable if reconditioned. If you have a digital path that works these things will loaf making the hop. Look at www.rpu-stl.com. Rick Neace often has some reconditioned ones available.

Plan on additional $450 for re-licensing/coordination.
 
frankberry said:
If you choose analog for your STL system, you'll need a pair of STL's.
You'll need to feed L+R into one of them and L-R into the other.
Even so, you may run into problems with the phase response between the two systems.
At the transmitter end, you will need some way of controlling the L+R level and the L-R level into your AM stereo exciter.
I the past, I have used an analog composite STL to get the AM audio to the transmitter.
I used an AGC feeding an FM stereo generator at the studio and an FM modulation monitor at the AM transmitter to recover the stereo audio.
I fed the output of the FM modulation monitor into the AM Optimod. It worked out nicely.
All in all, it may be less costly to purchase another digital STL for the FM. There is really no cheap way to accomplish the task.
Click to expand...

Ah, I think he said the Optimod was at the studio, not the exciter. Get a pair of Marti STL10s. One is left, one is right. Feed the output of the receivers into the left and right input of your AM stereo exciter. Problem solved.

I must interject however, that keeping the Optimod at the transmitter is the ideal situation. Get an Aphex Compeller to ride gain on the STL path.
 
Thanks guys. Just wanted to feel out some suggestions before I put a proposal together.

I appreciate the input...

Now, if any one of you ever needs to know how to do anything with the Audiovault, just ask me :)
 
Or you could use a conventional analog STL, take an fm tuner, go into the circuitry to the composite audio point, run the composite out from the STL to that point, and voila, at the tuner output will be L and R.
 
Mux to you.

I have been feeding sca signals over not the fm sca but the mux signal on my stl for some time. I am not sure how much mux bandwidth is avaialble but sca equipment is inexpensive compared to your options.

stl paths can be bi directional with a power divider from scala. if the path to fm and am are the same so much the better.
 
When I engineered an AM Stereo station back in the 80's the majority of the audio chain fed a standard FM stereo generator into a composite TL. At the transmitter there was a Belar FMS-2 modified to take the composite out of the STL receiver and demod it to left and right and that fed the NRSC processor to the stereo exciter. It worked quite well, too.
 
Bill DeFelice said:
When I engineered an AM Stereo station back in the 80's the majority of the audio chain fed a standard FM stereo generator into a composite TL. At the transmitter there was a Belar FMS-2 modified to take the composite out of the STL receiver and demod it to left and right and that fed the NRSC processor to the stereo exciter. It worked quite well, too.
Click to expand...

That's all well and good, until your STL, for whatever reason, takes a dump....or your stereo generator....or your Belar. Then you are off the air. With a discrete STL, you stay on the air...in mono. I have found it a good policy to keep as few components as possible in the chain. Fewer components, fewer points of failure.
 
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