FM Stereo Pilot

FM does it with frequency!
fmrfman
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FM Stereo Pilot

Post by fmrfman » Fri Jul 15, 2016 9:10 am

Gents:

We have a translator that receives our main signal off-air. The receive antenna is located atop a water tower that over the years has gained company with a host of cell panels. At some point our receiver could no longer discern the FM pilot signal. We are planning on switching over to an internet stream to feed the transmitter but of course our older PTEK 300 watt transmitter does not generate a stereo pilot. Without having to buy a separate processor is anyone aware of a "low cost" FM stereo pilot generator?

Mark

jammerdave
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Re: FM Stereo Pilot

Post by jammerdave » Fri Jul 15, 2016 11:28 am

Maybe? https://www.aareff.com/en/fm-transmitte ... er-kit.htm

Surely there are a bunch of standalone stereo generator/encoders out there somewhere..

df

fmrfman wrote:Gents:

We have a translator that receives our main signal off-air. The receive antenna is located atop a water tower that over the years has gained company with a host of cell panels. At some point our receiver could no longer discern the FM pilot signal. We are planning on switching over to an internet stream to feed the transmitter but of course our older PTEK 300 watt transmitter does not generate a stereo pilot. Without having to buy a separate processor is anyone aware of a "low cost" FM stereo pilot generator?

Mark

fmrfman
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Re: FM Stereo Pilot

Post by fmrfman » Fri Jul 15, 2016 11:46 am


Kelly
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Re: FM Stereo Pilot

Post by Kelly » Fri Jul 15, 2016 5:30 pm

Are you looking for a stereo generator, or a pilot tone generator? Even less expensive audio processors, which you would probably need if using an IP connection for an STL, should have a stereo generator built in.
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Deep Thought
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Re: FM Stereo Pilot

Post by Deep Thought » Fri Jul 15, 2016 11:30 pm

You don't just generate the pilot signal (that's just a 19 KHz tone at 8-10% modulation). Does your receiver output baseband (composite) audio to the transmitter? Something about this doesn't make sense.
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Dale H. Cook
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Re: FM Stereo Pilot

Post by Dale H. Cook » Sat Jul 16, 2016 5:41 am

Deep Thought wrote:You don't just generate the pilot signal ...
Deep is, of course, correct. It sounds to me as though the OP does not understand how FM stereo multiplexing works. The transmitted pilot signal must be the same 19 kHz signal that is doubled to 38 kHz and used to generate the difference signal in the stereo generator. The pilot has to have the same frequency and phase as the original 19 kHz stereo generator signal in order to successfully demodulate the difference signal.

There is no way to reconstruct the correct pilot signal from anything else in the baseband, and you can't just insert any old wall-eyed 19 kHz signal.
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TPT
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Re: FM Stereo Pilot

Post by TPT » Sat Jul 16, 2016 6:54 am

That E-bay link is just for the circuit board for a Pira stereo generator--Pira doesn't seem to make them anymore, but something like that would be the simplest solution. Similar stereo generator cards show upon Ebay from time to time.

Have a similar translator problem where a spur shows up on the adjacent channel to my primary signal. Composite receiver won't work, but I can get a clean demodulated signal off a Sony tuner that I feed into the stereo generator built into the translator transmitter (Nautel VS300).

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Re: FM Stereo Pilot

Post by ChuckG » Sat Jul 16, 2016 11:58 pm

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Dale H. Cook
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Re: FM Stereo Pilot

Post by Dale H. Cook » Sun Jul 17, 2016 7:14 am

TPT wrote:... something like that would be the simplest solution.
and
The OP wrote that he is not getting the pilot in the receiver at the translator site. Without the pilot he cannot decode the difference signal or the L and R signals, so a stereo generator does him no good. He needs a reliable way to receive the incoming signal.
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Re: FM Stereo Pilot

Post by RodeoJack » Sun Jul 17, 2016 10:47 am

Dale H. Cook wrote: The OP wrote that he is not getting the pilot in the receiver at the translator site. Without the pilot he cannot decode the difference signal or the L and R signals, so a stereo generator does him no good. He needs a reliable way to receive the incoming signal.
I think the OP figured that part out. He wants to stream to the translator. If he has a lot of bandwidth, he can process at the studio and put a simple sg at the transmitter. Otherwise, he needs an FM processor up there.

This also suggests he actually can stream his audio under the rules.

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KPJL FM
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Re: FM Stereo Pilot

Post by KPJL FM » Mon Jul 18, 2016 9:20 am

RodeoJack wrote:
Dale H. Cook wrote:
This also suggests he actually can stream his audio under the rules.
Only if it a 'fill-in' or booster authorization. Or one of those NCE stations out of Idaho or Ohio :roll:

The OP might want to investigate the condition of the receive antenna system before changing the system. After many cell panels being installed, there's a chance his gear is damaged. Also consider changing location of the antenna.
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Dale H. Cook
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Re: FM Stereo Pilot

Post by Dale H. Cook » Tue Jul 19, 2016 5:31 am

RodeoJack wrote:I think the OP figured that part out. He wants to stream to the translator.
The OP wrote:

"Without having to buy a separate processor is anyone aware of a "low cost" FM stereo pilot generator?"

so I read that as him wanting to regenerate the pilot, not that he wanted to generate a composite signal - my bad.
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Deep Thought
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Re: FM Stereo Pilot

Post by Deep Thought » Tue Jul 19, 2016 10:41 am

Dale H. Cook wrote:
RodeoJack wrote:I think the OP figured that part out. He wants to stream to the translator.
The OP wrote:

"Without having to buy a separate processor is anyone aware of a "low cost" FM stereo pilot generator?"

so I read that as him wanting to regenerate the pilot, not that he wanted to generate a composite signal - my bad.
fmrfman wrote:Gents:

We are planning on switching over to an internet stream to feed the transmitter but of course our older PTEK 300 watt transmitter does not generate a stereo pilot. Without having to buy a separate processor is anyone aware of a "low cost" FM stereo pilot generator?

Mark
He needs an audio processor *and* stereo generator. Connecting this to the Internet without the former is asking for interference complaints when it overshoots to 300%, and without the latter it's mono.
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RodeoJack
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Re: FM Stereo Pilot

Post by RodeoJack » Tue Jul 19, 2016 10:56 am

Deep Thought wrote: He needs an audio processor *and* stereo generator. Connecting this to the Internet without the former is asking for interference complaints when it overshoots to 300%, and without the latter it's mono.
Yes. Sorry if I didn't make that clear. Nowadays, most any box I consider a real FM processor generates a composite output, so I never have to consider separate SGs. I have very few stations (2) that output processed audio to their exciters, and those have SGs built-in. Those two are processing at the studio (not my idea), using Bric-Links to the transmitter. We've had this discussion on another thread, but they're using HE-ACC, and while they sound quite good, sibilants tend to splatter severely. We're going to try uncompressed PCM on my next visit, to see what that does. The owner really doesn't want to put the processing at the transmitter, due to the site being difficult to reach during the winter, so there's a bit of a struggle there.

Not really sure why he set up the links with compression in the first place... he has 500 megs to his site.

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Dale H. Cook
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Re: FM Stereo Pilot

Post by Dale H. Cook » Tue Jul 19, 2016 12:36 pm

RodeoJack wrote:The owner really doesn't want to put the processing at the transmitter, due to the site being difficult to reach during the winter, so there's a bit of a struggle there.
Almost any digital broadcast quality processor in recent decades has remote capability built in, so since you will have an internet connection to the site you should be able to control the processor from anywhere. Heck, the first digital processor (Cutting Edge Unity 2000, ca. 1988) had a remote control interface, but it was RS-232, a bit more difficult to control over the internet than modern web page interfaces.
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