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What Is the Best Way to Send FM Program Audio to a Sister Station 40 Miles Away?

D

dx7

We need a reliable way to get the program audio 24/7 from one of our FM stations to another full-power FM commercial sister station 40 miles from our transmitter.

Is there a dependable option other than a T-1 line?

What kind of web-based or wireless solutions might work?

Is it legal to use a directional receive antenna and FM tuner to pick up our audio signal off-the-air and re-transmit it to the station 40 miles away since it is not a translator? The ERP of the originating station is 15kw from an HAAT of 400ft.

Thanks,
dx7
 
What do you plan on doing with the audio when it gets to the 'sister' station. That makes a difference in the recommendations.
Click to expand...

Chris, the stereo audio from the primary station will need to arrive at the sister station as a stereo input on the main console. From there we will use a microwave STL to get the signal to the sister station's transmitter.
 
I think there's a pervasive fealing that too many stations rely on Internet streaming for program sourcing. In addition to loss of quality from the codecs, the Internet simply isn't reliable enough. If you have a line of sight and about $10,000+ to spare, consider a 950mHz licensed STL. If you are in a region where an analog STL will work, Nicom still makes some that are a lot cheaper than the current digital units. You could also try streaming via some of the high powered unlicensed access points by Ubiquity, EnGenius or Motorola, though I've not heard of any being used for hops over 10-15 miles yet. Maybe someone here has done it. You might need two or three hops to create a solid link.

You can legally get program audio to the sister station any way you want, including from an off-air receiver, provided of course it's 100% simulcast with the main station. There are some technical issues associated with pulling audio off-air, but if carefully done, it will work just as it does for translators. Assuming it's stereo audio and it's feeding the sister transmitter directly, I'd be sure to use a professional grade FM receiver with a composite output and a mute. I'd feed the composite output into a composite clipper for absolute peak control and that should work well and will sound fine, provided that the primary signal is strong enough to be received under all weather conditions. In addition, I would provide some backup audio feed (even if it's a local mp3 player) and a silence sensor to autoswitch if the main station goes down.
 
One option may be to go with a Tieline that has ISDN as the primary and Internet as the fail-over. I believe their product will do that if you have them help you configure it that way. I did quite a bit of research on this when I was planning a project.
 
In our area their is an interesting loophole for the long distance issue when it comes to ISDN. There is a good part of the state that will get an OKC number when ordering way out there in other parts of the state. That's a benefit of our state being backwards. The phone company's switch for ISDN is here. LOL! Otherwise asking for a line extention back to your home area where you can call a "local number" is the way to go.
 
In the early 80s the Steve Dahl/Garry Meier show (Chicago) had picked up affiliates in Detroit and Milwaukee.
Don't recall how the Detroit audio was carried, but Milwaukee simply did receive 97.9 and retransmit the audio
on the local affiliate.

Once, when the show originated at a theatre in Milwaukee, the reverse was done,
and some minor FM atmospheric effects from the first hop were audible on the Chicago end.
For a 70 mile link, it worked really well.
But for geek like me, it was pretty interesting to hear "rebroadcast dx".
 
Check out the SureStream option on APT codecs. It sends up to four separate streams of the same program over two different IP paths and reassembles them at the far end to make one stream out of whatever data made it through. I haven't used this particular option yet but they showed it at NAB this year and it was definitely interesting.

I'm using a pair of APTs now to send a fulltime audio stream via the internet. It works...well enough. It's on commercial-grade Metro Ethernet or T-carrier-delivered Internet services at both ends, no DSLs/cable modems. The connection will drop occasionally and the auto-reconnect is less than perfect. Still, it's way cheaper than a point-to-point service. I would do something like that with ISDN as backup (make sure it alerts you somehow when it dials the ISDN, otherwise you might be in for a big phone bill if there's an extended outage).

The Barix stuff handles lost connections a little better but the audio quality on the codecs is not up to par. Have not messed with the Tieline Bridge-It boxes yet but those are my next project. Regular Tieline stuff over the internet works well for remotes and regular shows, have not tried a fulltime service on it yet. I'm doing MPEG video over internet services as well. Again, good enough.

It all depends on the quality of the service you're getting. Metro Ethernet, FIOS, and dedicated T-Carriers are the best. Cable modems are pretty solid and DSLs are the last choice. Remember that most stations get their streaming audio to the providers via some sort of internet service - and that tends to be fine. It's doable.
 
We simulcast a Class A for years using off air into an Inovonics receiver--composite directly into transmitter, but it also has left and right out. 25 mile path. When we split off the station added 25 feet to tower (well, replaced tower 3 feet away from old tower), using a 6' dish on transmit and 8' on receive. Rock solid path using 606 Moseley composite

Non-com in Toledo had a 60 mile path using STL-8's for years. Hamtronics preamps on receive cured some minor fading problems. They were up 500' on transmit end, however.

Here's a free program to give you some idea if your path is possible or not. Best to get second opinion if it looks iffy:

http://kb9mwr.dyndns.org/n9zia/path.main.cgi

Since you want stereo audio into a console at the receive end, you could use used STL-10's for the path. Even with big dishes on both ends, & 7/8th feedline, it will still be cheaper over a couple years than telco costs.
 
You may not want to use the off-air signal because it has been processed. Additional processing at your second transmitter site may very well make the audio over-processed.
Your best bet is to use a 950MHz STL. You may need two hops for reliable operation.
 
Comrex Bric is a great product but we are using Barix. The new reflector service emails me if we loose ANY component. Annoying? Yes. Helpful? Yes.

We are feeding sister station 2 which is 40 miles distant, sister station 3 which is 70 miles, 4 150 miles, 5 160 miles, 7, 75 miles.

ATT promises 95% reliability with T1 and that isn't enough. We have 2 broadband providers.

STL land is another story. One site now has a 38 mile hop from the roof of a building 150 feet to a dish 400 feet at the tower.

One station in Earl Park Indiana has a 50 foot send site and a 300 foot receive site. During morning hours when there was fog it would loose signal to a station in Richmond Indiana area at 1000 feet on the send end. I even verified the License of the sender. We discovered a problem in the cable of the 50 foot site and fixed it. No vswr on the stl but after replacement the signal improved 3db. This did not always overcome the station 160 miles away. In some areas this happening is common which is why most engineers over engineer their path. Fix it now and forget it.

40 miles is not an optimum path in most places. What height do you have to work with? I can run the path for you, pm me.

With our stations we have a satellite waiver. This is requested when licensed or at any point in the program. If you don't have a main studio waiver, request one. If this is noted for financial reasons, and how hard is that to justify today, it is usually granted. If you need info please pm me.
 
I'm a big fan of Telos Zephyrs. May I suggest you check out a couple of their products? First of all, there's the classic Zephyr Extreme. Put one on each end of an ISDN link and the audio is fantastic, the link bulletproof. Never had one go down, and I've used them for remotes, program transmission and even STL links. If you can't get ISDN in your area, Telos makes a new box called Zip One, it's a Zephyr that uses an internet connection instead of ISDN. Sounds great. Of course, the internet is unpredictable and if your carrier glitches - so does your audio. (ISDN never glitches!)

There's one other option, too; it's called a Zephyr Iport. It sends 8 channels of audio over a dedicated digital link. But this sounds like it would be overkill for what you're doing.

-- Doc.
 
One thing that's really cool about the Zip One is that it automatically adjusts for poorer network connections and dials itself down when the conditions get worse. I have noticed I have to re-connect to make it go back up though so there's still some user intervention but at least you won't probably have spitting and sputtering on the air when dialing down the quality would have fixed it. The box is a bit clunky to me on config, but it does work. If you're on a dynamic IP their directory really helps things. I'm using one as a backup for sat. feed show. When the ISDN line fails (because ATT sucks) we have another way of getting audio to the uplink. It's saved us a couple times so far and we've only had it for a few months. LOL!
 
Tom Wells said:
In the early 80s the Steve Dahl/Garry Meier show (Chicago) had picked up affiliates in Detroit and Milwaukee.
Don't recall how the Detroit audio was carried, but Milwaukee simply did receive 97.9 and retransmit the audio
on the local affiliate.

Once, when the show originated at a theatre in Milwaukee, the reverse was done,
and some minor FM atmospheric effects from the first hop were audible on the Chicago end.
For a 70 mile link, it worked really well.
But for geek like me, it was pretty interesting to hear "rebroadcast dx".
Click to expand...
 
I had a really good explanation of how to design a reliable off air antenna, but I exceeded the time limit for modifications. It would take too much time to rewrite. The board administrators ought to think about a longer time limit for modifications.
 
Rather than build an antenna, or going to other extremes, how about popping for $600-700 and get a great receive antenna from Katerine-Scala. They make both log-periodic and yagis that are very good at receiving distant signals. http://www.kathrein-scala.com/fm_log.php Thay are built incredibly well, so you won't have to replace it every couple of years.

Couple that with a good translator style receiver, such as the BW Broadcast RBR-X1 http://www.fm-receiver.com/ and you have a very reliable combination.

A 40 mile hop should be no problem at all.
 
The plan was for a phased multibay antenna to add nulls in specific directions toward cochannels and adjacents, not to build a single antenna. The only requirement is that they be identical. Cheap ones would work just fine. Like you say, you might have to replace them though.
 
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