In another thread the thought of using an internet connection to provide content for multiple transmitters came up. I've been thinking about this since I may need to do the same thing. Here are my thoughts (though incomplete an untested).
In another thread the thought of using an internet connection to provide content for multiple transmitters came up. I've been thinking about this since I may need to do the same thing. Here are my thoughts (though incomplete an untested).
Yes this should work! If you feed all the transmitters with the same stream, then they should all be pretty much in the same time. The difficult part would be working out the hardware, and doing it on a limited budget. There are several IP-audio devices that you could buy, most of them are more geared towards remote broadcasts instead of using a Marti or ISDN or other phone line. But my thoughts are that if you were able to devote a small computer to do nothing but play back a stream, you could use this computer to feed a transmitter. Then all you would need is an audio stream (private or public) to carry the audio. Since we are going to use Shoutcast for our stream, I thought about using Winamp to do the playing portion for each transmitter. I was thinking about doing this over a 2.4Ghz wireless network, but it would be cheaper and more reliable over a wired network. Target computers would be one of the Via mini-ITX mainboards, probably with a slow CPU and fanless to cut down the amount of electricity used. The hitch would be to get Winamp to start when the computer boots, and getting it to connect to your stream without needing human intervention.
This is about where I stopped. Additional thoughts are that the delay between different transmitters might be enough to cause problems in the overlap area, but if you don't really have an overlap area, then it won't be a problem. The other thing I thought of is that at some point you will need to use approved transmitters, you can only have a certain number of kits running. I think that limit is 5 kits. And if you go with something like the Rangemaster, you might want/need to do things differently to allow them all to syncronize.
Greg,
From your posts on other threads I presume you are talking about a campus system. I have no expertise in internet audio but I do have another suggestion.
It would not be unusual if your campus has many wires running around building to building which could be available for audio feeds to transmitters at no cost. Telephone or CAT5 cable may be in place. At the college where I taught, the CAT5 and telephone trunk cables were left in place yet they were abandoned when the campus converted to fiber optics.
Just a thought.
Neil
Our campus has lots of fiber, as well as dry pair that I can steal, but I was actually thinking on a larger scale. If you are going to be streaming your audio, then all you would need to do is reserve the IP for your priority clients (for the tranmitters). If you happen to be able to get all this done on an intranet (like many school systems now have), then it makes life even easier.
At my place, we are a county owned/operated school, so in theory I might be able to stick a transmitter at every country owned property that has an internet connection. I was thinking about the Wifi because it would give us a way to do some remote broadcasts where there is no internet available. I nice high gain antenna up on the tower, and we would have line of sight to the "metropolis" and much of the surrounding suburbia. You can get pretty far out of some of those high gain directional 2.4Ghz antennas, especially if you have one on both ends.
At some time we will purchase a couple IP-audio devices so that we can cover sporting events and other things from different buildings, and also to allow a much more broad reach for any away sporting events that we might want to cover. Just about any other college is going to have an internet connection somewhere near the playing field, so all we would need is the IP address back to home, and suddenly a connection is made. But that will be farther down the road.
I could do the same thing put a cpu at the tower sites just to stream to. I did soem more talking and have been able to to come up with 5 tower locations to put transmitters. All would have access to electricity and phone lines.
The tower sites at the schools would be my first choice. That way they probably have a full time ethernet based internet connection that you could use. But first you need to start with one transmitter and see what kind of realistic range you get. And since you are going to have to use multiple transmitters, you might want to think about the Rangemaster for the reasons I've mentioned in a couple of other posts. That way you would have a rough performance baseline to determine the coverage of the other locations.
I wish I had more free time, playing with this kind of stuff is fun, and I would love to be able to come and help.
Yes I agree, I want to try to set up at me residence first, I am less then 1 mile form town as the bird flys. I want to see how far I get into town. I will look at purchasing a Rangemaster to see where I get. I have two clear frequency here during the day and night 1620 and 1640 are good. I have an HD radio in my van and I here nothing on those frequencies. I wish you did have time I nedd someone more experieced tech wise. I am better at programming, production and imaging.
An internet STL system has one major problem. It's called "latency" or the delay caused by data packets being transfered by servers between the head end and the target computers. Even cable modem systems have latency rates exceeding 20 to 30 seconds. The rate of latency will float up and down depending on the load on bandwidth over the internet.
Streaming audio can be sent over the internet, but each transmitter needs to have it's own frequency. The best idea is to test one transmitter installation. Then graph out the coverage of each similar transmitter site.
The latency challenge will not allow transmitters to use the same frequency, even though you might be able to "sync" up the RF signal. Those of us with internet live streaming radio stations have discovered by experience the challenge of audio latency. Good luck.
Marshall Johnson, Sr.
Senior Pastor, President
Rhema Christian Fellowship, Inc.
Rhema Radio - The Word In Worship
AM 1660 - FM 93.5
http://www.rhemaradio.org
The latency challenge will not allow transmitters to use the same frequency, even though you might be able to "sync" up the RF signal. Those of us with internet live streaming radio stations have discovered by experience the challenge of audio latency. Good luck.
OK, that answers that question. But the latency may not really be an issue since the client will need to buffer the audio to some extent. But getting them all to buffer to the exact same point in time would be impossible! I've tried this on about 16 computers all connected to the same lan (all in the same room too). Each machine was playing at a slightly different point, even though the settings were all the same. This was the one big problem that I thought would happen with this type of delivery system. So as long as you didn't have any over lapping coverage spots, it would work. But if it overlapped I can't suggest what it might sound like. For that test I was using ashoutcast server, and winamp as the client with AAC+ encoding. Even the decoding code make a small difference in the synchronization. Then again, maybe it was small differences in latency, though on this lan the latency is always extremely low