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More on Barnraisings!Sample Schedules and Schematics from Our Radio Barnraisings Below! Technical Information on Our Radio Stations!
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What Is a Barnraising?
Prometheus Barn Raising
South Arundel, Maryland
February 15 -18, 2002
And The Knee Bones Connected To The ...
how the bird street station will work:
Audio will start either with one of the sources: the microphones, the cd players, the turntables, tape decks, cart machines, the phone patch, the computer, or whatever. It its good to have a few free spaces on your mixer or patchbay in so that people with their own audio sources (like minidisc players) can plug directly into the mixing board. Until more affordable Emergency Alert System receivers come on the market, you are not required to purchase one of these by the FCC.
All of this plugs into the mixing console. It comes out all mixed together at the appropriate levels, and goes to several outputs, including the headphones, recording deck, and the monitor amplifier. Some stations use a "distribution amplifier" for this, but you can also use a regular home stereo amplifier, if you do not have too many places to go or too much distance to cover. The monitor will power the studio speakers and speakers in other rooms in the building. It can either have a radio receiver built into the same unit as most home stereos do, or you can plug one into it in order to compare the sound coming out of the mixer to what is actually being heard by the listeners. With all receivers, it is important to remember that they should have a good antenna in order to be able to pick up the station.
The audio signal goes from there into the audio processor. The audio processors job is to make sure that the audio is not too loud or too soft before it goes to the transmitter. Compressors and limiters are examples of some kinds of audio processors, and they are small and cheap. There are also very fancy and expensive ones that can do more things to your sound. We are using two inexpensive compressors wired in the chain, one to take care of pre-emphasis and the other to customize the sound. Then the signal splits. One side goes into the soundcard of the streaming computer. This computer encodes the audio digitally into 1s and 0s and sends it to the router, which allows several computers to be connected to the same cable internet connection. From the router, it goes into the cable modem to a Server on the internet. This is a company with a really big computer, so that anyone who wants to listen to you over the internet can hear a copy of the stream as it goes out.
The other direction that the signal goes is into the radio transmitter chain. The signal goes into the transmitter and the audio signal is transformed into a radio signal. It goes into up the transmission line, into a lightning arrester, which is hooked by a fat wire to the antenna mast, which is in turn connected by a fat wire to a ground rod. The radio signal continues up the transmission line, past the lightning arrester into the phasing harness, which in turn feeds the two circularly polarized antennas, where the signal then travels through space and time to the listeners receiver.
Not shown is the uninterruptible power supply which is connected to critical components, like all the computers, the mixing console and the transmitter. Also not shown is the grounding system for the audio components, all of which are connected by bare, braided copper wire to a grounding bus, and then connected to a good earth ground at the studio and transmitter site. This chart shows only the main studio, and does not show a "pre-production" studio, for taping shows to be broadcast later.
