Shorty, I use GE Mastr II repeaters & Mastr II mobiles for links. All these "flat audio" modifications are a waste of time. We have over 4 hops of links. The difference in simplex & duplex audio, if any, ain't enough to worry about. I don't understand the need to carve on perfectly good radios, designed by engineers a whole lot smarter than I, & gain very little in the real world.
Time & money can be put to better use on the real important stuff like antennas, duplexers, feed line, controller, & a good repeater to start with. I think sometimes modifications are done just for the sake of modifications. Fred N4GER -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Shorty Stouffer Sent: Wednesday, March 14, 2007 2:19 PM To: repeater builder Subject: [SPAM] [Repeater-Builder] Flat Audio Hi Group, Some comments of the flat audio thread... Flat Audio through a repeater simply means that the repeater does not mess with the audio through-put. The End-to-End audio path is flat through the repeater. There is no de-emphasis or pre-emphasis going on inside the repeater audio path. The repeater receiver leaves the audio alone, the controller leaves it alone, and the repeater transmitter leaves it alone. One of the tests that should be performed on every repeater is to test the audio frequency response through the repeater. A signal generator should be connected to the repeater receiver, and a full-quieting 1 kHz tone should be sent into the receiver, at say 3 kHz deviation. The repeater transmitter should be adjusted to also be transmitting 3 kHz of deviation, as measured on a service monitor. Then the audio frequency should be swept between 300 Hz and 3000 Hz in 100 Hz steps on the signal generator, and the transmitter deviation should not vary more than 1% or 2% from the 3 kHz deviation as viewed on the service monitor. That is flat audio through a repeater. In practical real-world service, every users transmitter pre-emphasizes the audio on transmit, and every users radio de-emphasizes the audio on receive. The repeater should leave the through-put audio alone, and your repeater will sound just like simplex does. No audio processing should be done inside the repeater, period. Jeff (Shorty) Stouffer, K6JSI Home: 760/ 724-4020 Cell: 760/ 716-7033 The WIN System The American Red Cross winsystem.org flataudio.com _____ Western Intertie Network www.winsystem.org
