> Flat Audio through a repeater simply means that the repeater > does not mess with the audio through-put.
Most two-way radio people never use the term flat audio repeater. We would assume most standard voice audio repeaters operate as the mentioned so the "flat audio repeater" has never really been applied by Industry as a real description. Some Amateurs seem to want to apply the label and confuse the heck out of everyone. It appears that these people have done a pretty good job... To the Industry... the proper term is more likely to be "transparent". > 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. In reality that never happens 100%... the receiver, audio interface circuit and the transmitter modulator always "color" the audio to some degree. > One of the tests that should be performed on every repeater is > to test the audio frequency response through the repeater. In and ideal world maybe... but doing something about the differences is a lot more work/effort than most casual repeater people would really care to deal with. > 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. Actually... it's better described as "transparent 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. I hope not... most ham radios are over deviated. I depend on my settings to clean/limit many of the users ctcss and voice deviations up quite a bit. Simplex audio sounds dull and weak compared to a well thought out repeater audio chain. > No audio processing should be done inside the repeater, period. Another whole topic... but I like the sound of repeater audio with a slight amount of voice audio processing/compression. Life goes on... cheers, skipp ps: See some of you at IWCE later this month.
