Hi, >Huh??? > >De-emphasized audio has a tilted frequency response BY DEFINITION!
No, de-emphasized audio has a flat response in our system. It's tilted if you feed flat audio into a de-emphasis circuit -- but we never do that. We always feed pre-emphasized audio into a de-emphasis circuit, thus we always get flat audio out. >It can only be sort-of considered "flat" in a SYSTEM sense where the >results of an end-to-end communication are considered. This >receiver hearing a transmission from a remote transmitter utilizing >a complementary pre-emphasis curve. Exactly! Our system takes flat audio in and delivers flat audio out, and has pre-emphasized audio in between. The definition of our system holds that the audio coming out of the de-emphasis stage is flat, just like the audio going into the pre-emphasis stage is flat. >Even then - the results are a long way from "flat" due to the >dynamic interaction of various modulation components with the >transmitter's limiter [depending on their level]. Separate subject. In strictly pre-emphasis and de-emphasis terms, you can't change the flatness. Pre-emphasis is always precisely +6.000 dB/octave and de-emphasis is always precisely -6.000 dB/octave. The most you can do is move the corners, but our system has definitions of where the corners should be. >Although this is the conventional equipment configuration - either >simplex or repeater and either amateur or commercial, clearly - in >either case - amateur or commercial - the term "flat audio" is used >to refer to systems or links that avoid the use of pre-emphasis >and/or de-emphasis in some manner with the objectives of better >audio quality, lower distortion, etc. Clearly? I don't think it's clear at all to an outside observer, even one with a technical background. Such a person will be misinformed because he will believe that we transmit flat audio from our radios and that our repeaters pass flat audio from the discriminator to the modulator. We don't do that. 73, Bob ________________________________________________________________________ AOL now offers free email to everyone. Find out more about what's free from AOL at AOL.com.
