Bob M. wrote: > This is getting slightly off the original topic... > > I suppose some mild amount of equalization can help, but it can also > be implemented completely incorrectly and cause a lot more harm than > good. > > Case in point (Dave M, start laughing) is a local UHF repeater. The > trustee has a slight hearing problem (loss of high-freq) and almost > all of the users have Yahoo handhelds (VX2s, etc). Naturally there's > an EchoLink port and multiple receivers, and links to just about > everything in the area. The main repeater has had its pre-emphasis, > audio filtering, and limiting defeated and a stereo EQ feeds it. > Basically it is a straight line from -20dB at the low end (20Hz) to > +20dB at the high end (20kHz) using both channels in series, way more > than the standard 6dB/octave pre-emphasis, and no low-pass cutoff > above 3 kHz. No test equipment was used to set up levels; it was all > done by ear in an attempt to get FM broadcast-quality audio out of a > 1 inch speaker. > > So with no limiting or low-pass filtering, the repeater puts out > strong sidebands up to 20 kHz away, pretty much ruining any use of > another repeater that's the reverse split, 25 kHz adjacent, and 13 > miles away. A deviation scope shows peaks out to 7 kHz, but a > spectrum analyzer shows a much wider bandwidth, almost all of which > is high-frequency noise from marginally weak signals that gets > amplified way out of proportion to the actual voice audio. >
You do know that's malicious interference, and he can be shut down? It's been done here!
