Jim Brown wrote: >> Because with the close spacing of signals in the various PSK sub-bands, a >> signal of more than about 50watts will completely annihilate all the other >> PSK signals and make that sub-band unusable for everyone else. > >This is urban myth that keeps getting propagated and eventually >everyone believes it as gospel. [...]
The reason why a strong signal will "annihilate all the other PSK signals" is that most users are trying to receive an entire 2.5kHz bandwidth in one gulp. This means that even one strong signal within that bandwidth will activate the AGC and drive all the other signals down. Regrettably most PSK users don't understand what is happening, so they have to rationalize it into simpler terms like "It's a crime to be loud." >There are MANY factors that contribute to signal strength, including >antenna efficiency and gain, antenna pattern, propagation, and yes, >transmit power. Of those factors, transmit power is the SMALLEST. And propagation is by far the BIGGEST factor in making someone's signal loud, for the most innocent of reasons. >What is FAR, FAR more important to prevent interference is making sure >that your signal is CLEAN -- no sidebands produced by audio distortion, >or by distortion in a poorly adjusted rig or power amp. IMD is certainly another important factor. Naturally, IMD will show far more clearly on a strong signal than a weak one so once again this gets rationalized into "strong = IMD". But PSK's big, unacknowledged 'elephant in the room' will always be the habit of receiving in a 2.5kHz bandwidth. Unfortunately this is deeply engrained in the PSK culture. -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
