>>> Is 2.1kHz really overly narrow for SSB transmit? I know people are >>> talking about 1.8kHz filters for RX, and it seems useless to transmit >>> energy that's not going to be used. It's certainly wide enough for >>> data modes. In fact, it might be useful to be able to TX through the >>> 400Hz filter in some of those modes. >>>
I seem to have lost track of (or even lost) some of the discussion here. Ed, W0YK commented on why a somewhat wider signal is good tactics for SSB contesting (that's much more relevant to his station then mine), but an interesting POV. Eric, WA6HHQ said that 2.1kHz bandwidth audio would sound "thin", and that was apprently undesireable. Is this just a marketing issue, or is it truly the case for communication? I know almost nothing about pyschoacoustics, but I do know that once upon a time, the Collins 2.1kHz mechanical filters were the standard in military comm gear. And I thought that the frequencies between 500Hz and 2500Hz were the significant ones for understanding speech. I note that the transmit audio can be tailored within that bandwidth by the 8-band TX EQ. The TX filter width is irrelevant if the signal going into the filter is very clean and bandwidth limited by the DSP, but I'm a belt and suspenders kind of person in some cases. I also note that these are 6db bandwidths, so that frequencies on the edge are going to be attenuated somewhat, which is why I wouldn't choose to use a 250Hz filter for a 170Hz FSK signal (I think some of those sidebands are significant, but haven't done any real research on this). But if I wanted to transmit a particularly clean signal, I might choose the 400Hz filter for that. 73, doug _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
