I wasn't so concerned about whether it's ISB, DSB, or whatever; I was more interested in the comment that it would make the rig easy to build. If a simple rig were built with two balanced modulators from a quadrature RF source (easy to do), using stereo audio with a sound card program designed for quadrature audio components would let you produce whatever kind of signal you wanted to... simple and inexpensive. And the corresponding receiver would also be simple and inexpensive.
If you wanted to produce a pair of PSK31 signals separated by, say, 150 Hz, with a pilot carrier between them, it'd simply be a matter of building the appropriate waveforms to make it happen that way. Basically, a cheap software-defined radio, covering a small segment of a single band with a single crystal oscillator. By the way, I just checked part 97 -- ISB is legal (type "B" emission) within certain guidelines... - ps Walt DuBose wrote: > If you place different data on either sideband, its ISB which is illegal or > if > not now, may be in the near future. > > However, if detecting either sideband independently does not produce separate > data streams, then its not ISB. > > DSB would only double the information of one sideband so you would want to > use > the other sideband for more data. > > The question you have to answer is which is better...doubling, being > redundant > as with interleaving or sending characters twice or obtaining a greater bit > rate > or raw throughput. > > Another consideration is what would the bandwidth be with DSB where two 350 > Hz > PSK modes were sent? The bandwidth would be 770+ Hz. > > I think that you would still need a raised cos or filter on the transmit > tones > as well as a brickwall filter on the received signal. > > Noticed I said think because I haven't really had time to totally digest the > use > of DSB but I kinda like the approach. A 100 watt PEP DSB transmitter is > sooooo > easy to build. Using the FCC-2 oscillator as described in the Feb. QST, and > a > low level diode balanced modulator and several stages of amplication, you > could > easily build a 100 watt PEP (50 watts per sideband) transmitter. But the > problem is finding an ISB receiver which you would need. Perhaps a direct > conversion receiver with a Q/I (?) detector and DSP brickwall filter would > work. > > Walt/K5YFW
