Skip you points are well taken. My point was not to mix another mode in with a RTTY contest.
If you really miss that smell of the machine oil and the "newsroom" clatter stop by some time. Still doing RTTY with a pair of 28's. One ASR and one KSR. John, W0JAB in the center of flyover country At 12:31 PM 11/19/2007, you wrote: >Maybe the FCC rules that say the minimum power needed for the communication >should be used also say that the minimum bandwidth needed for the >communication should be used! Of course, there is more to it than just that, >as multi-tone modes, such as MFSK16 or Olivia, etc, use more bandwidth in >order to better handle fading (and atmospheric doppler), but with an >increased latency that make them impractical for "RTTY"-type contesting with >fast exchanges. PSK63 is a reasonable compromise, and can be run at 1500 >watts as well as at 20 watts, as long as the amplification is kept linear, >and the equipment can handle a 90% duty cycle. > >The rationale for this is quite basic. For example, the phone bands have >just been expanded to accomodate more phone operators, at the expense of CW >and digital operating space. Therefore, if the minimum bandwidth for the >communication is used (by using PSK63 instead of RTTY, for example), there >will more room for CW and other digital modes. > >In the case of RTTY, the communication using PSK63 is very, very, similar to >using RTTY on a computer, except that PSK63 uses only about 1/5 the space of >RTTY. The speed of PSK63 is 100 wpm vs RTTY of generally 60 wpm, but the >extra speed is needed to compensate for the preamble and postamble of the >mode, so that during contest exchanges, the total exchange and turnover >times are roughly the same. PSK63 supports both upper and lower case, but >RTTY only supports upper case. However, PSK63 can also be typed and sent in >all upper case if desired. > >The comparison between RTTY and other digital modes is not nearly as close >as the comparison between RTTY and PSK63, so that supports the possiblity >that PSK63 can easily replace RTTY from a communication standpoint, and do >it in less bandwidth with a smaller error rate (due the to quicker >synchronization of PSK63), and with less power for the same distance (due to >the more narrow bandwidth and therefore better S/N). The main caveat is that >RTTY is better than PSK63 under multipath or atmosphic doppler conditions. >For these conditions, modes like Olivia and MFSK16 are more the equal of >RTTY, or even better. > >With a properly designed receiver (especially one that reduces AGC capture >by adjacent signals), more signals in the passband can be observed at one >time with PSK63 than with RTTY. > >I started with RTTY in 1956 with a Model 26 green-key machine, upgraded to a >Model 15 and later to a Model 19 with reperf, and enjoyed RTTY immensely. I >still miss the smell of the machine oil and the "newsroom" clatter of the >Model 15, and that is still available to those who have to have it, but for >the purpose of pure "RTTY"-type communication (and constests), the benefits >of PSK63 generally outweigh the benefits of RTTY, and would free up more >space for non-contesters during contests if RTTY were totally replaced by >PSK63. > >This is why I think there should be more encouragement to use PSK63 for >contests, including RTTY contests. > >73, Skip >KH6TY
