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 ----- Original Message ----- From: "Rud Merriam" <[EMAIL PROTECTED]> To: <digitalradio@yahoogroups.com> Sent: Monday, November 19, 2007 12:42 PM Subject: RE: [digitalradio] Re: PSK63 activity! This is also rationalization. The ability to provide disaster communications entails many skills. Good contesting is virtually meaningless to that skill set. Rud Merriam K5RUD ARES AEC Montgomery County, TX http://TheHamNetwork.net -----Original Message----- From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Monday, November 19, 2007 6:26 AM To: digitalradio@yahoogroups.com Subject: RE: [digitalradio] Re: PSK63 activity! However, if there is any practical reason for contesting other than vanity and ego, it would be learning to become better operators. In doing this, we make the best use of spectrum in preparation for serving others as a partial payment for the spectrum that was awarded to us for doing this public service when called upon to do so. -------------------------------------------------------------------------------- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.16.0/1139 - Release Date: 11/19/2007 12:35 PM
