Rick, You are correct regarding bandwidth, there was several discussions awhile back regarding the 30 meter band where some argued that we were restricted to 500Hz, I didn't subscribe to this and I thought 1Khz was acceptable. Anyway my thoughts are based on what space is available so as not to cause QRM to other users on the band, what I see from the MFTTY widths when selecting a mode is anywhere from narrow (29Hz) to (986Hz) plus a S/N ratio of -27 to 8db. The normal mode (speed) provides 75wpm at 936Hz (bw) and a 0db SNR were as the 1/2 speed provides a 38wpm at 468Hz (bw) and a -3db SNR. Frankly I believe that Olivia and Thor will accomplish the needs of digital operators better. Thanks for your input I learn something every day.
Happy Holidays and a safe and wonderful 2009 to you and the family 73 de Ron W4LDE Rick W wrote: > > Ron, > > Although I am not strongly supportive of wide bandwidth modes in what > has historically been the narrower portions of the HF bands, I will use > 1000 or even 2000 Hz modes under conditions where a given band is almost > devoid of signals, or under severe conditions. This is not a criticism, > but where do you find any reference to an "allowed bandwidth?" > > There are no specific HF digital frequencies that I am aware of here in > the U.S.It is true that on the HF bands we have RTTY/Data portions and > phone/image portions. Digital modes can be used throughout the bands > based upon the type of information to be transmitted. (The third symbol > in the ITU Classifications of Emissions). > > The one change in the past few years was allowing image (fax), whether > digital or analog, in the RTTY/Data portions of the HF bands, providing > the emission is 500 Hz or narrower. But non-phone emissions have no > specific bandwidth limit except that they may not "exceed the bandwidth > of a communications quality phone emission of the same modulation type." > > There is a special restriction for stations in automatic operation where > there can be a 500 Hz limitation. But there is no such limitation with > operators communicating from their control points. > > Finally, there are band plans from various groups, particularly the IARU > and while they appear at times to not properly reflect current actual > operating practices, they can be used as a guide. > > 73, > > Rick, KV9U > > w4lde wrote: > > Russell, > > > > Thanks for the #1 MFTTY QSO on 30 meters. I would suggest that since > > the stated Bandwidth for 1/2 speed is 468Hz that probably that keeps us > > inside the 500Hz allowed bandwidth for most of the digital frequencies. > > > > > > > >
