Usually, the Winlink bulletins specify the frequency as the average of the channel for P1 or P2, and 1500 Hz above the dial frequency for P3.
It has been long usual to define the frequency of an RTTY signal as the RF frequency of the mark tone. And so on. If you want to define univocally something on the air, you refer to some distinctive feature of its RF spectrum. How you achieve it does not matter, as long as you get the same frequency of that distinctive feature on the air. Otherwise, you must specify TWO things, dial frequency, +/- audio frequency. Why state two numbers if one is enough to define it ? 73, Jose, CO2JA --- expeditionradio wrote: > --- In digitalradio, W4LDE Ron wrote: >> I recommend that we all start using the VFO plus the audio >> frequency or waterfall frequency. Ron W4LDE > > Hi Ron, > > I agree. > > Some modes are appropriately defined by RF centre frequency, Some > modes are appropriately defined by VFO dial frequency. > > There certainly are many operators using digital soundcard modes who > do not have CAT control on their rigs, so their display does not show > the mode's RF center frequency. > > Probably the majority of hams on PSK31 don't use CAT control... they > simply set their VFO dial frequency to 14070 USB. To know their RF > frequency, they must calculate it by adding the audio frequency to > the dial frequency. Many of us understand this mainstream fact, and > define our sked frequency by VFO dial frequency + audio centre > frequency. > > There is a trend to simply use the USB VFO dial frequency as the > reference point for MFSK modes, with about ~1500Hz audio center for > the signal. This rule of thumb enables a sked QSO to switch any mode > or flavor that is desired by the operators at the time, and > appropriate for conditions. > > The digital protocols that use fixed frequency audio signals are > almost always defined by VFO dial frequency. Especially when there is > a mix of voice, images, and data, it is by far more convenient and > appropriate to simply call out the VFO dial frequency. > > Bonnie KQ6XA __________________________________________ V Conferencia Internacional de Energía Renovable, Ahorro de Energía y Educación Energética. 22 al 25 de mayo de 2007 Palacio de las Convenciones, Ciudad de la Habana, Cuba http://www.cujae.edu.cu/eventos/cier Participe en Universidad 2008. 11 al 15 de febrero del 2008. Palacio de las Convenciones, Ciudad de la Habana, Cuba http://www.universidad2008.cu
