[600MRG] Mark - Space frequencies / frequency

[Steve Elliston]

Hi Frank,

*1)*   490 / 518 Khz with a shift of 170 Hz means  +/- 85Hz of the carrier
frequency
So:
490kHz =
489.915kHz
and
490.085 kHz
and:
518kHz =
517.915kHz
and
518.085kHz

*2)* the foot note advises:
*"Assigned frequencies shown, for carrier frequencies subtract 1.7 kHz.
Typically specialized marine communications equipment uses assigned SITOR
frequencies while general purpose equipment uses carrier frequencies. Note
that stations share common frequencies."*
using NMF's 6314 kHz allocated freq as an example...
NMF could transmit FSK directly on 6314kHz
or
use a 1.7 kHz tone, shift keyed + / - 85 Hz in the USB with his tx set to a
carrier freq of  6312.3 kHz.
Either way the mark and space frequencies would be + / - 85Hz of 6314 kHz
ie
6313.915 kHz and 6314.085 kHz

(Of course, depending on his transmitter/modem he could use any combination
of carrier freq and modulated tone freq he liked...as long as he ends up
radiating on 6314 kHz.)

*3)* 630m WSPR dial freq i= 474.2kHz mode = USB.
Activity takes place in a 200 Hz band centred on 1.5 kHz (so from 1.4 kHz
to 1.6 Khz) in the USB .
If you were generating the frequencies directly (ie not using the USB) the
WSPR band would be from:
474.2 + 1.6 kHz = 475.8 kHz
to
474.2 + 1.4 kHz = 475.6 kHz
corresponding to mode = CW.

630m JT9:  as far as I can make out  JT-9 uses the same offsets as
WSPR...unlike on other bands.

I hope that helps?

73
Steve
G3XKR