[Fwd: LF: Narrow band modes - anyone?]
Sun, 03 Jan 1999 09:23:34 -0500
Andy Talbot wrote:
> Further to my last message on narrowband data modes.
> An alternative to PSK31 is 'Coherent' (BPSK) and is probably somewhat
> easier for most people to generate on LF - at least for those using direct
> carrier generation rather than a transceiver approach.
> A simple diode ring mixer in the PA drive (or even a changeover relay on
> the feed to the antenna !) will do the trick on transmit. For receive, a
> simple interface needs to be built. A version based on my PIC DSP interface
> with a different sampling rate and crystal is simpler still.
> At 1115z 1998/01/03 I'm currently transmitting SLOWCW with 10 second dot
> periods on 137.76 as requested by Marco. Only have 20 Hz steps so can't
> manage 137.77.
> Andy G4JNT / G8IMR