On Fri, 28 Nov 2003 03:26:01 GMT, "charlesb"
wrote:

Recently I have heard references from multiple sources about 9.6kb PSK
activity on HF bands.

I assume this refers to 9600 bit/s.


What's the deal on this? Is it a wide, multi-stream mode like Q15x25 mode?

It sounds illegal, but lots of things sound illegal if you are not familiar
with the facts. That's me...

A 9600 bit/s QPSK signal fits nicely within the same bandwidth
occupied by an AM phone transmission, with 8PSK (or 8QAM) the signal
would fit into the bandwidth of SSB phone transmissions. If the
bandwidth limit allows AM or SSB, then what is the problem with other
modes with similar bandwidths ?

I am not knowlegable about PSK packet. I do
have a "flexible" modem though, that will allow me to operate PSK packet at
a variety of baud rates... Isn't 1200 baud the limit on 10 meters, and 300
baud lower down?

That is a purely US specific issue.

Anyway, 1200 baud or 1200 symbols/s is quite capable of transmitting
9600 bit/s provided that the SNR is good. It requires that 8 bits are
transmitted within each symbol, i.e. each symbol can have 256 distinct
states. While 256PSK would hardly be practical, 256QAM might work with
high SNR and low phase distortion line of sight paths.

256QAM requires that the receiver must be able to detect more than 20
distinct states in both I and Q direction, thus quite small errors
will spoil the reception. However 64QAM (6 bits/symbol) are widely
used in Europe on the COFDM subcarriers used in digital television.

Paul OH3LWR