No subject

My small transmitter could easily create 20 Watts of OOK, FSK, or BPSK.  It
could also do QPSK.  I would guess that FSK would be a better first step away
from OOK.  The two frequencies would be easier to detect and lock onto that one
frequency and a stable phase reference.  Assuming we are using very slow QSK,
what happens if you miss the actual phase changes over several bit times, but
hear the mid-bit freq.  Using FSK, it would be easy to go back and determine
which freq is which bit, but deciding exactly what phase you have seen takes
more accuracy and more work.

You are correct Andre, either system has a significant penalty in creating real
power, and a linear power amplifier is better.  Maybe FSK would take less, but
if we are malking very minor FSK shifts, any non-linearities would probably
affect the frequency discrimination of FFTs by adding noise to nearby bins.

Anyway, let me know if I'm all wet.  As interest ramps up, we may need to
figure out how to easily reproduce my little direct digital sysnthesiser so
more LF people can have fun with other modulation schemes.

PS to Frank:  I have completed the LF preamp layout in Windraft, with two
copies per layout.  I can ut and paste more copies per printout.  Next step is
to make a few and test them.  I haven't played with the chemicals yet....

Terry, WB4JFI


Andre' Kesteloot wrote:

> Bob RIESE wrote:
>
> > I have been playing with Digi Pan PSK program on 20 meter; Under
> > uncrowded band conditions it will decode very weak signals, Looking at
> > the AMRAD 136 beacon using Digi Pan the signals appear the same or a bit
> > better.
>
> Hello Bob,
> You may also experiment with Winpsk, a very nice program indeed.
>
> As regard transmitting with psk, it would require using a linear amplifier.
> Now class B amplifiers on 136 are few and far between, require more
> attention than class D units, and of course, produce less power.
> Yet, it is certainly worth investigating.
>
> Thanks for your comments
> Andre' N4ICK
>
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