Thursday, 16 July 2009

SMD parts arrived from Digikey this morning.
I have done some test soldering and it appears
that I can hand solder 0402 parts. It seems
essential to use solder paste to hold the part in
place. A quick search of the internet seems to
show that the best way to do it is to use a cheap
hot plate. I will try hand soldering though.

Now I know why I gave up hardware and moved
to software!

I found an interesting section in my book about CPM.
"Digital Phase Modulation" ISBN 0-306-42195-X


"It has been verified that it is possible to have
constant envelope digital modulation systems
which are more power efficient than QPSK and MSK,
for example. In some cases the power gain is
considerable; complex block or convolutional would
be needed to achieve it with traditional memoryless
modulation methods, and their check symbols would
increase bandwidth. In the schemes presented here,
the code is built into the modulator itself. The
redundancy of the transmitted signal lies in its tree
structure, and not in the insertion of extra check
symbols, and thus all the schemes have an information
rate that is larger or equal to one. That is of great
importance to the bandwidth occupancy of the
transmitted signal."

Still I have not got to the part that tells you how difficult
it is to obtain carrier, symbol and modulation index (h)
synchronisation yet!

MIL-STD 188-181C cheats by transmitting an MSK preamble
which is much easier to obtain the information from.

Still if something is easy to do then it is not worth doing
I suppose.

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