The phase transitions will use bandwidth too.
What is the power spectral density of your proposal?
Numbers, please.
----------------------------------------

Well of course any phase transitions will use bandwidth, but 1800 0.1 deg
transitions spaced out over 1/2 bit-time will will use less than a single
180 deg instantaneous transition, so it should be bandwidth-conservative. I
don't have the numbers (perhaps some of our more mathematical colleagues can
comment), but I'm sure the result will be a reduced-amplitude set of
low-order sidebands traded off for additional low-amplitude higher order
sidebands. My question wasn't whether the modulation would use less
bandwidth, but whether it would 'work' at the receiving end.

Joe
W3JDR



"laura halliday" wrote in message
oups.com...
On Feb 11, 1:42 pm, "W3JDR" wrote:
Does anyone know if continuous phase modulation (CPM) of the RF carrier
will
work with PSK31 systems?

(snip...)

The DDS chips used in a lot of new QRP designs commonly have a
programmable
phase-offset register which adds a constant phase offset to the RF
carrier
generated by the chip in very small phase steps. It seems to me that a
very
well-controlled, constant envelope phase modulated signal could be
generated
by sequencing the phase offset register through all the values in a
raised-cosine pulse prior at the transitions of each transmitted symbol.
This would result in a very simple, bandwidth-efficient,
constant-envelope
PSK31 transmitter implementation in QRP rigs that employ DDS.

(snip...)

Is there a flaw in this reasoning?

Joe
W3JDR

The phase transitions will use bandwidth too.

We already know the power spectral density of PSK31.
What is the power spectral density of your proposal?
Numbers, please.

Laura Halliday VE7LDH "Que les nuages soient notre
Grid: CN89mg pied a terre..."
ICBM: 49 16.05 N 122 56.92 W - Hospital/Shafte