Opera's AM key-clicks ,
VERY True , there has to be an associated bandwidth, however
, hard non-conditioned on off keying of a carrier will produce
, key-click's , this was the subject of a e-mail , sent to me some
time back, over my TX bandwidth on 477 /op8 .
Notably , the email enquired as to how my Tx b/w was in
the order of 10 MHz or less and not the mode usual 400 / 500 MHz
Its quite simple, I use the audio drive , via a
totally linear TX path ma1723 > skanti amp
What appears to be a simple task, is often quite complex ,
as is the use of the R-PI as a rf carrier source
The integrity of the timing loops [ as before] are
compromised by the higher order IRQ requests , hence setting
a flag high/low , with a executed code routine to
generate a 'stable' carrier source cannot be relied on.
In the development of the Opera R-PI tx code , the action
of the IRQ's could be observed as random noise , acting
cycle by cycle , hence any long persistence in the
spectrum plot , simply masked the spurs , however , the Opera dsp
returned varying s/n levels for the same test set up , indicating
the channel background noise varied. [ opera decoder is a sampling
system running far faster than the data rate ]
The project was shelved , other than for hard on-off keying
of a free running carrier , in this the clock jitter is of no
consequence.
73-G,
