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Calculating total impedence....

I

Ian Buckner

Paul Burridge said:
Transient response is of significant interest at RF for
TDMA systems and radar, for example.

I'm just wondering about something someone said earlier in the thread.
|s the idea of pulsing an analogue RF circuit to deliberately try to
induce it to oscillate and thereby show up any inhrerent instability
in the system?
That would make a certain amount of sense. OTOH, there's something I
dimly recall about somone-or-other's factor. You carry out a
calculation using a relatively simple formula and if the answer comes
out at less than one, the system will be stable; if the answer's 1 or
more, then it's liable to oscillate. Anyone remember this or am I
dreaming it?
It's been a long while and one's memory can play tricks.
--

"Windows [n.], A thirty-two bit extension and GUI shell to a sixteen bit patch
to an eight bit operating system originally coded for a four bit
microprocessor and produced by a two bit company."

Try "Stern stability criterion".

This is not really what I was referring to, however.
In TDMA systems, the RF burst envelope edge shapes are
tightly controlled to ensure the transmitted spectrum meets
a specified mask. This is done by controlling the transient response
of any filters in the signal generation path, and "shaping" the
modulation function in the time domain (even to the extent
of having to pre-distort to cater for RF device non-linearity).

Regards
Ian
 
P

Paul Burridge

Paul Burridge said:
Transient response is of significant interest at RF for
TDMA systems and radar, for example.

I'm just wondering about something someone said earlier in the thread.
|s the idea of pulsing an analogue RF circuit to deliberately try to
induce it to oscillate and thereby show up any inhrerent instability
in the system?
That would make a certain amount of sense. OTOH, there's something I
dimly recall about somone-or-other's factor. You carry out a
calculation using a relatively simple formula and if the answer comes
out at less than one, the system will be stable; if the answer's 1 or
more, then it's liable to oscillate. Anyone remember this or am I
dreaming it?
It's been a long while and one's memory can play tricks.
--

"Windows [n.], A thirty-two bit extension and GUI shell to a sixteen bit patch
to an eight bit operating system originally coded for a four bit
microprocessor and produced by a two bit company."

Try "Stern stability criterion".

This is not really what I was referring to, however.
In TDMA systems, the RF burst envelope edge shapes are
tightly controlled to ensure the transmitted spectrum meets
a specified mask. This is done by controlling the transient response
of any filters in the signal generation path, and "shaping" the
modulation function in the time domain (even to the extent
of having to pre-distort to cater for RF device non-linearity).

Regards
Ian
 
P

Paul Burridge

Try "Stern stability criterion".

Your suggestion prompted me to look it up. The one I was actually
thinking of is the "Linvill Stability Factor" which may or may not
amount to the same thing. Neither Stern nor Linvill means anything to
me now, though. :-/
 
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