On 2/12/19 6:31 PM, Bob kb8tq wrote:
Hi
The normal approach as you head from HF up through stages to microwaves is to
stop
at various points along the way. Just where depends on the actual noise you
measure on
the sources you have. (Yes you have to measure them yourself).
Once you have your noise plots, you can pick likely crossover points for a PLL.
You then
design the PLL to hit those targets. After that you measure the result to see
how close you
got to your target. Then it’s off to teak this or that to improve things.
The step by step process continues through VHF to UHF to microwaves as you move
through
various steps. Indeed you may change your plan once you see what your
measurements tell
you about each design iteration.
A lot also depends on just what your target actually is. Running PSK 32 at 22
GHz is a bit
different than running WBFM HDTV at 5 GHz. What works for one may not be ideal
(or even
close) for the other.
So yes, it’s a great way to spend a couple of years fiddling around …..
Bob
Decades -
This is what people who design deep space transponders (particularly for
radio science measurements) spend their time on.
One set of requirements says "we want to make carrier only measurements
with ADEV <1E-15 at tau=1000 seconds with Doppler"
Another set of requirements says "we want to send data at rates between
10 bps and 10 Mbps"
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