Soundcard & libfftw/gnuplot/little C program? A card capable of 96Khz sample
rates is not expensive and this will give you almost DC to 40 odd Khz at
any frequency resolution you like, with 90+db dynamic range.
You can also trivially write code to calibrate out small delays in the
system (take one FFT (of a 0 range target), then subtract it from all the
real plots. Hell you have 2 channels of input available and know roughly
what the carrier frequency is, so you know how much IF delay is 90 degrees,
therefore you can fairly easily generate a Q channel as well as an I
channel.....
Why not get a commercial Gunn/Pin diode module they are readily available
and not expensive.
This thing contains a gunn osc in the rear part, a slot for coupling and a
pin diode across the waveguide. Fairly crude but probably good enougth. I
have seen them on the surplus market rated at up to a 100mW CW.
This then solves all your RF problems, except the horn....
You may not have enougth rf at the pin diode with the circulator approach
as they like quite a bit of IF drive. Your delayed signal is at constant
frequency right? So why not remove it in your post processing? Or if the IF
is leading on the leakage just increase the length of the IF feed line?
Coil of low loss coax (or length of waveguide) fed from attenuator and with
one or more impeadence discontinuities to create reflections? The coax is
convinient as it is inherently lossy at these frequecies and you can just
short it at the apropriate distance.
And I would appreciate if you can teach me how to create a
Seems like IF to one input of the mixer, audio to the other, output to the
recever should work? Actually this generates a DSB signal around the IF,
but as I doubt your rig is smart enougth to tell the difference....
Regards, Dan.
- posted
18 years ago