Dan wrote :-
> Your descriptions seem to indicate then that these devices can be
wired up fairly simply and put to work. Tell us more then, when you can.
They are indeed very easy to use, especially on transmit. On receive,
the I/Q demodulator has one or more variable-gain amplifiers which need
a control signal to reduce the gain if the input signal is too large.
This forms part of the AGC function; the control for which can either
come from the DSP or maybe from the ADC/Codec. This allows for a very
wide dynamic range.
Other than that the I/Q modulator/demodulators are relatively simple to
use. Of course, the appropriate microwave design techniques need to be
employed - correct impedance lines, good grouding, low-noise oscillators
etc, but that's also true of any microwave design - SDR or not.
I've put a simplified block diagram of an SDR for the 2.3GHz amateur
band on my website
ghengineering.co.uk/g8ubn
scroll to the bottom and there's a link to the PDF block diagram.
This is the part of the uWSDR project that I'm working on. FWIW, the
uWSDR team is also working on a 144MHz version following the same basic
design concept.
regards
Grant
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