Thanks for responding Glenn!

Provided you implement the Tayloe mixer with sufficient baseband
bandwidth (probably about 20 KHz for NBFM), you can mix, say, a 2 meter
FM signal to baseband and demodulate it with an audio discriminator
(some sort of audio frequency to voltage conversion scheme). Mix the
signal to be either exclusively in the upper or lower sideband of the
output. So, for example, a NBFM sig at 146.000 MHz mix with the Tayloe
mixer set to 145.990 MHz and select the upper sideband. The upper or
lower sidebands are, as you probably know, selected by phase shifting
and summing circuits following the Tayloe mixer (implemented in
software in SDRs). Note that SDRs like the Flex-Radio SDR 1000 do not
process incoming signals near 0 Hz anyway, but mix the desired signal
centered around about 11 KHz (I think).
So the phase shifter is NOT for flatten the group delay variance (source is
the Tayloe mixer low-pass)?

Is multiplying I with Q enougth to demodulate FM as in a quadrature
demodulator?
I cannot find a suitable theory page to look for.


The Tayloe mixer is a passive mixer terminated in large capacitors, and
similar performance can be obtained at VHF, UHF and microwaves with two
FET ring mixers driven with quadrature signals and also terminated with
capacitors (that is, no wideband transformer on the mixer outputs, but
capacitors followed by HiZ input differential audio amps). I've done
this with the Peregrine Semiconductor FET mixers.
Thank you for given the link to Peregrine. I read the datasheet. How do you
mix it?
At the moment I prefer the Tayloe mixer because of it's simplicity.
BTW: They have a nice low-power consumption PLL being compatible to
National.

At TI I found nice tinylogic capable of switching like a 4066 down to 500ps
....
Should be possible to run the mixer at 150MHz with it.

Only familiar with the dsPIC, though the others sound okay. The dsPIC
would work, though its 12 bit A/D doesn't give a lot of dynamic range.
Plenty for NBFM though, especially since you can run the signal(s)
through a limiter first. For NBFM sixteen bit DSP is sufficient.
How much dynamic range do I need? I thought about 100dB?
If I recall theory I loss 2dB if limiting the signal to remove AM sensitivy.

regards -
Henry