"Jimmie D" ) writes:
"Joerg" wrote in message
.. .
Tim Wescott wrote:

Jimmie D wrote:

Revamping an old homebrew SW receiver I built about 30 years ago. Is
there an IC that will serve as an AM SSB FM detector. The existing
AM/SSB detector is on a board the size of a playing card.

You could probably twist some of the FM/IF detectors into doing that.
Many of them have RSSI outputs that go as the log of the signal strength,
I've seen literature that suggests you can block the DC from that and
feed an exponential stage to get AM detection with built-in AGC. For
SSB, if you switched out the quadrature filter for FM detection and
injected a BFO into the appropriate pin you could get SSB.

But if you're playing around with a board the size of a playing card, why
not build three optimized detectors, or get ambitious and slap down a DSP
with appropriate ADC and DAC resources?


But be careful with a DSP in a receiver. They require a clock and generate
all kinds of RF noises. Might have to be in a can.

Of course, a DSP can do all sorts of other stuff like DRM. Although I
doubt DRM will ever make it into the market.

This old dog would have to learn some new tricks to implement DSP. I thought
I remembered seeing a chip somewhere that did SSb AM and FM.

Tim's right there is enough room for three descrete detectors. I can easily
squeeze it all in if I redsign the board, Maybe a PLL circuit for FM unless
someone can suggest something more modern. Probably a special purpose chip
available that I am not familar with. I wanted to adFM so I could use the rx
with VHF/UHF converter. IF is 455Khz.

Once you've gone to a PLL, you're mostly there. Add a bit of phase shift
network (the old analog Signetics PLLs always seemed to get away with a bare
minimum), and a product detector, and you've got your AM detector. Then
you've got your product detector, so all you need is a crystal oscillator
for a stable BFO.

Michael VE2BVW