"Norm Mann" wrote in message
news:vSzhi.529$fw2.411@trnddc04...

"Jimmie D" wrote in message
...

"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.

Anybody remember back in the "old days" using a super-regen receiver?
Centering the signal in the passband gave AM, tuning off to the side one
could slope-detect for FM and if the regen control was set high enough to
make the detector break into oscillation, (in essence, inserting a BFO)
one could then detect CW/SB signals.

Just reminiscing,

-NM



Seems like not so long ago I built a little rush box to listen in on Lo band
VHF hiway patrol.

Jimmie