Many years ago the great ham radio receivers often used triple conversion to get down to the Intermediate Frequency... if I remember it right.

And, I think they mostly converted down to 455kh as the Intermediate Frequency.

I'm wondering how modern receivers process the received RF signal until it is demodulated.

Thanks for any info.

 

On the opposite spectrum of superheterodyne receiver is DCR, direct-conversion receiver.
With modern digital technology we can receive and demodulate the signal directly.
Look up SDR, soft-ware defined radio.

https://en.wikipedia.org/wiki/Direct-conversion_receiver

https://en.wikipedia.org/wiki/Software-defined_radio

 

SDR, as usual with a lot of today's technology had military origins.

https://www.its.bldrdoc.gov/media/30649/bons_s.pdf

 

Ya, I always have been braining WHY western devices have 455 kHz whilst soviet devices have 465 kHz? Or there are no idea beyound only let it be anotherhow.


RE NsaSpook - My HackRF1 is worth to pay device, but those cheap USB stich is just the crap, it`s sencitivity is very low, noises criminallt high, and boosting the sensitivity by softwereadjusting givs catastrophy or in the speed of computer or blast of Nyquist noise. Never buy it for 5 USD.

 

Ya, I always have been braining WHY western devices have 455 kHz whilst soviet devices have 465 kHz? Or there are no idea beyound only let it be anotherhow.


RE NsaSpook - My HackRF1 is worth to pay device, but those cheap USB stich is just the crap, it`s sencitivity is very low, noises criminallt high, and boosting the sensitivity by softwereadjusting givs catastrophy or in the speed of computer or blast of Nyquist noise. Never buy it for 5 USD.

I would never use one as a professional receiver but as a general spectrum monitor (RF leakage detection using a cheap laptop) they do have a place in the field because they are low-cost and easily replaceable if lost or broken.

 

NsaSpook - Yes, me too, but there is one VERY disturbing nuance - if set the most widest screen resolution, the one screen drag by cursor means some 100kHz shift. For few MHz that is not a problem. But for many GHz its a hour to sweep say from 1 up to 2,4 GHz. Why they not programmed that all frequencies stands in the solely screen?

 

NsaSpook - Yes, me too, but there is one VERY disturbing nuance - if set the most widest screen resolution, the one screen drag by cursor means some 100kHz shift. For few MHz that is not a problem. But for many GHz its a hour to sweep say from 1 up to 2,4 GHz. Why they not programmed that all frequencies stands in the solely screen?

There are SDR scanner programs that generate full spectrum scans much faster than that but if you want speed, it's costs money.
https://www.rtl-sdr.com/

 

Yepppsk. But my religion not allows to buy ANY software product. Any discussion against religion are fruitless. Religion`s name is Creative Commons.

 

PS: none have commented why Wild West uses 455 kHz but communists East uses 465 kHz. Or none have no an idea why?

 

PS: none have commented why Wild West uses 455 kHz but communists East uses 465 kHz. Or none have no an idea why?

Maybe for the same reason the old Soviet bloc used 7.62x54R (.311) ammo that was slightly oversized for our .308 weapons. They could use our captured ammo in the Soviet weapons in a jam but we couldn't use their stuff.

 

Or like Spanish railway gauge was 5'6" while French gauge was 5' to prevent the French from invading Spain.