We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations. Always consult with the appropriate authorities if you have questions concerning what is permissable in your locale.

Author Topic: SDR - NBFM, or DSB, AM synchronous demodulation ? ?  (Read 6364 times)

Offline RadioAnarchy

  • Jr. Member
  • **
  • Posts: 43
  • south Louisiana swamp, bayou, and gator country.
    • Yahoo Instant Messenger - radioanarchy
    • View Profile
    • Radio Anarchy
    • Email
SDR - NBFM, or DSB, AM synchronous demodulation ? ?
« on: September 04, 2013, 2125 UTC »
hey Y'all...

I never messed with any SDR.

But have seen all this "waterfall" stuff.

So do these SDR's receive, in the MW/SW bands:  FM ? 
can  go narrow band FM ?
 have AM synchronous detection?   SSB ? DSB ? ? .

I have some things to try here soon...    I have a DSB modulator circuit
in my head, that can be applied to any of these little transmitters.
yes that is Double sideband, both upper and lower, no carrier,
or a low level carrier can be inserted, for synchronous demodulation.
The sound quality should be good, since there is no bandpass
filter involved.   

also may try narrow band FM....  1 Khz deviation or so..

years ago on 7415 kHz FM mode (the usual 5 kHz deviation)
I received on my Yaesu 757
the long version of "Inna Gadda Da Vida"     

funny, on the amateur radio bands you can not experiment like this.
It is too much work, or way too technical for most of them guys.
And they complain.    "oooh, to much bandwith"  etc. etc. etc.
Remember, on the HAM bands, when you hear them old guys with their
old vacuum tube radios in AM mode, it does not mean they know anything!!






rdla4

  • Guest
Re: SDR - NBFM, or DSB, AM synchronous demodulation ? ?
« Reply #1 on: September 04, 2013, 2229 UTC »
At least for and SDR-IQ, yes. NFM, WFM, DSB, Double Sideband Synchronous, Upper synchronous, Lower Syncronous.

In many respects, I think the demodulation <ability> is determined by the software that is used to "operate" the SDR. Some software handles synchronous AM better than others, I would expect the same on versions of FM. There is also a soft-limit on the bandwidth you can receive in FM mode.