NFM/WFM, kind of an odd TVDX Catch:

[OSUBucks]

is it normal for to receive a signal NFM signal than a WFM signal?

here in Elyria, Ohio, I was able to pick up an audio signal I believe from London, Ontario Canada on TV 69 using NFM mode but as soon as I flip it to WFM, nothing but static. The broadcast is intended for WFM of course, that's the thing that puzzles me. It was actually a tad off of the normal frequency for TV 69 which is 805.75, I was receiving the carrier on 805.7625.


I am pretty sure I was getting channel 69 (OMNI 1)from London anyway and not some sort of remote/image of something since I was hearing some sort of advertisement for reggae concerts and the guide says "Caribbean Vibrations" was on during then.

Take Care!

Tony

 

[VE3RADIO]

OMNI 1 is a Toronto based station. It is not uncommon for TV signals to travel the clouds.. i get Pittsburgh, Rochester and Buffalo all the time here in Toronto... in HD no less.

 

[kb2vxa]

A TV audio subcarrier is narrower than an FM broadcast signal so it won't be nearly as loud in WFM mode and unless the signal is quite strong WFM has a very poor signal to noise ratio so it just got lost in the sauce. NFM is WAY too narrow but you'll get decent results particularly in FM mode if you're willing to put up with the distortion.

Here's an experiment I never tried with a digitally controlled frequency stepped receiver that works very well with analog dial tuning, you may want to try it sometime. An AM receiver can demodulate FM quite well when tuned halfway between center carrier and the channel edge. It's technically known as "slope detection" because it puts the signal on the side of the IF passband slope which causes frequency changes to translate into changes in amplitude, FM is magically (mathematically) converted to AM by the detector stage. I'd just rock the dial back and forth until it came in loud and clear, interestingly enough the audio disappears when tuned to center carrier where the signal is strongest and likewise when tuned off the edge which makes the process very easy.