Tone heard over WLS (890) Evenings

[Ai4i]

Actually, if the two signals have perfectly matched signal strengths, then the detected volume of the "mixture" or "heterodyne" would be 100% modulation on positive and negative peaks. Whatever the signal percent of the weaker one to the stronger one is would be proportional to the detected volume.

 

[davideduardo]

Actually, if the two signals have perfectly matched signal strengths, then the detected volume of the "mixture" or "heterodyne" would be 100% modulation on positive and negative peaks. Whatever the signal percent of the weaker one to the stronger one is would be proportional to the detected volume.

Remember, this beat is being created in your receiver. If you have a receiver that has the ability to create very narrow bandwidth with nearly vertical slopes, you can "tune out" the het; DXers are very used to doing this to get 9 kHz separated Europeans from 10 kHz Western Hemisphere stations.

When we had receivers with crystal or mechanical filters, we'd often go to the widest bandwidth to look for hets, then select narrow bandwidth to DX the distant station.

 

[SomeRadioGuy]

Remember, this beat is being created in your receiver. If you have a receiver that has the ability to create very narrow bandwidth with nearly vertical slopes, you can "tune out" the het; DXers are very used to doing this to get 9 kHz separated Europeans from 10 kHz Western Hemisphere stations.

When we had receivers with crystal or mechanical filters, we'd often go to the widest bandwidth to look for hets, then select narrow bandwidth to DX the distant station.

Thats what I do. My radio has 3, 6 and 9 khz audio bandwiths.. i set it to 6 which is fine for the average US station, i don't get really anyone knockin into another station.. but at 6khz, if im tuned to say KKOB 770 ANQ, i'll hear that whine/het.. i switch audio to 3khz and tune up to 774khz to hear the 500kw transmitter from akita, japan

 

[Ai4i]

Synchronous detection is an even better way to reject an interfering carrier while preserving a relatively wide bandwidth.
It was an expensive proposition until Leonard Kahn came to the rescue with his mass-produced chips that separated the upper and lower sidebands.

 

[davideduardo]

Synchronous detection is an even better way to reject an interfering carrier while preserving a relatively wide bandwidth.
It was an expensive proposition until Leonard Kahn came to the rescue with his mass-produced chips that separated the upper and lower sidebands.

Of course, Leonard went on to kill the AM band with his lawsuits about AM stereo.

 

[Ai4i]

Of course, Leonard went on to kill the AM band with his lawsuits about AM stereo.

I had a portable Sony receiver (perhaps a 2010?) with one of his chips and it did/does what it did/does very well.
As for its original use, I have sampled most of the systems and ISB was technically the best;
it was the only system in which the stereo range matched the monaural range 100%.