Talk:Beat frequency oscillator

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Shound't that be a "highpass" filter such as your ear (instead of lowpass?)

The ear of course is technically bandpass. But in the context of the article I think lowpass makes the point better, because it emphasizes that it is the higher frequency components that the ear removes. --Bob K 18:43, 21 December 2006 (UTC)

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Edits irrelevant to BFO

@Wtshymanski: I'm about to undo two edits of yours and I need to explain why.

• You removed details about upper and lower sideband beat frequencies with respect to SSB reception and transmission. Granted, there were some irrelevant details, especially about the unusual use of upper sideband on the 5 MHz band. That stuff should go, but the lead says that a BFO can be used to demodulate an SSB signal - therefore, the relevant part of that info should not have been removed.
• You added a paragraph explaining how two signals can be beat together to make an audio oscillator. That process does implement the beating together of two signals, but it is not the function of the beat frequency oscillator, which is a specific section of a communications receiver. The process you're describing is explained at Frequency mixer, which is the appropriate article. Akld guy (talk) 01:52, 31 December 2018 (UTC)

Nonetheless, the beat frequency oscillator was a pretty common strategy for audio signal generators of a certain era. I have restored it and revised the murky stuff about "injection" to more closely match what the reference says. --Wtshymanski (talk) 04:28, 31 December 2018 (UTC)

I'm not denying that the technique has been used to generate audio tones or even higher frequencies, but I don't think I've ever heard of any publication, including instrument manuals, that used the term beat frequency oscillator. In the modern era, the term would be "heterodyne oscillator". I accept that the reference you provided uses the term "beat frequency oscillator" and note that it's dated 1932. Perhaps we need to make it clearer that this other application is an obsolete use of the term. As a hobby, I work on pre-World War 2 military transmitters and receivers (AN/ARC-5 and SCR-183) and am familiar with the pre-1940 HRO receiver. Akld guy (talk) 06:18, 31 December 2018 (UTC)

Is it obsolete? I've used one,and I'm not (quite) obsolete yet. And there's a description of a "beat frequency oscillator" signal generator on page 98 of "Principles of Modern Instrumentation", Spitzer and Howarth. I wonder if the HP journals are on-line some where? --Wtshymanski (talk) 22:42, 31 December 2018 (UTC)