Re: [Repeater-Builder] Audio Reproduction

6 Apr 2004 11:54:16 -0000



[EMAIL PROTECTED] wrote:
Hi Kevin,
 
Since the final result of a PM modulator is FM, the term True FM implies
that the modulator being spoken about is just that, truely FM, not PM.
 
The True output of a True phase modulator is Truly preemphasized audio.
 
The True output of a True frequency modulator that is preceeded by True pre-emphasis is also Truly preemphasized audio.
 
But using the term True FM implies there must also be a False FM, which would be PM.
 
So we can say that the True output of a False FM is Truly preemphasized audio.
 
Likewise, there is no need for True preemphasis ahead of a False FM to obtain preemphasized audio.
 
73,
Bob, WA9FBO

Hi Bob,

I agree with what you say, but I *think* you disagreed with what I meant.  <grin>
When we (Scott and I) go to build a repeater for someone or are talking about a radio set that has or needs an FM modulator, it gets referred to as true FM.  This helps us to eliminate confusion about what type of modulator needs to be installed into a radio set that ultimately transmits FM in any event.  The use of the term allows folks that aren't as radio inclined pick up on the fact there is a difference between FM and PM modulation, and eliminates the question "I thought it was an FM radio".

You see, we (Repeater Builder) offer repeaters with both types of modulation schemes, and there need to be a way to differentiate between the two modulators without adding confusion to the whole matter.  I'm sorry if you own into our way of thinking, but this was the best way of getting around a bad situation for folks that aren't as radio savvy and you and I (many of our customers), that I could come up with.

Kevin Custer


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