[AMPS] minimum distortion detectable

2 2@vc.net
Tue, 18 Sep 2001 13:27:37 -0700


>
>There was some illusion that the goal is to put the IMD 40 dB down 
>so it is the minimum detectable distortion to the human ear.
>
//    -  illusion - n.
1.a. An erroneous perception of reality. b. An erroneous concept or 
belief.
2. The condition of being deceived by a false perception or belief.
3. Something, such as a fantastic plan or desire, that causes an 
erroneous belief or perception.
...
-  allusion - n.
1. The act of alluding; indirect reference: Without naming names, the 
candidate criticized the national leaders by allusion.
2. An instance of indirect reference: an allusion to classical mythology 
in a poem. See Usage Note at allude. [Late Latin allusiĆ, allusiĆn-, a 
playing with, from Latin allusus, past participle of alludere, to play 
with. See ALLUDE.]

Ref.erence; American Heritage Dictionary, 2nd ed.

>That is not the problem.
>
>The problem is in an RFPA the distortion generates additional 
>frequencies that appear outside the passband of the transmitter. In 
>this case, we want the IMD to be below the minimum detectable 
>level on a receiver.
>
>I often can find signals 70dB or more out of my noise floor, so that 
>means 3rd order IMD of less than that amount is a problem.

//  My guess is that a -70db total IMD, SSB transceiver is not possible.  
The cleanest, modulated by a human voice transceiver, that I have ever 
measured was -38db (a TS-830S).   
>
>... ... ...

-  R. L. Measures, 805.386.3734, AG6K, www.vcnet.com/measures.  
end


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