At 2/12/2005 06:34 AM, you wrote:
>All,
>>
>>I agree. 3db is quite easily heard when I switch 3db in and out on my
>>step attenuator.
>>
>>Laryn K8TVZ
>
>Neil J pretty much nailed this one:
>
>>
>>It is generally accepted industry practice for path reliability
>>projection, e.g. Motorola Coverage Acceptance Standards, that 4dB C/N is
>>the point at which an FM communications receiver delivers 12 dB SINAD and
>>that 7 dB C/N is the point at which such a receiver delivers 20 dB quieting.
OK, so does this mean the noise temperature of a NBFM FM receiver can be
approximated by measuring the 12 dB SINAD point & then subtracting 4
dB? That would mean that the amount of signal from the sig. gen. is equal
to the total noise power at the front-end of the receiver within its
pre-detection bandwidth (~16 kHz) at that level (0 dB C/N means C=N).
I always thought that the 0 dB C/N level is the point at which a signal
would be barely detectable. However, that point is more like 6 dB below
the 12 dB SINAD level, at least on the receivers I've tried.
>I hope this wraps this thread up...
Sorry; at least I've steered it in a different direction.
Bob NO6B
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