The context that I was using is that nonlinear front ends cause a lot of
low level mixing products in the pass band in the presence of multiple
large signals in the front end. A more linear front end has less noise
showing up between the big signals. It is not atmospheric noise. I do
mean in the context of between the frequencies of large signals, not the
context of time that you suggest.
Quieter means to me less internally generated noise not low gain to make
it appear quieter.
I agree that the noise we all hear should be external to the receiver.
But in many cases it is not. A prime example is a heavy DX pile up.
When many people are calling the band noise appears to rise. This is
partially due to nonlinearities in the transmitters outside the
receiver, but is also partly due to nonlinearities in the receiver front
end including phase noise. A more linear front end with large signal
power handling capability and low phase noise along with a narrow
roofing filter appears much quieter without losing sensitivity. So the
weak dx signal is more likely to be heard even when the animals are
roaring just outside my pass band.
On a band with only a few signals or with high atmospheric noise levels
both the "good" front end and the poor one will sound the same. Many
people are confusing the "quietness" of good front ends in the top of
the line receivers such as Ten-Tec and K2 as a lack of gain even though
the weak signals pop up with
a better signal to noise ratio than many other receivers.
By the way, a receiver front end must not only be super linear for the
power range of the desired signal but must be able to maintain that
linearity for all of the power presented by all other (large) signals in
the front end pass band.
Aloha,
John KH7T
Tom Rauch wrote:
>I'm having a problem understanding something here. Maybe someone can help me
>out??
>
>----- Original Message -----
>From: "John Buck" <kh7t@arrl.net>
>
> > But the my ORION is slightly better than the K2 in digging out the weak
>
>
>>one next door to the local KW. The major benefit is how quiet the band
>>sounds in between signals in a pile up.
>>
>>
>
>By "between" I am going to assume John means "between" in the context of
>time, and not "between" related to frequency differences in signals.
>
>We want to be able to hear weak signals between static crashes or loud
>signals. By definition, that requires we clearly hear background noise
>between strong signals.
>
>Can anyone explain how a receiver that is significantly "quieter" than
>others (same approximate bandwidth in both) between strong signals also be
>good at weak signal reception?
>
>The noise we all hear should be external to the receiver. By definition,
>that means the noise is all the same source.
>
>73 Tom
>
>
>
>
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