Re: noise voltage (was: Conservation Laws)

[brian whatcott <inet@INTELLISYS.NET>]

At 00:19 3/16/00 -0500, John D wrote:
> > it is a given that commercial GPSs can lock functionally with a signal plus
> > noise at least as big as -170dBm and a low noise input amplifier can hardly
> > get much better than 3microvolt.Hertz.
>
> I don't know where that 3microvolt.Hertz number is coming from.  Certainly
> not from me.
>
> I tend to think of noise as being more like
>         nanovolts per root Hertz (into 50 ohms)


Excellent! That is the kind of magnitude *I* would have assigned too.

...But surely you mentioned something about digging out a signal
say 50 db smaller than noise - that seems to suggest a noise component
in this case of about -120dBm     orders of magnitude greater as you say....

 Did I remember this correctly? I haven't consulted the archive.



brian whatcott <inet@intellisys.net>
Altus OK