PSN-L Email List Message

Subject: Re: Signal To Noise Ratio
From: "Geoff" gmvoeth@...........
Date: Tue, 6 Nov 2007 02:26:21 -0700

Interesting Mr. Brad Douglas;

Im not sure about any of this
but it would be nice to understand
what is in the front end of the

I think there are very low noise devices out there
but it would be useless to use them
in any high noise environment like
ShortWave radio.

All one really needs is to keep the
combined circuit noise below the
ambient noise or you will have
a hard time seeing the those signals
riding near the natural grass.

The astronomers will supercool
their preamps to eliminate noise and
do any broadband shifting right in
the front end.

I think i would like to have
an Astronomical expert making the
electronics for my geophone
but fear I would not be able to
afford the liquid helium to
keep it in operation.

----- Original Message ----- 
From: "Brad Douglas" 
Sent: Saturday, November 03, 2007 5:48 PM
Subject: Re: Signal To Noise Ratio

> On Sat, 2007-11-03 at 16:50 -0700, Geoff wrote:
>> Hello Bob;
>> Have you ever heard of a low noise
>> GaAs op amp that is designed to work
>> like a op177G (typical opamp) or ??
> GaAs FETs go that low in frequency and still yield gain and stability?
> Lowest I've ever done is 144MHz and that was straining the chip,
> yielding decreased gain (but still higher than any non-GaAs FET).  If my
> understanding is correct, GaAs is "saturated" above 2GHz, making them
> ideal for microwave LNAs.
> Or have I entirely missed the point? :-)
>> Signal to noise ratio should be easily found
>> in google I think it simply is like
>> Expectided MDL signal power / Ubiquitous Noise Power
>> The higher the ratio the better the whatever.
>> Possibly expressed in db.
>> For power thats 10Log(Sig/Noi).
> That's mostly accurate:
> -- 
> 73, de Brad KB8UYR/6 
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