On Sat, 27 Jun 2015 13:43:16 +0100, Jeff Gave us:

On 27/06/2015 13:26, rickman wrote:
On 6/27/2015 4:07 AM, Jeff wrote:
On 26/06/2015 13:24, rickman wrote:
I read this post in an antenna group and I don't get how this guy is
coming up with a negative noise figure. Looks to me like he is
calculating the noise figure of a resistor, not the amplifier. Anyone
care to explain this to me?

The part that seems bogus is this...

The negative NF is defined as the amplifier noise being less than the
increase in noise due to the amplifier gain.

I thought noise figure was NF = SNRin / SNRout

Rick


Both definitions are correct and mean the same thing; a negative NF,
when expressed in dB, would be when the SNRout is less than the SNRin.
However, the big but is that an negative NF is not possible.

I don't think both definitions mean the same thing. If the amplifier
adds *any* noise it increases the NF above zero by the conventional
definition. The only way the NF can be negative is if the amplifier
removes noise from the input, or in other words, increases the SNR.


Yes that is correct, but the definitions are also correct. The flaw in
the negative noise figure argument is that it is not possible to have a
better SNRout than SNRin *for the same system conditions*.

The apparent negative noise figure only come about by comparing the NF
of the amp in a 50ohm system with the output from a system with
something different on the input.

The test method used is also very prone to measurement errors for low
noise figures.

Jeff

To me, NF refers to "noise floor".

Lets see him go below that.

GPS received signals are among the lowest "power" signals we currently
grab. They sit just above the noise floor.

On Sat, 27 Jun 2015 09:19:23 -0400, DecadentLinuxUserNumeroUno
wrote:

On Sat, 27 Jun 2015 13:43:16 +0100, Jeff Gave us:

On 27/06/2015 13:26, rickman wrote:
On 6/27/2015 4:07 AM, Jeff wrote:
On 26/06/2015 13:24, rickman wrote:
I read this post in an antenna group and I don't get how this guy is
coming up with a negative noise figure. Looks to me like he is
calculating the noise figure of a resistor, not the amplifier. Anyone
care to explain this to me?

The part that seems bogus is this...

The negative NF is defined as the amplifier noise being less than the
increase in noise due to the amplifier gain.

I thought noise figure was NF = SNRin / SNRout

Rick


Both definitions are correct and mean the same thing; a negative NF,
when expressed in dB, would be when the SNRout is less than the SNRin.
However, the big but is that an negative NF is not possible.

I don't think both definitions mean the same thing. If the amplifier
adds *any* noise it increases the NF above zero by the conventional
definition. The only way the NF can be negative is if the amplifier
removes noise from the input, or in other words, increases the SNR.


Yes that is correct, but the definitions are also correct. The flaw in
the negative noise figure argument is that it is not possible to have a
better SNRout than SNRin *for the same system conditions*.

The apparent negative noise figure only come about by comparing the NF
of the amp in a 50ohm system with the output from a system with
something different on the input.

The test method used is also very prone to measurement errors for low
noise figures.

Jeff

To me, NF refers to "noise floor".

Lets see him go below that.

GPS received signals are among the lowest "power" signals we currently
grab. They sit just above the noise floor.

And you believe everything that your government claims ?

The GPS DSSS signal is more than 1 MHz wide, so you could claim -30 dB
SNR. However, after despreading, the signal is only 1 kHz wide and the
data rate is only 50 bit/s wide. Thus, the SNR should be calculated at
25-50 Hz bandwidths, giving quite positive SNR.

On Sat, 27 Jun 2015 09:19:23 -0400, DecadentLinuxUserNumeroUno
wrote:

On Sat, 27 Jun 2015 13:43:16 +0100, Jeff Gave us:

On 27/06/2015 13:26, rickman wrote:
On 6/27/2015 4:07 AM, Jeff wrote:
On 26/06/2015 13:24, rickman wrote:
I read this post in an antenna group and I don't get how this guy is
coming up with a negative noise figure. Looks to me like he is
calculating the noise figure of a resistor, not the amplifier. Anyone
care to explain this to me?

The part that seems bogus is this...

The negative NF is defined as the amplifier noise being less than the
increase in noise due to the amplifier gain.

I thought noise figure was NF = SNRin / SNRout

Rick


Both definitions are correct and mean the same thing; a negative NF,
when expressed in dB, would be when the SNRout is less than the SNRin.
However, the big but is that an negative NF is not possible.

I don't think both definitions mean the same thing. If the amplifier
adds *any* noise it increases the NF above zero by the conventional
definition. The only way the NF can be negative is if the amplifier
removes noise from the input, or in other words, increases the SNR.


Yes that is correct, but the definitions are also correct. The flaw in
the negative noise figure argument is that it is not possible to have a
better SNRout than SNRin *for the same system conditions*.

The apparent negative noise figure only come about by comparing the NF
of the amp in a 50ohm system with the output from a system with
something different on the input.

The test method used is also very prone to measurement errors for low
noise figures.

Jeff

To me, NF refers to "noise floor".

It probably would to an utter imbecile such as you.


Lets see him go below that.

GPS received signals are among the lowest "power" signals we currently
grab. They sit just above the noise floor.

On Mon, 29 Jun 2015 09:34:52 +0100, Pomegranate *******
Gave us:

It probably would to an utter imbecile such as you.

Relating to you and your invasion of the group, it does mean noise
factor, just not electronics related. Just like *you* are not
electronics related or educated.

On Mon, 29 Jun 2015 05:42:57 -0400, DecadentLinuxUserNumeroUno
wrote:

On Mon, 29 Jun 2015 09:34:52 +0100, Pomegranate *******
Gave us:

It probably would to an utter imbecile such as you.

Relating to you and your invasion of the group, it does mean noise
factor, just not electronics related. Just like *you* are not
electronics related or educated.

C'mon DikeyGurl, remind me of how you came to be named DimBulb. I
could do with a good laugh!

On Mon, 29 Jun 2015 10:51:40 +0100, Pomegranate *******
Gave us:

On Mon, 29 Jun 2015 05:42:57 -0400, DecadentLinuxUserNumeroUno
wrote:

On Mon, 29 Jun 2015 09:34:52 +0100, Pomegranate *******
Gave us:

It probably would to an utter imbecile such as you.

Relating to you and your invasion of the group, it does mean noise
factor, just not electronics related. Just like *you* are not
electronics related or educated.

C'mon DikeyGurl, remind me of how you came to be named DimBulb. I
could do with a good laugh!

How can *I* remind YOU of some lame **** YOU made up?

On Mon, 29 Jun 2015 07:06:05 -0400, DecadentLinuxUserNumeroUno
wrote:

On Mon, 29 Jun 2015 10:51:40 +0100, Pomegranate *******
Gave us:

On Mon, 29 Jun 2015 05:42:57 -0400, DecadentLinuxUserNumeroUno
wrote:

On Mon, 29 Jun 2015 09:34:52 +0100, Pomegranate *******
Gave us:

It probably would to an utter imbecile such as you.

Relating to you and your invasion of the group, it does mean noise
factor, just not electronics related. Just like *you* are not
electronics related or educated.

C'mon DikeyGurl, remind me of how you came to be named DimBulb. I
could do with a good laugh!

How can *I* remind YOU of some lame **** YOU made up?

You're displaying your fetish again, ScatGurl.

In article , DLU1
@DecadentLinuxUser.org says...

On Mon, 29 Jun 2015 10:51:40 +0100, Pomegranate *******
Gave us:

On Mon, 29 Jun 2015 05:42:57 -0400, DecadentLinuxUserNumeroUno
wrote:

On Mon, 29 Jun 2015 09:34:52 +0100, Pomegranate *******
Gave us:

It probably would to an utter imbecile such as you.

Relating to you and your invasion of the group, it does mean noise
factor, just not electronics related. Just like *you* are not
electronics related or educated.

C'mon DikeyGurl, remind me of how you came to be named DimBulb. I
could do with a good laugh!

How can *I* remind YOU of some lame **** YOU made up?

Bears great resemblance?

Jamie

On Mon, 29 Jun 2015 10:51:40 +0100, Pomegranate *******
wrote:

On Mon, 29 Jun 2015 05:42:57 -0400, DecadentLinuxUserNumeroUno
wrote:

On Mon, 29 Jun 2015 09:34:52 +0100, Pomegranate *******
Gave us:

It probably would to an utter imbecile such as you.

Relating to you and your invasion of the group, it does mean noise
factor, just not electronics related. Just like *you* are not
electronics related or educated.

C'mon DikeyGurl, remind me of how you came to be named DimBulb.

Some of my work. ;-) Larkin gave him the "AlwaysWrong" name and IIRC
you gave him "Nymbecile". All appropriate.

I could do with a good laugh!

Which DimBulb will undoubtably furnish.

On Mon, 29 Jun 2015 21:18:11 -0400, krw wrote:

On Mon, 29 Jun 2015 10:51:40 +0100, Pomegranate *******
wrote:

On Mon, 29 Jun 2015 05:42:57 -0400, DecadentLinuxUserNumeroUno
wrote:

On Mon, 29 Jun 2015 09:34:52 +0100, Pomegranate *******
Gave us:

It probably would to an utter imbecile such as you.

Relating to you and your invasion of the group, it does mean noise
factor, just not electronics related. Just like *you* are not
electronics related or educated.

C'mon DikeyGurl, remind me of how you came to be named DimBulb.

Some of my work. ;-) Larkin gave him the "AlwaysWrong" name and IIRC
you gave him "Nymbecile". All appropriate.

I could do with a good laugh!

Which DimBulb will undoubtably furnish.

Yes, indeed!

Its regular explosions are a reliable source of amusement. What I find
so unbelievable is the idiot never learns! I suppose it is an easy
target, but I'm not proud.

Long live AlwaysWrong, DimBulb and Nymbecile!