Calibration of Noise Source - how to ?
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Calibration of Noise Source - how to ?

 
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Ernst Wawrzik
Guest
Posted: Sat Dec 03, 2005 5:35 pm    Post subject: Calibration of Noise Source - how to ? Reply with quote
Hi,
I recently acquired an hp 8970A Noise Figure Meter but w/o noise source.
I have a homebuild noise source as described in DUBUS magazine for the
PANFI some years ago and a hp 346C which was said to be defective
(however it still seems to produce some noise).

Is there any way to 'calibrate' such a noise source to at least some
tenths of a dB?

Does it work to measure noise figure of a (pre-)amp with a calibrated
noise source and then use the other noise source and adjust the ENR
setting in the 8970A until you get same reading compared to the
calibrated noise source?

Any comments are welcome

Regards EW

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Mark
Guest
Posted: Sun Dec 04, 2005 9:35 am    Post subject: Re: Calibration of Noise Source - how to ? Reply with quote
yes,

or....

if you have a calibrated noise source available, you can measure the
noise out of it and compare that to the noise out of your source... I
tknik the 8907 has a power mter mode as well that you could use for
this..

or use a spectrum analyzer with a pre-amp..

Note, the noise out of your homemade source will probably not be as
flat across a wide freq range as the HP one...

Mark
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Guest
Posted: Sun Dec 04, 2005 9:35 am    Post subject: Re: Calibration of Noise Source - how to ? Reply with quote
Ernst Wawrzik wrote:
Quote:
Hi,
I recently acquired an hp 8970A Noise Figure Meter but w/o noise source.
I have a homebuild noise source as described in DUBUS magazine for the
PANFI some years ago and a hp 346C which was said to be defective
(however it still seems to produce some noise).

Is there any way to 'calibrate' such a noise source to at least some
tenths of a dB?

Does it work to measure noise figure of a (pre-)amp with a calibrated
noise source and then use the other noise source and adjust the ENR
setting in the 8970A until you get same reading compared to the
calibrated noise source?

Any comments are welcome

Regards EW
The ENR of a noise source is the available excess noise power divided

by the available thermal noise power in dB and therefore depends on the
noise source reflection coefficients fired and un-fired so strictly
these have to be measured and the observed comparative (one source vs
the standard source using a low noise pre-amp) corrected.
Dick

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Nitro
Guest
Posted: Sun Dec 04, 2005 9:28 pm    Post subject: Re: Calibration of Noise Source - how to ? Reply with quote
Sorry if this has been mentioned. I have not followed the thread.
I have used a few of the Micronetics noise sources. They have a few
calibration documents on their site for their equipment. Don't know if they
will help you but here is one link (there are others.)

http://www.micronetics.com/noise/generator.html
http://www.micronetics.com/Noise/Source.html

On 3 Dec 2005 21:32:04 -0800, rqlhgl@ieee.org wrote:

Quote:


Ernst Wawrzik wrote:
Hi,
I recently acquired an hp 8970A Noise Figure Meter but w/o noise source.
I have a homebuild noise source as described in DUBUS magazine for the
PANFI some years ago and a hp 346C which was said to be defective
(however it still seems to produce some noise).

Is there any way to 'calibrate' such a noise source to at least some
tenths of a dB?

Does it work to measure noise figure of a (pre-)amp with a calibrated
noise source and then use the other noise source and adjust the ENR
setting in the 8970A until you get same reading compared to the
calibrated noise source?

Any comments are welcome

Regards EW
The ENR of a noise source is the available excess noise power divided
by the available thermal noise power in dB and therefore depends on the
noise source reflection coefficients fired and un-fired so strictly
these have to be measured and the observed comparative (one source vs
the standard source using a low noise pre-amp) corrected.
Dick
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Ernst Wawrzik
Guest
Posted: Mon Dec 12, 2005 1:35 am    Post subject: AW: Calibration of Noise Source - how to ? Reply with quote
Thanks to all of you for the information given.
Ernst

Mark:
Quote:
yes,

or....

if you have a calibrated noise source available, you can measure the
noise out of it and compare that to the noise out of your source... I
tknik the 8907 has a power mter mode as well that you could use for
this..

or use a spectrum analyzer with a pre-amp..

Note, the noise out of your homemade source will probably not be as
flat across a wide freq range as the HP one...

Mark
Back to top
 
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