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Author Topic: "noise floor" on a panadapter/SDR  (Read 7510 times)

AK4YA

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"noise floor" on a panadapter/SDR
« on: August 02, 2013, 11:21:28 AM »

If on the spectrum the peaks of all the noise spikes are right at around -100 dBm, and if the bed of where all the peaks originate from is at -120 dBm, then where do we say the "noise floor" is.  do we use the upper or lower numbers?  Or somewhere inbetween?
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N9VV

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RE: "noise floor" on a panadapter/SDR
« Reply #1 on: August 02, 2013, 03:09:11 PM »

[1]  DISCONNECT your Antenna
[2]  connect a reliable 50 ohm termination to the ANT input
[3]  look at the NOISE FLOOR :-)

GL de Ken N9VV
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KA4POL

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RE: "noise floor" on a panadapter/SDR
« Reply #2 on: August 02, 2013, 09:41:03 PM »

 The noise floor is the measure of the signal created from the sum of all the noise sources and unwanted signals within your system. So no outside signals wanted.
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N2MG

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RE: "noise floor" on a panadapter/SDR
« Reply #3 on: August 05, 2013, 05:49:43 PM »

I think the OP is referring to what one sees in a spectrum analyzer (frequency domain) plot.

http://m.eet.com/media/1075640/0503feat2fig9.gif

There's a bouncing "floor" in a plot like that... The OP wants to know: does one measure the peaks, valleys or in between?

I would typically measure to the tops (or just below) of the peaks.
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Mike N2MG
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KA4POL

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RE: "noise floor" on a panadapter/SDR
« Reply #4 on: August 07, 2013, 07:39:37 AM »

For one frequency it is the value you measure. For a frequency range you should take the average for that range.
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