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When I was (playing) testing with my Nose source noise source and TinySA, everything was fine at lower frequencies, but when the max frequency was 5GHz, there was a 10-20dB step at 3GHz. I don't think noise source does that,? but I wouldn't think TinySA would do that either. I ran calibration after this and as always it passed. Should TinySA Ultra be calibrated before use?

Yes, in the noise source PCB, there is a text NOSE SOURCE.

Bg7tbl 2016-03-06

By the way,? the noise source runs very hot at 12V. Amplifiers? in it may do? something extra.

https://www.eevblog.com/forum/testgear/_nose-source-bg7tbl-2016-03-06_/

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I? used? a 20dB attenuator between the noise source? and TinySa.

When I was (playing) testing with my Nose source noise source and TinySA, everything was fine at lower frequencies, but when the max frequency was 5GHz, there was a 10-20dB step at 3GHz. I don't think noise source does that,? but I wouldn't think TinySA would do that either. I ran calibration after this and as always it passed. Should TinySA Ultra be calibrated before use?

Yes, in the noise source PCB, there is a text NOSE SOURCE.

Bg7tbl 2016-03-06

By the way,? the noise source runs very hot at 12V. Amplifiers? in it may do? something extra.

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Sure, here it comes, all? two of them. Could a Wlan leak here, I didn't see the 2.4GHz peak? at first when my PC was off. (Clock on my SA is off.)

The step shows on? PC too.

The noise source is supposed to work at 12V,? but it runs very hot even at 10V. This is at 12V. I don't know how, but the problem may be at the source/Nose.

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FIG 2 is very interesting and might answer the 5GHz noise plot you are looking at. I increased the frequency set-up to what you used 10MHz-5GHz and low and behold, the noise trace looks very similar to what you are looking at with the "step" at 3GHz, and the following? trace replicating? the lower frequency portion. Could it be that the frequency response of the noise generator is actually lower than 1.5GHz or so? Interesting as to why this might happen. We can assume the ULTRA is at least as flat as the baseline noise shows us, so is it a function of the noise generator? Interesting question which begs more investigation (on another analyzer non ULTRA).

AS to the pulse shown with marker 1 @ 2.43GHz, this is direct pickup from my router wifi in close proximity to the analyzer.?

FIG 1. 10MHz-3GHz

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FIG 2. 10MHz-5GHz

Hope this might help.......Good Luck!!

Ted (KD7AQO)

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From: "Leif M via groups.io"
To: [email protected]
Cc:
Sent: Wednesday January 1 2025 2:39:46PM
Subject: Re: [tinysa] A step at 3GHz?

On Wed, Jan 1, 2025 at 01:13 PM, Leif M wrote:

When I was (playing) testing with my Nose source noise source and TinySA, everything was fine at lower frequencies, but when the max frequency was 5GHz, there was a 10-20dB step at 3GHz. I don't think noise source does that,? but I wouldn't think TinySA would do that either.

? ?I hope you read the page on limitations of enabling the Ultra mode and measuring wideband or scanning signals.? The step at 3GHz is normal for the noise source you are using.

? ?With a noise source, the Ultra mode mirror and spur elimination algorithms are weak as the method used to select the correct frequency, instead of a mirror, starts to break down.

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? ? The new Ultra+ ZS-407 may handle the 3GHz step better.? Hopefully someone who has the ZS-407 can provide test data.

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Herb

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Since the noise source generates a very wide bandwidth signal, this causes the mirror suppression algorithm of the tinySA ULTRA mode to fail. When the scanning frequency is greater than 3GHz the IF frequency of tinySA ULTRA switches from IF=LO-RF to IF=RF-LO, but due to the failure of the mirror suppression algorithm the RF-2IF signal is still displayed and you can see that the signal strength at 3.2GHz is close to that of the signal strength at 1.3GHz.

This is why we require the user to enter the unlock CODE in order to turn on ULTRA Mode, and we hope that the user will fully read the restrictions on the ULTRA Mode page before turning on ULTRA Mode.

The ULTRA mode of the ZS407 uses the same technology and is subject to the same limitations, except that this step occurs at a higher frequency.

Since the noise source generates a very wide bandwidth signal, this causes the mirror suppression algorithm of the tinySA ULTRA mode to fail. When the scanning frequency is greater than 3GHz the IF frequency of tinySA ULTRA switches from IF=LO-RF to IF=RF-LO, but due to the failure of the mirror suppression algorithm the RF-2IF signal is still displayed and you can see that the signal strength at 3.2GHz is close to that of the signal strength at 1.3GHz.

This is why we require the user to enter the unlock CODE in order to turn on ULTRA Mode, and we hope that the user will fully read the restrictions on the ULTRA Mode page before turning on ULTRA Mode.

The ULTRA mode of the ZS407 uses the same technology and is subject to the same limitations, except that this step occurs at a higher frequency.

I am a firm believer in using filters to make accurate measurements when in ultra mode. High pass filters work wonders and reduce /? prevent erroneous measurements.