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OWON XSA1032-TG 3.2G Spectrum Analyzer
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JeremyC:

--- Quote from: TomC on May 14, 2023, 06:09:20 pm ---I still see some places where they are selling this SA for less than MSRP, not quite as inexpensive as what I got a few months ago, but under $1000. Funny thing is that these examples at Amazon call it a handheld, in reality, it weights about 11 pounds (5kg). Maybe they made too many of them and let a batch go to non-traditional vendors dirt cheap. Who knows? :o

https://www.amazon.com/Oumefar-Precision-Generator-Resolution-regulations/dp/B08QJQX4BD/ref=sr_1_86?crid=S55K50VOUZ7C&keywords=XSA1032&qid=1684086658&sprefix=xsa1032%2Caps%2C146&sr=8-86&ufe=app_do%3Aamzn1.fos.5137e923-c7be-4142-979c-7c68b6c26f63

https://www.amazon.com/Portable-Tracking-Generator-Precision-regulations/dp/B08QJR3KFR/ref=sr_1_85?crid=S55K50VOUZ7C&keywords=XSA1032&qid=1684086658&sprefix=xsa1032%2Caps%2C146&sr=8-85

https://www.amazon.com/Portable-Generator-Resolution-Precision-regulations/dp/B093CZJ3ZH/ref=sr_1_84?crid=S55K50VOUZ7C&keywords=XSA1032&qid=1684086658&sprefix=xsa1032%2Caps%2C146&sr=8-84&th=1

https://www.amazon.com/Portable-Tracking-Generator-Resolution-regulations/dp/B08QJQ54XW/ref=sr_1_83?crid=S55K50VOUZ7C&keywords=XSA1032&qid=1684086658&sprefix=xsa1032%2Caps%2C146&sr=8-83&th=1

--- End quote ---

This entire thread looks to me like a SCAM!
Devices at Amazon in these links have the OWON brand grayed out from the label, take a close look!
In the initial post https://www.eevblog.com/forum/testgear/owon-xsa1032-tg-3-2g-spectrum-analyzer/msg4848032/#msg4848032 it is the same, there OWON is grayed out from the label.

Compare those pictures with https://www.testequipmentdepot.com/owon-xsa1032-tg-9khz-32-ghz-spectrum-analyzer-with-tracking-generator-kit.html

TomC:
To all the colleagues that have been following this thread. The attachments are photos of the equipment in my lab that I've been using to conduct the experiments and tests described in previous posts. I hope this satisfies any curiosity or suspicion of any type of nefarious purposes :phew:. With that out of the way, I would like to continue sharing with like-minded electronics enthusiasts, my experiences, discoveries, and doubts, as I try to learn and attempt to master new concepts and equipment  :-\.
TomC:
Residual FM Test

I've been curious about this spec since it isn't even mentioned on the XSA1032 manual or datasheet. So I got some information on what it means and how to test it (attachments 2 and 3), but I'm not sure I fully understand the steps. Particularly, when they say to use the peak-to-peak search function. I experimented with Peak Max Search and Peak Min Search, but it doesn't give consistent results. So finally I decided to instead use a Delta Marker spanning the full Sweep time. This is  more stable, especially after I increased the Sweep time to 400ms, but the dB reading still constantly changes, although more gradually. For the calculations I picked the highest number I saw after a few minutes, but again, it's possible that this is not much better than a random number, since I'm not, or don't know how to follow the instructions to the letter.

For the Demodulation Sensitivity I'm using the values from attachment 4:

   2800/18.49 = 151.4 Hz/dB

Notice that I'm using an RBW of 5kHz, even though the specs for the Rigol SA calls for 1kHz. I had to go with a minimum of 5kHz, because on this SA any less than that causes the Zero Span function to gray out, and the next steps calls for setting the SA to Zero Span.

For the Frequency Deviation I'm using the setup shown on attachment 5, and waiting a couple minutes while eyeing the dB value to record the highest value that pops-up:

   0.19 dB

So the residual FM comes to: 151.4 x 0.19 = 28.8 Hz

Of course, this number is more likely than not off. Even if the procedure I used turns out to be close enough to what's required, the Residual FM of the signal generator I'm using (Windfreak SynthUSBII) is not specified. So, as stated in the instructions, it may influence the final result.

I'd be grateful if anyone with better knowledge of this test helps clarify the instructions!
TomC:
Second Harmonic Distortion Test Part 1

The following is my interpretation of this test after reading a number of articles regarding this subject, hope I've got it right:

This test is used to determine the dBc value of the second harmonic generated by the SA while a fundamental signal is being applied at the SA's input. To get a valid reading the signal generator should be capable of producing a signal nearly free of harmonics, particularly the 2nd harmonic. To help achieve a harmonic free signal before applying it to the SA's input, an appropriate low pass filter can be used between the generator and the SA. Ideally, the low pass filter would only block the harmonics, particularly the 2nd harmonic.

The SA manufacturer's specs may be given as a dBc value when the specified fundamental is at the specified dBm level, for example, on the XSA1032 the Second harmonic distortion is specified as -65dBc when a -10dBm harmonic free ≥ 50 MHz fundamental is applied to the SA's input. This means, that although the input signal contains no harmonics, up to a -65dBc 2nd harmonic may appear on the SA's screen that was solely generated by the SA's internal circuits.

Alternatively, the SA manufacturer's specs may be given as an SHI value when the specified fundamental is at the specified dBm level, for example, on the DSA832E the Second Harmonic Intercept (SHI) is specified as +40dBm when a -20dBm harmonic free ≥ 50 MHz fundamental is applied to the SA's input.

The SHI value is a theoretical dBm level at which the fundamental's and 2nd harmonic's dBm levels coincide. Normally, this can't be achieved in practice. However, is a known fact, that as the fundamental's dBm level increases the 2nd harmonic dBm level also increases with a 2:1 ratio. Using this fact, the level where both signals would theoretically coincide can be easily calculated mathematically or graphically. I added information to the original XS1032 & DSA832E specs showing how to mathematically convert an SHI to a dBc value or a dBc value to an SHI, see attachment 1.

   Attachments 2 and 3 comprise one of the more relevant articles I read regarding this subject.

   Attachment 4 is graphical representation I put together illustrating how the XSA1032 & DSA832E SHI's can be obtained graphically.


I don't have a generator that meets the requirements necessary to properly evaluate the XSA1032 Second Harmonic Distortion, but on the second part I'll post the results obtained with the generators I have.
TomC:
Second Harmonic Distortion Test Part 2

To test the 2nd Harmonic Distortion on my XSA1032-TG, first I'm going to use my SynthUSBII signal generator. Attachment 5 shows the harmonic content specs for the main IC chip used in this generator. Since this generator's output is a square wave, the 3rd harmonic spec is a larger value than the second. But even the second harmonic spec is larger than the value required to get a valid reading of the SA's harmonic distortion. To perform the test the generator's output was set to 50MHz at approximately -10dBm (the output level is not calibrated).

For Attachments 6 & 7 the SA's span was set to 160MHz to allow to see the relative values of the fundamental and the 2nd & 3rd harmonics. The 2nd harmonic should be at marker 2, but with the current settings the noise floor is too high for it to be visible. I can't lower the noise floor because the SA won't let me set the Ref Level and the Attenuation to the values required for the test.

For attachment 8, to zero in on the 2nd harmonic, the SA's span was set to 100kHz and the center frequency to marker 2. Here the 2nd harmonic is visible because the noise floor is much lower. Since only a small signal is in the sweep's range, I was able (allowed by the SA) to set the Ref Level and the Attenuation to the values required for the test. The 2nd harmonic dBm value is around -62, since the fundamental is around -9dBm, the dBc value comes to -62 -(-9) = -53dBc. This is not even close to the -65dBc cited on the XSA1032-TG specifications, but that requires that the input signal be nearly harmonics free, which it isn't in this case.

Next I want to test the 2nd Harmonic Distortion on my XSA1032-TG using my AG1022F AWG. Attachment 9 shows the harmonic distortion specs for this generator which are much better than the ADF4351 specs. However, I'll have to perform the test with a 25MHz fundamental instead of the ≥ 50 MHz that the XSA1032 specs call for. Unfortunately, 25MHz is the highest frequency that my AG1022F can output. To perform the test the generator's output was set to 25MHz at 200mVpp. On a 50-ohm system 200mVpp is equivalent to around -10dBm.

For Attachments 10 & 11 the SA's span was set to 100MHz to allow to see the relative values of the fundamental and the 2nd & 3rd harmonics. The harmonics should be at markers 2 & 3, but with the current settings the noise floor is too high for them to be visible. I can't lower the noise floor because the SA won't let me set the Ref Level and the Attenuation to the values required for the test.

For attachment 12, to zero in on the 2nd harmonic, the SA's span was set to 100kHz and the center frequency to marker 2. Here again the 2nd harmonic is visible because the noise floor is much lower. Again, since only a small signal is in the sweep's range, I was able (allowed by the SA) to set the Ref Level and the Attenuation to the values required for the test. The 2nd harmonic dBm value is around -70, since the fundamental is around -10dBm, the dBc value comes to -70 -(-10) = -60dBc. This is closer to the -65dBc cited on the XSA1032-TG specifications, but still, the input signal is not nearly harmonics free as required, perhaps if I use an appropriate low pass filter I could get closer to a valid reading. Unfortunately, I don't have one at this time.

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