Channel Power measurement of 20MHz wifi

Has anybody done this? Does it work well? Can it be triggered? My purchase depends on the answer. Thanks

[Andrew]

Hi Ed,

Using the zero-span mode in Spike, it is possible to trigger on a WIFI signal, and perform a channel power measurement on that capture. See the attached picture with some relevant highlighting, showing a 20MHz WIFI capture in the 2.4GHz band.

The trigger level, capture length, and channel power bandwidth are all configurable.

Once you have the configuration setup just the way you like, you can store all settings to a preset file that can be quickly loaded the next time you run the application.

Let us know if you have further questions.

Andrew

• This reply was modified 2 years, 8 months ago by Andrew.

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Thanks!

Yes, more – if I save the configuration, can I call the file up remotely?

I can get the channel power number remotely as well?

I’ll be using either LabVIEW or python.

Ed,

Unfortunately, this specific measurement would not be possible remotely via programming. While our software does accept SCPI commands (that you could send from Labview or Python) for most functionality, the measurement as configured in the picture above (zero-span channel power) is one of the few that cannot be fully automated.

There are some alternatives,

If you knew exactly what WLAN protocol you were measuring and it was not MIMO, you could use our WLAN measurements to fully capture, demodulate, and report the channel power. All of this is available via SCPI programming. You can determine if your signal would be able to be measured under this measurement mode by browsing our WLAN feature document,
https://signalhound.com/content/tech-briefs/802-11b-a-n-ac-ax-wlan-modulation-analysis-in-spike/.

If you were comfortable processing I/Q data, you could use the direct device API to acquire I/Q data, and perform the triggering and channel power measurement yourself. The device APIs are provided in our SDK,
https://signalhound.com/software/signal-hound-software-development-kit-sdk/
Our API is primarily C/C++, but we have several examples on how to call our API from Python or Labview.
https://signalhound.com/software/signal-hound-instrument-drivers-for-labview/

If you would like to discuss your specific measurement requirements in more depth, consider reaching out to me directly at aj@signalhound.com.

Andrew

Just to make sure I understand:

If I have the measurement set up, can I get the result of the measurement out with SCPI?

Fully Automated setup may be asking too much, but you said:

“Once you have the configuration setup just the way you like, you can store all settings to a preset file that can be quickly loaded the next time you run the application.”

If that is the case, can I restore that state remotely?

If both answers are Yes I am good, I think.

Specifically for the zero-span channel power measurement, no, you cannot query that measurement via SCPI.

Yes to your second question, you can load presets remotely via SCPI.

Andrew

So I decided to look into this again, using Spike 3.8.2, and it still does not work. The response to chp:chp? in zero-span is the stale data from the swept acquisition. Updating on the screen, stale data using SCPI.

Once again, I would like to request this feature.

Hi Ed,

Unfortunately we have not added SCPI commands for the zero-span channel power measurements since your last messages.

You can see a full list of SCPI commands we support in the SCPI manual found in our SDK.
https://signalhound.com/software/signal-hound-software-development-kit-sdk/

There are no commands other than the ones in that document.

Andrew

Sorry for the tone of that message. Uncalled for, you guys are dancing as fast as you can. But, are there plans for this command for the next release? Or is it a total wish?

No worries Ed. This is not on our immediate road map and we have no plans to add it right now. I have added it to our customer request log but I cannot make any guarantees about when we would be able to look into this.

We recently added the average power readout (on the zero-span AMvTime plot) as a query-able value via SCPI. See the ZS:Fetch command. If you can get this value to work for you, that might be sufficient. Otherwise see my prior suggestions.

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