#252

[@loueckert4970]

Your presentations are always clear and filled with gobs of application tidbits. Yum!

[@scottwood1143]

Wow! That was a lot of light shined on a very complex subject! Enjoyed it. I'd love to see this used to extract/recover data from the FSK bursts.

[@w2aew]

The GP Digital Modulation Analysis option includes the ability to demodulate FSK (among many other modulation types), and can show a symbol table, constellation, eye diagram, etc. I'll do a future video on this.

[@silvergmc]

Thanks for taking the time to do these videos! Lot's of great info here!

[@hb0mb52]

Your videos are extremely informative. Just received RSA306b, would sincerely appreciate a future video on BLE and WiFi coexistence!

[@LiraLab]

Hello again Sir! I have been using this unit for months now. I've been always unplugging it from the USB after each use. However, I use it a lot (in a daily basis). I wonder if it is ok to let it always connected to the USB, selecting "disconnect device" on SIgnalvu PC before closing it, each time I finish some measurements. Would it damage the unit to let it always connected to USB for too long? I mean, as long as the computer is turned on too. I just want to avoid plugging and unplugging the cable every day in the lab. Thanks again!

[@w2aew]

There is no harm leaving it plugged in, I've run mine continuously for days...

[@LiraLab]

@@w2aew That's really nice! Thank you!

[@LiraLab]

@@w2aew Is there any way to increase the markers font size? Sometimes, I got to get close to the monitor to be able to read. I wonder if I could increase them so that I could read from a little far from a monitor.

[@LiraLab]

That's a real nice application for the USB SA. I am wondering what is the longest time domain window supported. Would it go to, say, 8s? Or is it limited to the minimum RBW? Thanks!

[@w2aew]

For the USB RSA shown here, the maximum time-domain capture of baseband IQ data within the analysis memory is 2 seconds. The RBW setting has no bearing on this. Longer recordings can be made with the Streaming feature, provided the PC has a fast enough SSD to keep up. Other RSAs in the product family, such as the benchtop units can acquire longer records.

[@LiraLab]

@@w2aew Oh, I see. I am actually interested in zero span measurements over time for some pre-certifications tests. For FCC, I basically need to look at a 20s time window and verify channel occupation no more than once over that period of time. Is this model able to provide that? Thanks a lot!!

[@w2aew]

@@LiraLab Yes, this can be done, but in a different way. Using Zero Span is essentially the "old fashioned" way of viewing spectral occupancy. There are several more modern ways of doing this. The DPX realtime spectrum display can be used which will show all transient spectral activity. This can be setup in a max-hold, and can also be recorded in a time-stamped waterfall type of display. There are other ways too - setting up a triggered acquisition to look for and capture signals within a frequency band is also possible.

[@DatNguyen-ju8go]

Help, I found your 3 videos about RSA and they are extremely helpful for me. My problem is I am seeing this warning or error: Not Aligned and another one is Warming up data not align. I looked at all the documents including the 650 pages but can not seem to fix this error or warning. Please help

[@w2aew]

The "warming up" message is simply a 20-30 minute timer since the RSA and the application was started. The "not aligned" message can be cleared by running an alignment (Tools>Alignment) - you just have to disconnect any signal from the input and run it, takes just a few seconds.

[@MalikMGul]

Great video. I have a question. Can you change the time division of soectrogram while its running, like you reduced it from 1 ms to few us. Or is it only possible once you pause it.

[@w2aew]

You can do it while it is running.

[@usmangul66]

@@w2aew thanks for the reply. Can you also comment on the min RBW and time division combination that you can achieve while running. Thanks

[@w2aew]

@@usmangul66 The minimum RBW and the minimum time/division are both a function of the acquisition BW (tied to Span). At wide spans, the RBW can go down to 100Hz as I recall, and the time / div is tied to the IQ sample interval which can be as low as 17.8ns. We can get close to 1Hz RBW at narrow spans.

[@danielgoldner5152]

Just a Q, is it possible to monitor a continual changing peak in frequancy speaking ? (marker to peak doesn't change when the peak is changing)

[@w2aew]

The markers do not have a "peak tracking" function at this time.

[@danielgoldner5152]

@@w2aew is there any other way to monitor peaks ?

[@w2aew]

Yes. Use the Spurious display. Set the threshold as desired and all peaks above the threshold will be tagged, tracked and tabulated

[@DreamyAchujk]

hi can we get complex fft / can we get phase value of the fft measured thru rsa518A

[@w2aew]

SignalVu-PC and the RSA518A will only give you the magnitude of the FFT. You can export the acquired baseband I/Q data to Matlab to compute the complex FFT result, if that is what you need. The RSA will also give you Phase Deviation vs Time, just in case that is helpful for your application.

[@DreamyAchujk]

@@w2aew phase deviation vs time for time domain right

[@DreamyAchujk]

@@w2aew also while getting time domain signal it is cdistirted at the frequency for which we transmitted while fft is correct. But I am getting that signal in to main only after a shift of 100khz. To get the time domain signal at the frequency transmitted shud I adjust bandwidth

[@w2aew]

@@DreamyAchujk The Phase vs Time will be phase with respect to the Center Frequency that is setup on the RSA. By default, phase is rotates such that 0 degrees is at the Trigger location. Narrower Span settings improve the SNR of the Phase vs. Time trace.

[@DreamyAchujk]

@@w2aewcan u give ur contact number

[@frankderks1150]

Can you show how saved files from the MDO3000 series can be used?

[@w2aew]

The MDO3000 doesn't give you a direct way to control how much time (IQ data) to acquire. You have indirect control over this by changing the RBW setting (narrow RBW = longer IQ record). With limited IQ data vs. time, there would be limited ability to fully examine the signal characteristics vs. time. The MDO4000 series on the other hand, does give you the ability to control the time duration of the IQ data, making it much more useful for collecting RF data for deeper analysis withing SignalVu-PC.

[@frankderks1150]

Does the data from the spectrograph history get downloaded? If so that might give some ability to view some signal characteristics over a time period.

[@w2aew]

The spectrogram can't be directly exported. Time trends in the spectrogram will only be long term trends because new traces are added the the spectrogram with each acquisition, so there is a substantial time gap between traces.

[@johanfourie9385]

Hi Alan. That was very informative. I would like a video on WiFi analysis. Example an off-air recording and how to set it up to do constellation diagrams and quality measurements. WiFi is always present and can be an easy demo to prospective customers.

[@w2aew]

I can do this in a future video. It should be noted however that measurements and analysis of off-air WiFi can be problematic for a number of reasons - the most common problems are due to unavoidable multi-path effects and co-channel interference in the highly crowded ISM band. Triggering and capturing a particular channel can be difficult with the USB RSAs due to the 40MHz wide trigger bandwidth, unless you can get close to a particular WiFi transmitter to make its signal stronger in the RSA. Most of what you see in off-air monitoring are beacon transmissions which have a gaussian spectral shape and are transmitted with 802.11b format. The data transmissions will have a more rectangular spectral shape, and are often 802.11g or 802.11n (at least for those found in the 2.4GHz ISM band), so a little experimentation in the demodulation settings will be needed.

[@johanfourie9385]

Thank you Alan. I have a A-0047 directional antenna which is helpful to point to the device to be analized.

[@geordirendum583]

can you make a video on tesla coils :p ?

[@PapasDino]

Gotta go out and buy more lottery tickets! Time correlation sure is a nice capability to have.

[@dishonoled9685]

thank you very much, very useful

[@ahbushnell1]

good video

[@BMRStudio]

I miss the paper draw :)))))

[@w2aew]

I will do more of my traditional videos as soon as I heal enough to be able to get into my basement lab.

[@joopterwijn]

How is the ankle, you must be bunn yhoping around by now!

[@w2aew]

Hopping and hobbling around on crutches still.

[@DeeegerD]

A bit complex - I'll need to practice - can you get Tek to send me a nice SA lol ;)