Video trigger in modulation analysis

[Ivan Ionov]

Hello,

I have a radio tx and trying to analyze its protocol with BB60C.
In zero span I clearly see how it transmits data in pulses, I can set video trigger on a pulse and see, that it is frequency modulated, as I understand it is 2FSK modulation.

I want to setup 2FSK modulation analys, but first bad thing – it doesn’t have video trigger, most of the time it tries to decode noise, not my short pulses. Please add this trigger (as well as external trigger), to start modulation analys on packet start.

BTW, Let me share my suggestions about zero span mode.

1) please, add option to save the FM, PM and AM data in csv format from zero span view. I can see the data, but can’t zoom in to get more details…

2) lower left specturm view is a bit useless, it shows the noise before the packet has started. Idealy this spectrum view must update itself when I put a marker on upper view to show the spectrum at that moment.

3) upper FM deviation chart has always MHz marks (doesn’t switch to KHz when deviation range is small). When I set fm deviaton to 3KHz, all chart marks are useless “0.00MHz”

4) center frequency edit box has not enough digits, it must have least 9 digits for 1GHz frequency, to tune to exact frequency especialy in phase modulation (to remove phase drift on the upper PM plot).

• This topic was modified 9 years, 5 months ago by Ivan Ionov.
• This topic was modified 9 years, 4 months ago by Andrew.
• This topic was modified 9 years, 4 months ago by Andrew.

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Hello Ivan,

Excellent feedback and suggestions. We are aware of the limitations of Zero-Span and hope we can address them in the future. We are also aware of the need for triggering in modulation analysis. As always, I cannot specify any time frame for when we might address these issues, but we do record all suggestions and feedback and use them when making decisions about what to pursue next. We very much appreciate it.

You might be interested to know that there is very basic I/Q capture functionality in Zero-Span mode along the bottom of the screen. It allows you to save a burst I/Q capture to a file as CSV. You would then need to convert it to an amplitude/phase/frequency value in a spreadsheet program, but this might help you.

Regards,
A.J.

Hello Ivan,

We just released a new version of the software which enables you to perform video triggering for digital demodulation. The version which adds this functionality is version 3.0.20 of the Spike software. I have specifically tested this with 2FSK. Let us know if this helps you with your application.

Regards,
A.J.

Thank you!

Video trigger works!
I can capture and decode 30ms pulse, repeating in 1sec, it was almost impossible to catch it and decode without video trigger.

The only bad thing I’ve noticed in new version – video trigger option sometimes makes software unresponsible, it hangs for a minute and then crashes. Usually it happens when I set video trigger on and then uncheck “auto IF bandwidth” to increase bandwidth from automatic 30kHz to 100-200kHz to get more accurate Eye Diagram. When I unchek “auto” it jumps to full 27MHz (may be it is too high for my settings?) and then software hangs.

I’ll try to find if I can reproduce the problem without any signal.

I see, orange led on BB60 means, that software is reading data, but led doesn’t become green even if I press “Single” in modulation analysis (when video trigger on). Why it is doing something in Single mode?

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Hi Ivan,

Glad to hear this helps your use case. I’ve made a note of your issue. As for the LED, the device is continuously streaming I/Q even if you press ‘single’. When operating the device in an I/Q data acquisition mode, the device either continuously operates or is idle. It is simply the way the device was designed.

Regards,
A.J.

Hi Andrew,

I’d like to share my small wish list to the Symbol Table view.

1. The Symbol Table is just a picture now, I can’t select decoded hex data by mouse to copy-paste it to other text editor (to check for difference of several packets of data). It would be great to change the style of this view to make text selectable. Ideally there can be a button to save decoded data to hex of binary file (or to autosave data to file if decode is successful).

2. If decoded data is too long to fit in the view, there’s no way to see the ending of the long data packet, especially in binary view. It would be helpful to add scroll slider to the Symbol Table.

Regards, Ivan

I agree, support both hex and binary; the VSG wants binary 111000’s, Spike wants Hex. Fortunately some of us memorized hex to binary in our misspent youth, let’s make it easier for “RF Engineers, The Next Generation”. (shout out to Star Trek)

Tisha Hayes

[Author]

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