Timed Capture of Measurement on Anritsu MS2721A/B

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kkiddkkidd
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Timed Capture of Measurement on Anritsu MS2721A/B

Post by kkiddkkidd » Mon Dec 31, 2018 9:03 am

Happy New Year's Eve.... I posted this on another reflector but know some of you have MS2721's.

I have became involved in an interesting (but unpaid) little project where I need a simple way to save repeated plots from either my A or B version 2721 by time. Once every X seconds or minutes over a period of several hours. I don't see any internal or MST function that will SIMPLY do that. It appears that the C version will do it internally. Anybody know of a SIMPLE way to do a timed capture on an A or B ver? Notice the emphasis on SIMPLE... IE, using a Windows script in PuTTY or other terminal to save a measurement on the instrument every X seconds. There is a remote scripting language for those units but I don't see any way to use it without writing a C or VB app. I have captured several hours of individual carriers using the internal "Save on Event" with a Limit line crossing as the event.

The rest of the story...
The situation is that our local power utility has installed smart meters that use the _shared_ unlicensed 902mhz ISM band for it's mesh network. I think that is probably a reasonable idea BUT they have monopolized the entire 902-928 spectrum. Their equipment transmits short bursts on channels spaced 300khz apart. A max hold measurement often shows my power meter transmitting on EVERY 300khz channel 902-928mhz within 10-12 minutes and other meters and "collectors" transmitting an EVERY 300khz channel almost continuously within range of a mobile antenna on my truck.

A local WISP uses that band for some of their last mile internet delivery and the meters have wiped out WISP service to a substantial portion of his 900mhz customers. The utility is quoting their vendors propaganda that their little bitty carriers can not possibly interfere with a 900mhz spread spectrum signal and that it is the WISP equipment at fault. An occasional little blip of their carrier would certainly not kill the WISP WIFI signal but the almost constant barrage of carriers will certainly do so.

And of course there is a future project to move most of our 440mhz ham repeater receiver links to the 902mhz band where amateur radio (as a secondary licensed service) has precedence over all unlicensed devices.

I am collecting data for a presentation to the utility but would like to have a time lapse of the max hold capture as it fills with carrier hits.

Regards,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

kcbooboo
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Re: Timed Capture of Measurement on Anritsu MS2721A/B

Post by kcbooboo » Tue Jan 01, 2019 6:01 am

No specific answer regarding the Anritsu, but some SAs have an external trigger input that you could attach a timer circuit to.

One problem you'll likely have is that the spread-spectrum transmissions are brief and a moving target. Most SAs have a swept frequency for the horizontal axis, and this sweep takes a finite amount of time. As both the input signal and the SA's oscillator are continuously moving about, the chances of catching these brief transmissions falls rapidly. Peak-Hold is about the best you can use, but it will amass signals it just happens to catch and hold those until you clear the screen, which probably isn't what you want.

There are some expensive real-time SAs that are designed to capture short, moving, random input signals such as spread-spectrum. I don't know how they do that, unless they've got multiple oscillators. Good luck finding one to borrow.

Happy New Year.

Bob M.

Ray
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Re: Timed Capture of Measurement on Anritsu MS2721A/B

Post by Ray » Tue Jan 01, 2019 7:34 am

I hope everyone is having a great New Years,

I've had good luck using a DATAQ DI-1120 external 14 bit A/D converter (<$200) to capture long-term data from some older SAs. If the SA has an external X and Y axis output ports, you can just record the data on a couple of the available four channels. The DI-1120 comes with some good software (USB interface) and exports CSV files for Excel (these data sets can be large depending on the sample period). The setup is quick and the supplied software is easy to use.

Ray

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kkiddkkidd
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Re: Timed Capture of Measurement on Anritsu MS2721A/B

Post by kkiddkkidd » Tue Jan 01, 2019 9:17 am

kcbooboo wrote:
Tue Jan 01, 2019 6:01 am
No specific answer regarding the Anritsu, but some SAs have an external trigger input that you could attach a timer circuit to.

One problem you'll likely have is that the spread-spectrum transmissions are brief and a moving target. Most SAs have a swept frequency for the horizontal axis, and this sweep takes a finite amount of time. As both the input signal and the SA's oscillator are continuously moving about, the chances of catching these brief transmissions falls rapidly. Peak-Hold is about the best you can use, but it will amass signals it just happens to catch and hold those until you clear the screen, which probably isn't what you want.

There are some expensive real-time SAs that are designed to capture short, moving, random input signals such as spread-spectrum. I don't know how they do that, unless they've got multiple oscillators. Good luck finding one to borrow.

Happy New Year.

Bob M.
And a Very Happy New Year to everyone. I missed the ball drop for about the 30th year in a row...

The 2721 may have a trigger input but it does a fine job of catching the short bursts free running. Sweep is not the problem. Automatically capturing and saving it to memory is the issue.

The meters transmit for about 1.5-2.0 seconds each time and the sweep rate at that band width is about 300ms.

The 2721b has a number of ways to capture and save traces but not by time. It has a function that will capture a trace when a signal crosses a limit line. That works great to capture single signals but I am wishing to capture a peak hold trace at even intervals to show how quickly their junk fills all available spectrum. IF you try to use it with peak hold, it starts capturing _every_ sweep after one crosses the limit line. I suppose that I could use that and manually pick out the frames that I need.

The mem card that I have in the instrument will hold over 10k trace captures. By slowing the sweep down a bit, my TN public school math sez that it should hold about 10hrs of captures.

I can capture the plot with the push of a button but am not really wanting to sit beside the instrument for several hours staring at a clock.
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

kcbooboo
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Re: Timed Capture of Measurement on Anritsu MS2721A/B

Post by kcbooboo » Wed Jan 02, 2019 6:34 am

How about a small interval timer and a small doorbell-size solenoid sitting over the button you need to record/save the trace? It seems that all you need is a finger to push a button every so often, so make a finger.

Bob M.

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kkiddkkidd
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Re: Timed Capture of Measurement on Anritsu MS2721A/B

Post by kkiddkkidd » Wed Jan 02, 2019 8:14 am

kcbooboo wrote:
Wed Jan 02, 2019 6:34 am
How about a small interval timer and a small doorbell-size solenoid sitting over the button you need to record/save the trace? It seems that all you need is a finger to push a button every so often, so make a finger.

Bob M.
Now there is an idea... I am waiting to see if the system goes back to fast poll at it's usual time and if the end of sweep capture doesn't work, I have several various solenoids and door lock actuators that might work. I was hoping for a software solution since the instrument has full software remote control capability but beyond the basic remote control app included with MST, coding will be required and I don't have time (nor the desire) to do all that for a free project.
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

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jthorusen
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Re: Timed Capture of Measurement on Anritsu MS2721A/B

Post by jthorusen » Fri Jan 04, 2019 3:15 am

Here's a dumb idea: Get yourself a video camera and set it up to photograph the screen. If you just record several hours of video, you should be able to show the screen filling up. Alternatively, you can interface the camera to a computer and have it do video capture at whatever interval you desire. You can then show the individual screens and then superimpose them with PhotoShop or a similar program to show what happens over time.

Just a thought.

Regards,
James K. (Jim) Thorusen
KB6GM
Central Coast Electronics
www.centcoast.com
NW Oregon Consulting Bdcst Eng.

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kkiddkkidd
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Re: Timed Capture of Measurement on Anritsu MS2721A/B

Post by kkiddkkidd » Fri Jan 04, 2019 9:50 am

jthorusen wrote:
Fri Jan 04, 2019 3:15 am
Here's a dumb idea: Get yourself a video camera and set it up to photograph the screen. If you just record several hours of video, you should be able to show the screen filling up. Alternatively, you can interface the camera to a computer and have it do video capture at whatever interval you desire. You can then show the individual screens and then superimpose them with PhotoShop or a similar program to show what happens over time.

Just a thought.

Regards,
That is Plan B. I have gopro's and knockoffs that do time lapse. I was wanting to try to do the captures automatically internal to the instrument but it may come to a camera.
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

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