Help please to set-up a priority project.

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1 Dec 2010
Posts: 6

My Cleverscope arrives tomorrow and I am sure we will have fun together. I have one particular project that I would like to get into operation as quickly as possible and I am hoping that somebody can point me in the right direction to save development time. I apologize for not working on the project myself before asking for help but I am under a really tight time schedule so please forgive me.

I need to plot the performance of an RF transmitter/receiver pair in an area of open ground, typically the area would be about 50 meters square. The antenna, receiver and Cleverscope package will be in a fixed test location at the edge of the area and the transmitter will be carried around the area . What I would like to be able to do is to consider this area as a grid and walk around the area pushing the transmitter button at every grid point. There could be up to 2500 grid intersection points. At each point I need to log the peak voltage from a crude signal strength output on the receiver. Clearly the time relationship between samples is random although the path walked will follow the grid pattern. The optimum end result would be to be able to save the grid data points to an Excel file (the layout of the cells in the Excel sheet would actually correspond directly to the physical grid pattern on the ground). I would then like to use these data points to construct a contour map of the transmission/reception characteristics of the site. If the characteristics are bad, change the position of the antenna, receiver and Cleverscope and try again. If this sounds time consuming I can tell you that we presently do these tests by trial and error and that is really time consuming.

Questions.
1. What trigger mode would be most suitable for the data collection? It will probably need to be based on ""single-shot"" trigger but it will need to be automatic in that we cannot go back to the Cleverscope after each transmission and set up for the next shot as we would have to do with my bench scope.
2. What logging mode would be best?
3. Is DDE the technique to use? I do not know anything about this subject, just saw the section in the manual and it looked applicable.
4. I have a netbook computer that would be ideal for this use because of its size, weight and battery life. It meets the minimum computer specs in the manual and it has USB2.0 but it has a pretty slow speed processor (an Atom) so will I see any performance problems or do I need to use my full-power laptop?

Thanks for any help you can give. In future I will try to be a contributor.

3 Dec 2010
Posts: 396

Hello Brian,
Thanks for acquiring a Cleverscope! Ok, to do what you want is not too hard, provided you can generate a reliable trigger. Lets assume that you always measure a signal from your transmitter, so all you have to do is record peak amplitude - as a measure of signal strength.

First up, you will need to setup the scope graph window in time and amplitude so that you can capture the signal strength pulse when it happens. Set the trigger level so that you get a reliable trigger no matter where you are in your 50 m square. Next choose View/Display Signal Info to display the signal information window. Click the Show Logging button (top right of the Signal Information window). Lets assume you are looking at the A channel. Tick the Pk-Pk check box, so we record the peak value of the signal strength. Uncheck Log Channel B. Set the Update interval to 0, so that you save on every trigger. Set the Log File type to Excel. Click on the folder button to the right of the Log File Name, and navigate to a folder, and enter a name of the excel file you want the results to go to. Get ready to start your test. Click 'Start Logging' in the Signal information Logging area. The excel sheet you named should be created and open (if the file already exists, a new sheet will be created). Click 'Triggered' to start acquiring. Because there are no triggers nothing will be saved yet. Now get onto your Grid, and do a transmit. This should trigger the scope once, and the value will be saved to the excel file. Carry on doing this, and you should wind up with an excel file with all the values you captured as a linear sequence in a column, along with the time of each trigger. After having captured your grid, click on 'Stop Logging ' button, and the excel file will be saved. Now do the necessary things you need in the excel file, and you should have your signal strength plot.

I would think the netbook should be fine.

Good luck!

9 Dec 2010
Posts: 6

Thanks Bart,
I actually completed the first job in Southern California yesterday. I did not try the full area logging but I can see how this would be done. The Cleverscope/netbook combination worked beautifully - the Cleverscope running off an external 12 volt battery, the test receiver off its internal battery pack and the netbook from its internal battery.

The trigger problem was solved by triggering from a decoded RF address signal in the test receiver that is not effected by noise as is the raw signal strength output of the test receiver. I could even use the decoded signal of the test receiver to supply a trigger pulse for viewing the signal strength output from a second independent receiver that had no decode output.

I was able to carry out comparative transmitter power output tests, comparative receiver sensitivity tests, best location for an antenna test and local environmental noise output measurements to the accuracy I require.

All in all, you folks produce an incredibly flexible and easy to use piece of equipment - I am working on other odd-ball applications for the near future.
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