serial modem communication bit error rate

[DonDefensor]

I would like to create a LW application which communicate on serial port between 2 modems. I have to send a pseudo random number from one computer to the other and I need to check the bit-error rate continuously. I'll also have to monitor the speed of the communication. And is needed to make available to set a telephone number where the program can search for the other station.

So I will create 2 VI's.
How can I monitor the bit error rate? My idea is that I generate a pseudo random number with Binary MLS with seed, than convert it into string which I can send through the serial port. On the other I recive the string and than I have to compare it with the original one (so I create another Binary MLS with the same seed as on the 1'st VI.) than I think I should XOR them, but how? And how can I set a telephone number?

Thanks in advance to everyone!

Madarász Atilla

http://digitus.itk.ppke.hu/~madat/sajatanyagok/compare.PNG

[mikeporter]

My how time flies, the very first application I ever created in LV was doing bit error rate testing of modems. Of course that was 1985 and we are talking LV 1, running on a Mac II... Oh well...

In any case, you can certainly take the approach of building the whole thing in LV, but you might want to consider getting a BER tester and simply using LV to control the tester and the modems under test. If you count the time (and costs) associated with developing and validating your own solution, this could also be the low-cost approach. I just did a quick search and found a lot of economical solutions.

Mike...

[DonDefensor]

Thanks for the answer, Mike.

I need to make the whole thing in LV, because it's written in the specification in the project.
If you remember your main ideas when you made the similar app, please tell me.

Atilla

[DonDefensor]

Well, I managed to measure the bit error rate. The idea was to convert a string into unsigned byte array and than XOR.

My second problem is now to measure the communication speed between the modems. Waiting for ideas. Unfortunately I'm not able to test the whole communication, as I don't have any serial ports in my PC, that's why I really need your experiments.

I attached my code.

Thanks,
Atilla

[Dennis_Knutson]

You algorithm for calculating bit errors is not correct. With some simulated data, I don't get any way near the right answer. Look at the code below and try that. Insert some data that matches and then insert single bit errors.

I also don't see the point of converting the binary sequence to a string and then using the Byte Array to String. Put the Byte Array to String directly on the output of the Binary MLS function. And why use two of them? If you want a longer sequence, change the number of samples from 128 to 256.

Message Edited by Dennis Knutson on 05-13-2007 09:39 PM

Message Edited by Dennis Knutson on 05-13-2007 09:42 PM