Implementing Manchester Decoder

[kulsman]

I am trying to implement the Manchester decoder in labview based on this algorithm.

Algorithm can be found here:

http://www.cypress.com/?rID=55345

I am having difficulty in implementing the 3/4th bit--time delay.

I am fairly new to labview programming, so I would greatly appreciate any suggestion.

[GerdW]

Hi kulsman,

what did you program so far?

How are you reading the digital values in? Do you use external triggering or do you read the DI with a fixed sample rate?

Are you trying to detect edges in the signal?

Btw. you can also decode the bits by detecting any edges (rising/falling) in the signal and using the negated value just after the detected edge. No need to wait for "3/4 bit delay"...

[kulsman]

Hello Gerdw,

This is my basic setup. [photodiode -> amplifier -> c-RIO]

I was think of connecting a analog input module to the c-RIO.

As far as the code,I have just started last night. I created a while loop so that it is constantly running, and I started to look into the DAQ.

How do you detect any edges (rising/falling) in the signal? Is this part of special Labview module?

Thanks,

Rahul Madhu

[GerdW]

Hi Rahul,

- cRIO don't use DAQ(mx), they use the ScanEngine or the FPGA...

- EdgeDetection as easy as it is...

[crossrulz]

What I have done in a similar situation is oversample the waveform.  So if the data is supposed to come in at 1MHz, I would sample at something more like 4MHz or 8MHz.  Since you are looking for a 3/4 bit time, the rate should be divisible by 4x the bit rate.  Then you can easily figure out where the transitions were.