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Problem with dropped receive start bit.

Please see: "MT MSK Transciever" as an example.

 

I am using the student version of LabVIEW and trying to learn more about modulation methods and noticed that

several of the Modulation Toolkit examples have problems with dropping the recieved start bit.

 

Is this a "bug" or is this something that does happen in real-world situations.

 

Thank you for any help with this "problem?"

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Hi OldLabVIEWer,

 

This is expected behavior! The first bit that you are seeing is actually a guard bit and it is used to account for filter delay. This is explained further if you dig into the block diagram of the MT MSK Transceiver example and open up the Align array subVI (mod_align TX and RX bit sequence.vi). The comment on it's block diagram explains that, due to filtering delay in the demodulator, the TX Bit Sequence and RX Bit Sequences are unequal in length and the guard bits in the TX Bit Sequence need to be removed before aligning the sequences.  

 

Following the guard bit, there are 10 sync bits (which are used to align the transmit and receive data). The actual message bits will follow these sync bits. 

 

I hope this helps! If you have further questions, I would recommend posting on the RF Measurement Devices forum as this will be a better resource for questions related to RF toolkits and measurements.

Julia P.
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