BER measurement for GMSK transmission with USRP wirelessly

Good day everyone,

My sincere apology in advance if this question has been asked before,
but i tried search thru the archives but to no avail.

Currently, I am trying to calculate the BER for GMSK, But first I
started off on a perfect channel without USRP.

My current block diagram is as follows:

“Random Source”
0s and 1s, 10^6 windows -> “Throttle” -> “GMSK Mod (default settings)”
-> “GMSK Demod (default settings)” -> “Error Rate Block”

I am feeding in “Error Rate block” with the random source and the “GMSK
Demod” Output.

I am getting BER of 50%… Anyone knows what is wrong?

In fact, I saved the input and output as binary files. I found out that
they are not very identical especially in terms of binary length. I
tried input 9 bits of binary and I obtained 63 bits from the GMSK Demod
Output.
Is there something that is missing?
Hope someone can advise me. Thank you :slight_smile:

Best Regards,Sun

GMSK Mod takes in packed bytes, Demod outputs unpacked bytes (e.g. 1
bit per byte). You may need to perform a conversion. Best way to
figure out is to post a screenshot of your flowgraph.

Good day everyone,
Cool. Got it working. Thank you Vanush V. for your reply.
By the way, does anyone knows how does QAM Mod takes in and QAM Demod
output their data?

Similarly i found out that they are both not identical but cant figure
out how the data is formed.
Thanks for your time reading.
Regards,Sun

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