[Discuss-gnuradio] Transmit and receive suing GMSK

[Jamie Wo]

Hi all,

I am currently working on tranmiting and receiving data using 2 USRPN210s. I got some ideas from here and did this task using GMSK in GRC. 

The transmit side: File source --> Packet encoder --> GMSK Mod --> UHD sink.

The receiver side: UHD source --> GMSK Demod --> Packet decoder --> File sink.

Data in file source can be received by the receiver. However, I am not sure whether the data has been received correctly. Does anyone know how to test it ? 

My method is to use  wav source and audio sink like this:

The transmit side: Wav source --> Packet encoder --> GMSK Mod --> UHD sink.

The receiver side: UHD source --> GMSK Demod --> Packet decoder --> Audio sink.  (samp_rate 48K). 

I think if the sound received on the receiver is the same as the wav file, the data may be correctly received. However, after I tried this, the sound received was disjointedly, not as smooth as the wav source,  and "audio underrun" happened sometimes.

However, when I put all the blocks in one flow graph without UHD like this:

wav source --> Packet encoder --> GMSK Mod -->  GMSK Demod --> packet decoder --> audio sink.(samp_rate 48K),  it works very well. 

Does anyone meet the same problem  or know how to solve it? Is my way to test how to receive correctly right? 

To do what I want, is there any other blocks that need to be added in the GRC? 

Please give me some guidance.

Thanks in advance.

Jamie