RF packet length of narrowband benchmark_tx

GNU Radio
1

Hello,

I am using narrowband benchmark_tx.py example to transmit packets. Each
single packet is separated from its neighbors by a second.
The parameters I am using:

benchmark_tx_modified.py -m gmsk -s 4000 -r 1000000 --tx-amplitude=1 -f
2.402G -A TX/RX --tx-gain=25

benchmark_rx_modified.py -m gmsk -r 1000000 -f 2.402G -A RX2 --rx-gain=0

At the receiver side (different USRP device), I am converting the
complex stream into magnitude_squared then into a file sink. What I
should receive according to parameters above is a packet of 64000
samples. This is because sps (sample per symbol) equals to 2. (4000 * 8

  • 2 = 64000). However, using MATLAB, I am receiving extra ~31500
    samples!!! Please have a look at the attached image.
    I tried different packet sizes, modulation, etc, but there are still
    ~31500 extra samples.

Thanks,
Zaher

2

Hello,

Any comment or suggestion is highly appreciated.

3

Hello guys,

Please I want your help in this issue.

Zaher