How to send data into many bursts?


#1

Hi all,

My task was to develop a GFSK transmitter based on the following
requirements

• Preamble : 55 55

• Synchro : F6 72

• L-field ( data + CRC) : 20

• Data (30 bytes) : FFFFFFFFFFFFFFFFFFFFFFFFFF0110AABBBBBBCE9800010

• CRC : FECB

• Modulation : GFSK

• Deviation : +/-2,4KHz +0,2%

• Modulation index : 2

• Filter index : 0.5 BT

• Bitrate : 2400 bit/s

• Carrier Frequency : 169.41 Mhz

I ve designed a transmitter based on gnuradio as follow

The main blocs are :

1.File source block which contain the data to be transmitted,

  1. GFSK Mod block :I choose the number of samples per symbol (sps)=
    100, I used the following equation to calculate the sensitivity
    sensitivity = Pi * modulation Index / sample par symbol and filter index
    BT= 0.5

3.Rotational resampler block: the interpolation = samp_rate * (sps
-1) and decimation is equal to my sample_rate

4.And finally a multiply const block that feeds the USRP sink and Gui
FFT and time sinks

I am using gnuradio 3.7.9.2, USRP X310 with UBX daughterboard and UHD
003.010

I ve visualized my signal with a spectrum analyzer and It looks good ( I
hope that what I did was correct).

I would like to transmit the data above in a bursted mode, I ve tried to
use the PDU to stream bloc and the unpacked to packed bloc but I was
always getting a continuous transmission.

Any hint please on how to make data contained in my file bursted ?

Thanks in advance.