My task was to develop a GFSK transmitter based on the following
• 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,
- 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
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 188.8.131.52, USRP X310 with UBX daughterboard and UHD
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.