Hi all, I am new to gnu radio, I did look around at different places at the internet but did not really find an answer. I am trying to send data using a GFSK transmitter in a bursted mode (ie :I need to send the “Premable +Synchro + L-field + data +CRC” N times per second). Eventually, my task is 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 have designed a transmitter based on gnu radio as follow The main blocs are : • 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 BT= 0.5 • Rotational resampler block: the interpolation = samp_rate * (sps -1) and decimation is equal to my sample_rate • And finally a multiply const block that feeds the USRP sink and Gui FFT and time sinks I am using gnuradio 22.214.171.124, USRP X310 with UBX daughterboard and UHD 003.010. I have visualized my signal with a spectrum analyzer and It looks good ( I hope that what I did was correct ). Now, I am trying to burst my data. In fact, I would like to transmit the “Premable +Synchro + L-field + data +CRC” N times per second. I have 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 ? Best regards.
on 2017-01-12 16:36
on 2017-04-17 12:53
In telecommunication, a burst transmission or data burst is the broadcast of a relatively high-bandwidth transmission over a short period.Burst transmission can be intentional, broadcasting a compressed message at a very high data signaling rate within a very short transmission time. This technique is popular with the military and spies, who both wish to minimize the chance of their radio transmissions being detected, a low probability of intercept (LPI) and low probability of recognition. Data bursts can occur naturally, such as when the download of data from the internet briefly experiences higher speeds. It can also occur in a computer network where data transmission is interrupted at intervals. Burst transmission enables communications between data terminal equipment and a data network operating at dissimilar data signaling rates. http://essaysthatwins.com/