Synchronizing Probelm in GFSK

February 19, 2017 | 89 is viewed

I designed a  GFSK Transceiver in gnuradio-companion, when i start to TX,TX data with  HackRF One and RTL-SDR , i receive data approximately true, but data had some shifts in 0 and 1.

In Simulation i tested TX and RX for files of text and  wav. In it every thing is ok, but when i used omocomsdr source and sink for real world, i see shifting data that i received.


Now i know i should synchronize between Transmitter and  Receiver:

Fig1:Time Synchronization in Wireless Networks[1]

I know in digital circuit we have three type synchronization:

1. Frequency synchronization
2. Packet synchronization
3. Clock recovery

so we need define any part: from gnuradio mailig list is quoted:

To solve #1, you can use a PLL or Costas loop, pilot tones, or a
frequency estimator of your choice to remove the unavoidable carrier
frequency offset caused by using separate oscillators on TX and RX.

To solve #2, real communication systems generally use a preamble, a
predefined data sequence at the start of each transmission, which the
receiver can use to find the start of each transmission and to obtain a
channel estimate. If your transmission is continuous in nature, you
won't need to do this part.

To solve #3, Gnuradio includes two blocks designed to recover clocked
data from a demodulated signal: the M&M clock recovery block, and the
polyphase filterbank clock recovery block. Both are closed-loop
algorithms which attempt to recover clock-aligned data at the original
clock rate.

So i want  to with data solve synchronization our TX,RX:

you can see our experient problem in youtube video:


Finally my problem is solved In gnuradio-companion. wwe used Packet Synchronization in our projects.

we used  packet encoder and packet decoder to our projet the grc file (for gnuradio 3.7.1) is shared in below links:



I announced i can send file mp3,mp4,ts,txt format file successfully it is same as bluetooth.I hope this post be useful for readers.



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