Example Code

QPSK Demodulator

This IP is a part of LabVIEW FPGA RF Communications Library available on NI Labs.

This IP performs digital demodulation of a QPSK modulated signal. The specs of this IP are as follows:

1. Corrects frequency offsets upto 50kHz.

2. Corrects symbol timing offsets upto 0.5% of the symbol rate.

3. Implements a 31 tap matched filter with programmable filter roll-off (alpha) in the range (0.4, 1.0).

4. Has the ability to demodulate in the presence of doppler shift upto 75kHz at doppler rate <=2kHz/s.

5. Maximum clock rate= 20MHz.

6. IP requires two samples per symbol (Maximum Symbol rate = 10MS/s).

7. Device utilization summary ( Xilinx Virtex II Pro P30)

Number of BUFGMUXs    7 out of    16    43%

Number of External IOBs    403 out of 556    72%

Number of MULT18X18s    71 out of 136        52%

Number of RAMB16s    18 out of 136        13%

Number of SLICEs    6498 out of 13696      47%

Required: Fixed-Point Math Library for LabVIEW FPGA

Please post your comments, feedback, queries so that we can improve the demodulator design.

Example code from the Example Code Exchange in the NI Community is licensed with the MIT license.

Comments
kkhaleel786
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There is no Zip file attached along with.,

Please do upload the Zip file

gizem11
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I dont have any idea about error .I cant find anything with sample per symbol. How can i solve ? Do you Know?

Capture.PNG

Vinay_Kumar
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The error suggests that the symbol map is empty or incorrect.

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