Egypt's National Authority for Remote Sensing and Space Sciences (NARSS) training - Educational Satellite Program (ESP)

1. X-BANDTRANSMITTER
BASEBAND DSP MODULE
Alexandria University
Mo’menAhmed
Supervised by:
Eng. Hany Bekhit / Eng.Aya Mohamed
X-Band Transmitter DSP project 1

2. Outline:
• X-band transmitter
• Why baseband DSP ?
• Tools
• Matlab, Simulink and FPGA implementation
• Synthesis
• Lessons learnt
• Future work
X-Band Transmitter DSP project 2

3. X-band transmitter block diagram
8 – 8.4 GHZ
X-Band Transmitter DSP project 3

4. Why Baseband DSP?
X-Band Transmitter DSP project 4

5. Sending image data
without using DSP
X-Band Transmitter DSP project 5

6. I received
Inverted data
X-Band Transmitter DSP project 6
While sending data through space, bit stream could be
inverted causing errors on receiving

7. Use
Differential encoder
X-Band Transmitter DSP project 7
• Hides data in transitions
• Overcome polarity inversion of received data

8. I lost
synchronization with you
X-Band Transmitter DSP project 8
While sending data through space, streams of ones and zeros
causes the loss of synchronization

9. Use
Scrambler
X-Band Transmitter DSP project 9
• Prevents streams of zeros or ones makes receivers easily
detect data and synchronize with sender
• 20 bit shift register

10. I received data with
high Bit Error rate
X-Band Transmitter DSP project 10
To send data with low BER, use high power amplifiers but
they consume lots of power and money

11. Use
Convolutional encoder
X-Band Transmitter DSP project 11
• Convolutional coding acts as an error detection and
correction unit hence decease BER with the same
transmitted power

12. DSP module functions
• To receive the clock and data from clock and data interfaces
• To apply the DSP algorithm on the transmitted data.The DSP algorithm
includes differential encoding, scrambling and convolutional encoding
• To generate test data pattern to be used in the self-test mode of operation
X-Band Transmitter DSP project 12

13. MATLAB Simulink block diagram
X-Band Transmitter DSP project 13

14. X-Band Transmitter DSP project 14
Tools
- Matlab Simulink
- Xilinx ISE Design suite
Artix-7 NEXYS 4 DDR
FPGA

15. PRS (test pattern generator)
X-Band Transmitter DSP project 15

16. Differential Encoder
X-Band Transmitter DSP project 16

17. Scrambler
X-Band Transmitter DSP project 17

18. Convolutional Encoder
X-Band Transmitter DSP project 18

19. Clock Divider
X-Band Transmitter DSP project 19
• Inputs 100 MHZ, outputs 100 and 50 GHZ
• System operates at 50 GHZ, 100 GHZ for half bit delay

20. DSP Block diagram
X-Band Transmitter DSP project 20

21. Top level simulation
X-Band Transmitter DSP project 21

22. Top level implementation
X-Band Transmitter DSP project 22
• Output_Q_buff is the Quadrature output
• /Inst_convolutional_Encoder/out_I is the In-phase output

23. Synthesis results
X-Band Transmitter DSP project 23
Module Max.
Frequency
# of
Registers
Clock
Buffers
I/O
Buffers
Top module 634.115 MHz 43 1 4
PRS 851.798 MHz 7 1 3
Differential Enc. 944.287 MHz 1 1 4
Scrambler 851.789 MHz 21 1 4
Conv. Enc. 707.214 MHz 8 1 5
Clk. Divider 685.871 MHz 1 1 5

24. Lessons Learnt
• Matlab Simulink for DSP
• In Chip debugging
• In Chip verification
• ChipScope Pro with Artix-7 FPGA
X-Band Transmitter DSP project 24

25. Conclusion and FutureWork
• DSP is very important for satellites communications
• To improve this work, optimization to the recourses used on the FPGA and
maximum frequency
• X-Band transmitter module could be implemented
• Modulation on OQPSK design
X-Band Transmitter DSP project 25

26. Questions ?
X-Band Transmitter DSP project 26