The document describes a BPSK RF receiver developed by Team 10. The objective was to successfully demodulate BPSK data sent at RF between two DSPs, demonstrating a programmable back-end receiver. It provides end-user benefits like a simple point-to-point communication solution and capability to handle multiple modulation schemes. The design includes an RF front-end using filters and mixers to select the desired signal frequency band and downconvert it. The back-end is implemented on a DSP using a phase-locked loop for carrier recovery and symbol timing circuits to demodulate the BPSK data and recover the transmitted symbols. Simulation and test results showing the transmitted and recovered signals are presented along with analysis of signal quality and bit

1. BPSK RF Receiver
Team 10
Michael Russell
Shawn Kuo
Amit Patel

2. Objective
 Successfully demodulate BPSK data
sent at RF from one DSP to another
 Demonstrate feasibility of
programmable back-end receiver
 Develop future tool for DSP lab

3. End-user Benefits
 A quick and simple point-to-point digital
communication solution
 Scalable module that is capable of
handling multiple demodulation
schemes without hardware redesign
 Capable of receiving over a large
frequency range

4. Original Design Review
Design Schematic
BW ~ 10's of MHz's AD8343 AD605 f =44.1KHz
Universal Eval PC
Rx CS4226 DSP
AR5000 AD605 fc = 10.7 MHz CODEC
ECS-10.7-7.5B
AD605 Teraterm
PBP-10.7 BW ~ 200 KHz
fc=10.7 MHz - 11.025 KHz
DDS CPLD
AD9854 LO
Mach211SP
Crystal 60 MHz

5. Software Implementation
 Differential BPSK
 Pi-Radian Ambiguity
 Symbol Quantization and Unmapping
 Phase-Locked Loop
 Carrier Recovery
 Coherent Detection
 Symbol Timing

6. Differential BPSK Symbol Mapping

7. Phase-Locked Loop

8. Symbol Timing

9. Simulation Results
Generated BPSK Waveform Received BPSK Waveform

10. RF Receive Stage
10.7 MHz BPF Fixed Gain Amp 0.528 MHz LPF Software
Transmitted 8dB
BPSK DSP 2
Attenuator
25 dB
Function
Generator 10.7 MHz LPF
(Simulates Noise)
Fixed Gain Amp
25d B
3dB
Attenuator
21.4 MHz LPF
DDS Local
Oscillator
DSP 1

11. RF Stage - Preselector
Maching Network Monolithic Monolithic Maching Network
Crystal Filter Crystal Filter
Ta se F n t no Pe e c rd )
rn fr u cio f rs l t ( B
eo P ae f rsl t
h s o Pee c r
eo
0
h g e r_3 ( ,1)
20
0
...cin _N tok ..S2 )
c g ewr_3 ( ,1)
...t in _N tok ..S2 )
-0
1
10
0
-0
2
-0
3
w
0
-0
4
-0
10
-0
5
h
-0
6
-0
20
1 .6
0 7 1 .6
0 8 1 .6
0 9 1 .7
0 0 1 .7
0 1 1 .7
0 2 1 .7
0 3
1 .6
07 1 .6
08 1 .6
09 1 .7
00 1 .7
01 1 .7
02 1 .7
03
f qM z
r , H
e
f qM z
r , H
e

12. Preselector Matching Network
Input Impedance
30
50
m1
Matching Network 30
00 m1 fq 0 0 H
r =1 .7 M z
e
Rn 7 7 5
i =2 5 .7 6
20
50
R 20
00
in
C L
R
R2 10
50
C1 L2
R=5 Oh
0 m
C=4 p L .8 u
0 F =5 5 H
10
00
R= 50
0
0
10
50
10
00
50
0
m 2
Zin = 2580 - j 1040 ` Xn
i
0
fq 0 0 H
r =1 .7 M z
e
X =- 0 3 4
in 1 3 .4 8
- 0
50
m2
- 00
10
- 50
10
- 00
20
1 .0
0 1 .5
0 1 .0
1 1 .5
1 1 .0
2
fqM z
r , H
e

13. Measured Signals
 Transmitted signal
 Signal after preselector
 Signal after mixing (baseband)
 Unfiltered DDS signal (LO)
 Filtered DDS signal

14. Transmitted Signal

15. Filtered Signal

16. Filtered Signal

17. Baseband Signal

18. Unfiltered DDS (LO)

19. Filtered DDS (LO)

20. Output Interface
 Write decoded characters to memory
and serial port simultaneously
 Interact with serial port through Tera
Term

21. Theoretical Probability of Error
Q
Constellation
I
Symbol B Symbol A
Q
Constellation
w/Noise I
Symbol B Symbol A

22. Theoretical Probability of Error
Received Symbol:
Mapping Q
I
Symbol B Symbol A
Result: Q(sqrt(2*Energy/Noise)) or Q(sqrt(2*SNR))

23. Calculating SNR
The SNR was calculated by measuring separately
measuring the signal power and the noise power
after the preselector filter.
10.7 MHz BPF Fixed Gain Amp
Transmitted 8dB 25 dB
BPSK Attenuator
Function Noise Measured Here
Generator
(Simulates Noise)

24. Calculated Probability of Error
 Calculated Byte Error (upper bound)
 Took 125KB of data
 Accurate for large amounts of noise
 Good order of magnitude approximation for
low noise

25. Error Results
Error Calculations
Theoretical Calculated
Noise Level (p-p) Noise SNR (dB/dB) Noise SNR (W/W) Perror (%) Perror (%)
100 mV 26.60 457.000 5.00E-199 0.00
500 mV 11.32 13.550 1.00E-05 0.05
800 mV 7.20 5.025 0.60 0.18
1500 mV 1.74 1.490 4.22 1.30
3000 mV -4.30 0.372 19.50 6.80

26. Tolerance of PLL
 Variation in Frequency
 Drifting in DDS
 Temperature
 Result
PLL Frequency Tolerance
Noise Level (p-p) Upper Bound (Hz) Lower Bound (Hz)
100 mV 9 -32
500 mV 8 -32
800 mV 8 -32
1500 mV 8 -32
3000 mV 8 -31

27. Successes
 Demodulated BPSK data sent at RF
from one DSP to another
 Demonstrated feasibility of
programmable back-end receiver
 Breadboard design produced expected
behavior

28. Challenges
 Transmitting BPSK signal at RF
 Used passive mixer and DDS
 Used coaxial channel instead of air
 Bandlimiting Signal
 Use of Narrow Bandwidth Crystal Filter
 Matching Network
 Working around Serial Port interrupts

29. Future Developments Rev1.1
 Solve Serial Port Issues for live data
 Printed Circuit Board
 Add Faster A/D
 Implement more Demodulation
Schemes

30. Questions???