BPSK RF Receiver

Team 10Michael Russell

Shawn KuoAmit Patel

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

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

Original Design ReviewDesign Schematic

BW ~ 10's of MHz's AD8343 AD605 f =44.1KHz

CS4226AR5000 AD605 fc = 10.7 MHz CODEC

ECS-10.7-7.5BAD605

PBP-10.7 BW ~ 200 KHzfc=10.7 MHz - 11.025 KHz

DDS AD9854 LO

Mach211SP

Crystal 60 MHz

UniversalRx

EvalDSP

PC

Teraterm

CPLD

Software Implementation Differential BPSK

Pi-Radian Ambiguity Symbol Quantization and Unmapping

Phase-Locked Loop Carrier Recovery Coherent Detection

Symbol Timing

Differential BPSK Symbol Mapping

Phase-Locked Loop

Symbol Timing

Simulation ResultsGenerated BPSK Waveform Received BPSK Waveform

RF Receive Stage 10.7 MHz BPF Fixed Gain Amp 0.528 MHz LPF Software

TransmittedBPSK

25 dB

10.7 MHz LPF

Fixed Gain Amp 25d B

21.4 MHz LPF

Local Oscillator

FunctionGenerator(Simulates Noise)

8dBAttenuator

3dB Attenuator

DDS

DSP 1

DSP 2

RF Stage - Preselector

10.67 10.68 10.69 10.70 10.71 10.72 10.73-60

-50

-40

-30

-20

-10

0

freq, MHz

...ching_Network_3..S(2,1))

Transfer Function of Preselector (dB)

10.67 10.68 10.69 10.70 10.71 10.72 10.73-200

-100

0

100

200

freq, MHz

...tching_Network_3..S(2,1))

Phase of Preselector

Monolithic Crystal Filter

Maching Network

Maching Network

Monolithic Crystal Filter

Preselector Matching Network

Matching Network

Zin = 2580 - j 1040 `

LL2

R=L=5.85 uH

RR2R=50 Ohm

CC1C=40 pF

m1freq=10.70MHzRin=2757.756

0

500

1000

1500

2000

2500

3000

3500

Rin

m1

m2freq=10.70MHzXin=-1033.448

10.0 10.5 11.0 11.5 12.0-2000

-1500

-1000

-500

0

500

1000

1500

freq, MHz

Xin

m2

Input Impedance

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

Transmitted Signal

Filtered Signal

Filtered Signal

Baseband Signal

Unfiltered DDS (LO)

Filtered DDS (LO)

Output Interface Write decoded characters to memory

and serial port simultaneously Interact with serial port through Tera

Term

Constellation

Constellation w/Noise

Q

ISymbol ASymbol B

Q

I

Symbol ASymbol B

Theoretical Probability of Error

Mapping

Result: Q(sqrt(2*Energy/Noise)) or Q(sqrt(2*SNR))

Q

I

Received Symbol:

Symbol ASymbol B

Theoretical Probability of Error

The SNR was calculated by measuring separatelymeasuring the signal power and the noise power after the preselector filter.

10.7 MHz BPF Fixed Gain AmpTransmitted 25 dBBPSK

FunctionGenerator(Simulates Noise)

8dBAttenuator

Noise Measured Here

Calculating SNR

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

Error Calculations

Theoretical CalculatedNoise Level (p-p) Noise SNR (dB/dB) Noise SNR (W/W) Perror (%) Perror (%)100 mV 26.60 457.000 5.00E-199 0.00500 mV 11.32 13.550 1.00E-05 0.05800 mV 7.20 5.025 0.60 0.181500 mV 1.74 1.490 4.22 1.303000 mV -4.30 0.372 19.50 6.80

Error Results

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 -32500 mV 8 -32800 mV 8 -321500 mV 8 -323000 mV 8 -31

Successes Demodulated BPSK data sent at RF

from one DSP to another Demonstrated feasibility of

programmable back-end receiver Breadboard design produced expected

behavior

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

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

Schemes

Questions???