Lag%20Correlator%20Testing

1
Lag Correlator Testing

• Aria Meyhoefer
• Carnegie Mellon University
• Summer 2001

2
The Lag Correlator

• What it is
• How it works
• What I did with it
• Reflections
• Transmissions
• Signal Response
• Conclusions

3
17 Unit Lag Correlator
Inductor
Diode Array
Capacitor
Balun
4
How It Works

• Antennas read signals off the sky with path
  difference depending on source angle

• Signals travel along paths of equal length to
  Correlator

• Inside correlator delay lines remove signal path
  delays

• Each element of mixer array in the correlator
  measures the power from a particular direction

• The correlator also allows measurement of the
  spectrum of any signal detected

5
Testing the Correlator

• Signal Response Test
• Send same signal into both inputs of correlator
• Use different path lengths to create interference
• Read response from oscilloscope
• Reflections Test
• Send signal into correlator through directional
  coupler
• Terminate other input and output
• Power reflects back though directional coupler to
  oscilloscope
• Transmissions Test
• Send a signal into one input of correlator
• Read signal from other input of correlator
• Find attenuation of correlator

Same microwave signal of 9dBm from 0.01 to 26.5
GHz was always used
6

• Compared to mixer results
• Expected Response One part in 158
• Measured Response One part in 6000
• Correlator is only 2.6 effective

7
Reflections Results

• Left input reflects 21 of the power
• Right input reflects 16 of the power

8
Transmission Results

• 0.03 mV from right to left
• 0.02 mV from left to right
• Sweep generator outputting 0.4 V
• Average attenuation of about 42 dB

9
Summary

• Correlator Response only 2.6
• Correlator Reflects about 18.5 power
• Attenuation of 42 dB

10
Thanks

• Jeff Peterson Carnegie Mellon
• Jeff Rapadas Device Technologies