4-75
OFFSET FROM CARRIER (Hz)
Required to
“see” 4km/hr
target
“Good’
oscillator
at rest
“Good’ oscillator on
vibrating platform (1g)
Radar oscillator
specification
-50
-100
-150
53 dB
dBc/Hz
100K
10K
1K
100
10
1
1
10
100
1K
10K
100K
Impacts on Radar Performance
·   Lower probability of detection
   ·   Lower probability of identification
      ·   Shorter range
         ·   False targets       
•  Data shown is for a 10 MHz,
    2 x 10-9 per g oscillator
•  Radar spec. shown is for a coherent
    radar (e.g., SOTAS)
Phase Noise Degradation Due to Vibration
    At X-band, for example, low phase noise 70 Hz from the carrier is required to detect slowly moving (4 km/h) objects. Shown above is an example of the phase noise degradation due to vibration - showing phase noise vs. offset frequency from the carrier. The phase noise degradation was 53dB at 70 Hz from the carrier.  In the example on the next page, a degradation > ~25 dB causes the radar to have a zero probability of detection for 4 km/hr objects.  Therefore, with the degradation shown above, the radar was blind to slow moving objects.