NOTE: The loss of six feet of RG
6. Measure pulse width (PW) and pulse repetition
214/U coaxial cable is approximately
terms of seconds (PW = 1 x 10-6 sec, PRT = 1.11 x 10-
1.1 dB at S-band frequencies. The
actual loss of the test cable should
be measured at 3050 MHz.
7. Calculate radar duty cycle (0.0009) as follows:
7. Connect oscilloscope at receiver output
Duty Cycle = PRT
trigger oscilloscope from pulse generator.
frequency controls to identify test video signal on
minimum) as follows:
test signals and carefully adjust frequency vernier to
Average Power Recorded in Step 4
maximize test signal amplitude.
Peak Power = Duty Cycle Calculated in Step 7
9. Increase signal generator output attenuation
setting until test signal is just visually discernible in the
5.24.2 Receiver Sensitivity (Minimum Discernible Signal
- MDS) Measurement
NOTE: Adjustment of the pulse
1. Set (master) Indicator POWER switch to ST BY.
generator delay control will aid in
identifying the test signal at the
equivalent) output power level at 3050 MHz per its
threshold of discernibility.
3. Set signal generator controls as follows:
10. Verify MDS, calculated as follows, is less that or
equal to -98 dBm.
MDS = (Signal Generator
a. Frequency: 3050 MHz
Attenuation) - (Directional Coupler Attenuation) (Test
b. Output Level: -67 dBm
c. Modulation: External pulse
NOTE: For 20 dB directional coupler
4. Adjust pulse generator (or equivalent) for an
loss and 1.1 dB cable loss, the signal
output pulse having the following characteristics:
generator must be set to -76.9 dBm
or less for an MDS of -98 dBm.
Voltage: 25 5V peak
5.24.3 Antenna/RF Cable VSWR Measurement
Frequency: 1800 Hz
Width: 10 usec
Rise/Fall Time: 2 usec maximum
2. Convert return loss to VSWR using the chart
5. Connect pulse generator output at signal
generator external pulse modulation input.
6. Connect signal generator RF output to
NOTE: The VSWR requirement is
FORWARD port of directional coupler using six foot
1.65:1; this requirement is based on
RG214/U coaxial cable.
a 1.5:1 VSWR for the rotary joint and
antenna and a 1.1:1 VSWR for the RF