User`s guide

FM Discriminator Measurement Examples 10
Agilent E5505A User’s Guide 253
FM Discriminator Measurement using Double-Sided Spur Calibration
Required Equipment
Table 40 shows equipment required for this example in addition to the phase
noise test system and your DUT.
Determining the discriminator (delay line) length
Perform the following steps to determine the minimum delay line length (τ)
Possible to provide an adequate noise to measure the source.
1 Determine the delay necessary to provide a discriminator noise floor that is
below the expected noise level of the DUT. Figure 181 on page 254 shows
the noise floor of the discriminator for given delay times (τ).
2 Determine the length of coax required to provide the necessary delay (τ).
(Eight feet of BNC cable will provide 12 ns of delay for this example.)
3 Determine the loss in the delay line. Verify that the signal source will be
able to provide a power level at the output of the delay line of between +5
and +17 ICBM. Be sure to take into account an additional 4 to 6 dB of loss in
the power splitter. (The loss across 8 feet of BNC cable specified in this
CAUTION
To prevent damage to the test set’s components, do not apply the input signal to
the signal input connector until the input attenuator (N5500A Option 001) has been
correctly set for the desired configuration, as shown in Ta ble 4 1 . Apply the input
signal when the connection diagram appears.
NOTE
To ensure accurate measurements allow the DUT and measurement equipment to warm
up at least 30 minutes before making the noise measurement.
Table 40 Required Equipment for the FM Discriminator Measurement Example
Equipment Quantity Comments
Signal Generator 1 +19 dBm output level at tested carrier frequency.
Calibrated FM at a 20 kHz rate with 10 kHz Peak
Deviation.
Power Splitter 1 NARDA 30183
Delay Line Delay (or length) adequate to decorrelate source
noise.
Phase Shifter 1
± 180 ° phase shifter at lowest carrier frequency
tested.