Specifications

Detector/Discr. Input Frequency is the frequency of the input signal
connected to the HP 11848A's phase detector. The Detector/Discriminator
Input Frequency is used to:
• Select the appropriate Low Pass Filter (LPF) in the HP 11848A Phase
Noise Interface. For frequencies < 95 MHz, the system enables the
2 MHz LPF to eliminate feedthrough of the fundamental signal and
the additive products out of the phase detector. When the 2 MHz LPF
is enabled, the maximum offset frequency the system can measure is
2 MHz.
• Set the frequency of the Calibration Source when the Calibration
Source is under system control.
Frequency Parameter Considerations
• If the Carrier Frequency defined for the measurement is incorrect, the
Computed Output calculations may be in error. Verify that the Carrier
Frequency displayed on the Result Graph is the correct frequency.
When computing Sigma of Tau from a Result File you must ensure that
the Carrier Frequency in the Instrument Parameter display represents
the carrier frequency of the Result File.
2-36 Instr. Params: $N w/FM Discriminator