11
Measurement, Display and Control – continued
Analog demodulation, continued
PM demodulation (typical)
Carrier locking Automatic
Demodulator bandwidth Same as selected measurement span
Modulation index accuracy ±0.5º (deviation < 180°, modulation rate ≤ 500 kHz)
Harmonic distortion Deviation ≤ 180°.
Modulation bandwidth ≤ 50 kHz –60 dBc
Modulation bandwidth > 50 kHz and ≤ 500 Hz –55 dBc
Spurious Relative to 180° deviation
Modulation bandwidth ≤ 50 kHz: –60 dBc
Modulation bandwidth > 50 kHz and ≤ 500 Hz –55 dBc
Cross demodulation < 1° PM on an 80% modulation index AM signal, ≤ 1 MHz modulation rate
FM demodulation (typical)
Carrier locking Automatic
Demodulator bandwidth Same as selected measurement span
Modulation index accuracy ±0.1% of measurement span, deviation ≤ 2 MHz, modulation rate ≤ 500 kHz
Harmonic distortion (cardinal spans)
Modulation rate ≤ 50 kHz, deviation ≤ 200 kHz –60 dBc
Modulation rate ≤ 500 kHz, deviation ≤ 2 MHz –55 dBc
Spurious (cardinal spans)
Modulation rate ≤ 50 kHz, deviation ≤ 200 kHz –50 dBc
Modulation rate ≤ 500 kHz, deviation ≤ 2 MHz –45 dBc
Cross demodulation < 0.5% of span of FM on an 80% modulation index AM signal, ≤ 1 MHz modulation rate
Time gating Provides time-selective frequency domain analysis on any input or analog
demodulated time-domain data. When gating is enabled, markers appear on the time
data; gate position and length can be set directly. Independent gate delays can be set
for each input channel. See “Time and waveform” specification for main time length
and time resolution details.
Gate length, maximum Main time length
Gate length, minimum Window shape/(0.3 x frequency span) where window shape is:
Flat-top window 3.8
Gaussian window 2.2
Hanning window 1.5
Uniform window 1.0
Markers
Types Marker, offset, spectrogram
Search Peak, next peak left, next peak right, peak lower, peak higher, minimum
Copy marker to Start freq, stop freq, center freq, ref level, despread chan, offset to span, counter to
center freq
Marker functions Peak signal track, frequency counter, band power, couple
Band power Can be placed on any time, frequency, or demodulated trace for direct computation of
band power, rms square root (of power), C/N, or C/No, computed within the selected
portion of the data.
Trace math Trace math can be used to manipulate data on each measurement. Applications
include user-defined measurement units, data correction, and normalization.
Operands Measurement data, data register, constants, jw
Operations +, -, x, /, conjugate, magnitude, phase, real, imaginary, square, square root, FFT,
inverse FFT, windowing, logarithm, exponential, peak value, reciprocal, phase unwrap,
zero