Freescale Semiconductor, Inc.Modulator Functionality
Device and Signals Set-up
Measurement Set-up
Video Black Level
Audio signal: 1Khz, 205mVrms.
This is measured using a Rohde &
The audio signal 205mV at 1kHz is supplied by the Audio Analyzer, and
the FM demodulated signal deviation is indicated on the Demodulator in
Khz peak.
Schwarz AMFS Demodulator in B/G and This value is then converted in% of FM deviation, based on specified
a HP8903A Audio Analyzer at 1kHz
standards.
Audio Frequency response
The audio signal 1KHz 100mV
is supplied by the Audio Analyzer,
rms
demodulated by the Demodulator and the audio analyzer measures the
AC amplitude of this demodulated audio signal: this value is taken as a
reference (0dB).
The audio signal is then swept from 50Hz to 15KHz, and demodulated
AC amplitude is measured in dB relative to the 1KHz reference.
Audio pre-emphasis and de-emphasis circuits are engaged, all audio
analyzer filters are switched OFF.
Video Black Level
Audio signal: 50Hz to 15KHz, 100mV
This is measured using a Rohde &
Schwarz AMFS Demodulator in B/G and
a HP8903A.
rms
Audio Distortion FM
The input rms detector of the Audio Analyzer converts the ac level of the
combined signal + noise + distortion to dc. It then removes the
fundamental signal (1kHz) after having measured the frequency. The
output rms detector converts the residual noise + distortion to dc. The dc
voltmeter measures both dc signals and calculates the ratio in% of the
two signals.
Audio: 1Khz, adjustable level
Video Black Level
This is measured using a Rohde &
Schwarz AMFS UHF Demodulator in B/G
and a HP8903A Audio Analyzer at 1kHz.
The output level of the Audio analyzer is
varied to obtain a deviation of 50kHz
indicated on the Demodulator.
ADist = (Distorsion + Noise) ⁄ (Distorsion + Noise + Signal)
Audio Signal to Noise
The Audio Analyzer alternately turns ON and OFF it's internal audio
source to make a measure of the Audio signal plus noise and then
another measure of only the noise.
Audio: 1Khz, adjustable level
The measurement is made using the internal CCIR468-2 Filter of the
Audio Analyzer together with the internal 30+/-2kHz (60dB/decade)
Lowpass filters.
The AMFS demodulator uses a quasi-parallel demodulation as is the
case in a normal TV set. In this mode the Nyquist filter is bypassed and
the video carrier is used without added delay to effectuate intercarrier
conversion. In this mode the phase noise information fully cancels out
and the true S/N can be measured
Video: EBU Color Bars
This is measured using a Rohde &
Schwarz AMFS Demodulator in B/G and
a HP8903A Audio Analyzer at 1kHz. The
output level of the Audio analyzer is
varied to obtain a Modulation Deviation
of 25kHz indicated on the AMFS
Demodulator.
ASN(dB) = 20 × log(Signal + Noise) ⁄ (Noise)
12 Modulator Functionality
12.1 Power Supply
The two device Vccs (pins 11 and 14) must be applied at the same time to ensure all internal blocks are
correctly biased. All other pins must not be biased before Vcc is applied to device.
MOTOROLA
MC44BC375/U/J/T Technical Data
For More Information On This Product,
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MOTOROLA [ MOTOROLA ]
