Section 4 - Waveform Mode
VM700A Option 01 (NTSC) & Option 11 (PAL) User Manual
4-9
Fixed IRE (NTSC Only): When highlighted, overrides the Zero Carrier
Pulse and Bar Reference selections in the current Measurement Locations
file, and fixes the IRE scale to 0 IRE = 0 Volts, 140 IRE per Volt.
This choice provides soft keys to select any of six filter characteristics or no
filter. When filters are engaged, measurement or timing information may become
less reliable.
Pressing the Filter Select soft key brings up the following submenu:
No Filter: displays the waveform without any filtering (default).
High-pass Filter: removes luminance from the signal. The pass band is
approximately 2.5 MHz to 6 MHz.
Low-pass Filter: removes chrominance from the signal. The pass band is
approximately 0 MHz to 1 MHz.
Diff Step Filter: removes chrominance from the signal, then displays the
direction and relative size of signal transitions.
LF Noise 7.5 kHz/10 kHz/15 kHz: removes all signal information above
the specified frequency.
Pressing the Clamp Couple soft key brings up the following submenu:
Position Backporch: sets the clamp position to the back porch and the
clamp level to 0.0 Volts.
Position Sync Tip: sets the clamp position to the sync tip and the clamp
level to –0.3 Volts (–0.29 V for NTSC).
Clamp Slow: selects slow clamp speed. This allows hum effects to be
visible, but is useful for coping with large DC offsets on an input signal.
Clamp Fast: selects fast clamp speed. This removes DC offset, hum, and
bounce effects from the signal.
DC Coupling: selects DC coupling (no clamping).
Manual Adjust: brings up the following submenu:
Position: adjusts the horizontal clamp position within a line.
Level: adjusts the clamp voltage level from –1.28 V to 1.27 V in 10 mV
steps. Adjustments outside ±300 mV may cause APL measurement
problems.
Clamp Slow: selects slow clamp speed. This allows hum effects to be
visible, but is useful for coping with large DC offsets on an input signal.
Filter Select
Clamp Couple
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