User manual

Bank C-A: Input Loss Mode
The Input Loss Mode function selects what type of video appears at the system’s four outputs when
the input signal is lost or invalid. These choices are available:
• Black - SDI black.
• No Output - flat line, no signal present.
• Freeze - the last valid image is automatically frozen (ADC-8032B-S only).
The freeze is determined by the Freeze Mode function.
Use the following steps to set the Input Loss Mode:
1. Select Bank C, and rotate Function Select to position A.
2. Select the desired mode according to the table below:
• Toggle Mode Select up to advance up the list.
• Toggle Mode Select down to descend down the list.
Bank Function Select Mode Select Heads-Up Display Label Default
C A
+ Freeze
No Output
- Black
IN LOSS FREEZE
NO OUTPUT
BLACK
BLACK
Important
It is recommended that the Hotswitch Mode and Input Loss Mode
have the same setting: both set to freeze, or both set to black. There
is circuitry in the sync stripper that removes unwanted impulses to
make the circuit more noise tolerant. During a hotswitch, this could
cause the ADC-8032B to interpret the signal has been lost. Since the
Input Loss mode overrides the Hotswitch mode setting, having one
set to freeze and the other set to black could lead to a momentary
glitch on the output.
Bank C-B: Hotswitch Mode
The ADC-8032B uses a phase-locked-loop (PLL) to synchronize its pixel clock to the incoming
signal’s line rate. Because of this, any disturbance to the incoming line rate, such as an untimed
switch outside the lock window of the PLL, will cause the PLL to lose lock. It can take several fields
before the PLL can regain lock, and until it does so, the decoder cannot properly decode the incoming
video. The result is that untimed switches will result in a disruption to the output video.
To mask this disruption, a hotswitch mode was created. This is accomplished by momentarily freezing
the last good frame, or momentarily going to black while the untimed switch occurs. Going to black is
recommended since the output can be forced to black as soon as the hotswitch condition is detected.
Freezing must wait until the next field, in which case a single corrupted field could get through to the
output.
4-22 • Using Banks ADC-8032B User Manual (Iss. 02B)