LT4446 – Auto Changeover for the LT4600
The LT4446 is a changeover unit that automatically switches the signal from the primary signal to the backup signal when problems are detected in the primary signal. Two systems of input signals (primary and backup) are connected to the LT4446. The changeover detects errors in the amplitude of the primary input signal.
A single LT4446 provides 11 channels. These channels can receive SDI, NTSC/PAL black burst, HD tri-level sync, AES/EBU digital audio, and word-clock signals. SDI signals are switched with relays; all other signals can be switched with electronic switches. The power supplies are redundant. Alarms are generated when errors occur.
- I/O Connectors:
The LT4446 is equipped with 11 sets of I/O connectors (a single set consists of a primary input connector, a backup input connector, and an output connector).
- Input Switching:
Relays are used to switch between the primary signals and backup signals of channels 1 to 3. High speed electronic switches are used to switch between the primary signals and backup signals of channels 4 to 11.
- Input Signal Selection:
On channels 1 to 3, you can select SDI signals (3G, HD, SD), NTSC/PAL black burst signals, or HD tri-level sync signals.
On channels 4 to 8, you can select NTSC/PAL black burst or HD tri-level sync signals.
Channels 9 and 10 are exclusively for AES/EBU digital audio signals.
Channel 11 is exclusively for word-clock signals. It also receives TTL signals.
- Faulty Detection:
When an input signal level error is detected, the LT4446 lights the panel fault LED as well as the panel LED that indicates the channel that is causing the problem. This feature allows quick investigation of the problem.
Channels 4 to 11 are equipped with high-speed fault detection circuits. These enable the LT4446 to switch to a backup signal with barely any disturbances shown on the screen when problems, such as interruptions, occur in the primary signal.
- Alarm Detection:
If an error is detected at an output connector of channels 4 to 11 or at the power supply, a panel LED indicating where the error occurred lights up to alert the user.
- Power Supply Start Time:
A delay for starting the fault detection at power up can be set to approximately 1 minute or approximately 4 minutes, depending on the rise time of the system signal source that the LT4446 is connected to.
- SNMP v1 Ready:
Error monitoring over an Ethernet network is possible. Traps are issued for error detection, panel control, and remote control. In addition, the error details and DIP switch settings (except for the user-defined fault detection level) can be read as status information. IP address configuration software is included.
- Redundant Power Supply:
Redundant power supply provides extra reliability. Alarms are generated when an error occurs.
LT4446 Changeover Data Sheet