LT 4448

Changeover Unit


Compatible with LTC Signals
Redundant Power Supply for Increased Reliability


LT 448 combination with two LT 4600As

The LT 4448 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 LT 4448, and the LT 4448 detects errors in the amplitude of the primary input signal.

A single LT 4448 provides 11 pairs of BNC and LTC channels. These channels can receive SDI, NTSC/PAL black burst, HD tri-level sync, AES/EBU digital audio, word-clock, and LTC signals. It can be used in combination with the LT 4610/LT 4611/LT 4600A.


Provides 11 channels (a single channel consists of a primary input, a backup input, and an output) on a single unit.

Relays are used to switch between the primary signals and backup signals of channels 1 and 2. High-speed electronic switches are used to switch between the primary signals and backup signals of channels 3 to 11. For LTC, switching is possible between primary signals and backup signals for three inputs.

The input signal type can be selected. On channels 1 and 2, you can select SDI signals (3G, HD, SD), NTSC/PAL black burst signals, or HD3 tri-level sync signals. On channels 3 to 8, you can select NTSC/PAL black burst signals or HD3 tri-level sync signals. Channels 9 and 10 are exclusive to AES/EBU digital audio signals. Channel 11 is exclusive to word-clock signals (TTL input). LTC channels are exclusive to LTC signals (2 Vp-p differential input).

LTC channels provide three systems of two inputs (primary and backup) and three systems of one output. In addition, an LTC cable (sold separately) can be used to connect to a LT 4610 (Sync Generator).

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 LT 4448 is connected to.

Redundant power supplies are available for increased reliability. Alarms are generated when errors occur.

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Related accessories

Product Name Model Remarks
LTC Cable LC2183 Conversion cable used when combining an LT 4448 changeover unit and LT 4610 sync generator