This is were two programme paths are used across a distance, and circuitry decides which path to use, switching over to the other path on failure. The decision is generally based on signal level, but is then complicated by mono/stereo and signal status if AES3. Sometimes a reserve path is required should both main paths fail.

Most of the time the system should be fully automatic, but include manual override to allow maintenance. Our customers generally require a simple programme path with no level adjustment or processing, and a copper path with magnetically latched relays was chosen for the APCU.

(The APCU is in the standard installation range)

A Piglet was designed in 2009 that had the 2:1 features. However the APCU was a better solution at the transmitter sites, so the Piglet was not taken further.

A simple 2:1 switcher based on magnetic relays on the BCD110125 Eurocard was used in BBC NBH in 2013 with manual control, and a Coax version for DVB switching.

By 2014, the BCD121101 FPGA based Eurocard was mature enough to be offered as a solution. This innovative card has four AES3 inputs and outputs, GPI and remote status capabilities. The FPGA directly decodes AES3 streams and creates AES3 outputs, so that only RS422 buffers are required in the signal path to the FPGA.

The BCD Audio designed DSP and microcontroller are embedded to the FPGA.

The 2:1 switching was achieved in the FPGA, with signal detect, fail time and threshold algorithms in the firmware. Simple LED status and external override inputs completed the card.

Several Installer-48 racks have been supplied over time, the last being for BBC Wales in 2020.

Available to special order.