BCD AUTOMATIC LINK CHANGEOVER UNIT - APCU
Intended for and installed at many transmitter sites, this programme changeover unit can select between two incoming stereo programme signals, and in the event of a failure of the primary path, switch to a third back-up signal. It may be controlled and monitored remotely.
The rear panel has the inputs and outputs; two main stereo inputs, input A and input B are connected using two pairs of XLR-F connectors. A further stereo 'Reserve' input uses two more similar connectors. An RS232 port uses a 9-pin D-sub connector for configuration, and a 15-pin version provides connections for external control and tally indication of the indicators on the front panel. An IEC mains inlet and 2.5mm coaxial connector connect AC and DC power.
The front panel has indicators for current signal path status and 'Auto', 'Alarm' and 'Fail' status. An LED shows the presence of power. There are two recessed, three-position toggle switches for signal routing. One controls the selection between the two main inputs, A or B or 'Auto'. The second controls the selection between the main selection or reserve input or 'Auto'. Thus the signal routing may be forced to accept a particular configuration or may be controlled automatically according to the settings for signal priority.
The unit is completely configurable in software, to adjust the operation of the unit to suit particular requirements. Path A & B can have equal priority, and switching will occur only on failure of the active channel. Alternatively path A can be restored after pre-set delay time, if the signals are present, overriding B, which is now a secondary input. Switching to the reserve input takes place after a preset time during which the selected main signal has failed. Similarly the time and conditions before returning to the main programme signal when the reserve has failed may also be preset. The signal detection threshold may also be set between 0 and -40dB. Individual signal detectors may be disabled for mono working. A recessed switch on the rear panel enables the setup mode. A terminal is connected to the RS232 port, and is used to configure the unit.
The signals are connected by magnetically latching relays, ensuring that the programme path is maintained during a power failure. The six signal detectors have high-impedance electronically balanced inputs. As a result, degradation of the programme signals is minimal, even under no-power conditions.
Power source: 90-250V AC 50/60 Hz, 12-24V DC 250mA maximum. Dimensions: 1U rack-mounting, 140mm deep. Weight: 600g.