BCD PPM DRIVE CARD - AES-3 Digital audio - iPPM
This software-controlled card takes an AES-3 digital audio input signal and uses pulse-width modulation to provide a highly accurate display of the peak programme level on analogue meter movements. Remote control facilities allow selection of various modes, and headroom settings, and outputs are provided to drive status indicators.
The card fits directly to the rear of type 74A and 74B meter movements (See Sifam Peak Programme Meters), to provide an output conforming to BS 6840 in terms of linearity, ballistics, attack and decay-time.
Connections are by pin headers. The AES-3 input connection is transformer balanced. Inputs are provided for control switches for MS, S+20 modes, M and S may be set to -6dB or -3dB. A header is also provided for setting headroom, or ‘line-up’. This may be set to give 16 different calibration settings, which are software dependant and are set using the RS422 port. A hexadecimal switch may be connected with some simple components to choose between these, or they may be linked on the card. Driver outputs are provided for: AES lock and V-flag error (on to show error), clip indication for either channel, overload on either channel, S+20 mode active, MS mode active. Indicators may be LED or lamps.
Sampling frequency: 24kHz to 100kHz samples supported. Signal: 16 or 24-bit resolution. Meter output: 0.1dB accuracy. Indicator drivers are open collector outputs, maximum current sink per output 100mA. DC power: 8V to 30V from one or two power supplies. Current: 100mA at 10V, 50mA at 20V DC, not including LEDs/lamps. AC power: 15V AC may be used from a centre-tapped transformer and is recommended for use only when using LED indicators, not lamps.