User`s manual

1.2: EXTERNAL PROCESSOR CAPABILITY

The PCAP II Plus EXTERNAL PROCESSOR unit is a high-performance, self-contained digital signal

processor and contains 38 DSP microprocessors, which are allocated as follows:

• 24 FIR filter processors which can be configured as 1 to 6 independent audio processors.

These flexible processors may be combined into mono and stereo configurations. Any of these

processors may be configured as an adaptive or adjustable digital FIR filter

• Two FIR spectral equalizer processors

• Four sample rate conversion processors

• Four FIR highpass filter processors

• Three general-purpose microprocessors which execute special DSP software, implement the

dual FFT spectrum analyzer, communicate with the PC via RS232, and provide system control

• One high-performance floating-point DSP processor that performs broadband noise reduction

functions and other advanced algorithms

Analog-to-digital and digital-to-analog conversion is performed by stereo, 24-bit, sigma-delta

converters which perform 64x oversampling.

The base processing sample rate is adjustable from 7.2 kHz (3.2 kHz bandwidth) to 36 kHz (16 kHz

bandwidth), regardless of the input sample rate when the digital input is used (sample rates from

25-108kHz are supported via asynchronous conversion). All processing sample rates are exact

multiples of 50 Hz and 60 Hz, allowing maximum filter performance at harmonics of these frequencies.

Digital, 200Hz highpass filters are provided on all inputs (pre-process) and on all outputs (post-

process) to remove rumble and other low-frequency noises.

Microprocessor-controlled limiters are provided on both analog inputs to prevent overload. When

using the S/PDIF digital inputs, the limiters prevent the digital signal from exceeding a specified dB

level.

Digital AGCs are provided to compensate for near party/ far party voice level differences.

Ten stand-alone nonvolatile memories are provided for onboard storage and recall of filter setups

created by the PCAP II Plus Master Control Program. This allows the external processor to be

operated in any of 10 previously-stored setups without being connected to a PC.