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Operation
About the 5750's Signal Processing Features
Dual-Mono Architecture
The 5750 implements full dual-mono architecture in both the AGC and the multiband compressor sections. You can
couple each band in both the AGC and multiband compressors to a variable extent—anywhere from perfect stereo
coupling to completely uncoupled operation. The coupling control determines the maximum amount of gain
imbalance permitted between the left and right channels in a given band, and therefore the amount of stereo image
shift permitted in each frequency band.
Although the processing is dual-mono, you cannot adjust setup controls independently on the left and right
channels—we assumed that the 5750 would always process stereo program material.
Signal Flow
The signal flows through the 5750 through the following blocks:
•
Input Conditioning, including sample rate conversion, defeatable 30 Hz highpass filtering, and defeatable phase
rotation
•
"Multipath Mitigator" phase corrector
•
Stereo Enhancement
•
Two-Band Gated AGC, with target-zone window gating and silence gating
•
Equalization, including high-frequency enhancement and Subharmonic synthesizer
•
Multiband Compression with embedded HF clipping and additional HF limiter
•
"Intelligent" Clipping with distortion control, distortion cancellation, and anti-aliasing
•
Overshoot Compensation
•
DSP-derived Stereo Encoder (generator)
•
Composite Level Control Processor
Input Conditioning: The 5750 operates at a 64 kHz sample rate and power-of-two multiples thereof (up to 512 kHz
in the stereo encoder). This allows user-selectable bandwidths from 15 to 20 kHz at the HD output.
The 15 kHz lowpass filtering in the analog processing's peak limiting section has a stopband that begins at 17 kHz.
This provides the necessary ±2 kHz protection for RDS/RBDS subcarriers as well generous protection of the 19 kHz
pilot tone.
The 5750's output spectral control is immaculate, ensuring maximum stereo and RDS coverage.
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