FM Broadcast Processor

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The DAVID II combines simple-yet-effective and comprehensive audio processing with a digital-synthesis stereo generator. The result is an FM airchain of surprising performance and exceptional value. Audio processing functions employ quasi-digital pulse-width-modulation (PWM) techniques for stable, adjustment-free operation.

DAVID II also has built-in combining for SCA or RDS/RBDS subcarriers. plus an adjustable composite clipper.


  • Digital synthesis of the composite multiplex signal for best stereo separation and stable operation.

  • Processing employs feedforward pulse-widthmodulation (PWM) for a full, smooth and bright sound without artifacts.

  • Built-in composite processor maximizes modulation density. Internal combining for SCA or RDS subcarriers.

  • Very easy to set-up and use. Generic, readilyavailable components for worldwide servicing ease.



Frequency Response

±0.5dB, 20Hz-15kHz

Stereo Separation

55dB, 50Hz-15kHz (typically 60-70dB)


Better than 75dB below 100% modulation in baseband and subcarrier. Any “digital” noise components above 54kHz are –70dB or better.


<0.5%THD in baseband and subcarrier at 95% modulation with processing engaged.

Crosstalk (M/S or S/M)

Nonlinear crosstalk is better than –50dB, 50Hz-15kHz. Linear crosstalk (through processing and filters) is better than –40dB.

Stereo Pilot

19kHz, ±1Hz; adjustable between 6% and 12% relative to 100% modulation.

Program Line Inputs (L/R)

Active-balanced, bridging; accept program audio levels between –15dBu and +15dBu.

Subcarrier Input

Unbalanced input for SCA or RDS subcarriers at levels between –20dBu and 0dBu for nominal 5-10% injection.

Low-Pass Filtering

7-pole, phase-corrected, active-elliptic LPF with proprietary overshoot compensation.


75µs or 50µs with jumper selection.

Gated AGC

±10dB capture range with slow (0.5dB/sec.) correction for long-term input level variations.


Fast peak limiter with secondary “platform” for dynamic range compression. Independent high frequency limiter protects the pre-emphasis characteristic.

Composite Processing

0dB to 3dB adjustable clipping of the baseband prior to pilot and subcarrier insertion.

Composite Output

75-ohm, unbalanced; variable between 1V p-p and 8V p-p, corresponding to 100% modulation.

Sampling Rate

608kHz (16X subcarrier oversampling)

Power Requirements

105-130VAC or 210-255VAC, 50/60Hz; 15W

Size and Weight

1- 3/4” H x 19” W x 7” D (1U); 7 lbs.