Xử lý phát thanh FM 718 David III

• Third-generation DAVID processing
• FM processor/generator
• Easy to install and use without the need for external test equipment
• 3-band feed forward Pulse-Width-Modulation (PWM)
• Gated-AGC (Automatic Gain Control)
• PIPP (Polarity Independent Peak Processing) limiter and a built-in adjustable composite clipper
• Digital synthesis of the multiplex baseband signal

 FREQUENCY RESPONSE
±0.5dB, 20Hz-15kHz

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

NOISE
Better than 70dB below 100% modulation in decoded L/R audio. Individual digital noise components above 54kHz are –70dB or better.

DISTORTION
<0.5%THD in baseband and subcarrier at 95% modulation with PIPP* limiter defeated; <1.5% at any level of modulation with PIPP* limiter 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.

PRE-EMPHASIS
75μs or 50μs selected by internal jumpers.

PIPP* LIMITER 
(*Polarity Independent Peak Processing) Proprietary circuitry assures full carrier deviation by program audio regardless of signal asymmetry. The limiter may be defeated with a front-panel switch.

LOW-PASS FILTERING
The 7-pole, phase-corrected, active-elliptic LPF includes proprietary overshoot compensation.

COMPOSITE CLIPPER
Baseband clipping may be adjusted between 0dB and 3dB. Clipping is performed prior to pilot injection.

STEREO PILOT
19kHz, ±1Hz. Pilot is adjustable between 6% and 12% relative to 100% modulation.

DIGITAL SYNTHESIS SAMPLING RATE
608kHz (16X subcarrier oversampling)

COMPOSITE OUTPUT
The 75-ohm, unbalanced BNC output is variable between 1V p-p and 10V p-p with reference to 100% carrier modulation.

POWER REQUIREMENTS
105-130VAC and 210-260VAC; 50/60Hz; 20W.

SIZE AND SHIPPING WEIGHT
23” x 16” x 2” (2U); 8 lbs
584mm x 406mm x 51mm ; 3.6 kg 

718DataSheet.pdf

718Manual.pdf