AM Broadcast Processor

THIS PRODUCT IS NO LONGER IN PRODUCTION

The 222 was originally developed as a "post-processor" to ensure US broadcasters' compliance with FCC-mandated occupied-bandwidth regulations. It incorporates a fast, asymmetrical peak limiter, independent pre-emphasis-protection limiting, and a very sharp-cutoff low-pass filter with proprietary overshoot control. The 222 finds ready application in a wide variety of AM broadcast situations. In addition to the NRSC 10kHz cutoff for medium-wave AM broadcasting in the US, any high-frequency protection characteristic between 4.5kHz and 15kHz can readily be accommodated to meet other domestic and overseas needs. Though the 222 is intended to provide basic final limiting, a "floating platform" release characteristic yields sufficient program dynamics compression that often the unit can be run "barefoot" between the console and transmitter with good results.

Features


  • Meets US (NRSC-compliant) and overseas AM transmission specifications

  • Separate pre-emphasis protection limiter

  • Active multipole low-pass filtering

  • Feedforward Pulse-Width-Modulation (PWM)

  • Built-in asymmetrical peak controller

  • Optional cutoff frequencies available (9kHz, 6.4kHz & 5kHz)

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Specifications


Frequency Response

(pre-emphasis defeated):

  • “PROOF” mode: ±0.5dB, 10Hz–15kHz

  • 222-00 (NRSC): ±1dB, 10Hz–9.7kHz

  • 222-01 (Euro MW): ±1dB, 10Hz–8.7kHz

  • 222-02 (US SW): ±1dB, 10Hz–6.2kHz

  • 222-03 (Int’l SW): ±1dB, 10Hz–4.85kHz

Distortion

Less than 0.2% THD, 10Hz–cutoff with Peak Limiter OFF. Less than 1% THD, 200Hz–cutoff with Peak Limiter ON.

Noise

Better than 75dB below full carrier modulation (assuming NRSC de-emphasis).

Fixed Pre-Emphasis

The US version follows the “truncated” 75μs curve specified by the NRSC transmission standard. Alternative versions employ pre-emphasis appropriate to the service and the cutoff frequency.

Input

Active-balanced, bridging; accepts nominal program line levels between –15dBu and +15dBu.

Output

Active-balanced, 600-ohm resistive source; delivers 0dBm to +15dBm into 600 ohms.

Output Asymmetry

Positive peak amplitude is continuously variable between +100% and +130% of the negative peak value.

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