Blonder Tongue – IFDM – IF Demodulator/Modulator

  • Synchronous Video Detector Provides Exceptional Differential Phase and Gain Response
  • External Video Loop – Allows Insertion of Video Signal Processing Equipment
  • IF Output Carrier Phase Locked to IF Input Carrier
  • Automatic IF Bypass Mode During Power Loss
  • Manual External Video/IF Bypass Mode Selection
  • Rack Mountable – 1 EIA (1.75″) Rack Space


The IFDM is a high quality, commercial grade, IF signal processor. The unit consists of two sections, an IF demodulator and an IF modulator. The IFDM provides an external video loop, allowing for conditioning of the baseband video signal. These features make the IFDM an ideal interface to a wide variety of signal processing equipment, especially those requiring stringent performance characteristics. Some applications suited for IFDM include, digitally based noise reducers and ghost cancelers.
The IFDM demodulator section utilizes a keyed AGC, Nyquist filter, and a synchronous video detector. This design provides superior differential phase and gain characteristics over the entire IF input level range (+13 to +42 dBmV). The baseband video output of the demodulator is available via an external video loop. A wide array of signal processing and conditioning equipment can be inserted to achieve a desired video performance. The baseband video is then modulated onto the IF output carrier. This IF output section is phase locked to the IF input section, thereby ensuring minimal phase noise and exceptional signal reproduction. The 4.5 MHz aural subcarrier output of the demodulator is fed directly to the modulator circuitry. This feature preserves the integrity of the original aural signal. The modulator provides sufficient output level (+22 to +42 dBmV) to satisfy the IF input requirements of all professional, heterodyne processors.

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