IF Converter & Filter Unit


IF Converter & Filter Unit


The function of this Unit is to convert the IF sub-bands  of  a satellite  signal to a common 70MHz/80MHz frequency and make the converted signal  available for further processing. Developed to comply with very strict technical and operational requirements, the IF Converter incorporates advanced design and new-generation technologies in the areas of signal processing (frequency synthesis, mixing and  filtering.) and microprocessor control. The Unit is configured in a  3U 19” standard rack, the circuits are assembled into plug-in modules which can be plugged out for inspection , troubleshooting or replacement without switching the equipment off.

The modules complement includes:

  • IF Interface Module, this module provides input/output separation, adjustments on the input signal level through combined attenuations / amplifications,  and splitting  of the signal into three outputs which are fed to three mixer modules.

  • Mixer Module, each mixer module extracts the 25 kHz channels from the  IF channel available at the output of  the IF Interface Module, which are applied to the mixer circuits for frequency conversion to a 70MHz IF, filtered by high-selectivity filters and made available at the module output.

  • Synthesizer Module, this module contains three high spectral purity, programmable PLL synthesizers which generate the  injection frequencies used in the mixing processes for channel extraction and frequency conversion.

Operation of the synthesizer module is programmed  by the CPU internal to the Unit through keyboard and display


Microprocessor Module located on the Unit front panel, this module contains:

  • a CPU card

  • a keyboard card

  • a display card

Interconnected  over shielded flat cables.


The module is also provided with interface circuits for CBIT and IBIT.

  • Power Supply Module, it includes two identical power supply circuits in a redundant configuration, each with a rated power  which exceeds by 50% the nominal power consumption of the Unit. Front panel leds indicate the presence of malfunctions.




A summary of the technical characteristics of the IF Interface Unit  developed for an international satellite communications programs is given below:


Input IF central frequencies                            62.5507 68.500/77.450MHz

IF conversion frequencies                               70MHz for 1 to 4 channels

                                                                         80MHz for 5 channels

70MHz IF filter bandwidth                                23kHz @3dB

80MHz IF filter bandwidth                                200kHz @ 1dB

Filter’s group delay                                          30µ sec

L.O. rejection                                                    ≥70dB


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