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HF modem

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HF modem

A modem is developed for information transmission in HF channel with transmission rate of 1200-4800 byte/s

A modem has perfomance data

  • Frequency range: 300-3400 Hz, in basic mode-500-3000 Hz (could be narrowed and extended by software)

  • Operation concept: multifrequency (parallel) with PSK modulation and optimum noncoherent reception.

  • One is used, two and three multiple phase modulation.

  • The basic rates: 600, 1200, 2400, 3600 4800 bit/sec.

  • The stable work is provided for frequency shift ±100 Hz.

  • Error Correcting technique: Trelliss Code Modulation with interliving, Viterby algorithm.

  • Time of synchronism: is no more than 0.5 s for frequency shift of ±10 Hz, is no more than 2.5 s for frequency shift of ±100 Hz.

  • Interface: analog - based on TLC32046, digital - RS-232C.

Implementation: 1 TMS320C31 DSP (for C25 and C50 is under development):

  • Power consumption: not more than 5 W.

  • Input line-symmetric, 600 Oh, with dynamic range -5 dB up -35 dB.

  • Output line-symmetric, 600 Oh, with dynamic range +3 dB up -35 dB.

  • Plate dimensions: 1,2 dm2.

  • Modem's supply 5 V.