Accession Number : ADA116859

Title :   HF Wideband Modem.

Descriptive Note : Final technical rept. 30 Mar 79-30 Nov 81,


Personal Author(s) : Ellins,Victor ; Anderson,Peter H ; Sandler,Mark N

PDF Url : ADA116859

Report Date : Apr 1982

Pagination or Media Count : 196

Abstract : This was an engineering effort to design, simulate, implement and test two HF modems capable of sustaining data rates of 4800 b/s or greater over standard 3 KHz HF channels. The first twelve months of effort encompassed propagation analysis, modulation waveform parameter selection overall modem and decision feedback equalizer (DFE) design, error control study, computer simulation, and real-time hardware and software design tasks. Subsequent work included the real-time modem implementation, preliminary (factory) acceptance testing and final (RADC DICEF) acceptance testing tasks. Also an initial live link test was included. The two identical high data rate HF modem (HFWBM) terminals offer reliable data communication at rates above 1 b/s/Hz over practical HF radio circuits. The charcteristics and performance of the HFWBM have been shown to meet or exceed all contrast specifications. Under the contract operation at 2400 b/s and 4800 b/s were requirements, while operation at 9600 b/s in a 3 kHz channel was stated as a design goal. The HFWBM has been demonstrated to be capable of sustaining rates of 2400 b/s, 4800 b/s, 7200 b/s and 9600 b/s in 3 kHz channels. An innovation developed in this effort, a square-root Kalman equalizer adaptation algorithm, has been shown to have the tracking agility and stability characteristics required to successfully follow the time-varying HF channel.

Descriptors :   *Modems, Selection, Computerized simulation, Parameters, High frequency, Modulation, Broadband, Computer programs, Propagation, Errors, Test methods, Real time, Control, Waveforms

Subject Categories : Electrical and Electronic Equipment
      Non-radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE