SubSystems for HF Application

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Sub-Systems for HF Application
MICOM- MD 4800 Data Voice OVER HF
Rafi Hana M.Sc.E.E General Manager MOBAT A
Tadiran Communications Division
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The New HF Systems Advantages
Stable and Accurate Frequencies - Improves the
Quality ALE STD (141B) - Simplifies the
Operation New MODEM Technology - Expanded the
Use of Data App. New Digitized Voice Technique -
Improves the Voice Quality Reduces
the HF Noise.
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Voice Data Applications based onVOCODER HF
Data Modem

• VOCODER 1200, 2400 bps
• MODEM MIL-STD-188-110B
• Side Effect
• Encryption AES Standard

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Basic Block Diagram
PC RS232 USB
Interface
HOST CPU
AES Encryptor
188-110B MODEM
Audio Handset Fixed Lvel
1200,2400 VOCODER
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Basic System Configuration
Secure Voice Data
Plain Voice
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Special Features

• V-AMD Allows Voice- Messages that penetrate
  negative-SNR channels for emergency application
• Operational features
• REC. Recording messages.
• SEL. Selecting one / five.

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Encryptor

• AES Advanced Encryption Standard.
• The New Federal Information Processing
  Standard (FIPS)
• Keys 7 technician-key (option 31k)
• HMI PC-menu or MICOM front panel.
• OTAR Select Keys (Option Key Loading)

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Voice Coding

• Two approaches for Voice coding
• Waveform Coders
• Among popular methods CVSD?, ADPCM?, PCM?
• (16K,32K,64K bps)
• Parametric representation (Vocoders)
• Speech model derived from speech characteristics
• Low bandwidth (600,1200,2400 bps)

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Vocoders
Speech model
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Vocoders

• Two principal families of Voice Coders
• Source Codecs - operate based on the speech model
  ( LPC)
• Hybrid Codecs - attempt to bridge between Source
  Codecs and Waveform Codecs (MPE, RPE, CELP, MBE,
  MELP).

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Performances
MOS - Mean Opinion Score Voice Quality measure
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Our's Vocoder - Performances
Digital voice is the New Generation Requirement
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MODEM

• MIL-STD-188-110B 75-4800 bps
• with better Adopt performance.
• DSP Implementation Ready for Future Growth

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Basic MODEM BLOCK DIAGRAM
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CONSTELLATION FOR MIL-STD-188-110B sec. 5.3.2
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Modem Performance

• Performance is NOT essentially dictated by SNR.
• ISI-length Doppler-Spread
• can cause modem collapse in spite of very
  high SNR.

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Surface Performance
a 300 bit/sec 8PSK Serial Tone MODEM
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MOBAT-MODEM PERFORMANCE VERSUS STANDARD
PERFORMANCE MIL-STD-188-110B sec. 5.3.2
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• HF CHANNEL Multi-Path (RAYS)
• IN STANDARDS LITERATURE
• Watterson 1970 Measurements
• Found up to 4-Rays (Multi Path).
• Two Magneto-ionic components.
• ETSI DRM STANDARD (Digital Radio Mondiale)
• Up to 4-Rays should be tested.
• Field-test found 5-Rays.
• MIL-STD-188-110A, 110B, STANAG-4539,
• Only Two-Rays should be tested.
• In Real HF Conditions There are More than 2 Rays.

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MODEM Visualization Tools Scatter-Diagram
Impulse-Response
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• MOBAT HF-MODEM
• MULTI-RAY
• OVER-STANDARD TESTING
• Up to 5-Rays were tested.

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FIELD-TESTS RESULTS Conducted Nov 28 Dec 10
2002 Link-Range 200 KM
Testing Tools
Summary of field test results from 9/12/2002
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Received Signal for the 3 cases above From field
test results of 9/12/2002
6 dB/Div
Despite the severe conditions, reception was
achieved with BER0.
Spectrum for 2400, long, 9.387MHz, time 100100
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6 dB/Div
Spectrum for 150, long, 9.387MHz, time 133800
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Signal for 2400, long, 5.395MHz, time 145850,
length 40 sec
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6 dB/Div
Spectrum for 2400, long, 5.395MHz, time 145930
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Summary Recommendations

• We presented the MICOM MD-4800
• As a new Technology application for Digital
  Secure Data and Voice
• Our recommendations
• To add one more ray to the 110B STD.
• To specify a voice coder for HF application.
• To add a Voice-AMD to the STD.

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MICOM MD-4800 Technology for the New Generation
Thank You