JITC HF EMail Testing

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JITC HF E-Mail Testing

• Eric E. Johnson
• New Mexico State University

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Test Technology Development and Demonstration
(TTDD) Projects

• Facilitate transition of technology from
  laboratories
• Enhance developmental test (DT) capabilities
• Optimize technology use throughout life cycle

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HF Test Facility Subproject

• Augment existing HF testing capabilities
• Improve testing posture for emerging standards
  and technologies
• Series of feasibility evaluations
• HF E-Mail
• High-speed modems
• Third-generation ALE

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NMSU Participation

• Test Design
• Data Analysis
• HF Test Node Operation

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NMSU Test Node in 2001
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Obligatory Antenna Picture
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E-Mail Demonstration in 2001

• HF Messenger (version 2.1)
• Harris and Rockwell 110B modems
• Manual frequency and data rate control
• Automatic traffic generation

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NMSU JITC Path
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Solar Conditions
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Manual Frequency Selection

• High sunspot numbers 100 270 (avg 200)
• Frequency pool 3, 4, 6, 7, 9, 11, 13,
  15, 17, 20, 27 MHz
• Frequency selected using ICEPAC
• Propagation confirmed manually with JITC

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Automatic Traffic Generation

• Uses cron on a linux machine
• Example crontab entry
• 00,10,20,30,40,50 mail hfemail_at_carr
  lt message.txt
• Modify sendmail.cf to route mail via barnes

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Experimental Conditions

• Modem data rate set manually
• Short interleaver
• File sizes 1 kB and 10 kB
• Message generation rates 6 or 12 per hour
• HF Messenger set for 2 tries for each msg

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E-Mail Demo Results

• Over 1700 messages exchanged error-free between
  NMSU and JITC June Dec 2001
• 1 10 kB text messages very reliableJPEG files
  (50 150 kB) sometimes failed
• Typical latency (1 kB _at_ 600 bps) 32 s for
  messages delivered on first try55 s for second
  try

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CY 2001 Findings

• Rockwell, Harris 110B modems interoperable
• Reliability of email transport
• 2/3 of messages delivered on first try (_at_300-600
  bps)
• Early software crashed too often better now
• SNR on this channel showed lognormal variation
  (as expected).

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Future Work

• Evaluate fully automated HF email system,
  including ALE and adaptive data rate(when
  software available)
• Investigate robustness under multi-station load,
  network congestion
• Evaluate 3G ALE/ARQ