Geoff Spells

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HFCC Broadcasting Statistics

• Geoff Spells

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Overview

• HFCC/ASBU/ABU-HFC joint HF seasonal schedule
  database
• Technical Analysis
• Statistics derived from database and technical
  analysis
• Conclusions

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Database Used for Analysis

• To produce valid statistical information,
  database should contain-
• All HF broadcasting requirements world wide
• Requirements to be those actually used in
  practice
• Realistic technical assessment of congestion
• Although a number of HF broadcasting databases
  exist, Operational joint HFCC/ASBU/ABU-HFC
  seasonal database gives closest match

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Operational HFCC/ASBU/ABU-HFC Seasonal Database

• Joint database is for each of 2 seasons per
  year-
• A - end March to end October
• B - end October to end March
• Contains majority of broadcasting requirements
• Contains requirements for frequencies outside HF
  bands allocated to broadcasting service
• Data at around 1 month after start of
  broadcasting season used for analysis
• Limited monitoring results indicate data is at
  least 95 accurate

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All co-ordination groups
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Technical Analysis

• Technical analysis performed using
  Recommendations ITU-R P.533 and BS.705
• Fieldstrength at each of the ITU 912 test points
  calculated for each hour for specific months each
  season
• CIRAF ZONE quadrants identified where requirement
  has fieldstrength greater than 55dB at one test
  point within quadrant

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Technical Analysis Collision Identification

• Interference situation (Collision) is identified
  where for 2 requirements on the same or 5kHz
  adjacent frequency -
• Part of wanted service area of both requirements
  is common
• Unwanted requirement has fieldstrength greater
  than 55dB in part of service area of wanted
  requirement

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Comments on Transmitter Hours

• Number of transmitter hours notified has
  stabilised at around 16,000 per season
• Overall reduction of 15 in hours since a peak in
  2002 but reasonably stable for last 4 seasons
• In bands between 4-10 MHz
• Contain more than half of hours coordinated
• Small overall variation in hours but recognisable
  seasonal variation
• Around 10 hours in WARC-92 bands
• Around 16 hours outside broadcast bands (OOB)

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Comments on Satisfied Hours

• Results have been averaged across all seasons
  from B00 to B06
• Bands below 6 MHz do not appear to be congested
  probably due to requirements not included in
  database
• In bands between 6-10 MHz
• Inband frequencies are heavily congested
• WARC-92 band frequencies are less congested
• OOB frequencies are less congested still

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Comments on Satisfied Hours

• Less than 62 of frequency hours are satisfactory
  in each of the 6, 7 and 9 MHz bands
• 7 MHz band appears most congested
• Congestion does vary with season so 4 MHz and 7
  MHz become more congested in B seasons

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Conclusions

• The Joint HFCC/ASBU/ABU-HFC is good basis for HF
  broadcasting statistics
• Although there has been a small reduction in
  requirement hours in the last 5 years, the number
  of transmitter hours appears to have stabilised
  at around 16,000 hours per day
• This overall reduction is due to a number of
  complex factors which are difficult to quantify

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Conclusions

• However, one such factor is the success of the
  informal coordination procedure which has allowed
  Frequency Managers plan and manage transmissions
  in a more rational and effective manner
• The bands between 6-10 MHz are heavily congested
  so that more than a third of requirements are
  unsatisfactory
• Despite reports that HF broadcasting is dying,
  statistics demonstrate HF broadcasting is alive
  and thriving

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Thank you for your attention