Communications VT Communications comprising VT Merlin Communications and Vosper Mantech Group Geoff Spells HFCC Broadcasting Statistics.

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VT Communications comprising VT Merlin Communications and Vosper Mantech

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Geoff Spells

HFCC Broadcasting Statistics

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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