UHF2 Band Reversal Study

1. UHF2 Band Reversal Study Presented by Dr. Richard Dewey

2. TCI brief from the RA • Assess proposed band reversal strategy • Establish mathematical model for strategy • Estimate cost for implementing strategy

3. Mathematical model • REQUIRES • Accurate Rules database • Engineering procedures for implementing change strategy

4. Modus Operandi • The proposal suggested using Birmingham as a suitable place where both communal and single channel sites could be found. • In the event the Hog’s Back and Heathrow Airport were used

5. Hog’s Back • Chosen as typical communal site • Immediately showed deficiencies in the Rules database. (NGR and antenna height anomalies) • Intermodulation Products not excessive • UHF2 traffic too light to make useful measurements

6. Hogs Back Radio Site

7. Heathrow • Site Survey limited to Terminal 3 • Measurements difficult due to the high noise floor and lack of resolution of the spectrum analyser • Off airport monitoring equipment gives more accurate results • Rules database inaccuracies noted

9. Terminal 3 Short Term Car Park(North Lift Shaft)

10. Existing frequency assignments around Heathrow

11. Simplified UHF2 Spectrum Diagram for the Heathrow Area

12. Free space coupling between stacked dipoles

13. A Possible Solution for difficult sites At least 50 metres Tx Antenna Rx Antenna This arrangement is temporary for use during the changeover period but could become permanent if the site were to be managed by a third party.

14. Interference Analysis • An interference analysis was conducted and the following conclusion reached: At least 500 metres separation is required between sites to minimise the effects of blocking and wideband noise causing desensitisation

15. An Automatic means of Reassigning Frequencies • Use a relational database such as MS Access • Filter out all sites greater than 500m apart • Isolate whether they are communal or single user

16. Automatic Reassignment • See example: Appendix 7 of Report

17. CONCLUSION • Despite identified deficiencies in the Rules database . . . . . • A procedure for automatic frequency reassignment has been identified and is documented in the TCI report.

18. Future Work • A pilot project should be commissioned to determine the number of licensees who can be reassigned without recourse to special measures. • Further site work should take place at Heathrow to determine the noise floor so that a viable cost effective changeover strategy can be developed for the site.

19. Future Work cont. • The question of who pays for special equipment to aid the process should be addressed. • A detailed questionnaire should be sent to licence holders to determine what costs they are going to incur. The replies will need careful scrutiny as it is likely that such costs may be inflated in order to avoid the disruption.