THE SERVICE AREA OF THE ROWRIDGE TELEVISION TRANSMITTER

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1 RESEARCH DEPARTMENT THE SERVICE AREA OF THE ROWRIDGE TELEVISION TRANSMITTER ReportNoe K=131 (1958/26 ) Ge le Ross D,W, Taplln, Grad,IDE.E. A. R@ Will I ams le Rhodes (w. Proctor wilson)

2 Tbis Report is tbe property ot tbe Britisb Broadcasting Corporation and a81 Dot be reproduced in any form witbout tbe written permiasion ot tbe Corporation.

3 Report No. K-131 THE SERVICE AREA OF THE ROWRIDGE TELEVISION TRANSMITTER Section Title Page SUMMARY,, 1 1 INTRODUCTION,, 1 2 GENERAL, 1 3 RESULTS "..., 1 4 CONCLUS IONS AND DISCUSS ION 3 5 REFERENCE 3 APPENDIX 4 I

4 November 1958 Report No. K-l31 ( 1958/26) THE SERVICE AREA OF THE ROWRIDGE TELEVISION TRANSMITTER SUMMARY The results of a recent field strength survey of the Rowridge television transmitter are given in the form of a table and map. It was found that the area served by the transmitter is less than that predicted from the site tests, particularly in the coastal regions. Additional tests showed that the effective radiated power (e.r.p.) and horizontal radiation pattern (h.r.p.) of the transmitter are correct; no errors have come to light as a result of re-examining the site test data and the cause of the discrepancy between the site test measurements and the existing service area is therefore unresolved. 1. INTRODUCTION The Rowridge television transmitter came into full service on 11th June From 12th November 1954 until the final installation was completed a temporary service was provided by an aerial 180 ft (55 m) above ground level. 2. GENERAL The Rowridge vision transmissions are provided by a 5 kw transmitter on Channel 3 (56' '75 Mc/s) driving an aerial consisting of four dipoles arranged vertically on the north mast face. The mid-point of the aerial is 38'7 ft (118 m) above ground level and the site is 450 ft (13'7 m) above mean sea level, The maximum and minimum e.r.p.s are 31 kw and 1'8 kw respectively, the minimum in the h.r.p. being necessary in ofder to protect the service area of the Caen television transmitter which uses a frequency of 52'4 Mc/s. The transmission is vertically polarized. The survey was carried out by measuring the field strength of the sound transmissions with an aerial mounted 15 ft (4'6 m) above ground level. All results have been corrected to correspond to the field strength 30 ft (9'1 m) above ground level for the peak-white value of the vision transmission. 3. RESULTS The results of the survey are presented in a field strength contour map and in tabular form. The map T.445 (Fig. 1) shows the 5'0, 2'0, 1'0, 0'5, 0'2 and 0'1

5 " Chipping Sod~ury (0'5 x ~=, El'D1S}:ql:. ~ jchippcnham - -AP,iTH /. /-...:...:.!~ ~, x omelksham '. (.../. Dcvizes \ 0 Trowbridge "'Axbridge oradstosk, \ x,' ) /02 -e oweils~'1 0 rome I.. / 0 armlnstu /~ 0 2 o Glastonbury,: i:ijti longpor t 0 Ilchester 0 Population within"- 0-2 SmV/m 341,900 -X-' WENVOE O 5mV/m 1,390,800 O./mV/m 2790, CRYSTAL PALACE entnor ST. C ATHE RINE'S POINT Note: Tht c.ontours t9preunt field strength in mv/rn 30 It (9' I m) aboyf 9tound exceeded at 50 % of receiving si Us in 0 given locality. The value exceeded at 90 % at teceivin9 sitcls may be as much os IOdB below the i~1 ~~Il yin~~cdat~~i '~~u~heo'r~oan:.ou r" porti c uiar Iy Fig. I ROWRIDGE (Measured) Channel3 (56'75Mc/s) Site height: 450ft.(J37m)AMSL Aerial height, 387ft (1I8m)AG L E.R.P.: ' 8-3IkW Aerial: 4 tier. Dipoles spaced from mast by 0 39~ Polarization: Vert ical Scale ~ 0 ~ W 30 Miles boc~=====""""",,c" ~=_ ~ Kilometres 10 0 [

6 3 mv/m contours of Rowridge and the 0'5, 0 2 and 0'1 mv/m contours of Crystal Palace and Wenvoe, the geographically adjacent television transmitters. From this map it will be seen that the nominal service area of Rowridge (limit for rural areas = 0 1 mv/m) overlaps that of the adjacent transmitters and that in some sectors the overlap is at a much higher field strength level. For example, between Crystal Palace and Rowridge the 0 5 mv/m contours overlap roughly from Basingstoke to Steyning. All service areas shown on the map are free from co-channel interference for 90% of the time and in the areas where this form of interference may be expected for 1 to 2j of the time the adjacent transmitter provides a good service. Nevertheless, Rowridge does not provide an adequate signal in certain towns on the coast. For example, in Brighton and Hove, where the median field strength is 0'25 mv/m, and in Weymouth, where the median field strength is only 0'14 mv/m, the service is poor. Worthing with a median field strength of 0'27 mv/m, is marginal. With the exception of these towns, the principal towns are reasonably well served, examples being Bournemouth, Dorchester, Salisbury, Winchester, Southampton and Portsmouth, where the median field strengths are 2 mv/m, 0 53 mv/m, 0 71 mv/m, 1 6 mv/m, 4 7 mv/m and 4'2 mv/m respectively. Full details of the field strength in towns with populations greater than 2000 are given in the Appendix. 4. CONCLUSIONS AND DISCUSSION The service provided by the Rowridge television transmission is not entirely satisfactory. In particular, the field strengths along the coastal areas east and west of Rowridge are less than the values derived from the site test measurements 1 by amounts varying between 1 and 10 db. In an attempt to discover the reasons for the discrepancies, all the site test data have been re-examined, and the e.r.p. of the Rowridge aerial in various directions checked against an omnidirecti(lmal aerial mounted on the top of the mast. No error has been found in the site test data and the h.r.p. was found to be correct. The discrepancy must therefore be due to the numerical values obtained during the site tests not being accurately related to the final condition in some way, such as error in readings, siting of the test (balloon) aerial or tropospheric conditions during the period of the site tests. Apart from the disappointing results in the two coastal directions, Rowridge is well sited to cover adequately the major part of the population of the area. 5. REFERENCE 1. Research Department Report No. K-085/3 (1951/6), "South Hampshire and Isle of Wight Television Site Tests~ Final Report".

7 ...-, 4 APPENDIX Field Strength in mv/m at 30 ft (9'1 m) AGL Town Max. Median Min. Aldershot 0'56 0'14 0'04 Alton 0'5 0'32 0'14 Amesbury 0'4 0'28 0'2 Andover 0'89 0'45 0'13 Angmering 0'5 0'3 0'16 An gmering-on-se a 0'5 0'34 0'16 Arundel 1'0 0'34 0'13 Ash 0'35 0'2 0'1 Aseot 0'14 0'09 0"05 Bagshot 0'13 0'07 0'04 Basingstoke 0'63 0'22 0'03 B ill ing shur st 0'56 0'32 0'18 Bishop's Waltham 8'9 3'5 2'2 Blandford 2'5 0'71 0'18 Bognor Regis 1'3 0'75 0"32 Bournemouth 8'9 2'0 0'32 Bracknell 0'15 0'09 0'05 Bramley 0'13 0'1 0'06 Brighton and Hove 1'8 0'25 0'03 Broekenhurst 6'3 4'2 2'0 Bulford 0'32 0'21 0'13 Burgess Hill 0'5 0'15 0'08 Calne 0'18 0'06 0'03 Camberley 0'25 0'13 0'07 Capel 0"2 0'15 0'08 Chandler's Ford 7'1 3'2 1~8 Chichester 2'5 1'4 0'45 Chiekerell 0'63 0'22 0'13 Chiddingfold 0'63 0'38 0'14 Chobham 0'2 ' 0'09 0'05 Crawley 0'18 0'12 0'07 Crewkerne 0'28 0'11 0'06 Crowthorne 0'22 0'14 0'08 Cuekfield 0'53 0'27 0'08 Devizes 0'32 0'19 0'09 Dorehester 1'1 0'53 0'22 Durrington 0'56 0'34 0'11 Eastleigh 5'0 2'7 1'3 Emsworth 3'5 2'0 1'1 Fareham 10 5'6 2'0 Farnborough 0'2 0'11 0'04 F arnh am 0'4 0'19 0'07 Fawley Fernhurst 1'4 0'75 0'35

8 5 Town Max. Median Min. Ferring 0"45 0"32 0"18 Fleet 0'22 0"17 0"00 Fordingbridge 1"8 1"1 0"4 Frimley '18 0"1 Frome 0"25 0"14 0"08 Godalming 0"45 0"25 0"06 Gosport 7"9 5"6 2 8 Guildford 1"0 0'12 0"03 Haslemere 0"89 0"27 0"11 Havant 4 0 3"0 1"6 Haywards Heath 0'56 0"14 0'05 Horndean 5"6 2"5 0"71 Horsham "22 0"05 Hungerford '12 0"05 Hurstpierpoint 0"32 0"15 0"00 Kingsclere "12 0"05 Lancing 0"35 0" Lee-on-the-Solent "0 Lewes 0"11 0'03 0"01 Littlehampton 1"3 0"4 0"16 Lyme Regis 0' "05 Lymington Lyndhurst 7" "0 Lyneham 0"16 0"11 0'06 Lytchett Minster "56 Mar lborough 0'25 0'11 0'03 Mere 0'32 0"2 0'1 Middleton 0"71 0"56 0'25 New Alresford 1" Newbury 0" "04 Odiham '11 0"08 Petersfield 3"2 1"0 0"32 Petworth 0"63 0"28 0"00 Pewsey 0" "09 Portchester 5"0 3"8 2"2 Portsmouth 28 4"2 1"1 Pulborough 1"4 0"63 0"22 Radstock 0"16 0'06 0"02 Reading 0'4 0"1 0"02 Reigate 0"4 0"13 0'05 Ringwood 2 0 1"3 0"5 Romsey 4"0 2"2 1'3 Rottingdean 0"5 0"2 0"04 Salisbury 2" '2 Seaford 0" "04 Selsey 2"8 1"7 0'89 Shaftesbury 1'8 0"75 0"11 Sherborne 0"4 0"16 0"07 Somerton 0"14 0"08 0"05

9 .-- -, 6 Town Max. Median Min. Southampton 16 4'7 1 0 Steyning ' Stockbridge '1 Storrington '11 Swanage 7 9 1'6 0'45 Tarrant Hinton 0' Thatch am ' Titchfield 13 6'7 3 5 Totton 5' Trowbridge '04 Wareham Warminster Water looville 5' Weymouth 0' '08 Wickham 5 6 3'0 1 4 Wilton Wimborne Minster '5 Wincanton 0'79 0' Winchester 5' Winnersh Witley 0' Woking '14 0'03 Wool Wootton Bassett ' Worthing Wokingham '04 Yeovil 0" '04 MV Printed by B.B.C. Research Department, Kingswood Warren, Tadworth, Surrey

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