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RESEAl:1CH DEPARTMENT

THI~ SERVICE AREA OF TEE -- -----.. .... _--KIRK 0 I SHOTTS TRANSMITTER

-- Investigation byg ,_ D.E 0 Susans

Report written byg RoAo Rowden

'-~ ,.j&¥1-A -i-~ rr~ .

(Wo Proctor Wilson)

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R8P01IT No. L088 May, 1952. Figs. 1 - 3

'rIlE SER7ICE AREA GB' THE KIRK 0 I SHo'rTS ':PRANSMITTER ,_~_"_, __ __ _ e.~ ______ .. ,. __ _...-,_ ._ .... _~._.,_. _____ .. ~ __ ,"""._.,_ .... ~_.~ _r .... ~,~ .. _. __ ,_~_-....... _____ ~-...... _ .... -,_

'I. SmTIlKARY ........ _-------

This re port gives -the results of a survey of the service area of the Kirk 0' Shotts transmttter with all field strength figures and contours cqrrected for a peak white power of 50 kW. 'rhe contours confirrrithose predicted from the site test and. given in Research Report lL076/2o

It is sbmvn that troubles due to mul tipath transmission are slight ar..d that, in most cases, a relatively simple cLirecti~nal receiving aerial will effect a cure or a considerable improvement.

" L. IlJ'l'}l ODUC'JiI mr

:F'ield strength measurements and. general observations of the service from the 5 kW transmitter which went into service on 14th J\1arch, make possible ane,cGurate prediction of the performance of the high power transmi tt~r d,ue for service in the Au,tumn of 1952.

This report gives the results of tue survey made vrith a vehicle fitted with normal field strength measurement equipment and carrying, in addition, a television receiver and special directional aeria,ls for the observation of echo effects (ghosts) 0

30 FIELD SrrRENGrrn SURVEY

A detailed survey was mad.e over the whoie of the area, and from this a contouI' map, li'ig 0 1, has beon prepared 0 This map shows the mean positions of the various field strength contours for a peak white power of 50 kW on the vision frequency of 56.75 MC/So Special measurements were made to determine the extent of the variations of field strengths in Edinburgh and Glasgow, and. contour maps for these cities are sho/min Figso2 and 3. The maximum, mean ano. minimum values for a selection of towns in central Scotland and for the ve:rious districts of Edinburgh and

,Glasgow are given in Tables I, 11 and Ill.

Most of the measurements during the survey had to be made on the SOUYH1

, transmitter becEmse the vision transmitter was not continnouslyavaiiable. Frequent checks were, however, made of the field strengths on both transmissions and it was fom1d that, on average, the sound/y,ision field strength ratio was correct.

Frequent observations of test card C were made both with the vehicle stationary and in motion.

In general, the area. wa.s'comparatively free from severe echo effects, but in }Jarticular localities precautions will have to be taken by the use of a suitable receiving aerial in order to remove or alleviate trouble due to multipath effects.

The large urban areas of Glasgow and Edinburgh were found to bo comparatively free from echoos, l)ut the; area to .the west of Glasgow on either side of the River Clyde is subject to echo intorference duo mainly to the large dock ·cranes. The effeot is such that the echoes tend to persist as'far as a quarter of a mile on either side of the river. A reoeiving aerial oonsisting of spaced. dipolo olements, having a figure-of-eight polar diagram, 11mB p;;enerally succossful in eliminating the' major eohoes.

:Beyond Gourook and round the coastal road towards Largs; the direct .signal is VOl'y woak indeed, and is at pla.oos much too yvoak to be moasurod with tho normal apparatus. The echoes here, ~,,:;,'c:J' of a very cliffuso naturo and. are apparently reflocted from the hills on the opposito sido of tho Clyde. Tho receiyod tolovision picturo cannot be oonsidered to bo of any valuo.

In tho aroa l)otwoon Stirling awl Dollar ochoes are particularly notioo2ble and are thought to bo d.uo to scatterod rofloctions from thc) hillfl lying immodiately to tho north of the Stirling­Dollar r02,d. An aorial- vii th D, Good front-to-backratio was effoctivo in giving et oon3io,orablo impl'ovomont of the diroct to roflocted Gignn,l. It was found that tho ochoos attenuatod r<',pidly whon movi ~lg etway from tho hills aml they wore of nec;ligi'blc amplitudo Ctt Allon,. Tho tovm of Callander is also

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affectect by echoes from hills to the north an,l aGain a "cardioid" type of aerial and reflector system was fountl to 'be effective 0

In many of the steep aided. valleys, such ;:~"s those occurr1ng in the outer part of the service area to the north-west of the transrni tter, echoes are reflectecl from hills on all sides of the receiving point. It is irnpossi l)le to recommen,i anyone tYl)e of receiving aerial tha.t will effect a cure in all cases, and it is obvious-that a method of trial and error will have to be resorted to by any viewer V~LO is receiving strong echoes.

It was found that, in general, increase in receiving aerial height improved the direct sie;:nal-to-echo ratio 0 In som,:;! cases, the ratio was also very critically dependent upon the exaot position of the receiving aorial and a .lateral movement of loss than a foot in the liosi tion of the aerial would effeot a large improvement.

It ie true to state that in terms of population, since most of the cerious ochoes occur in the mountainous regions of the sorvice area, r10arly all viowers will be froe from troul)lo and. the genoral situation is lP;:oly to be far bett~r than in the oaso of the Holmo Moss service are2,. Echoes from gas hol(lors, water coolin(,' towors, etc, are, of oourso, presont but the trouble can usually to alloviatocl by the use of a directional recoi ving aerial.

60 CONCI,USIOJ.;S

The survey of tllO sorvice aroa of tho Kirk 0' Shotts trans­mi tter has confirmoll the prooictions mad.e 3,S a rOBul t of thosi te tosts carried out in 19490 '11110 high pow(3r transmitter will proviclo a satisfactory fi.eld strength in all tho larger centres of population in the lowland Scottish rogions. Troubles duo to wul til'Jath interferonco effects should be re lati vely slight and will bo confined to a small percentage of the total IJopulation ",lJlo to rocei vc a s(~tisfaotory sorvice. In most o2,ses' of t:eoublo duo to eche effects, a cure or a oonsiderable improvement would. be effected by moans of a relatjvely simple directional rooeiving aorial system.

l.ffiP

Town

JiJdinburgh Glasgow Glasgow (including hll!1ediate suburrJs)

Airclrie Alloa Ardrossan Arbroath A~!r

Barrhead lleitp; ]i~3'g'ar

Blaircowrie :Ere chin Burntisla,nd

Carnoustie Carnwath Clydebank Coat1Jrid{"Se Coupar Angus Cowdenbeath Crieff Cumnock Cupar

Dalkeith Dumfries Dunl)ar Duml)arton 'Dunblane Dlmdee DU.nfermline Dunoon

KInK 0 I SJI()lrTS

Maximum ----~.

38 70

no

140 30 0.5 0.62 0,45

10.0 1.Q 5.5 0.45 0.17 5.0

0.85 24 24 50 0.47

12·5 1500 0.5 1.2

4.0 0.2 0.8 405

20.0 208

30.0 7·5

. Mean Minimum -~---

9.2 0.76 19.0 0041 20.3 3.5

90 50 24 8 0.4 0.25 0.3 0015 0.3 0.22

6.0 3.5 0.67 0.3 2.4 1.5 0035 0.17 0.09 0.07 305 1.7

0.4 003 14 10 7.5 3.5

30 20 0.35 0.3 8.0 2.5 2·5 006 0.23 0.1 0.6 0.35

1.5 0.55 0,12 0.07 0.'6 0.5 1.6 0.8

15.0 500 0.7 0012

20.0 12.0 4.0 0.75

.,

TABLE I (Continued) .~--......~-..-.. ....

!~~~,.:~~~_?_~_r:.~.n_gji~_~n_.JE.YL ID at .,10 .. .!t._~.!::..~~~ve_ gr_~1:lE_a..~} e ve].

T01:vn Maximum Mean :Mi ni mum --..---_-...- ---H'alkirk 12.0 6.0 3.2 :B'or1'a1' 0.17 0.1 0.09

Ga.lashie1s 0.32 0.14 0.08 Girvan 0.17 Oql 0.09 Gourock 2.0 1.2 0.35 G1'eenlaw 0.14 0.08 0.04 Greenock 2·5 1.5 1.0

Hamilton 0.12 0.06 0.03 ilelensl:nlrch 0035 0.25 0.1

Innerleithen 0014 0.13 0.1 Irvine 0.7 0.5 0.3

Kilmarnock: 1.0 0.4 0.28 Kinrosc 5.0 2.5 1.4 Kirkcaldy 0.8 0.4 0.28 Kirriemuir 0·5 0.37 0017

Lanark 44 18 5.0 Lares {0.07 Laud.er 0.05 0.05 0.04

e Leven 200 1.5 1.3 r;inli th::sow 18 8.5 5.5

Maybole 005 0·45 0.12 lHontrose 0.17 0012 0.09 Hotherwel1 0.08 0.05 0003

New Gallovray. 0.09 0.08 0.07 Nowton Stewart 0.10 0.06 0.05 North :Berwick 1.3 0.6 0035

Paisley 10 7.0 6.0 Peebles 0.75 0.3 0.18 Perth 0.5 0025 0.1 Port Glasgow 3.5 2·5 1.5 Prestwick 0.6 0037 0.32

Queel1sf'erry 2.6 1.4- 0095

T~]LE ~ (Con-tinued)

Field Stren~th in mVLm at 30 ft. above .£round level

Town Maximum Mean Minimum

Renfrew 10.0 8.5 . 7.0

St. Andrews 0.27 0.16 0.1 Saltcoats 0.75 0.4 0035 Sanquhar 0.55 0.23 0.17 Stirling 16.0 7.0 1.5

e Strathaven 10.0 8.0 2·7

KIRK 0' SIJO'.PTS

EDINBURGH

Fie1d.S~!,~n?£t}2:_j.1l_n:.YLl? at .lO f~o above B:.r_?2:lE~~e~

Maximum Mean Minimum ~"-.~---.... ----

Centre 32 9.5 4.7

No Granton 9.5 706 3.8

N. :Leith 4.4 1.9 0.7 71 .b. Portobello 2.5 1.6 1.2

·E. Joppa 2.2 1.6 1.2

S 0 J~ 0 NGwington 8.8 7.0 5.0

S.E. Crdgmi11ar 7.6 5·0 3.2

So Morningside 19.0 9.5 5.0

s. Liberton 7.6 5·4 3.2

S. w. GorCs'ie. 19.0 12~5 905

e So Vio Colinton 28 22 12.5

~~o~yo Slclteford 38 22 9·5 ("'i VT I,) 0 .V 0 Sighthill. 14 12.5 ll.O , .. Wo Corstor:phj.ne 32 25 16.0

w. Stenhouse 14 12.5 ll.O

}Jo~:jo 3took·bricL{~e 9.5 6.3 3.2

iT 0 '?lo Davidsons Mains 24 16 12·5

TABLE III

KIRK 0 t SHOTTS

GLASGOW

})'Iaximum Mean Minimum --~--~ ... --,---- -----

eo City Centre 19 9.5 4.7

1'L Maryhill 21 9.5 5.0

No Bishopbriggs 19 14 401

N .EL I\'[il1erston 53 35 20

Eo ShettleDton 63 47 22

I • Eo To11cross 63 47 20

;) 0 ~8 0

, Gorbals 32 19 ,9.5

SoEo Rutherglen 88 50 35

Sob o Cam liuDl an@; 88 44 20

So Cathcart 32 19 14

S. Giffnock 1205 6.3 305

So CrosElhil1 19 16 12.5

S. Pol1okshie1ds 38 32 22

S. Po1lokshaws 25 17 11

s. rl'horni:lie bank 20 :17 14

Wo Nitshill 22 19 16

Wo Crooks ton 25 20 19

W. Renfrew 10 805 7

w. vVhiteinch 1205 10 7.9

lifo W. Ke1vinside 16 12.5 9.5

NoW. :Particle 19 9 .. 5 4.1

N.W. Eearsden 38 3~~ 25

ISWI I

12.5.52

<Xl co o ~

I­tt o Q. UJ

BBC

~ "" .

FIG.I

I I o 10

KIRK 0' SHOTTS VISION TRANSMITTER CHANNEL 3 56·75 MC/S. VERTICAL POLARISATION

SCALE I

20 MILES

30 POWER PEAK WHITE 50k W

40 MAST HEIGHT 750ft

AERIAL GAIN 3db FIELD STRENGTH CONTOURS IN mY/m AT 30ft ABOVE GROUND

BfRDElN

N

TI24

11 ! j

Thl. drawinllapedflcltlon I1 cM property of tit. British Broadc:utlnr CorporatIon and may not be reproduc.cl or dlldoMd to • thAnt pan, lit any fomI wIthout cM wrIt:tAIn per­.... on of the Corporation.

CORSTOR PHINE

APPD

~.

SCALE I 1

MILES

N

2

'-PORTOBELLO

'\:""'" ""'OD

10 ( , r FIG.2 MEAN POSITION OF FIELD STRENGTH CONTOURS IN EDINBURGH FROM KIRK 0' SHOTTS 56-75 Mc/s

POWER PEAK WHITE 50 kW MAST HEIGHT 750ft AERIAL GAIN 3 db

FIELD STRENGTH CONTOURS IN mY/m AT 30 ft ABOVE GROUND T 25

ISSUE 1

12· 5· 52

BBC

N

BISHOPBRIGGS

20

CATHCART

FIG.3 MEAN POSITION OF FIELD STRENGTH CONTOURS IN GLASGOW FROM KIRK 0' SHOTTS 56·75 Mc/s POWER PEAK WHITE 50 kW MAST HEIGHT 750 ft

AERIAL GAIN 3 db

FIELD STRENGTH CONTOURS IN m m AT 30 ft A&OVE GROUND T 126