Codan-radio Radio Repeater Systems Training Guide Manuel d'utilisateur télécharger pdf (Page 45)

RADIO REPEATER SYSTEM | TRAINING GUIDE

Appendix A: Drawing Coverage Maps Page 37

A repeater site is proposed at a

high point above the BRIDGE Base

Station. A coverage map is drawn

for the proposed repeater site to

determine if the coverage would be

adequate. Examine the coverage

map of BRIDGE A.R.S. (shown in

Figure A-3) to learn how the map

was drawn. Note the right hand side

of the long ﬁ nger of coverage to the

north where each successive range

of hills blocks off correspondingly

more area. Following is an anaysis

of the section within the square FL.

Our site is at 1372 meters or 4500

feet. Because this particular map

is marked in feet, we’ll use this

measure throughout the remainder

of this section. At the bottom left

of the square we have a good

“drop-off” from our repeater site

in the direction of Skoonka Creek,

therefore we’ll be able to see up

the Skoonka Creek valley until

our view is blocked by the next

mountain (the 5000 ft. shoulder of

Botanie Mtn.). As our view swings

to the north, the south shoulder of

Arthur Seat blocks our vision at

least down to the 4000 ft. level.

Arthur Seat is over 5000 ft. high so

we are not going to see anything

behind except mountain peaks in

the distance.

Figure A-3: BRIDGE A.R.S. Mobile Coverage Map

If it was not for the broad northern shoulder on our unnamed mountain that we are naming BRIDGE

ARS, we would see right into the town of Spences Bridge, but it does lie in shadow. When drawing the

area close to the repeater site (2 or 3 km) you may want to inspect the 1:50,000 map of the site for more

detail, although small “lumps” in that area can usually be ignored. We have arbitrarily placed right and

left hand edges of this shadow at the 3000 ft. level. Note that the outermost (from the site) line more or

less follows the 3000 ft. level but bulges further away at the angle which matches the higher foreground.

Again arbitrarily, the outer coverage line follows the apparent gap up Murray Creek, stopping at the

5000 ft. level between Murray and East Murray Creeks. Our line then follows the height of land at the

head of Teit Creek to the eastern shoulder at the 4000 ft. level, thence north to Nicoelton Mountain

where it is again blocked to the 3000 ft. level. The thin strip of shadow shown on Tweal Creek is one

of those you could safely leave out as it is quite close to our site and one of those small “lumps” is the

cause. The larger shadow discussed previously is worthwhile including as its width indicates there is

an area where signals may be non-existent. Note that the closer the contour lines are to each other, the

steeper is the terrain. With a little practice you will be able to draw such a mobile coverage map that is

quite accurate.

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Codan-radio Radio Repeater Systems Training Guide Manuel d'utilisateur Page 45

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