User Manual

ManualsBrandsADC Telecommunications ManualsElectronicsDigivanceÂ® Long Range Coverage Solution 1900 MHz

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Table Of Contents

ADCP-75-126 • Issue B • April 2002 • Section 4: Operation

Page 4-8

©

2002,

ADC

Telecommunications,

Inc.

4. Calculate

the

total

composite

signal

power

from

the

BTS

using

the

following

formula:

P

tot

=

P

c

+

10Log

N

–

(see

Note)

Where,

P

tot

is

the

total

composite

power

in

dBm

P

c

is

the

power

per

carrier

in

dBm

as

measured

in

step

2,

and

N

is

the

total

number

of

channels.

5. Determine

the

total

cable

loss

that

is

imposed

by

the

forward

path

coaxial

cable

that

links

the

BTS

to

the

HU

and

also

any

insertion

loss

imposed

by

splitters

or

combiners.

6. Subtract

the

total

cable

loss

and

any

insertion

losses

from

the

total

composite

power

calculated

in

step

4.

7. Subtract

–25

(the

midpoint

of

the

required

range)

from

the

value

determined

in

step

6.

The

difference

(which

should

be

positive)

equals

the

value

of

the

external

attenuator

that

is

required

to

reduce

the

forward

path

signal

level

to

fall

within

the

required

range.

The

following

formula

outlines

the

required

calculations

for

steps

6

and

7:

P

tot

–

(Cable

and

insertion

loss)

–

(–25)

=

Va l u e

of

external

attenuator

required

8. Select

an

attenuator

that

is

as

close

to

the

value

calculated

in

step

7

as

possible.

Select

a

value

that

will

adjust

the

signal

level

of

the

composite

input

signal

to

fall

within

the

specified

range.

9. Install

the

external

attenuator

in

the

coaxial

cable

that

is

connected

to

the

FORWARD

RF

IN

port

at

the

HU.

10. Subtract

the

value

of

the

external

attenuator

used

in

step

9

from

the

total

composite

signal

power

(P

tot

)

and

record

the

result.

This

value

will

be

required

when

setting

the

attenuation

of

the

HU’s

internal

forward

attenuator.

Note:

Subtract

16.23

dBm

if

calculating

the

composite

power

for

a

CDMA

system.

Note:

If

the

input

signal

level

is

already

within

the

required

range

of

–10

to

–40

dBm,

then

no

external

attenuator

is

required.

Caution:

The

Host

Unit

can

be

damaged

if

it

is

overdriven

by

the

BTS.

Always

install

an

external

protective

attenuator

at

the

Host

Unit

FORWARD

RF

IN

port

if

the

forward

path

composite

input

signal

level

is

greater

than

–10

dBm.