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Noise generator
As an example, we will calculate step by step the
attenuation from the socket in Bedroom 2 on the
2nd fl oor:
Metres of cable T100
5+1+7 = 13 metres of cable
Frequency
Attenuation
20
3.5 + 9.5 + 13x0 + 0.6 = 13.6 dB
55.25
4.5 + 8.5 + 13x0 + 0.6 = 13.6 dB
99
4.5 + 8.5 + 13x0 + 0.6 = 13.6 dB
120
4.5 + 8.5 + 13x0 + 0.6 = 13.6 dB
175.25
4.5 + 8.5 + 13x0.08 + 0.6 = 14.64 dB
210
4.5 + 8.5 + 13x0.08 + 0.6 = 14.64 dB
274.25
4.5 + 8.5 + 13x0.08 + 0.6 = 14.64 dB
The theoretical attenuation is calculated in a similar
way in the rest of the installation sockets.
Freq.
20
55.25
99
120
175.25 274.25
Bed1
12.1
12.1
12.6
12.6
12.6
13.4
Study
12.1
12.1
12.6
12.6
12.6
13.4
Bed2
12.1
12.1
12.6
12.6
12.6
13.56
Bed3
12.1
12.1
12.6
12.6
12.6
13.64
LivR1
13.6
13.6
13.6
13.6
13.6
14.24
LivR2
13.6
13.6
13.6
13.6
13.6
14.24
Bed1
13.6
13.6
13.6
13.6
13.6
14.32
Bed2
13.6
13.6
13.6
13.6
13.6
14.64
Kitch
13.6
13.6
13.6
13.6
13.6
14.32
As you can see, the bedroom 2 socket on the
2nd fl oor is the worst, as it is the one with the
highest attenuation in all frequencies.
- The signal power at the output of the noise
generator should be at least 60 dBμV in order to
compensate for the 22 dB attenuation undergone
in the high frequencies in the installation's worst
socket.
- As in the previous example, make a note of all the
reference frequencies.
- Next, connect the noise generator to the
distribution network input, as indicated in the
The total attenuation will be:
Attenuation
+ Atenuación
splitter_5435
splitter_5438
Atenuación
+ Atenuación
cable
socket
The attenuation of each element will depend on
the frequency, thus obtaining:
Frequency
Attenuation
471.25
5 + 8.5 + 13x0.12 + 0.6 = 15.16 dB
607.25
4.5 + 8.5 + 13x0.12 + 0.6 = 15.16 dB
855.25
4.5 + 8.5 + 13x0.15 + 0.6 = 15.55 dB
950
5.5 + 9.5 + 13x0.18 + 1.5 = 18.84 dB
1350
5.5 + 10 + 13x0.21 + 1.5 = 19.73 dB
1750
5.5 + 10.5 + 13x0.24 + 1.5 = 20.62 dB
2150
5.5 + 11.5 + 13x0.27 + 1.5 = 22.01 dB
The following table is the result:
210
471.25 607.25 855.25
950
1350
1750
13.4
13.8
13.8
14.1
18.3
18.6
18.9
13.4
13.8
13.8
14.1
18.3
18.6
18.9
13.56
14.04
14.04
14.4
18.66
19.11 19.47 19.83
13.64
14.16
14.16
14.55
18.93
19.32 19.71 20.10
14.24
14.56
14.56
14.8
17.94
18.68 19.42 20.66
14.24
14.56
14.56
14.8
17.94
18.68 19.42 20.66
14.32
14.68
14.68
14.95
18.12
18.89 19.66 20.93
14.64
15.16
15.16
15.55
18.84
19.73 20.62 22.01
14.32
14.68
14.68
14.95
18.12
18.89 19.66 20.93
installation picture.
- Measure the selected reference frequencies in
the worst socket or at the place or places where
you want to evaluate the losses. The power
measured should coincide approximately with
the theoretical value that ought to be calculated
as follows:
Power
= Power
- Attenuation
SALIDA
ENTRADA
It is necessary to take into account that both the
bandwidth and the resolution fi lter must be the
same when measuring the signal power provided
22
by the generator, and the powering of the signal in
the sockets (or in any network element where you
+
3
.- How to check the headend in an
installation:n:
- Connect the noise generator to the headend
input, keeping in mind that the input level
must not be too high so as not to saturate the
headend elements. Remember that if the -30dB
2150
19.2
19.2
4
.- Analysis of the frequency response of the
fi lters and amplifi ers, thus allowing their
adjustment.
In this case it is usually advisable to use the -30
dB output of the noise generator, in order to
avoid saturation in the single channel amplifi er.
wish to carry out a measurement).
output is used, you must use a 75 W load in the
main output.
- Connect the fi eld meter to the output.
- This way it is possible to check that all the
elements that make up the headend work
correctly, and that the levels of the channels that
form the headend have been equalised correctly.
Generador ruido
Noise Generator
R e f . 5 9 3 0
Level Adx.
5 - 2.150 MHz
0 1
9
-30 dB
8
2
ON
7
3
6
4
5
0 - 10 dB
234796
C55
C65-69
C58
C61
Remember that if the -30 dB is used, you must use
a 75 W load in the main output.
- Connect the noise generator to the amplifi er
input (in this case it is a single channel amplifi er).
The signal at the generator output is as follows:
23
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