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practical

ssible,

5. TRANSMITTER CHARACTERISTIC

A. Field strength and transmission range

What is meant by a field strength of 15 pV

1m?

It is a value indicating the strength of a radio wave which is expressed by the voltage induced

in a conductor of 1 meter long (unit length) placed in space. In other words, the value of 15

1m means that the voltage induced in a 1-meter-long conductor by a radio wave is 15 pV

(15/1,000,000 of one volt).

Transmission range by a field strength of 15 pV

A highly sensitive radio set is normally possible to receive an input of several dB .•

use. However, if the noise level in surroundings is high, reception will be almost .

unless the desired signal input level is considerably higher than the noise input le.e.

The relation between the desired signal and the noise levels is normally expressec as a signal-

to-noise

(SIN) ratio. In general, the SIN ratio needs to be morethan 20dB (that ·s. -" e signal

strength is ten times the noise strength).

The field strength of 15 pV

1m is equivalent to 23.5 dB.

The field strength measured at 23.5 dB is good enough for practical use in s

noise level is lower, but in urban or industrial areas where the noise level is g e, t e SIN

ratio becomes lower. It is, therefore, necessary to get near to the radio so . order to

improve the

SIN ratio.

o Transmission range varies depending on radio set performance (sensitivity,

e·

o Transmission range varies depending on the noise level around the rece'

(Normally, the noise level in urban areas is approximately 20 dB.)

o When there are high-rise buildings or hills on the propagation path, the prac::-

mission range will be shorter.

B. Transmission range depending on surroundings

Since the field strength produced by the TM-1 00 is very feeble and ~" e a~-"~-;' - orter

for the radio wavelength in use, the transmission range may be a~e ~. ions

of surrou nd ings.

Any conductive material located close to the TM-1 00 makes .- weak or

strong. Such variations are closely related to the radio a

Radio field strength becomes weak in the following cases.

o Communication between a room enclosed by eTa

concrete building) and the qutside

o Though the window is open, it is smaller for

o Communication over obstacles such as fe ces

-9-

c as a ferro-

Glenn Sim HC

Brand	Casio
Model	TM-100
Category	Watch
Language	English

Casio TM-100 User Manual

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Casio TM-100 Specifications

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