JUMO 902931 Wtrans Receiver with Wireless Data Transmission Operating Manual - Manual (Page 14)

3 Basic principles
14
If, for example, the transmission duration of a signal is 5 ms followed by a 995 ms transmission
pause, the duty cycle is derived from the following calculation:
3.2 General information about wireless transmission
Wireless signals are electro-magnetic waves, the signal of which weakens during travel from
the transmitter to the receiver (this is referred to as path attenuation). The field strength reduces
inversely proportional to the square of the distance between the transmitter and receiver.
In addition to this natural range restriction, a reduced range may also be the result of the fol-
lowing causes:
•
Ferroconcrete walls, metallic objects and surfaces, heat insulation, or windows with vapor
deposited metal layer reflect and absorb electromagnetic waves and, for this reason, a
dead spot is formed behind.
• The antenna is installed at an insufficient height; install as high as possible above the floor
and ensure a line of sight between the transmitter and receiver.
The following values are reference values relating to permeability of wireless signals:
The maximumrange between the transmitter and receiver is 300 m in the open air when using
the antenna holder for wall mounting on the receiver side. Optimum reception is achieved when
there is a clear line of sight between the transmitter and receiver.
When installing the receiver in a control cabinet or behind concrete walls or ceilings, always
use the antenna holder for wall mounting and antenna cable on the receiver side.
t
S
t
G
-----
5 ms
1000 ms
----------------------- 0.005 0.5 % = = =
Material Permeability
Wood, plaster, glass uncoated 90 to 100 %
Brickwork, press boards 65 to 95 %
Armored concrete 10 to 90 %
Metal, aluminum lamination 0 to 10 %
TIP!
The device manufacturer's antenna holder for wall mounting is specially designed for the
lambda/4 antenna and ensures optimum reception quality.
Antenna holders for wall mounting not produced by the device manufacturer may disrupt the
reception and cannot guarantee optimum reception.
TIP!
The device manufacturer's antenna cable has an attenuation of 0.8 dB/m. From a technical
standpoint, we recommend using the shortest possible antenna cable to ensure good recep-
tion.