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Tx: Transmitter
Rx: Receiver
Figure 8: Radio wave along the wall
It is also recommended that a wireless receiver and sensor not be placed directly below or on top of each other; for example, if a wireless receiver is
placed in the ceiling then the sensor should not be placed on the wall just below the ceiling, on the same vertical axis as the receiver. The sensor or the
receiver should be relocated to obtain a better transmission range.
Tx: Transmitter
Rx: Receiver
CEILING
FLOOR
Side View
Relocate sender or
receiver
Relocate sender or
receiver
Both the sender and
receiver should NOT
be on the same axis
Figure 9: Wireless Receiver Ceiling Installation
Unrelated transmitters should be more than 6.5 ft (2 m) away from the receiver to avoid possible interference (cell phone, GSM/DECT, WiFi, cordless
phones, RFID reader).
Repeaters
Repeaters are wireless devices that help deal with the transmission problems that were mentioned previously. A repeater receives transmissions and re-
sends an amplified signal to the receiver. The transmission range can thus be increased and obstacles can be bypassed, as illustrated in the next figures
about repeaters.
Sheet
Metal
Tx: Transmitter
Rx: Receiver
Receiver
Figure 10: Use of repeaters to bypass obstructions
High Penetration Angle
Tx: Transmitter
Rx: Receiver
Receiver
Figure 11: Use of repeaters to avoid unfavorable penetration angle
