Laird Controls North America Inc. 818A ユーザーズマニュアル
Command Pro Engineered Systems
User Manual
User Manual
10
142134
5 O
PERATIONS
Laird Command Pro Wireless Control Systems are designed to control industrial machinery. These rugged
controls are built to survive the wear and tear of life in factories, mills, and foundries.
These systems comply with operation requirements under Part 15 of the FCC Rules and Regulations. This
These systems comply with operation requirements under Part 15 of the FCC Rules and Regulations. This
means that neither the operator nor the company need apply or register for a license to operate this
equipment.
The basic system consists of a transmitter and a receiver. The transmitter sends commands to the receiver
The basic system consists of a transmitter and a receiver. The transmitter sends commands to the receiver
through radio waves in the 900 MHz band. Receivers operate at 120 VAC 50/60 Hz power. Operation from
other power sources is also available.
5.1 How the System Works
5.1.1 Frequency
Laird Command Pro equipment operates in the 902 to 928 Megahertz (MHz) frequency band. A wavelength
at our frequency is 12.9 inches.
Like light, 900 MHz radio signals pass through glass and plastics, and reflect off of walls, buildings, and metal
Like light, 900 MHz radio signals pass through glass and plastics, and reflect off of walls, buildings, and metal
structures. Unlike light, 900 MHz radio signals penetrate all plastics including those opaque in color, as well
as thin-gauge steel, dry wood, dry concrete, plasterboard, fog, and rain. However, the signal will not readily
pass through trees, earth, water, people, aluminium, copper, and some window tints.
5.1.2 Range and Antenna Coverage
Antennas convert radio signals into radio waves, and convert radio waves back into radio signals. They can
send and receive in all directions or in a single direction, depending on their design.
An omnidirectional antenna is like a light bulb, and a directional antenna is like a flashlight. Metal objects
An omnidirectional antenna is like a light bulb, and a directional antenna is like a flashlight. Metal objects
reflect radio waves, just as a mirror next to a light bulb will reflect light. Metal objects near an antenna alter
the intended pattern of an antenna by either shading or reflecting signals.
Our standard antennas are omnidirectional; they ‘see’ equally well in all directions. We have other antennas
Our standard antennas are omnidirectional; they ‘see’ equally well in all directions. We have other antennas
that will ‘see’ further in one direction for special applications.
5.1.3 License-Free Channels
The 902 to 928 MHz spectrum accommodates many license-free users and is set aside by the FCC as an ISM
Band (Industrial, Scientific, and Medical). We have the ability to change frequencies in this band and have 81
different channels that we can assign to the transmitter and receiver. The actual frequency is coded into the
receiver and transmitter at the factory but may be changed to one of the other 80 channels in the field if
desired.
Other devices in this band include wireless phones, computer data links, and inventory equipment. As a
Other devices in this band include wireless phones, computer data links, and inventory equipment. As a
condition of using this band, products must accept and handle interference from other users.
The 900 MHz band works well for most users, and not being burdened with licensing regulations is desirable.
The 900 MHz band works well for most users, and not being burdened with licensing regulations is desirable.
The FCC has allowed 50,000 microvolts per meter field strength on this band, which is 250 times higher than
other unlicensed frequencies below the band. This allows our systems to operate very reliably in the presence
of other signals.