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1. General Product Description
SMART Amplifier (SMARTAMP) is a new bi-directional antenna-mount amplifier designed to
match any advanced spread spectrum system, either direct sequence or frequency hopping,
to allow the extension of the operating range in wireless environment. It is provided in a wide
range of frequencies, such as 900 MHz, 2400 MHz, or 5800 MHz where advanced spread
spectrum systems are operated. It works in Time-Division Duplex (TDD) mode that allows
the radio device sharing the antenna in different time intervals. SMARTAMP consists of an
intelligent algorithm and Automatic Gain Controlled (AGC) circuits to maintain the output
power and prevent transmit signal saturation. The input transmit power level is sensed by the
Radio Frequency (RF) sensor and the gain is automatically adjusted to minimize the signal
distortion so that the desired signal quality can be assured.
This product has a wide range of wireless applications in Wireless Local Area Network
(WLAN), Wireless Local Loop (WLL), Wireless Internet Access (WIA), wireless modem
connection with point-to-point, point-to-multipoint, where the Time Division Duplex (TDD)
technology is used.
2. Background
In wireless applications, when longer operating range is required, the add-on antenna
amplifier and DC injector set are often a choice. Because of different site layout and
hardware configuration, it is almost impossible for amplifier manufacture to design the
amplifier and fit all applications. Typically, in most applications, the interconnection cable
could have different length from a few feet to a few hundred feet. The attenuation between
DC injector and bi-directional amplifier could be few dB to more than 20 dB. Also, different
radio modems have different output powers. Thus, the system installer must carefully
measure the input RF power at the antenna amplifier and specify the gain of the amplifier in
order to maintain the system performance. With different systems, different amplifiers are
required. With this invention, the major difference as compared to other existing technology,
is the “SMART function” - power level detection and automatic gain control circuit. With
SmartAmp, the gain can be intelligently adapt to the input power level in a wide range and
automatically further adjusted to accommodate the cable and connectors loss, by however
length and configuration. The output power level is monitored and maintained intelligently,
hence the desired performance can be achieved in all hardware configurations for TDD
wireless applications irrespective of installation environment.
The table below summarizes the difference between SMARTAMP and other TDD antenna-
mount amplifier product.
Differences Between SmartAmp and Other TDD Amplifier
SMARTAMP Other TDD Amplifier
Transmit gain Intelligent self adjusted Fixed
Transmit power level Maintained Varies, depending on input power
level
Transmit signal distortion Minimized at all time Much worse at high input power
levels
Input power range
requirements Wide range accepted Designed for narrow range only
