Murata Electronics North America 5811M Manual Do Utilizador
© 2003 Cirronet
Incorporated
1
M-5811-0008 Rev -
1. INTRODUCTION
The WIT5811 radio transceiver provides reliable wireless connectivity for either
point-to-point or multipoint applications. Frequency hopping spread spectrum technology
ensures maximum resistance to noise and multipath fading and robustness in the presence of
interfering signals, while operation in the 5.8GHz ISM band allows license-free use and
worldwide compliance. A simple serial interface supports asynchronous data up to 921600
bps. An on-board 12 KB buffer and an error-correcting over-the-air protocol provide
smooth data flow and simplify the task of integration with existing applications.
point-to-point or multipoint applications. Frequency hopping spread spectrum technology
ensures maximum resistance to noise and multipath fading and robustness in the presence of
interfering signals, while operation in the 5.8GHz ISM band allows license-free use and
worldwide compliance. A simple serial interface supports asynchronous data up to 921600
bps. An on-board 12 KB buffer and an error-correcting over-the-air protocol provide
smooth data flow and simplify the task of integration with existing applications.
- Multipath fading impervious
frequency hopping technology
with 75 frequency channels
(5729 - 5821MHz).
with 75 frequency channels
(5729 - 5821MHz).
- Supports point-to-point or
multipoint applications.
- Meets FCC rules 15.247 license-
free operation.
- Superior range to 802.11 wireless
LAN devices.
- Transparent
ARQ
protocol
w/12KB buffer ensures data
integrity.
integrity.
- Digital addressing supports up to
64 networks, with 62 remotes per
network.
network.
- Low power 3.3v CMOS signals
- Simple serial interface handles both
data and control at 115,200 or
921600 bps.
921600 bps.
- Fast acquisition typically locks to
hopping pattern in 2 seconds or less.
- Selectable 25 mW or 250 mW
transmit power.
- Built-in data scrambling reduces
possibility of eavesdropping.
- Nonvolatile
memory
stores
configuration when powered off.
- Smart power management features
for low current consumption.
- Dynamic TDMA slot assignment
that maximizes throughput.
1.1. Why Spread Spectrum?
The radio transmission channel is very hostile, corrupted by noise, path loss and
interfering transmissions from other radios. Even in a pure interference-free
environment, radio performance faces serious degradation through a phenomenon
known as multipath fading. Multipath fading results when two or more reflected rays of
the transmitted signal arrive at the receiving antenna with opposing phase, thereby
partially or completely canceling the desired signal. This is a problem particularly
prevalent in indoor installations. In the frequency domain, a multipath fade can be
described as a frequency-selective notch that
interfering transmissions from other radios. Even in a pure interference-free
environment, radio performance faces serious degradation through a phenomenon
known as multipath fading. Multipath fading results when two or more reflected rays of
the transmitted signal arrive at the receiving antenna with opposing phase, thereby
partially or completely canceling the desired signal. This is a problem particularly
prevalent in indoor installations. In the frequency domain, a multipath fade can be
described as a frequency-selective notch that
shifts in location and intensity over time as
reflections change due to motion of the radio or objects within its range. At any given
time, multipath fades will typically occupy 1% - 2% of the 5.8 GHz band. This means
that from a probabilistic viewpoint, a conventional radio system faces a 1% - 2% chance
of signal impairment at any given time due to multipath.
time, multipath fades will typically occupy 1% - 2% of the 5.8 GHz band. This means
that from a probabilistic viewpoint, a conventional radio system faces a 1% - 2% chance
of signal impairment at any given time due to multipath.