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DNT24 Integration Guide - 10/19/11
1.0 DNT24 Introduction
DNT24 transceivers provide highly-reliable wireless connectivity for point-to-point, point-to-multipoint and
store-and-forward radio applications. Frequency hopping spread spectrum (FHSS) technology ensures
maximum resistance to multipath fading and robustness in the presence of interfering signals, while
operation in the 2.4 GHz ISM band allows license-free use in most regions of the world. The DNT24 sup-
ports serial data rates for host communications from 1.2 to 250.0 kbps, plus three SPI data rates from 125
to 500 kbps. On-board data buffering plus an error-correcting radio protocol provide smooth data flow and
simplify the task of integration with existing applications. Key DNT24 features include:
•
Multipath fading resistant frequency hopping
technology with up to 24 frequency chan-
nels, 2406 to 2475 MHz
•
Receiver protected by low-loss SAW filter,
providing excellent receiver sensitivity and
interference rejection important in outdoor
applications
•
Ad Hoc TDMA operating mode supports a
large number of remotes with low latency
for burst data streaming
•
Simple interface handles both data and con-
trol at up to 250.0 kbps on the serial port or
500 kbps on the SPI port
•
Support for point-to-point, point-to-multipoint,
peer-to-peer and store & forward networks
•
AES encryption provides protection from
eavesdropping
•
FCC 15.247 and IC RSS-210 certified for
license-free operation
•
Nonvolatile memory stores DNT24 configura-
tion when powered off
•
Five mile plus range with omnidirectional
antennas (antenna height dependent)
•
Selectable 10 or 63 mW transmit power levels
•
Transparent ARQ protocol with data
buffering ensures data integrity
•
Automatic I/O event reporting mode simplifies
application development
•
Analog and Digital I/O supports wireless
sensing applications
•
I/O binding mode provides wireless transmis-
sion of analog and digital values
1.1 Why Spread Spectrum?
A radio channel can be very hostile, corrupted by noise, path loss and interfering transmissions from
other radios. Even in an interference-free environment, radio performance faces serious degradation from
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 phases, thereby partially or completely
canceling the signal. This problem is 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 band. From a probabilistic viewpoint, a
conventional radio system faces a 1% - 2% chance of signal impairment at any given time due to multi-
path fading.
Spread spectrum reduces the vulnerability of a radio system to both multipath fading and jammers by dis-
tributing the transmitted signal over a larger region of the frequency band than would otherwise be neces-
sary to send the information. This allows the signal to be reconstructed even though part of it may be lost
or corrupted in transmission.
