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©2009 by RF Monolithics, Inc.
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DNT2400 - 08/18/09
1.0 Introduction
The DNT2400 series transceivers provide highly reliable wireless connectivity for point-to-point, point-to-
multipoint and peer-to-peer applications. Frequency hopping spread spectrum (FHSS) technology en-
sures 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 world wide. The DNT2400 supports all stan-
dard serial data rates for host communications from 1.2 to 460.8 kb/s. On-board data buffering and an
error correcting radio protocol provide smooth data flow and simplify the task of integration with existing
applications. Key DNT2400 features include:
•
Multipath fading resistant frequency hop-
ping technology with up to 37 frequency
channels per subband
•
Dynamic TDMA slot assignment that maxi-
mizes throughput and CSMA modes that
maximizes network size
•
Support for point-to-point or point-to-
multipoint applications
•
AES encryption provides protection from
eavesdropping
•
FCC 15.247, IC and ETSI certified for
license-free operation
•
Nonvolatile memory stores DNT2400 con-
figuration when powered off
•
10 mile plus range with omnidirectional
antennas (antenna height dependent)
•
Selectable 1, 10 and 63 mW transmit power
levels
•
Transparent ARQ protocol with data
buffering ensures data integrity
•
Selectable RF data rates of 38.4, 115.2, 200
and 500 kb/s
•
Analog and digital I/O simplifies wireless
sensing
•
Auto-reporting I/O mode simplifies applica-
tion development
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 do-
main, 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 multipath fading.
Spread spectrum reduces the vulnerability of a radio system to both multipath fading and jammers by
distributing the transmitted signal over a larger frequency band than would otherwise be necessary to
send the information. This allows a signal to be reconstructed even though part of it may be lost or cor-
rupted in transmission.
