User's Manual

March 2001
Spread Spectrum
Radio System
About This Manual This manual contains a description of the spread spectrum radio
(SSR) system designed by Modular Mining Systems (MMS). Its use is
intended for MMS personnel and clients who may be responsible for
the system’s operation. Detailed installation and checkout procedures
are provided in a separate installation guide. Detailed user interface
information is also provided separately. The definitions of acronyms
used in this manual are given in Appendix A. The radio module
specifications are provided in Appendix B.
System Description The MMS-designed SSR system is based on direct sequence spread
spectrum (DSSS) technology, which provides a substantial
improvement in signal-to-noise performance over conventional
modulation techniques. Operating in the ISM 2.4- to 2.4835-GHz
frequency band, the transmitted signal is spread within the frequency
domain by using an 11-bit Barker sequence chipping code to obtain a
transmission bandwidth of 22 MHz and data rates of 1 and 2 Mb/s.
The received signal is strengthened by a processing gain of 10.4 dB,
thereby increasing the signal’s resistance to interference.
The improved radio performance and increased bandwidth, as
compared with a 9600-b/s narrow-band system, reduces congestion in
mines with large equipment fleets. Intensive graphic images, such as
updates for the Color Graphics Console (CGC) screen, and large
amounts of diagnostic data can be efficiently transmitted.
The SSR system comprises two major subsystems: the mobile
equipment system and the repeater system. The primary hardware
includes Hubs, radio modules, and mobile repeater stations. Rather
than one or two conventional narrow-band repeaters, the SSR system