User's Manual

March 2001
B
Radio Module
Specifications
General
Description
The 2.4-GHz DSSS spread spectrum radio is based on the Intersil
PRISM I chipset (Intersil was formally Harris). The Intersil PRISM I
information can be found at the following Web site:
www.intersil.com/prism/ (Select PRISM I * 2 Mb/s product link.)
Because MMS used the Intersil design for the radio, most of the
specifications in this appendix are directly from Intersil
documentation. However, two major areas differ and are reflected in
these specifications
• MMS replaced the Intersil PA/switch chip with a new amplifier
design and a separate antenna switch.
• The radio has no MAC (Media Access Controller) chip and,
instead, is controlled through a custom link with the Hub
(MMS computer).
MMS replaced the Intersil PA/switch chip to achieve 1 watt of output
power (the maximum permitted by the FCC) instead of just 18 dBm.
The additional power provides an increased range so that the radios
can be used in an open-pit mine with line-of-sight being
approximately 8 miles node to node. As required by the FCC for radios
with over 20 dBm (100 mW) of power, the power setting is adjustable.
The controlling link is a 22-Mb/s LVDS digital link between the radio
and the Hub. The radio must be connected to the Hub, and the radio
board has a built-in antenna. As an option, MMS would like to cut the
antenna off the board and use an omnidirectional antenna.
MMS plans to sell approximately 2100 of the PRISM I radio design
before exploring the PRISM II design from Intersil.