User's Manual

COMPANY CONFIDENTIAL
RF-TWACS Based AMR System DCSI CUSTOMER PRODUCT SPECIFICATION
May 30, 2003 Application Notes – Rev. 1 3
The installer has the latitude to create any workable network on site, and is able to
confirm that it functions prior to leaving the site. A hand-held radio tool called the Hand-
Held Transceiver (HHTR) is available to support installation, configuration, change-outs
and other field operations. An HHTR is shown in Figure 3.
Figure 3 – Hand-Held Transceiver (HHTR) Front View
Frequencies between 902 MHz and 928 MHz are used. This part of the UHF radio
spectrum is known as the 900 MHz Industrial, Scientific and Medical band (ISM) and is
unlicensed. DCSI’s radio devices operating in this band comply with FCC regulations
and rules. The radio link is a two-way half duplex, uses pseudo-random sequence
frequency hopping spread spectrum technology, and FSK modulation. All transceivers
include an integral received signal strength indicator (RSSI), obtain receipt verification,
and perform automatic retries of failed communications.
A frequency hopping algorithm is used to: comply with FCC regulations, reduce potential
interference to and from other services operating in the same band, reduce the likelihood
of eavesdropping, and to minimize the effects of selective fading.
The RMTRs do not run continually. Instead, they run only in response to external events
that cause power to be applied to its microprocessor. When the external event has been
dealt with, the power is turned off from the microprocessor. This is done to extend