Xylem H-4271 - Manual (Page 5)

Chapter 1
Introduction
1.0 Introduction
The W
ATER LOG ® H-4271 is a 1-watt FHSS (Frequency Hopping Spread Spectrum) telemetry
modem. The modem transfers a standard asynchronous (RS-232) serial data stream and operates
within the ISM 900 MHz frequency band. Two or more H-4271 modules are required; one
connected to the data recorder and one located at each remote site.
The radio link uses modern frequency hopping spread spectrum telemetry radios. Spread
spectrum technology is highly secure and has good interference immunity. The radio operates in
the license-free, 900 Mhz ISM Band eliminating the need for any FCC licensing.
Key features:
! ! ! ! Low system cost
!
! ! ! 1.0mW to 1.0Watt power output
!
! ! ! 9 - 18VDC supply voltage
!
! ! ! Up to 14 mile operation with dipole antenna
!
! ! ! Supports point-to-point, point-to-multipoint and repeater operating modes
!
! ! ! Built in power management including “sleep & sniff” modes.
!
! ! ! No configuration necessary for standard point to point communication
!
! ! ! Free setup, configuration and test software.
1.1 Description
Internally the H-4271 modem employs an industrial 9XTend RF module manufactured by Digi
International Inc. In addition, the modem includes a high efficiency DC/DC converter, RS-232
transceiver and a power down circuit. Complete specifications and a user manual for the
9XTend OEM module are available at
www.digi.com
1.2 Reliability
When properly configured and installed, the H-4271 telemetry data link will have good
performance. However, as with any radio apparatus, interference, noise and other factors can
corrupt communications. Retries and other schemes can help recover from corrupted data or lost
messages. If your application requires 100% accuracy or you cannot tolerate missing data scans
do not use a radio link.
1.3 LED Indicators
The H-4271 has two LED indicators, marked RxDat and TxDat. The green RxDat LED flashes
whenever a data packet is received. The yellow TxDat LED flashes whenever a data packet is
transmitted.
H-4271
Introduction 1-1