Casella CEL Nomad portable weather station - Manual (Page 58)

High power radio with power supplied to the nomad via landline
Full control and real-time data download
Passive high or low power radio
Continuous “near real-time” data download
GSM Full control and real-time data download on
dial-up (customer to arrange contract etc.)
8.1 Direct Cable Link
A direct cable link is able to provide continuous full-time communication
between the Nomad weather station and the PC. Temporay connection is made
when visiting the Nomad unit to download stored data.
A simple permanent cable link can be used when the PC and Nomad
are located no more than 50 m (160 ft) apart, for example when the PC is in a
nearby shelter.
A land-line interface (Part number 142009C) is available for distances
up to 500 m. This is connected via a single cable (Part number W4/1602/4) that
carries both 24 V DC power for the Nomad unit and communication signals that
use the RS485 protocol. (Please consult Casella CEL for further details or when
greater distances are required.)
Operation with these methods of communication are described in
Chapter 3.
8.2 CompactFlash Cards
CompactFlash Cards enable a larger quantity of data to be stored by the Nomad
unit. The standard Sensus Digital Data Logger installed in a Nomad system can
store up to 516 kB of data. CompactFlash Cards can store up to 256 MB.
CompactFlash Cards also allow simple transfer of data when visiting
the Nomad unit, as the card can be removed - complete with data - and taken
back to the laboratory or office for downloading to the PC.
Inserting CompactFlash Cards is detailed in Section 2.3, operation is
described in Chapter 3, while brief technical details are given in Section 7.6.
8.3 High Power Radio Link
Casella CEL can supply a High Power
Radio link that communicates
between Nomad and PC over a
line-of site range up to 20 km (12
miles).
When the Nomad weather
station is powered via a landline, the
high power radio will be configured
at the factory, ready for use with
continuous two-way communication.
Control and data download will be as
described in Chapter 3.
When the Nomad system
must depend for power only on the
solar panel and internal battery, the high power radio will be configured at the
factory for use as a passive link. This will allow only one-way communication,
with data being transmitted continuously to the PC as described in Chapter 4.
8.3.1 High Power Radio Transmitter Specification
RF Frequency 400 MHz - 480 MHz
RF Power 5 mW to 12 W
Communication
Figure 25: The high power radio transmitter
Page 58 of 68
NOMAD Portable Weather Station
Users Handbook