Campbell Scientific RF300-Series DRL VHF/UHF Radio Transceivers - Manual (Page 7)

1-1
SECTION 1. GENERAL RADIOTELEMETRY NETWORK
1.1 INTRODUCTION
Data retrieval from a remote site can be difficult.
To accomplish data collection from isolated
sites Campbell Scientific, Inc. utilizes a
radiotelemetry (RF telemetry) network.
Dataloggers can be accessed by RF telemetry
which requires no physical connection from the
computer to the datalogger. The RF telemetry
link reduces the number of visits to a remote
site for data collection.
The RF telemetry network is designed for
complete computer control. One computer can
establish communication with up to 254 remote
sites. PC208W Datalogger Support Software
allows data collection from the datalogger,
transmitting datalogger programs, and
displaying current readings from the datalogger.
The requirements specific to a RF telemetry
network include:
•
The distance between radio stations should
not be greater than approximately 25 miles.
•
The stations should not have major
obstacles between them; therefore, they
should be within line-of-sight of each other.
The stations communicate over a radio
frequency which is specified in Megahertz
(MHz, 132 to 170 MHz and 403 to 512 MHz are
supported). A data communication network
must have its own specific frequency to prevent
interference from other sources. Typical radio
frequencies are either VHF (Very High
Frequency) ranging from 132 to 170 MHz or
UHF (Ultra High Frequency) ranging from 403
to 512 MHz. A typical RF system is shown in
Figure 1-1.
Telemetry network’s three basic components
are:
•
Field Station
•
Base Station
•
Repeater Station
FIGURE 1-1. A Basic RF telemetry Network