Specifications

A Remote Automated Water Quality Stream Gauging System Design 4
4
2.1.8. Telemetry
The telemetry system uses the mobile phone network where available. Where mobile phone
coverage is not available, satellite based telemetry is employed.
The CR10x data logger is capable of communication using circuit switched data at 9600
baud. A Campbell Scientific SC105 is required to interface between the modem and the data
logger. The modems are powered through a relay that can be operated using a control port
on the logger. Power is cycled once per day so that the modem is required to search for and
reconnect to the network. Satellite modems are powered down until they are required for
communication to save battery power.
GSM
GSM telemetry uses a Wavecom Fastrack modem.
3G
The other type of mobile phone based communication uses a Maxon Modmax 6280 3G data
modem.
Satellite
Satellite telemetry is provided by a NAL Research A3LA-D Iridium Satellite Modem.
The configuration settings for each type of modem are detailed in Appendix 1 – Modem
Setup.
2.1.9. Relays
There are two types of relays used to control components of the auto station.
An Omron G3R-ODX02SN
(G3R) solid-state relay is used for controlling devices that draw
less than 2 A, such as the modems. These can be operated using a 5 V output from a control
port on the data logger.
A dual relay setup is used to control the submersible pump. A G3R is controlled from the
wiring panel of the data logger as it can be switched by 5 V. This relay is used to supply 12 V
to a 12 V DPDT 10 A power relay which switches 24 V power to the pump.
2.2. Infrastructure
There are two primary structural component groups within a standard gauging site, the
platform located on the stream bank and the in-stream sensor mount. Design plans for all
components are shown in Appendix 2 – Design plans.
2.2.1. Platform design
The platform houses the solar panel array, power system and enclosures for the auto
sampler and data logger. The platform allows enough room for at least one person to safely
access all components.
Initially stream gauge platforms were constructed in-situ. This was a labour, resource and
time intensive process. This method also posed significant safety issues including but not
limited to fire, electrocution and risks associated with working at heights.
Two platform designs (Figure 1) were developed to allow this structure to be prefabricated
and transported to the installation site.