In the world of dredging and hydrographic survey the tide gauge has largely been replaced by RTK GPS, giving high quality tidal Z values local to the point of measurement. However, the relative low cost and reliable logging tide gauge is nearly always deployed as a backup device and also provides a gross check on the GPS values.

For port and harbour operations reliability and cost are the main parameters of interest. An ideal scenario would be an RTK antenna deployed on a buoy to send real time height values back to the port control via telemetry. In reality the cost of an RTK rover unit with its associated base station and telemetry do not represent value when compared with a more conventional tide gauge. The vulnerability of the rover system together with the fallibility of radio telemetry are also potential weaknesses when the system is required to provide data even during storm and bad weather conditions.

The Trimble Juno ST handheld is a low cost Mobile PC device with non-rugged GPS receiver for field data collection and mobile GIS. The Juno ST handheld is Trimble's most compact, fully-integrated field computer. It delivers 2 to 5m accuracy in the field and an integrated WAAS receiver enables real-time corrections. Integrated Bluetooth and wireless LAN technology provide options for connecting to the internet and corporate networks to access data. It is powered by industry standard Microsoft Windows Mobile version 5.0 software, providing all the benefits of an open platform for mobile devices.

The TideM8 is a modular design system with various discreet elements that can be combined together to form a specific tide gauge system. It has been designed to interface directly to external displays or computers using Bluetooth or the Ohmex Short/Long range radio telemetry modems for serial communications. The final system can be connected to a range of devices including data logging PCs or dedicated LCDs, offering simple remote display of numeric data.

Using Bluetooth communications the user does not have to make a physical cable connection to the gauge to download data or modify internal settings. The user comes to within a reasonable distance of the gauge (>100m) to log on, then uses a hand held Pocket PC device such as the Juno to download data stored on the instrument.