This article is from the Bat Conservation Trust’s membership magazine.
To find out more about bats and how to become a member
visit the Bat Conservation Trust’s website - http://www.bats.org.uk/
or call the free national (UK) Bat Helpline on 0845 1300 228. 

How to get the best out of your Handheld Three-Element Yagi Antenna

The Yagi Three Element Antenna is gamma tuned for receiving signals from longer distances. Heavy duty spring loaded folding elements and a pistol grip handle make this the ideal portable, general use antenna.

Features:

• Gamma tuned

• Folding elements for easy transportation and storage

• Pistol grip handle for ease of use

• Suitable for use with an Australis 26k Scanning Receiver

• Antenna bag also available separately

Frequencies available:

148MHz, 151MHz, 160MHz, 173MHz

Omni-Directional Whip Antenna

Magnetic-based, omni-directional, designed to sit on roof of vehicle. Can withstand wind pressure of 100kph.

Recommendations

For detection of signals within a prescribed radius to establish presence of the transmitter. Once a signal is detected, the antenna changes to a directional antenna to establish the bearing of the signal.

Size for 151 MHz:

1380mm H X 90mm

Weight:

830g

The tag sends coded acoustic ‘pings’ at a frequency of 69kHz. Each ping can include telemetry data as well as the tag’s serial number, enabling fast and efficient processing.

Coding the acoustic pings helps to increase battery life and the number of tags that can be used on a single frequency.

The tag is activated using an internal magnetic switch. When the magnet supplied is removed from the outer skin, the tag is activated. Replacing the magnet will trigger the internal magnetic switch and deactivate the tag.

Titley Scientific's acoustic tags allow researchers to:

• Conduct Fish Survival Studies
• Monitor Fish Migration/Passage/Trajectory
• Track Fish Behaviour in Two or Three Dimensions (2D or 3D)
• Measure Bypass Effectiveness at Dams and other Passages
• Observe Predator/Prey Dynamics and More

Titley Scientific offer the T11, T14, T17 model tags.

Expected Battery Life

Battery life for each tag size is entirely dependent on:

• Power output: the Acoustic Tags have a standard power output up to 147dB +- 3dB re 1uPa @ 1m. Tailored power output levels are available upon request
• Types of sensors included
• Time shelved: Tag life will be reduced if it is shelved for a long period of time. Transmitters should be activated within two months of delivery. For more information, contact us.
• Delay between transmissions (in seconds).
• The Acoustic Tags have six standard delays available with user-specified delays possible on request(see below).

Transmission rate varies randomly 45% about the nominal delay value. For example, a 90 second nominal delay indicates that the tag transmits randomly every 50 to 131 seconds.

Projected battery life is an estimate and users will experience a decrease in battery life if their tags are operating in extreme conditions.

In the Field

Titley Scientific acoustic tags have been used on an expedition by James Cook University to track the finescale movements of Tiger Sharks and Green Sea Turtles around Raine Island (Far North Queensland) during the turtle nesting season.

A total of 22 Tiger Sharks were tagged through the use of a pole with a tag applicator on the end. The sharks were attracted by baits to the research vessel. The expedition also involved the tagging of 16 Green Sea Turtles by use of a thin wire attached to the underside of the shell.