PERDIX VHF Transmitter Circuit Boards - Integrated Antenna

 Since launching, our 20 and 25mm diameter circuit boards have been used around the world to successfully track both wildlife and equipment.  We have found, however, that many projects require the antenna to be incorporated within the housing to prevent damage to the antenna or reduce visibility. We have therefore developed a VHF transmitter board that has an antenna integrated into the PCB board.

Transmitter design

PERDIX integrated antenna VHF transmitters are built using a 35mm x 55mm rectangular single-sided PCB board. The board also has two 2.5 mm holes to allow the board to be fixed using small bolts or screws if required.

How it works

The PERDIX transmitter consists of an OOK modulated crystal Oscillator and frequency multiplier with two stage RF filter and antenna matching. It has a processor which controls the main functions of the transmitter. Activity monitoring is achieved by the use of an omnidirectional tilt and vibration sensor, this senses movement regardless of orientation of the transmitter. A magnetically operated switch is used to turn the transmitter on and off. By placing a small magnet that requires close to the unit the transmitter is activated or deactivated. No visual indication of the unit being on or off is provided as this would consume extra power and therefore shorten the battery life.  A VHF tracking receiver should therefore be used to confirm if the transmitter is activated.

Standard transmitter settings

The transmitter has two predefined modes, mode 1 is normal mode and transmits a single 17.5 mS RF pulsed carrier and is repeated every 1.6 seconds. Mode 2 is controlled by the activity sensor which is activated when the predetermined activity timer has been exceeded, typically this is 18 hours.  When there has been no movement during this time period, mode 2 is then activated. This gives two 17.5 mS transmitter pulses separated by 150mS to produce a “double beep” on the VHF receiver and is repeated every 1.5 seconds. If any activity is detected when in mode 2, the 18 hour counter is reset and the transmitter returns to mode 1. The TX power of this transmitter is 4.9 mAh.

Battery type and life

The PERDIX integrated antenna VHF transmitter boards have been designed so that a range of coin cells can be easily attached. These include Panasonic lithium cells, CR2025/HFN (165 mAh, 2.5 g), CR2032/HFN (225 mAh, 3.0 g), CR2354/HFN (560 mAh, 6.0 g) and CR2477/HFE (1000 mAh, 10.5 g). To give an idea of battery life, a CR2477 would provide a battery life of 650 days. Please note that battery life can vary depending on environmental conditions.

Transmitter frequencies

Currently we have frequencies available in 150, 151 and 173 MHz ranges.

Can any of the settings be changed?

Although the settings cannot be changed by the user, we are able to adjust some of the parameters during manufacturing to meet a particular projects needs (MOQ applies). These include the non-activity period (1.5 seconds to 30 days) and pulse spacing. Please contact us to discuss your requirements further.