The wire snare detector was a proof of concept project that was implemented to support and help African ranges find and dismantle a cruel animal trapping devices that is significantly impacting animal populations in Africa. The African Wildlife Conservation Fund indicates that wire snares are a near-perfect killing machine which has impacted wild animal populations and has driven them into the brink of extinction. Giraffe numbers have dwindled from 140,000 to just 80,000 within 15 years, many of them caught by crude snares and poached for commercial meat trade. Animals often die a prolonged and painful death and a detector that can facilities locating these devices efficiently could prevent the butchering of these animal populations and safeguard them for the future.
A previously designed UWB pc board was used as the basis for the Impulse Radar section.
An Arduino module was connected to a TFT LCD touch screen display module and the stack was powerd by a lithium polymer battery.
The battery fits between the back of the Arduino board and the UWB board to form a compact stack. From top to bottom the boards are Touch screen display, Arduino microcomputer, battery and the UWB Impulse Radar board. The board is designed with the parts located on the back side of the board away from the battery
The USB connector that is visible near the finger is accessible thru an opening that is on the enclosure. It is used for charging the battery and for updating the Arduino software.
A short length of coaxial cable and three terminators was utilized to cause a reflection that acts like a Radar impulse reflected off an object. The software shows a graph of distance versus received signal beginning at the left where the display text says "0 meters". The text at the other end reads "19 meters". For the display positive signal is drawn in yellow above the center axis and blue for negative signals below the center axis. When the unit is switched on it displays the full range, for this device 0 to 19 meters.
To examine the signal near the middle of the display, touch the screen near the 3 meter point and drag to the right lifting it at about the 5 meter point to change the view as shown in the animaiton above. Swipes to the left returns to the full range display.
Thus far, the return signal is simulated using the mis-terminated cable. That is because I have not yet been able to get an echo signal that is strong enough. The fault is that the receiver needs more sensitivity and the antenna needs significant work. I have done some antenna work. For example here is a pair of directional TEM horn antennas I built.
Although they look good, they are not usable at a low enough frequency for this project. This is an area that needs a lot of future work.
The next steps on this project include:Designing and building second generation printed circuit board that incorporates the design changes learned from testing the first board design. The new printed circuit board would include a better transmit pulse generator and a more sensitive receive amplifier.
Design and build a pair of directional, non-dispersive, TEM horn antennas that have good impedance match and operate well at the lower frequency band that is best suited to penetration of foliage. The horn antennas shown in the photo above do not operate well below 600 MHz whereas the best area for this project is near 200 MHz.
If good echo reception is achieved, then making the device practical to manufacture can be done. However I don't want to give the impression that it is a sure thing since this has not been done before and so far I have not seen any echo received through the antenna and the UWB board's receiver circuitry.