24 March 2015
Disentangling Effects of Noise from Presence of Anthropogenic Infrastructure: Design and
Testing of System for Large-scale Playback Experiments
Rrf: Rosa et al. • Noise Playback System
PATRICIA ROSA,1,2 Natural Resources Institute, University of Manitoba, Winnipeg, MB R3T
2M6, Canada
COLIN R. SWIDER, Natural Resources Institute, University of Manitoba, Winnipeg, MB R3T
2M6, Canada
LIONEL LESTON, Natural Resources Institute, University of Manitoba, Winnipeg, MB R3T
2M6, Canada
NICOLA KOPER, Natural Resources Institute, University of Manitoba, Winnipeg, MB R3T
2M6, Canada
1
E-mail: rosap@myumanitoba.ca
2
Present address: 70 Dysart Road, Winnipeg, MB R3T 2M6, Canada
SUPPORTING MATERIAL
The solar-powered broadcasting units each contained an array of 5 150-W (8.7-A, 12-V) solar
panels (SunForce Products, Montreal, QC, Canada), for a potential 750-W (43.5-A) maximum
power. We estimated the maximum power consumption of the system to be approximately 300 W
by summing the expected power consumption of all the components (charge controller, inverter,
speakers, and iPod; Morningstar 2009, LOUD 2011, Schumacher Electric 2012). We then
designed the system so that the solar panels would generate a potential 750-W maximum power
(350 W more than we anticipated needing). Given the potential for cloudy days and the necessity
to broadcast noise continuously throughout the night, this overcompensation ensured that the
batteries could be recharged during a relatively short period of sunlight.
The panels were mounted on a frame constructed from 38-mm × 89-mm pressure-treated
lumber. The dimensions of the frame were 3.8 m (l) × 1.1 m (h) × 1.5 m (w). This height and
width combination held the solar panels at an angle of roughly 55° from vertical. This angle
optimized solar irradiance on the panels, given the latitude of our study sites and the time of year
the study was conducted (Boxwell 2013).
We wired the 12-V solar panels in parallel to maintain the voltage at 12 V throughout the
system. Parallel wiring is also advantageous because if one of the panels fails, the rest of the
array is still functional, whereas failure of a panel in a series circuit would result in failure of the
entire system. We used weather-resistant, 6-AWG copper wire to accommodate the current and
minimize voltage loss over the length of the wire in the system. Using wire that is too thin is
inefficient because it results in voltage drops as wire length increases (Morningstar 2009). The
stock wiring built into the solar panels was spliced onto the 6-AWG wire by crimping metal
eyelets onto wire ends and connecting them with a nut and bolt. The exposed metal was then
wrapped with electrical tape. This connection method was used to connect wires throughout our
system.
The positive and negative leads from the solar panel array connected to the PV+ and PV−
terminals in the charge controller. We interrupted the positive lead with an on/off kill switch that
allowed us to cut power from the solar panels to the rest of the system quickly and safely. We
used a TriStar 45 charge controller (Morningstar Corporation, Newtown, PA) because its 45-A
capacity exceeded our potential system maximum of 43.5 A. We grounded the system by wiring
the charge controller to a grounding plate buried beneath the system. Copper grounding wire (6AWG) was used for this connection.
The Battery+ and Battery− leads from the charge controller connected to the battery
array. We used an array of 4 6-V deep-cycle golf cart batteries (Exide, Milton, GA; Commercial
Series, Product no. 10-2010-0). Deep cycle batteries provide constant current over long periods
of time and can survive repeated discharge/recharge cycles. We wired them in a series-parallel
arrangement to adapt the 6-V batteries into a 12-V configuration.
Current from the batteries was directed to a Schumacher 410-W power inverter, which
converted direct current (DC) to alternating current (AC) and supplied the 8-GB iPod Nano and
the 2 Mackie SRM350v2 loudspeakers (LOUD Technologies, Woodinville, WA) with AC power.
We used this model of power inverter because the 410-W capacity exceeded the expected power
consumption of the speakers and iPod. The iPod connected to the speakers with a 1/8” to dual ¼”
audio cable. Powered speakers were used to eliminate the need for an amplifier. For a detailed
rationale for speaker selection, see Discussion in the main manuscript.
The batteries, speakers, iPod, charge controller, and inverter were contained in a 1.2-m (l)
× 0.9-m (w) × 0.7-m (h) plywood box adjacent to the solar panel array, which protected the
electronic components from the elements. The speakers projected sound through 36-cm (w) ×
56-cm (h) screened holes in opposite sides of the boxes. Additional 75-cm (l) × 3-cm (h)
screened slots located on the sides not containing speaker holes assisted in ventilation to prevent
overheating. The boxes were painted white to reflect light and prevent heat absorption. The
boxes were elevated approximately 0.2 m above the ground on cement cinder blocks, to prevent
decay from moisture and to aid in sound projection. We installed a 1-m-high metal technical
fence (Boomers Services, Brooks, AB, Canada) around each unit to prevent damage from cattle,
for a fenced area of 7.3 m (l) × 4.9 m (w).
LITERATURE CITED
Boxwell, M. 2013. Solar angle calculator. In Solar electricity handbook. Greenstream,
Warwickshire, England, United Kingdom. http://solarelectricityhandbook.com/solarangle-calculator.html. Accessed 15 Jan 2014.
LOUD. 2011. SRM350v2 powered loudspeaker owner’s manual. Loud Technologies,
Woodinville, Washington, USA.
Morningstar. 2009. TriStar solar system controller: installation and operation manual.
Morningstar, Washington Crossing, Pennsylvania, USA.
Schumacher Electric. 2012. Model PID-410 power inverter owner’s manual. Schumacher
Electric, Mount Prospect, Illinois, USA.