development of a power and communication ...amp, and the batteries were discharged from their fully...

Development of a Power and Communications System for Remote Autonomous GPS and Seismic Stations in Antarctica

Ezer Patlan Almeida

Academic Affiliation, Fall 2007: University of Texas at El Paso

RESESS Summer 2007

Science Research Mentor: Seth White Writing and Communication Mentor: Dr. William Prescott

Community Mentor: Matt Beldyk Peer Mentor: Nicole Ngo

ABSTRACT

We are addressing the challenge of operating a permanent GPS station in the harsh environment in Antarctica. The power and communication systems must operate year-round in the polar region where it is freezing, windy, and dark during the winter. We are working on three major parts of the GPS station: improving the power system, communication system, and mechanical design. We are investigating four areas related to the design of permanent GPS stations for the polar regions. 1). Analysis of wind power data was performed to compare wind speed versus power generated from wind turbine. 2). A test series was performed by applying varying voltages to power ports A and B of a GPS receiver. This was done to understand the power switching behavior of the receiver when it is powered from two independent sources. 3). A battery tester was evaluated to determine its accuracy. This tester may be used by engineers in the field to evaluate battery health, so ensuring its accuracy is critical. 4). Testing to determine GPS receiver and Iridium antenna interference was also done. This testing focused on understanding what distance between antennas was necessary to reduce the interference. The data and experiments with the equipment produced helpful results for the project and will improve permanent GPS technology for the polar regions.

This work was performed under the auspices of the Research Experience in Solid Earth Science for Students (RESESS) program. RESESS is managed by UNAVCO, with funding from the National Science Foundation and UNAVCO. RESESS partners include the Significant Opportunities in Atmospheric Research and Science Program, the Incorporated Research Institutions for Seismology, the United States Geological Survey, and Highline Community College.

1. Introduction

The Global Positioning System (GPS) is a satellite-based system which allows precise positioning with respect with time. The equipment uses an antenna that tracks satellite signals and records into the GPS receiver. A continuous GPS (CGPS) station can record the motion of the plate tectonics and ice sheets. The purpose of this study is to develop equipment that will aid in understanding Antarctica’s geology, tectonics, the crustal response to changing ice load, and ice sheet motion. Antarctica is subject to various forms of lithospheric deformation including mantle plunge and faulting. In eastern Antarctica, there is one active volcano, Mt. Erebus, on the edge of the Ross Ice Shelf. It is believed that this volcano is the byproduct of a mantle plume. It is an upwelling of abnormally hot rock within the Earth's mantle. The Transantarctic Mountains in the western part of Antarctica were formed by fractures in the Earth’s crust. There is an underlying rift (produced by tensional tectonic forces that occur when two plate boundaries separate each other) in the western part of Antarctica that causes faults which reach the seafloor. East Antarctica may have resulted from two different processes. 1). It is a vast Archean craton containing the oldest rocks during the period of the supercontinent. 2). It contains several Proterozoic orogenic belts surrounding smaller Archean blocks (Tingey, 1991). When an increased volume of ice occurs, the earth’s crust flattens as a result of the increased ice load pressing against the earth’s surface. The crustal response to the changing ice load provides information about the magnitude of past ice sheets and the rheology of the crust (Ivins and James 2005). The change in morphology in Antarctica is called Glacial Isostatic Adjustment (GIA).

The CGPS will help determine whether the bottoms of ice sheets are frozen to bedrock or sliding. In either case, it provides information to scientists comparing models of thermal structure to determine the response of the Earth past ice sheet changes. GPS is also used to monitor the deformation on Antarctica. The precision in the CGPS data will provide a better understanding in the ice dynamics. CGPS provides long continuous data records that help scientists understand ice and crustal deformation. In addition, CGPS can be attached to solid rock and monitor the changes in velocities and direction of plate motion. Also, the CGPS can be used with an antenna attached in ice at around 20 to 30 meters depth, thus providing better data on ice-dynamics (Hamilton et. al. 1998).

This project is focused on testing several aspects of the equipment used in harsh environments like Antarctica: temperature, battery, wind power, and antennas. Prototype equipment has been installed in Antarctica and in a test bed in the mountains near Boulder, Colorado. The goal of this project is to develop a system that can operate year-round in the polar regions with continuous power and data communications.

RESESS 2007, Ezer Patlan, 2

http://en.wikipedia.org/wiki/Mantle_%28geology%29

http://en.wikipedia.org/wiki/Plate_tectonics

2. Methods

The study examined the following aspects of system design: analysis of wind power data, GPS receiver power-switching behavior, testing accuracy of a battery analyzer, testing GPS receiver and Iridium antenna interference.

a. Analysis of Wind Power Data

The wind power data was analyzed from a prototype permanent GPS experiment located in the top of Niwot Ridge, near Boulder, Colorado. The data was collected in the autumn 2006. The GPS system was powered by one Forgen 500 wind turbine and one battery. Because the wind turbine was not powerful enough to operate the GPS system continuously, the GPS system had numerous on/off cycles during the test, depending on the wind speed and the charge stored in the battery.

To analyze the data, wind speed was integrated and compared with the charge used by the GPS system during each on/off cycle, assuming that all power delivered by the wind turbine was consumed by the GPS receiver via the battery. Because the wind turbine did not produce any power during winds below 5 m/s, all wind data below 5 m/s was excluded from the integration. Then, linear regression was utilized to generate a relationship between this data.

b. GPS Receiver Power Switching Behavior GPS receiver can operate using two independent power sources, one of each is connected

to the two input power ports. In this case, it is important to know exactly how the GPS receiver decides which power source to draw from.

The experiment with a GPS receiver and a power supply was used in order to observe any type of behavior that would help determine which ports (A or B) would take power from the power supply. First, we established a test matrix to set out the various setting and procedures in the GPS receiver power switching behavior. Second, the GPS receiver was installed with both power ports connected to the power supply. Two experiments were conducted. The first experiment entailed the application of constant voltages (Table 1). The second experiment entailed continuously varying voltages (Table 2). We observed how the GPS used the two available power ports under different input voltage conditions. Table 1. Constant Voltage Test Matrix Test # Step 1

0 Apply 13V on A, B off (off=0V) 1 Apply 13V on B, A off (off=0V) 2 Apply 11.5V on A, B off (off=0V) 3 Apply 11.5V on B, A off (off=0V) 4 Apply 10.5V on A, B off (off=0V) 5 Apply 10.5V on A, B off (off=0V) 6 Apply 10.5V on B, A off (off=0V) 7 Apply 13V on A, 11.5V on B 8 Apply 11.5V on A, 13V on B


Table 2. Continuous Voltage Test Matrix Test # Step 1 Step 2 Step 3

0 Set power supply to 13V A and B

Turn off power supply Then turn on

1 Start A at 14V, B off Decrease A until off 2 Start B at 14V, A off Decrease B until off 3 Start A and B off Increase A until on 4 Start A and B off Increase B until on

5 Start A and B at 6V Increase A unit on Then increase B until above A

6 Start A and B at 6V Increase B until on Then increase A until above B

7 Start A and B at 14V Decrease A until 6V Then decrease B until 6V 8 Start A and B at 14V Decrease B until 6V Then decrease A until 6V 9 Start A at 14V and B off Decrease A until off Increase B until on

10 Start B at 14V and A off Decrease B until off Increase A until on

11 Start A and B at 13V Increase A until 15V

12 Start A and B at 13V Increase B until 15V

13 Start A and B 13V Decrease A at 10.4V

14 Start A and B 13V Decrease B at 10.8V

c. Testing the accuracy of a battery analyzer A series of tests was performed to verify the accuracy of an ACT Intelligent Battery

Tester, which measures Ampere hour (Ah) capacity, room temperature, and voltage. This test was done because it is important to know the health of batteries that are being used in the field, and so knowing the accuracy of the battery tester is critical. This experiment would help engineers or scientists to check the battery easily and accurately, and know how long the battery will last under a designated load.

Each battery was charged, and then their capacity was measured with the tester. The test was recorded and repeated until two or three Ah measurements that were close to each other were obtained. Then, the discharge current and voltage versus time were recorded while discharging each battery using an adapter connected to the computer. The test was performed with three different types of 12 volt lead-acid batteries, a 12 amp-hour (12AH), an 18 amp-hour (18AH), and a 100 amp-hour (100AH) capacities. The discharge test was performed at a rate of 1 amp, and the batteries were discharged from their fully charged state to 10.8 V. A total of eight batteries were tested: two 12 amp-hour, three 18 amp-hour, and three 100 amp-hour sizes.


d. Testing GPS Receiver and Iridium Antenna Signals

In the polar regions, the Iridium satellite system is often the only communications system available; however the Iridium frequency is very close to a GPS frequency, so interference is often seen. Thus, it is important to determine the ideal distance between an Iridium antenna and a GPS antenna that will minimize interference at the GPS receiver.

The equipment was installed on the top of the roof of UNAVCO in Boulder, Colorado. From June 27th, 2007 to July 24th, 2007, the GPS was moved over a range of distances spanning from 10 to 70 feet away from the Iridium antenna, occupying a different location each day. The Iridium antenna was fixed at a height of 68.25 cm, a height that was low compared to the height of the GPS antenna. The GPS antenna height was measured to observe if the signal would be affected by height changes when the GPS antenna was moved.

Coordinated Universal Time (UTC), local time, antenna height and distance were recorded. We also recorded comments about any weather that might affect the GPS.

MOVE # Start Time

End Time Date Distance

GPS Antenna Weather

UTC UTC Month Day 10 Feet Height cm Comments Start 1937 6 27 10 111.8 cloudy

1 1722 1732 6 28 20 108.7 sunny 2 2310 2315 6 29 30 110.1 sunny

weekend not moved 6 30 -- -- -- weekend not moved 7 1 -- -- --

3 2303 2315 7 2 40 109.5 sunny

No Move -- 7 3 -- -- Thunder Storm

No Move Holiday 7 4 -- -- -- 4 2349 2358 7 5 50 106.6 sunny 5 2343 2352 7 6 60 105 sunny

weekend not moved 7 7 -- -- -- weekend not moved 7 8 -- -- -- No Move -- 7 9 -- -- -- No Move -- 7 10 -- -- -- No Move -- 7 11 -- -- -- No Move -- 7 12 -- -- --

6 2312 2322 7 13 70 107.4 sunny weekend not moved 7 14 -- -- -- weekend not moved 7 15 -- -- -- no move -- 7 16 -- -- --

7 1710 1719 7 17 20 103.4 sunny No Move -- 7 18 -- -- --

8 2348 2353 7 19 10 106.7 sunny 9 2300 2318 7 20 30 107.2 sunny

weekend not moved 7 21 -- -- -- weekend not moved 7 22 -- -- -- No Move -- 7 23 -- -- --


10 2337 2337 7 24 40 111.4 sunny 11 2406 2412 7 25 50 108.4 cloudy 12 2230 2245 7 26 60 105.3 cloudy 13 2315 2332 7 27 70 109.5 cloudy

weekend not moved 7 28 -- -- -- weekend not moved 7 29 -- -- -- No Move -- 7 30 -- -- --

14 2350 15 7 31 20 113.7 cloudy 15 2330 2340 8 1 10 113.8 cloudy

3. Results & Discussion

a. Analysis of Wind Power Data Figure 1 shows the data obtained from the Niwot Ridge wind turbine test. Although there

is significant scatter in this data, a linear regression was generated for this data to obtain a linear relationship between the integrated wind speed and the charge used by the GPS system. This relationship was (GPS Charge Used, amp-hours) = 0.0069 * (Integrated Wind Speed > 5 m/s, m/s-hours)

This equation provides an approximate relationship which can be used to estimate the amount of power that will be provided by a Forgen 500 wind turbine in a location where wind speed data is available. Note that this analysis was performed for a high-altitude site (11,600 ft); therefore the wind turbine produced less power for a given wind speed than it would at lower elevations. The fact that power delivered by a wind turbine varies roughly proportionally to the air density can be used to adjust this relationship for different elevations.

Niwot Ridge Forgen 500 Test Autumn 2006

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 1400.0 1600.0

integrated wind speed (m/s-hours)exclude < 5 /ms

GPS

cha

rge

used

(a

mp-

hour

s)

Figure 1. GPS charge used versus integrated wind speed, excluding wind < 5 m/s.


b. GPS Receiver Power Switching Behavior The meaning of the various LED’s on the GPS receiver is as follows: • A green power port LED indicates that there is enough voltage to power the GPS receiver, and the GPS receiver is drawing power from that port. • A red power port LED indicates that there is enough voltage to power GPS receiver, but the GPS receiver is not drawing power from that port.. • The LED glows steadily when there is a strong voltage. • The LED flashes when the voltage is getting low. • When the GPS receiver is on, the yellow data LED flashes to indicate that the GPS receiver is writing a data file. For each test, the GPS receiver was not connected to an antenna and was unable to track signals from satellites. However, the GPS receiver still showed a flashing yellow data LED, even though no satellite signals were available. • When the GPS receiver is off, the yellow data LED (flashing or solid) indicates that the GPS receiver is receiving voltage, but not enough to power the GPS receiver. • When the GPS receiver is receiving zero or very low voltage, all LEDs are off • When the GPS receiver turns on, all LED’s flash for several minutes as the receiver is booting up. • When voltage to the GPS receiver is slowly decreased, all LED’s will flash briefly as the receiver shuts itself down. Test Series #1 Constant Voltage.

Table 1 describes the voltage limit necessary to turn on or turn off the GPS receiver. Also, it shows the voltage and current that each port draws. For example, in Tests 1 and 2 show when the GPS receiver turns on. When port A is at 13V and the other is off or when port A is off and port B is at 13V, it receives power from the port that is on. Also, the port that receives power will have a solid green power LED while the other port is off (off = 0V). Tests 3, 4, 5, and 6 demonstrate when the GPS receiver turns off. In addition, when 11.5V is applied to port A and 0V applied to port B (or vice versa), the GPS receiver does not turn on. There is no power coming from either port. However, the data LED is solid yellow in both cases, which indicates that the voltage level is not high enough to turn on the receiver. The observation is the same result when I applied 10.5V to either port with the other port off. Tests 7 and 8 demonstrate which port the receiver prefers to draw power from. In Test 7, the GPS receiver drew power from port A, which had a higher voltage than port B. However, port B showed a solid red LED,


indicating that the voltage available on port B was high enough to be used as backup. However, when the voltages were reversed in Test 8, the receiver still drew power from port A, even though its voltage was lower than port B. This indicates that port A is the port that the GPS receiver prefers to draw power from, if power is available.

In summary, these tests showed that 13V on either port A or port B is enough to turn the GPS receiver on. These tests also showed that 10.5V or 11.5V on either port A or port B is not enough to turn the GPS receiver on, however the data LED will be solid yellow. Finally, I observed that if both ports have voltage, and the voltage on either port is 11.5V or 13.0V, then the GPS receiver prefers to draw power from port A. Table 1. Constant voltage tests. Test # Description V(A)

A(A) V(B) A(B)

LED A LED B LED Data

1 13V on V(A), V(B) off

13 / 0.20

0 / 0 solid green

off flashing yellow

2 13V on V(B), V(A) off

0 / 0 13 / 0.23

off solid green

flashing yellow

3 11.5V on V(A), V(B) off

11.5 / 0

0 / 0 off off solid yellow

4 11.5V on V(B), V(A) off

0 / 0 11.5/ 0

off off solid yellow

5 10.5V on V(A), V(B) off

10.5 / 0


6 10.5V on V(B), V(A) off

0 / 0 10.5/ 0

off off solid yellow

7 13V on V(A), 11.5V on V(B).

13 / 0.20

11.5/ 0

solid green

solid red

flashing yellow

The meaning of the labels in the table: V(A) – Voltage on power port A V(B) – Voltage on power port B A(A) – Current (Amperes) on power port A A(B) – Current (Amperes) on power port B LED A – light emitting-diode shows status of power port A LED B – light emitting-diode shows status of power port B LED Data – shows status of data file when receiver is on; shows low-voltage level when receiver is off.


Test Series #2: Continuously Varying Voltage.

Table 2 summarizes the results of varying voltage tests. Test 1 shows the sequence in which the GPS turns off when the input voltage on port A is

decreased. When port A is at 14V along with port B off, the LED A would turn solid green. Also the LED data would have a flashing yellow. However if port A decreased to 11.6V the solid green would turn into a flashing green meaning the voltage on port A had decreased to a low level. Then, when port A is at 10.9V, the port A LED turned off and the GPS receiver turned off, however the data LED was still flashing. Around 10.2V the data LED turned off.

Test 2 shows the sequence in which the GPS turns off when the input voltage on port B is decreased. When port B is at 14V along with port A off, the LED B would turn solid green. Also the LED data would have a flashing yellow. However if port B decreased to 11.6V the solid green would turn into a flashing green meaning the voltage on port B had decreased to a low level. Then, when port B is at 10.9V, the port B LED turned off and the GPS receiver turned off, however the data LED was still flashing. Around 10.2V the data LED turned off.

Test 3 shows the sequence in which the GPS turns on when the input voltage on port A is increased. When port A reaches 10.5V with port B at 0V, the LED A and LED B are off, and the LED data turns solid yellow. The GPS receiver started to reboot around 12.1V and the port A LED turned solid green. Also the data LED was flashing yellow.

Test 4 shows the sequence in which the GPS turns on when the input voltage on port B is increased. When port B reaches 10.5V with port A at 0V, the LED A and LED B are off, and the LED data turns solid yellow. The GPS receiver started to reboot around 12.1V and the port B LED turned solid green. Also the data LED was flashing yellow.

Test 5 showed how the GPS receiver behaves when the voltage is increased on port A then port B. To start, both ports were in equilibrium at 6V and the GPS receiver was off. By increasing the voltage in port A to 10.5V, the data LED is solid yellow. Then at 12.1V the GPS receiver turned on with a port A LED solid green. Also, the data LED was flashing yellow. Then, as voltage to port B was increased, the port B LED was flashing red around 10.6V. Later, at 11.5V in port B, the port B LED was solid red. After 12.4V, port B LED continued to be solid red.

Test 6 showed how the GPS receiver behaves when the voltage is increased on port B then port A. To start, both ports were in equilibrium at 6V and the GPS receiver was off. By increasing the voltage in port B to 10.4V, the data LED is solid yellow. Then at 12.1V the GPS receiver turned on with a port B LED solid green. Also, the data LED was flashing yellow. Then, as voltage to port A was increased to 10.5V, the power A LED was flashing green, but power B LED is solid red at 12.1V. The power A LED stopped flashing at 11.8V then became solid green. As the voltage in port A was increased until around 13.1V and there was no change in the LED’s.

Test 7 showed how the GPS receiver behaves when the voltage is decreased on port A then port B. To start, both ports were in equilibrium at 14V and the GPS receiver was on. The power A LED is solid green, the power B LED is solid red, and the data LED is flashing yellow. When port A voltage is decreased there is a change in the power A LED from solid to flashing at 11.6V. Later, the power A LED is turns off when it reaches 10.6V, and power B LED becomes solid red to solid green at 14V. When port A reaches 6V there is no change in the LED’s. Then when the voltage to port B is decreased, power B LED is flashing green at 11.5V. When port B is


at 10.9V both powers LED’s are shut off, however, the LED data is flashing yellow. When port B is at 10.3V the flashing yellow LED data turns off. NOTE: During Test 7, an unexpected result was seen where the GPS receiver split its power draw between ports A and B around 10.6V. This behavior was tested in more detail in Tests 9, 10, and 11.

Test 8 showed how the GPS receiver behaves when the voltage is decreased on port B then port A. To start, both ports were in equilibrium at 14V and the GPS receiver was on. The power A LED is solid green, the power B LED is solid red, and the data LED is flashing yellow. When port B voltage is decreased there is a change in the power B LED from solid to flashing red at 11.4V. When port B voltage reached 10.5V, the port B LED turned off. After port B reaches 6V there were no change in the LED’s. Then, when port A voltage was decreased, then the power A LED was flashing green at 11.5V. When port A is at 10.9V, port A LED turns off and the GPS receiver turns off, but the LED data is flashing yellow. When port A reaches 10.2V, the data LED turns off.

Test 9 showed how the GPS receiver can split its power draw between ports A and B. At the start of the test, the power A LED was solid green at 14V and the receiver drew 0.20 amps through port A, the power B LED was solid red at 13V and 0A, and data LED was flashing yellow. When port A decreased to 10.6V, the receiver began to split its power draw from both ports, 0.16A through port A and 0.11A through port B. During this time, the power LED’s varied between two states: LED A flashing green with LED B solid red, or LED A off and LED B solid green. When port A decreased to 10.5V, there was 0.10A through port A and there was now more power drawn through port B with 0.15A. When port A reached 10.43V, the receiver completely switched to port B, where it was drawing 0.21A. The port B power LED was now solid green.

In test 10, the test sequence for test 9 was repeated but with port B decreased from 13.0V to 10.8V and held at that lower voltage. At the start of the test, the power A LED was solid green at 13V and the receiver drew 0.20 amps through port A, the power B LED was solid red at 13V and 0A, and data LED was flashing yellow. When the voltage on port B was decreased to 10.8V, the power B LED was flashing red. Then when voltage on port A was decreased to 11.6V, the power A LED was flashing green and the receiver still drew 0.23A through port A. At 10.6 V, the power A LED is flashing green but now port A was only drawing 0.15A while port B was drawing 0.11A. The power LEDs also alternated states while power draw was split between ports. At 10.50 V, the receiver continued to split power draw, 0.10 through port A and 0.15 through port B. At 10.43V, unlike test 9 the receiver simply turned off and did not attempt to draw power from port B.

In test 11, the test sequence for test 9 was repeated but with port B held at 10.7V. In this case, when port A was decreased to 10.6V, the receiver did not split its power draw between ports, it simply turned off.

In summary, Test 1 and Test 2 showed the behavior of the receiver when the voltage supplied to a single power port was decreased from 13 to 0V. The receiver behaved identically whether power was applied to port A or port B. Similarly, Tests 3 and 4 showed that the receiver also behaves identically when the voltage supplied to a single port is increased from 0 to 13V. Therefore, when the receiver is powered from only one port, there is no difference if port A or port B is used. Tests 5 and 6 showed that if the voltage on port A is 10.5 or above, the receiver prefers to draw power from port A rather than port B, even if the voltage on port B is higher than port A. Tests 7 and 8 examined the behavior when voltages to both power ports are decreased, one after the other. In Test 7 it was seen that if port B has a high voltage, at approximately 10.6V


the receiver will stop drawing power from port A and run from port B. It was also seen during test 7 that the receiver will split its power draw between ports A and B when the voltage on port A reaches 10.6V. This behavior was studied more closely in tests 9-11. However if there is no voltage on port B, then the receiver simply shuts off when voltage on port A reaches 10.9V. Tests 9 through 11 showed that the receiver will actually draw power from both power ports when the voltage on port A is decreased to between 10.60 and 10.43V. However, the exact behavior here depends on the voltage level on port B, as described above.

Table 2. Varying voltage tests. Test #

Description V(A) A(A)

V(B) A(B)

LED A

LED B LED Data

1 V(A) at 14V, V(B) off. Decrease V(A) until off.

14 / 0.20

0 / 0 solid green off flashing yellow

11.6 /0.23

0 / 0 flashing green

off flashing yellow

10.9 / 0 0 / 0 off off flashing or solid yellow

10.2 / 0 0 / 0 off off off

2 V(B) at 14V, V(A) off. Decrease V(B) until off.

0 / 0 14 / 0.25 off solid green flashing yellow

0 / 0 11.6 /0.26

off flashing green

flashing yellow

0 / 0 10.9 / 0 off off flashing or solid yellow

0 / 0 10.2 / 0 off off off

3 V(A) and V(B) off. Increase V(A) until on.

10.5 / 0


12.1 /0.24



4 V(A) and V(B) off. Increase V(B) until on.

0 / 0 10.5 / 0 off off solid yellow

0 / 0 12.1 /0.23

off solid green flashing yellow

5 V(A) and V(B) at 6V. Increase V(A) until on, then increase V(B) until above V(A).

10.5 / 0


12.1 /0.23


12.1 /0.23

10.6 / 0 solid green flashing red flashing yellow

12.1 /0.23

11.5 / 0 solid green solid red flashing yellow

12.1 /0.23


6 V(A) and V(B) at 6V. Increase V(B) until on, then increase V(A) until above V(B).

0 / 0 10.4 / 0 off off solid yellow

0 / 0 12.1 /0.21

off solid green flashing yellow

10.5/ 0.20

12.1 / 0 flashing green

solid red flashing yellow

11.8 / 0.20


13.1 / 0.20


7 V(A) and V(B) at 14V. Decrease V(A) until 6V. Then decrease

14 / 0.2 14 / 0 solid green solid red flashing yellow


V(B) until 6V.

11.6 / 0.2



10.6 / 0 14 / 0.23 off solid green flashing yellow

6 / 0 11.5 /0.28

off flashing green

flashing yellow

6 / 0 10.9 / 0 off off flashing or solid yellow

6 / 0 10.3/ 0 off off off

8 V(A) and V(B) at 14V. Decrease V(B) until 6V. Then decrease V(A) until 6V.

14 / 0.20

14 / 0 solid green solid red flashing yellow

14 / 0.20


14 / 0.20

10.5 / 0 solid green off flashing yellow

11.5 / 0.20


off flashing yellow

10.9 / 0 6 / 0 off off flashing or solid yellow

10.2 / 0 6 / 0 off off off

9 V(A) and V(B) 13V. Decrease V(A) at 10.4V.

13 / 0.20

13 / 0.0 solid green solid red flashing yellow

11.6 / 0.20

13 / 0.0 flashing green


10.6 / 0.16

13 / 0.11 flashing green OR off

solid red OR solid green

flashing yellow

10.5 / 0.10

13 / 0.15 flashing green OR off


flashing yellow


10.43/0.0

13 / 0.21 off solid green flashing yellow

10 V(A) and V(B) 13V. Decrease V(B) at 10.8V. Decrease V(A) at 10.4V.

13 / 0.20

13 / 0 solid green solid red flashing yellow

13 / 0.20

10.8 / 0 solid green flashing red

flashing yellow

11.6 /0.23


flashing red flashing yellow

10.6 / 0.15

10.8 / 0.11

flashing green OR off


flashing yellow

10.5 / 0.10

10.8 / 0.15

flashing green OR off


flashing yellow

10.43 / 0

10.8/ 0.20

off off off

11 V(A) at 13V and V(B) at 10.7V. Decrease V(A) at 10.4V.

13 / 0.20


11.6 /0.23


Flashing red

flashing yellow

10.6 / 0.0

10.7 / 0.0 off Off off

The meaning of the labels in the table: V(A) – Voltage on power port A V(B) – Voltage on power port B A(A) – Current (Amperes) on power port A A(B) – Current (Amperes) on power port B LED A – light emitting-diode shows status of power port A LED B – light emitting-diode shows status of power port B LED Data – shows status of data file when receiver is on; shows low-voltage level when receiver is off.


c. Testing the accuracy of a battery analyzer

Four tests of the analyzer were run: 1. Different methods of using the battery analyzer It was found that the way in which the battery analyzer clips are connected to the battery terminals makes a difference in the battery capacity measurement. Two methods were tried, called “touch” and “attach”. “Touch” refers to holding the alligator clips by hand and pressing them against the terminals. “Attach” refers to clipping the alligator clips onto the terminals and leaving them untouched during the measurement. When the alligator clips are “touching” the battery terminals it does not respond with an accurate reading. However, the battery analyzer responds with better accuracy when the clips are attached to the terminals. Two charts below illustrate a difference in measured capacity between the two contact methods. In the Touch chart the capacity is generally much lower than in the Attach chart. “Touch” Chart:

Experiment Test Connection ID Number

Volts (V)

Capacity (Ah)

1 1 touch 12AH1 12.65 9.651 2 touch 12AH1 12.69 9.652 1 touch 12AH2 12.73 10.32 2 touch 12AH2 12.72 10.33 1 touch 18AH1 12.63 83 2 touch 18AH1 12.57 8.34 1 touch 18AH2 12.83 94 2 touch 18AH2 12.72 95 1 touch 18AH3 12.57 10.36 1 touch 100AH1 12.77 27.56 2 touch 100AH1 12.76 27.56 3 touch 100AH1 12.7 27.57 1 touch 100AH2 12.77 38.007 2 touch 100AH2 12.66 38.007 3 touch 100AH2 12.66 38.00

“Attach” Chart:

Experiment Test Connection ID Number

Volts (V)

Capacity (Ah)

1 1 attach 12AH1 12.74 15.31 2 attach 12AH1 12.71 15.31 3 attach 12AH1 12.67 15.31 4 attach 12AH1 12.59 171 5 attach 12AH1 12.62 172 1 attach 12AH2 13.18 13.652 2 attach 12AH2 12.85 13.65


2 3 attach 12AH2 12.64 13.652 4 attach 12AH2 12.65 15.32 5 attach 12AH2 12.98 15.32 6 attach 12AH2 12.81 15.32 7 attach 12AH2 12.75 172 8 attach 12AH2 12.65 173 1 attach 18AH1 12.93 11.33 2 attach 18AH1 12.73 11.33 3 attach 18AH1 12.54 11.33 4 attach 18AH1 12.66 10.653 5 attach 18AH1 12.72 10.653 6 attach 18AH1 12.58 10.653 7 attach 18AH1 12.53 114 1 attach 18AH2 12.93 11.654 2 attach 18AH2 12.66 11.654 3 attach 18AH2 12.76 11.654 4 attach 18AH2 12.81 124 5 attach 18AH2 12.76 124 6 attach 18AH2 12.94 125 1 attach 18AH3 12.98 95 2 attach 18AH3 12.66 95 3 attach 18AH3 12.78 9.35 4 attach 18AH3 12.64 9.35 5 attach 18AH3 12.55 10.36 1 attach 100AH1 12.83 73.256 2 attach 100AH1 12.81 73.256 3 attach 100AH1 12.8 73.256 4 attach 100AH1 12.77 73.256 5 attach 100AH1 12.74 656 6 attach 100AH1 12.7 657 1 attach 100AH2 12.65 81.507 2 attach 100AH2 12.65 81.507 3 attach 100AH2 12.61 81.507 4 attach 100AH2 12.64 73.257 5 attach 100AH2 12.63 73.257 6 attach 100AH2 12.58 73.25

2. Comparison of battery analyzer with discharge tests for new batteries The Discharge Chart below illustrates the difference in capacity measured by the Battery analyzer versus the actual battery capacity from the discharge test. For simplicity, the chart below only shows results from brand new batteries; the remaining batteries are discussed later. Each of these new batteries had a good capacity as shown by the discharge tests. However, the Battery analyzer overestimated the capacity for the 12AH batteries, underestimated the capacity for the 18AH batteries, and underestimated capacity for the 100AH battery.


Discharge Chart:

Experiment Number

Battery ID Number

Discharge Capacity (Ah)

Capacity from Battery Tester (Ah)

1 12AH1 12.45 15.30 - 17.0 2 12AH2 13.01 13.65 - 17.0 3 18AH1 18.19 10.65 - 11.3 4 18AH2 18.62 11.65 - 12.0 6 100AH1 88.7 65.0 -73.25

3. Comparison of battery analyzer with discharge tests for a bad battery One test was also performed with a battery known to be damaged (100AH3). The battery analyzer and discharge test both showed that this battery had a very low capacity. This shows that the battery analyzer can identify a damaged battery. Discharge Chart:

Experiment Number

Battery ID Number



8 100AH3 0.6407 7.3 - 8.65 4. Comparison of Battery analyzer with Discharge Tests for Batteries Exposed to Extreme Cold Two batteries were also tested that had been cold-cycled many times between -20ºC and -40ºC, and once to -70ºC. For both batteries the discharge capacity was low, however the Battery analyzer showed a good capacity. This indicates the batteries were both damaged by low temperatures, but that the battery analyzer was not able to identify this damage. There was a repeat test in the discharge capacity but there were no repeated tests in the capacity from battery tester. Discharge Chart:

Experiment Number

Battery ID Number



7 100AH2 53.92 73.25 - 81.50 9 100AH4 52.25 65.0 - 89.75

10 100AH2 36.95 Not Tested 11 100AH4 41.35 Not Tested

d. Testing GPS Receiver and Iridium Antenna Signals The number of observations per slip is a measure of the GPS receiver’s ability to record

data without interruption. An interruption in the satellite signal (e.g. interference) produces a “cycle slip”. The data from 01:00 to 14:00 UTC was analyzed. Data during the 00:00 UTC hour was not used because in that hour the GPS antenna was moved. In Figure 2, the observations per slip in the 1-second were low enough to show that there was interference between the Iridium and GPS antenna, and then as the separation between the Iridium and the GPS antenna increased, the observations per slip increased and indicate little interference. Between 10 and 30 feet we


found interference between the Iridium and GPS antenna, however, from 40 to 70 feet it was difficult to distinguish cycle slips caused by Iridium from those caused by other sources. Figure 3 shows obs/slip from the 0.2sec GPS data. When the GPS antenna is moved from 0 feet to 40 feet there is a diminished interference, however, again it becomes difficult to interpret the data from 40 to 70 feet antenna separation.

Figure 2. Observations per slip versus distance at 1 sec

Distance vs. Avg. obs/slips data recorded at 1sec on the Annex building

0

5

10

15

20

25

30

0 10 20 30 40 50 60 70 80

Thou

sand

d

Distance away from Iridium antenna in feet

Avg

. obs

/slip

s (0

1:00

-14:

00)


Distance vs. Avg. obs/slip data recorded at 5hz on the Annex building

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60 70 80

Thou

sand

s

Distance in feet

Avg

. obs

/slip

(01:

00-1

4:00

)

Figure 3. Observations per slip versus distance at 5 Hz or 0.2 sec

4. Conclusion

As a result of our analysis of the wind power data, engineers can predict the amount of power delivered by a Forgen 500 wind turbine by calculating the wind speed times a slope number (0.0069): [Turbine output at 12 V (amp-hours)] = 0.0069 * [Integrated wind speed (m/s-hours)] where all wind speed data below 5 m/s is excluded from the integrated wind speed. This relationship was derived using data from a high elevation site (11,600 ft), however the slope can be adjusted proportionally to air density to yield results for sites at different elevations. The GPS power switching behavior tests showed important results about how the receiver functions when powered by two separate power sources. First, it was seen that if the receiver is powered from one power port only, it behaves identically whether port A or port B is used. Second, when power is applied to both ports, the receiver prefers to draw power from port A even is the voltage on port A is lower than port B. Third, if power is applied to both ports but the voltage level on port A is low (between 10.60 and 10.43V), then the receiver will split its power draw between both ports. When using the battery analyzer, it responds with better accuracy when the clips are attached to the terminals as opposed to being held on the terminals with the hands. Comparing the battery analyzer with discharge test, each new battery had a good capacity as shown by the discharge tests. However, the Battery analyzer showed a high capacity for the 12AH batteries and a low


capacity for the 18AH and 100AH batteries. Also, the battery analyzer and discharge test both showed that a damaged 100 amp-hour battery had a very low capacity, indicating that the battery analyzer can identify a damaged battery. Finally, when comparing the battery analyzer with discharge test for batteries exposed to extreme cold, for both batteries the discharge capacity was low, however the battery analyzer showed a good capacity. This indicates the batteries were both damaged by low temperatures, but that the Battery analyzer was not able to identify this damage. Finally, it was shown that interference from an Iridium antenna diminishes as the separation between Iridium and GPS antennas is increased, for both 1-second and 5-Hz GPS data. However, between 50 feet to 70 feet it is difficult to distinguish interference caused by Iridium versus that caused from other sources. The data and tests might provide helpful results the behavior of the equipment and communications which improves the permanent GPS system.


REFERENCES Milne, G. A., Davis, J. L., Mitrovica, J. X., Scherneck, H. G., Johansson, J. M., Vermeer, M., Koivula, H., Space-Geodetic Constraints on Glacial Isostatic Adjustment in Fennoscandia. Science, Vol. 291, 1-5 (2001). Pfost, D., Casady, W., Shannon, K., Precision Agriculture: GPS. University of Missouri- Columbia. 1-6 (1997). UNAVCO and IRIS and Polar Community (2006). The Collaborative Research: Development of a Power and Communication System for Remote Autonomous GPS and Seismic Stations in Antarctica. NSF Proposal, 1-15.


development of a power and communication ...amp, and the batteries were discharged from their fully...

Documents