21 here - <strong>ONLY TRAINED STAFF SHOULD ATTEMPT OTHER ACTIONS</strong>, so |
21 here - <strong>ONLY TRAINED STAFF SHOULD ATTEMPT OTHER ACTIONS</strong>, so |
22 please do not disturb cables, antennae or other external parts of the device. |
22 please do not disturb cables, antennae or other external parts of the device. |
23 Any such tampering is likely to result in an non-functional village DTN router |
23 Any such tampering is likely to result in an non-functional village DTN router |
24 so please don't do it!</p> |
24 so please don't do it!</p> |
25 |
25 |
26 <p>Figure 1 shows a village DTN router deployed in Staloluokta in 2009.</p> |
26 <p align="center"> |
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27 <a href="images/smaller-node.jpg"><img alt="Village DTN router" src="images/smaller-node-thumb.jpg"/></a><br/> |
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28 Figure 1 shows a village DTN router deployed in Staloluokta in 2009.<br/> |
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29 (For all images on this page, you can click on the image for a full-sized version.) |
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30 </p> |
27 |
31 |
28 <h2>Turning On and Off</h2> |
32 <h2><a name="onoff" id="onoff">Turning On and Off</a></h2> |
29 |
33 |
30 <p>The large switch at the side of the device is used to turn it on and off. |
34 <p>The large switch at the side of the device is used to turn it on and off. |
31 The device requries approximately two minutes to fully boot and bring up all of |
35 The device requries approximately two minutes to fully boot and bring up all of |
32 the WiFi, mail and web services. <strong>PLEASE BE PATIENT - DO NOT CONSTANTLY |
36 the WiFi, mail and web services. <strong>PLEASE BE PATIENT - DO NOT CONSTANTLY |
33 SWITCH THE DEVICE ON AND OFF!</strong> Doing so could damage the device, in |
37 SWITCH THE DEVICE ON AND OFF!</strong> Doing so could damage the device, in |
34 particular, the filesystems - such an error would be the equivalent of a |
38 particular, the filesystems - such an error would be the equivalent of a |
35 hard-disk failure in a laptop.</p> |
39 hard-disk failure in a laptop.</p> |
36 |
40 |
37 <p>Figure 2 shows the ON/OFF switch in the "ON" position. </p> |
41 <p align="center"> |
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42 <a href="images/S-on.jpg"><img src="images/S-on-small.jpg" alt="switch"/></a><br/> |
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43 Figure 2 shows the ON/OFF switch in the "ON" position. |
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44 </p> |
38 |
45 |
39 <p>Figure 3 shows the ON/OFF switch in the "OFF" position.</p> |
46 <p align="center"> |
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47 <a href="images/S-off.jpg"><img src="images/S-off-small.jpg" alt="switch"/></a><br/> |
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48 Figure 3 shows the ON/OFF switch in the "OFF" position. |
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49 </p> |
40 |
50 |
41 <p>Figure 4 shows a user switch the device to the "ON" position.</p> |
51 <p align="center"> |
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52 <a href="images/S-turingon.jpg"><img src="images/S-turingon-small.jpg" alt="switch"/></a><br/> |
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53 Figure 4 shows a user switching the device to the "ON" position. |
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54 </p> |
42 |
55 |
43 <p>That's all very simple so far, but its gets a little more complicated when |
56 <p>That's all nice and simple so far, but its gets a little more complicated when |
44 we need to understand how the device manages its use of power.</p> |
57 we need to understand how the device manages power, which is, of course, in |
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58 short supply in Padjelanta!</p> |
45 |
59 |
46 <h2>Power Management</h2> |
60 <h2><a name="power" id="power">Power Management</a></h2> |
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61 |
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62 <h3>Basic Power States</h3> |
47 |
63 |
48 <p>As a solar-powered device, the village DTN router must manage its power so |
64 <p>As a solar-powered device, the village DTN router must manage its power so |
49 as to conserve battery in case there is not sufficient sunlight to charge the |
65 as to conserve battery in case there is not sufficient sunlight to charge the |
50 batteries. We have implemented a power management module for the village DTN |
66 batteries. We have implemented a power management module for the village DTN |
51 router with the following features:</p> |
67 router with the following features:</p> |
52 <ul> |
68 <ul> |
53 <li>When sufficient power is available and the device is operating normally, |
69 <li>When sufficient power is available and the device is operating normally, |
54 it is in the "UP" state. In the "UP" state, all WiFi, mail and web services |
70 it is in the "UP" state. In the "UP" state, all WiFi, mail and web services |
55 are operating.</li> |
71 are operating.</li> |
56 <li>When power levels are lower, the device may switch to a standby mode of |
72 <li>When power levels are lower, the device will switch to a standby mode |
57 operation for a short period (30 minutes) to allow some time for the |
73 for a short period (30 minutes) to allow time for the |
58 batteries to recharge, this is the "STANDBY-SHORT" state. In this state the |
74 batteries to recharge, this is the "STANDBY-SHORT" state. In this state the |
59 device uses much less power, but no services are available as the processor |
75 device uses much less power, but no services are available as the processor |
60 in the device is asleep, just like a laptop in standby mode. After 30 |
76 in the device is asleep, just like a laptop in standby mode. After 30 |
61 minutes, the device will power up, and if power levels are sufficient will |
77 minutes, the device will power up, and if power levels are sufficient will |
62 change to the "UP" state.</li> |
78 change to the "UP" state.</li> |
63 <li>If power levels fall further, the device will </li> |
79 <li>If power levels fall further, the device will enter the "STANDBY-LONG" |
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80 state, where it will go to sleep for 3 hours.</li> |
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81 <li>And if power levels drop very low, then the device will power itself |
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82 off completely, until the batteries have been recharged to approximately |
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83 50% full. This can take three to four hours with good sunlight, but |
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84 substantially longer in bad weather conditions.</li> |
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85 <li>Finally, the device is set to put itself to sleep overnight, between |
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86 22:00 and 06:00, in order to conserve power.</li> |
64 </ul> |
87 </ul> |
65 |
88 |
66 <p></p> |
89 <p>In each of the sleep or standby states, the device displays the time |
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90 at which it is set to reboot, but note that after reboot, the device may |
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91 go right back to sleep, if the power conditions warrant taking that |
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92 action.</p> |
67 |
93 |
68 <p></p> |
94 <h3><a name="override" id="override">Override Mode</a></h3> |
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95 |
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96 <p>Whilst the device is sleeping, if a communications opportunity arises (e.g., |
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97 a helicopter arrives), the device will not detect this since its radios are |
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98 off, and we could lose the opportunity to send and receive data, which would be |
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99 unfortunate, since such opportunities are relatively rare. However, a user who |
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100 is present can turn the device on temporarily. The device will power itself up |
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101 for 30 minutes, during which it will operate normally (if there is sufficient |
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102 power), and then transit to whatever is the appropriate state, depending on the |
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103 power conditions. This is the "OVERRIDE" mode of operation.</p> |
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104 |
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105 <p>The device can be put into the OVERRIDE state at any time that it is |
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106 sleeping.</p> |
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107 |
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108 <p>To put the device into the OVERRIDE state, the user simply turns |
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109 the switch to the "OFF" position, waits 5 seconds, and then turn the |
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110 switch to the "ON" position. As usual it will take 2 minutes for the |
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111 device to reboot, but it will then be in the OVERRIDE state and all |
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112 WiFi, email and web services will be operational.</p> |
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113 |
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114 <h3><a name="powersummary" id="powersummar">Summary of Power States</a></h3> |
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115 |
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116 The table below summarises the different power states. Since the |
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117 battery voltage level is displayed on the <a href="screen">LCD screen</a> |
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118 we include the approximate voltage levels corresponding to each of |
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119 the states. Voltage levels are somewhat technical, but provides the |
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120 best way to measure the battery level, for the kind of battery we |
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121 are using. The nominal voltage level when operating is 12V but in |
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122 fact the levels fluctuate between 11.1V and approximately 13V |
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123 depending on the state of the battery.</p> |
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124 |
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125 <p/> |
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126 |
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127 <table border="1"> |
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128 <tbody> |
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129 <tr> |
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130 <th>State</th> |
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131 <th>Briefly</th> |
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132 <th>Description</th> |
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133 <th>Voltage Levels</th> |
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134 </tr> |
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135 |
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136 <tr> |
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137 <td>UP</td> |
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138 <td>Fully functional</td> |
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139 <td>The device is operating normally as a WiFi access point, email and web server</td> |
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140 <td>11.6V and above</td> |
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141 </tr> |
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142 |
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143 <tr> |
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144 <td>STANDBY-SHORT</td> |
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145 <td>Sleep for 30 minutes</td> |
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146 <td>The device is sleeping, to try charge the batteries.</td> |
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147 <td>11.4V to 11.6V</td> |
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148 </tr> |
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149 |
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150 <tr> |
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151 <td>STANDBY-LONG</td> |
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152 <td>Sleep for 3 hours</td> |
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153 <td>The device is sleeping, to try charge the batteries.</td> |
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154 <td>11.1V to 11.4V</td> |
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155 </tr> |
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156 |
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157 <tr> |
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158 <td>OFF</td> |
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159 <td>Entirely powered off</td> |
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160 <td>Either switched off manually, or else power is too low even for sleep</td> |
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161 <td>11.1V and below</td> |
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162 </tr> |
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163 |
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164 <tr> |
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165 <td>OVERRIDE</td> |
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166 <td>Work for 30 minutes</td> |
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167 <td>The device will try operate fully for the next 30 minutes, if power permits</td> |
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168 <td>N/A</td> |
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169 </tr> |
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170 |
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171 </tbody> |
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172 </table> |
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173 |
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174 <h2><a name="screen" id="screen">LCD Screen</a></h2> |
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175 |
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176 <p>TBD</p> |
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177 |
69 </body> |
178 </body> |
70 </html> |
179 </html> |