router-screen.html
changeset 4 1715f50a066d
parent 3 1d832a05eb87
child 5 10a6882c7671
--- a/router-screen.html	Thu May 27 15:03:28 2010 +0100
+++ b/router-screen.html	Thu May 27 16:34:37 2010 +0100
@@ -23,9 +23,13 @@
 Any such tampering is likely to result in an non-functional village DTN router
 so please don't do it!</p>
 
-<p>Figure 1 shows a village DTN router deployed in Staloluokta in 2009.</p>
+<p align="center">
+<a href="images/smaller-node.jpg"><img alt="Village DTN router" src="images/smaller-node-thumb.jpg"/></a><br/>
+Figure 1 shows a village DTN router deployed in Staloluokta in 2009.<br/>
+(For all images on this page, you can click on the image for a full-sized version.)
+</p>
 
-<h2>Turning On and Off</h2>
+<h2><a name="onoff" id="onoff">Turning On and Off</a></h2>
 
 <p>The large switch at the side of the device is used to turn it on and off.
 The device requries approximately two minutes to fully boot and bring up all of
@@ -34,16 +38,28 @@
 particular, the filesystems - such an error would be the equivalent of a
 hard-disk failure in a laptop.</p>
 
-<p>Figure 2 shows the ON/OFF switch in the "ON" position. </p>
+<p align="center">
+<a href="images/S-on.jpg"><img src="images/S-on-small.jpg" alt="switch"/></a><br/>
+Figure 2 shows the ON/OFF switch in the "ON" position. 
+</p>
 
-<p>Figure 3 shows the ON/OFF switch in the "OFF" position.</p>
+<p align="center">
+<a href="images/S-off.jpg"><img src="images/S-off-small.jpg" alt="switch"/></a><br/>
+Figure 3 shows the ON/OFF switch in the "OFF" position.
+</p>
 
-<p>Figure 4 shows a user switch the device to the "ON" position.</p>
+<p align="center">
+<a href="images/S-turingon.jpg"><img src="images/S-turingon-small.jpg" alt="switch"/></a><br/>
+Figure 4 shows a user switching the device to the "ON" position.
+</p>
 
-<p>That's all very simple so far, but its gets a little more complicated when
-we need to understand how the device manages its use of power.</p>
+<p>That's all nice and simple so far, but its gets a little more complicated when
+we need to understand how the device manages power, which is, of course, in 
+short supply in Padjelanta!</p>
 
-<h2>Power Management</h2>
+<h2><a name="power" id="power">Power Management</a></h2>
+
+<h3>Basic Power States</h3>
 
 <p>As a solar-powered device, the village DTN router must manage its power so
 as to conserve battery in case there is not sufficient sunlight to charge the
@@ -53,18 +69,111 @@
   <li>When sufficient power is available and the device is operating normally,
     it is in the "UP" state. In the "UP" state, all WiFi, mail and web services
     are operating.</li>
-  <li>When power levels are lower, the device may switch to a standby mode of
-    operation for a short period (30 minutes) to allow some time for the
+  <li>When power levels are lower, the device will switch to a standby mode 
+    for a short period (30 minutes) to allow time for the
     batteries to recharge, this is the "STANDBY-SHORT" state. In this state the
     device uses much less power, but no services are available as the processor
     in the device is asleep, just like a laptop in standby mode. After 30
     minutes, the device will power up, and if power levels are sufficient will
     change to the "UP" state.</li>
-  <li>If power levels fall further, the device will </li>
+  <li>If power levels fall further, the device will enter the "STANDBY-LONG"
+	state, where it will go to sleep for 3 hours.</li>
+  <li>And if power levels drop very low, then the device will power itself
+	off completely, until the batteries have been recharged to approximately
+	50% full. This can take three to four hours with good sunlight, but 
+	substantially longer in bad weather conditions.</li>
+  <li>Finally, the device is set to put itself to sleep overnight, between
+	22:00 and 06:00, in order to conserve power.</li>
 </ul>
 
-<p></p>
+<p>In each of the sleep or standby states, the device displays the time
+at which it is set to reboot, but note that after reboot, the device may
+go right back to sleep, if the power conditions warrant taking that
+action.</p>
+
+<h3><a name="override" id="override">Override Mode</a></h3>
+
+<p>Whilst the device is sleeping, if a communications opportunity arises (e.g.,
+a helicopter arrives), the device will not detect this since its radios are
+off, and we could lose the opportunity to send and receive data, which would be
+unfortunate, since such opportunities are relatively rare.  However, a user who
+is present can turn the device on temporarily. The device will power itself up
+for 30 minutes, during which it will operate normally (if there is sufficient
+power), and then transit to whatever is the appropriate state, depending on the
+power conditions. This is the "OVERRIDE" mode of operation.</p>
+
+<p>The device can be put into the OVERRIDE state at any time that it is
+sleeping.</p>
+
+<p>To put the device into the OVERRIDE state, the user simply turns 
+the switch to the "OFF" position, waits 5 seconds, and then turn the
+switch to the "ON" position. As usual it will take 2 minutes for the
+device to reboot, but it will then be in the OVERRIDE state and all
+WiFi, email and web services will be operational.</p>
+
+<h3><a name="powersummary" id="powersummar">Summary of Power States</a></h3>
+
+The table below summarises the different power states. Since the
+battery voltage level is displayed on the <a href="screen">LCD screen</a>
+we include the approximate voltage levels corresponding to each of
+the states. Voltage levels are somewhat technical, but provides the
+best way to measure the battery level, for the kind of battery we
+are using. The nominal voltage level when operating is 12V but in
+fact the levels fluctuate between 11.1V and approximately 13V
+depending on the state of the battery.</p>
+
+<p/>
 
-<p></p>
+<table border="1">
+<tbody>
+<tr>
+<th>State</th>
+<th>Briefly</th>
+<th>Description</th>
+<th>Voltage Levels</th>
+</tr>
+
+<tr>
+<td>UP</td>
+<td>Fully functional</td>
+<td>The device is operating normally as a WiFi access point, email and web server</td>
+<td>11.6V and above</td>
+</tr>
+
+<tr>
+<td>STANDBY-SHORT</td>
+<td>Sleep for 30 minutes</td>
+<td>The device is sleeping, to try charge the batteries.</td>
+<td>11.4V to 11.6V</td>
+</tr>
+
+<tr>
+<td>STANDBY-LONG</td>
+<td>Sleep for 3 hours</td>
+<td>The device is sleeping, to try charge the batteries.</td>
+<td>11.1V to 11.4V</td>
+</tr>
+
+<tr>
+<td>OFF</td>
+<td>Entirely powered off</td>
+<td>Either switched off manually, or else power is too low even for sleep</td>
+<td>11.1V and below</td>
+</tr>
+
+<tr>
+<td>OVERRIDE</td>
+<td>Work for 30 minutes</td>
+<td>The device will try operate fully for the next 30 minutes, if power permits</td>
+<td>N/A</td>
+</tr>
+
+</tbody>
+</table>
+
+<h2><a name="screen" id="screen">LCD Screen</a></h2>
+
+<p>TBD</p>
+
 </body>
 </html>