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--- projects:apex-ii [2010/11/22 08:23] – [Power] jonsowman
+++ projects:apex-ii [2011/10/25 20:45] (current) – priyesh
@@ Line 1: / Line 1: @@
 ====== Project Apex II ======
+{{:projects:apex-ii-logo-640.jpg|}}
 Following in the footsteps of Apex I and its unfortunate loss, Version 2 of the high altitude weather balloon launched by Sutton Grammar School sets out to achieve the same objectives. With a completely redesigned payload and tracking system, we hope to make this version easier to track & find.
@@ Line 10: / Line 12: @@
 ===== Project Details =====
-This project is complete - the payload has been launched once and more launches are planned. See [[http://twitter.com/apex_ii|Apex II on Twitter]] for more information.
+This project is complete - the payload has been launched once and more launches are planned. See [[http://twitter.com/apexhab|ApexHAB on Twitter]] for more information.
-We have a PDF detailing the technical hardware on the payload. This can be found [[http://balloon.hexoc.com/media/apextech.pdf|here]].
+We have a PDF detailing the technical hardware on the payload. This can be found [[http://www.apexhab.org/wp-content/uploads/2011/01/apextech.pdf|here]].
-Contact us: send an email to our mailing list at [[project-apex@googlegroups.com|project-apex@googlegroups.com]]
+Contact us: send an email to our mailing list at [[team@apexhab.org|team@apexhab.org]]
+{{:projects:apexiips.jpg|}}{{:projects:small_apex-ii-launch4.jpg|}}{{:projects:small_apex-ii-launch1.jpg|}}{{:projects:small_apex-ii-r6.jpg|}}
+{{:projects:track-mp.png|}}
 ===== Payload Hardware =====
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 Radiometrix appnotes seem to suggest that bit balancing is very important with these modules and tone based operation gets around this issue to an extent. The other option is using a proper **bipolar encoder**.
+During Launch 1 we suffered difficulties in decoding due to the combined effect of severe temperature drift and the AFC in dl-fldigi losing track due to the extended radio-off period for uplink. For Launch 2, we will be addressing these issues by using a new transmission regime. We will transmit a packet on 300 baud three times over without radio breaks, just a ~3second carrier gap. Then will come a 50 baud packet with //only// GPS data (no sensor data), after which will be a ~20second uplink window.
 ==== GPS ====
@@ Line 55: / Line 62: @@
 Due to the camera used it is not possible to supply the camera with power externally, making it impossible to power cycle externally. However, it may still be possible to include a power cycle within internal scripting.
+For Launch 2, these are being rescripted using LUA to attempt to get around some of the reliability issues we saw during Launch 1 - see the git repo on github for source code.
 ==== Power ====
 Our power supply will be 4xAA Energizer Lithium batteries. They retain their capacity even at low temperatures and over a wide range of discharge rates
-The alternative is one or two 3.6V Lithium Thionyl Chloride cell(s) from Saft Batteries (check MDS). These are available for around £10-£15. Versions are a C-cell @ 5.5Ah @ 50g, or a [[http://www.mdsbattery.co.uk/shop/productprofile.asp?Model=&ProductGroupID=2244&Brand=&DepartmentName=&DepartmentID=|D-cell @ 13Ah @ 100g]].
 In either case, regulators will be implemented (Maxim LDOs?) as different systems will require different voltages.
@@ Line 66: / Line 71: @@
   * PIC microcontroller - 3V3
   * Camera - 3V7 LiIon
-  * GSM phone - ~3.7V
+  * GSM phone - ~3V7
   * IRD - 2V5-3V for the inverter circuits
@@ Line 76: / Line 81: @@
 A simple 555/transformer based inverter should suffice. A large cap will be needed to try and smooth out recharging and for the inevitable higher discharge rate at altitude. Need some serious decoupling and noise suppression to prevent cap recharging interfering with RF comms.
-Possiblity of continuous ADC on the cap terminals to keep charge rate as low as possible whilst maintaining required voltage. The flight computer can disable charging whilst the radio is transmitting to avoid RF/EMI spikes.
+Possiblity of continuous ADC on the cap terminals to keep charge rate as low as possible whilst maintaining required voltage. The flight computer **must** disable charging whilst the radio is transmitting to avoid RF/EMI spikes.
 A daughterboard to the flight computer PCB will convert the output from these sensors to a count value which the flight computer can request once a minute, before it is reset to 0.
@@ Line 87: / Line 92: @@
 We'll be using the standard AM-SSB capable radio and dl-fldigi to decode the incoming signals from the balloon. It's after that that things get a little more complex.
-We would like to be able to visually plot the balloon's position on a map without relying on an internet connection. As such we aim to write software to take data from fldigi and output it to the tracking system we used on Apex I as this worked brilliantly. The data will be fed to APRSPoint and then Mappoint 2004 so we can see the balloon's position on the Mappoint map.
+We would like to be able to visually plot the balloon's position on a map without relying on an internet connection. As such we aim to write software to take data from fldigi and output it to the tracking system we used on Apex I as this worked brilliantly. The data will be fed to APRSPoint and then MapPoint 2004 so we can see the balloon's position on the Mappoint map.
 We will have a 3G internet dongle in at least one of the vehicles so decoded data from the radios can be fed to the DL server. Provided we have internet connectivity we can also use the DL tracking web page to see balloon position, altitude, ascent rates, etc. However we aim to implement all this functionality locally so as to not rely on net connection.
-The software is called "Apex Packet Handler" and is written in C#.
+The software is called "Apex Packet Handler" and is written in VB.
 ===== Team =====
@@ Line 103: / Line 108: @@
   * Andrew Cowan
   * Richard Morris
+  * Dominic Branford
+  * Priyesh Patel
+  * Philip Warren
+  * Alex Landless
+  * Edward Branford
+  * Michael Woodgate
 === Staff ===
   * J. Costello
-  * R. Turner
+  * R. Beaumont