projects:apex-ii
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| projects:apex-ii [2010/11/21 21:39] – [Project Details] jonsowman | projects:apex-ii [2011/10/25 20:45] (current) – priyesh | ||
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| ====== Project Apex II ====== | ====== Project Apex II ====== | ||
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| 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. | 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. | ||
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| ===== Project Details ===== | ===== Project Details ===== | ||
| - | This project is complete - the payload has been launched once and more launches are planned. See [[http:// | + | This project is complete - the payload has been launched once and more launches are planned. See [[http:// |
| - | We have a PDF detailing the technical hardware on the payload. This can be found [[http://balloon.hexoc.com/media/ | + | We have a PDF detailing the technical hardware on the payload. This can be found [[http://www.apexhab.org/wp-content/ |
| - | 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]] |
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| ===== Payload Hardware ===== | ===== Payload Hardware ===== | ||
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| Current designs designate three modes of data transmission. One on the minute, one at 20 seconds past, and one at 40 seconds past. Each transmission will be preceeded by a specific tone denoting the mode. The receiver can adjust itself to the correct decoding system and then decode the packet. This prevents the two becoming de-sync' | Current designs designate three modes of data transmission. One on the minute, one at 20 seconds past, and one at 40 seconds past. Each transmission will be preceeded by a specific tone denoting the mode. The receiver can adjust itself to the correct decoding system and then decode the packet. This prevents the two becoming de-sync' | ||
| - | * RTTY - 50 baud radioteletype. Proven atmospheric penetration and is required for use of the DL network. | + | * RTTY - 50 baud radioteletype. Proven atmospheric penetration and reliability. |
| - | * Fast RTTY - 300 baud radioteletype. This slightly quicker mode should be easier to pick up in moving vehicles as the chance of dropping parts of the packet is smaller. | + | * Fast RTTY - 300 baud radioteletype. This slightly quicker mode should be easier to pick up in moving vehicles as the chance of dropping parts of the packet is smaller. |
| - | < | + | |
| - | * Faster AFSK - better for moving vehicles as reduced chance of dropped packet sections.</ | + | |
| 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**. | 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**. | ||
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| + | 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 ==== | ==== GPS ==== | ||
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| 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. | 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 ==== | ==== Power ==== | ||
| - | Our current plan for power supply will be 4xAA Energizer Lithium batteries | + | 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:// | + | |
| In either case, regulators will be implemented (Maxim LDOs?) as different systems will require different voltages. | In either case, regulators will be implemented (Maxim LDOs?) as different systems will require different voltages. | ||
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| * PIC microcontroller - 3V3 | * PIC microcontroller - 3V3 | ||
| * Camera - 3V7 LiIon | * Camera - 3V7 LiIon | ||
| - | * GSM phone - ~3.7V | + | * GSM phone - ~3V7 |
| * IRD - 2V5-3V for the inverter circuits | * IRD - 2V5-3V for the inverter circuits | ||
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| A simple 555/ | A simple 555/ | ||
| - | Possiblity of continuous ADC on the cap terminals to keep charge rate as low as possible whilst maintaining required voltage. The flight computer | + | Possiblity of continuous ADC on the cap terminals to keep charge rate as low as possible whilst maintaining required voltage. The flight computer |
| 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. | 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. | ||
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| 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'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' | + | We would like to be able to visually plot the balloon' |
| 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. | 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" | + | The software is called "Apex Packet Handler" |
| ===== Team ===== | ===== Team ===== | ||
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| * Andrew Cowan | * Andrew Cowan | ||
| * Richard Morris | * Richard Morris | ||
| + | * Dominic Branford | ||
| + | * Priyesh Patel | ||
| + | * Philip Warren | ||
| + | * Alex Landless | ||
| + | * Edward Branford | ||
| + | * Michael Woodgate | ||
| === Staff === | === Staff === | ||
| * J. Costello | * J. Costello | ||
| - | * R. Turner | + | * R. Beaumont |
projects/apex-ii.1290375561.txt.gz · Last modified: 2010/11/21 21:39 by jonsowman