T minus 20 hours... and cancelled

Weather reports coming in suggest rain for most of tomorrow and possibly high winds at ground level at our launch and recovery sites. In view of this information we are now 'No go' for launch this weekend.

As I suggested in an earlier post, our launch window is likely now closed until the new year, however the additional time may allow the construction of more receivers - as the saying goes: every cloud....

Weather update from Metcheck

All eyes are on the weekend weather as there is the potential for some really quite nasty weather to sweep in off the Atlantic on Sunday as a deepening low moves across the country.

Confidence is still rather low over the exact track this system will take, which in turn will affect where the heaviest rain and strongest winds occur. As things stand at the moment, the low looks set to deepen quickly as it approaches Britain and Ireland, with a possible north-eastwards track across southern Ireland and then across northern England. This would bring the heaviest rainfall across central parts of Britain, with the strongest winds to the south and east of the low.

T minus 2 days

Another rollercoaster of a day with the weather models 00Z and 06Z models (both NOGAPS and GFS) suggesting that the nasty upper level winds out in the Atlantic would be coming over the UK just as we launch. Up at 9000 metres the indication was that wind speeds would be exceeding 100 knots! Our track was predicted to be almost 90 miles East of our launch site and to make matters worse heavy rain was also forecast.

I've just re-run the flight prediction based on the 12Z model and we have have a much more reasonable track. The rain is an unknown factor with no agreement in the models and different weather sites predicting wildly different weather. From what I can tell, cloud cover and the likely hood of rain falls as we move East - so we may be launching in cloudy skies and retrieving in clear ones.

Tomorrow is a VERY big D-day for us - fairly early on were going to have to give a 'go/no go' because we don't want to have delivery of Helium if it can't be used. So I'll be running the weather models tomorrow morning and hoping we have a consensus from the 00Z and 06Z runs.

This D-day is even bigger than that though. Our launch window is now closing due to factors such as team availability, daylight hours and weather considerations to name but a few. As such a launch between November and January is not particularly likely - so this may well be our last chance to launch in 2009.

As of this moment we are still 'GO'. Check back tomorrow to find out what D-day brings!

T minus 3 days

GFS has been giving us wildly different predictions all day with 00Z, 06Z and 12Z model runs producing very different tracks. We still don't know if there will be rain, although the wind is likely to take our balloon North Westerly.

Currently still 'GO' for launch.

Avionics: Ready for flight

Here you can see, for the first time, the full avionics package loaded into the capsule. The long copper wire along the bottom is the transmit antenna and the small block on top is the GPS antenna.

GFS & NOGAPS: Massive disagreement

As I mentioned in an earlier post NOGAPS and GFS do not always agree... actually a lot of time they don't agree. However, sometimes the differences in them are really quite massive.

The charts below are for the same day and time and are off of the same model run. The coloured areas show the amount of precipitation that is expected to have fallen in the 12 hour period prior to the listed time - so in this instance between 0600-1800 on Saturday 31 October. As you can see they don't look very much alike. My gut instinct says NOGAPS is closer to being right and I really hope that's the case!

Camera and phone tests complete

The mobile phone is working perfectly having over 50% battery life even after well over 2 hours of tracking. The £5 credit loaded is going to be more than enough for our purposes.

Our camera ran for 1 hour and 23 minutes before running out of space on the card - but still with 25% battery remaining. I'm going to adjust the script to take 5 pictures a minute instead of 6 as we'd like to get a runtime of more than 100 minutes.

T minus 4 days

A "Pay As You Talk" Vodafone SIM has now been acquired for our Windows Mobile device and is now having a full retest. At the same time the camera is also being retested with a 4Gb SDHC card (actually its an 8Gb card formatted to 4Gb!). The reason for dropping to 4Gb from 8 is that our CHDK firmware will not boot on the camera from a FAT32 partition.

Prediction on upper level winds have changed a little, showing an increase of 20 knots. We'll be monitoring the situation, but we are currently still 'go for launch'.

Zephyrus 1 Launch: T minus 5 days

We've been looking at the predicted tracks and examining wind and rain predictions for this coming weekend and we're fairly happy with what we are seeing. No rain is predicted during daylight hours (top chart), upper winds are showing as being no higher than 60 knots (middle chart) and surface winds, although not ideal should still be below 15 knots (bottom chart). Upper and surface winds are showing as being SW on the NOGAPS model and WSW on the GFS model - and either would suit us.

We're now looking at a Saturday launch. Stay tuned.

Track looks promising for coming weekend...

...but heavy rain may prevent launch:

Weather decides whether (to launch)

With all the equipment pretty much ready to go, we are now at the mercy of the weather. Whilst rain is an issue - the wind is even more so. Our gas has to be ordered at least 24 hours before launch as the canister has to be hired by the week - which means we need to predict when we will have the right conditions. Just to make things that little bit more tricky, standard weather reports are of no use to us as surface winds give no indication of upper wind strength, or even direction!

We have access to a balloon flight prediction website (provided by Cambridge University) which gives forecasts for up to 120 hours ahead - but we cannot place complete faith in just this. Although many weather prediction models exist, none are accurate all of the time and often they models can disagree quite substantially.

Only a couple of models are available free to the public (most are expensive subscriptions): GFS, used by the aforementioned prediction website, and NOGAPS. The idea will be to combine the information from both models (which can be analysed for free on the US Navy's weather website) and using the website provided by CU.

At the moment the weekend doesn't look too promising, but I'll be checking later on as the models are re-run every six hours and drastic changes are not uncommon.

Camera test complete

We currently only have a 2Gb card installed in our camera, which we now know needs to be replaced with an 8Gb for launch. Our test shows that we will use around 2Gb every 50 minutes - so we could theoretically get 200 minutes of footage with the higher capacity card. In reality though the batteries would not last for 200 minutes (and we expect our payload to have returned to Earth within 100 minutes).

Although not a 100% realistic test, for one I had to delete the contents of the memory card and restart the script, the battery lasted two full cycles. The CHDK/SDM software suggested there was still around 20-25% battery life left at the end of this test - a good indicator that we will have power for the entire duration of our flight.

No launch yet... Camera now undergoing testing

Weather over the weekend would have made a launch impossible... but thats not why we couldn't launch. The script being run by the camera kept activating the flash unit, which would have drained the batteries very quickly and would have been completely pointless.

Yesterday I finally perfected the script which also turns off the LCD backlight. The camera will take 8 pictures, 5 seconds apart, and then follow up with 20 seconds of video. After that the script will return to taking pictures.

As I write this the camera is now running this script to test how long the batteries will last. We would ideally like it to be able to run for 2 hours on a charge - but around 90 minutes will suffice.

End to end test #1

A full end to end test has now been completed - including testing Andy's software which will keep us fully up-to-date on the balloon's exact position. This is the first time that the entire GPS/radio component of the avionics has been given a full shakedown. We have tested individual components - even to the point of seeing the GPS data in Hyperterminal, but this was the very first time that we had seen a live updated position in Google Earth (and Google Maps on Windows Mobile). I'm very happy to report that this first test was successful.

I do have my doubts as to whether we will be ready for launch this weekend. The camera still needs to be programmed to our specification and has to be fully tested. Phil is still concerned about our descent rate with our current 'chute and this also will need testing in conjunction with our 'release candidate' capsule. With so much achieved so far, well beyond our original concept (check the early posts!), we won't be rushing to launch before everything is confirmed to be flight ready.

Radio TX/RX - Flight Ready

Ground Antenna - Flight Ready

GPS Hardware - Flight Ready

Tracking Software - Flight Ready

Windows Mobile - Flight Ready

Camera - To be programmed

Gas (He) - To be purchased 24 hours before launch

Parachute - Testing required

Capsule - Testing required

End to end link now ready

The radio link is now eseentially complete and pretty much ready for flight. Andy is putting the finishing touches to the PCB, which is no more complicated than drilling a hole for the BNC connector. The link has been tested with the GPS unit and is working as expected - although we did need to make some additional configuration changes so that the 3D fix sentences were returned.

Hopefully we will have some video proof posted tomorrow :-)

Transmitter PCB made but launch delayed

Recently its been looking more and more likely that we would have to push our launch date back. We are moving along quite swiftly now, the transmitter's PCB has been given its acid bath and clean and is now ready for soldering. Despite this, we are going to have to delay by at least one week.

We're hoping to have the fully working transmitter by the end of play tomorrow, allowing for a full range of tests to be conducted over the weekend. The race will then be on to finish the camera scripts and to create the outer capsule.

As always, stay tuned!

Call us mad!

So new antenna built so we had a pair...so need to do a range test..knowing it would never work in a million years. I took the receiver and sexy new Copper Antenna home and Dave took the transmitter and the old antenna to his place. Now...we live (as the crow flies) 5.26 miles apart so we were really not expecting ANY kind of signal getting through on the ground in an urban environment so...imagine my surprise to see a flashing yellow light! now it was not a full signal...but still OVER 5 MILES!!

How cute is that! it's like a 1980's mobile

After a little bit of moving the board round to line up the Ariel's BNC connection..she is all boxed up. I do like the key switch (that was my idea!)

The light....it flashes

Here is the video our wonderful flashing light! Green light power, yellow light is GPS data being received (honest)

Receiver complete

Phil should have some photos and videos of the finished article to put on here - but for now you'll just have to take my word for it. Complete with flashing LED on receipt of data, the unit is now fully boxed and ready for use.

The completion of this is mainly down to Andy's work - from creating the PCB schematic, to working out how to use standard office equipment to assist in etching the board, then drilling and soldering the PCB! Even the box itself was drilled by Andy in the boot of his car.

In other news... The faulty camera was returned weeks ago and the ebay shop really let us down. They have returned our money - but after a long delay and this has forced us to go camera hunting again. This time we're going with a Canon IXUS 75. It meets all of our criteria and is much lighter than our previous selection. I won the camera earlier today on ebay (which Phil then paid for) and we now await delivery.

With the camera delay (and the original problems we had with the receiver) it now seems unlikely that we will hit our target date - but a lot of progress has been made recently, so our date shouldn't slip by too much.

It's amazing what you can get up to in the office

Ingredients

1. Copper Board
2. A page from a glossy magazine
3. A heavy duty office laser printer
4. A laminator turned all the way to 11

Once Andy got the PC design sorted we were looking for ways to transfer it onto the copper board...we didn't have any laser transparencies or an iron to hand so time to bring in some old fashioned British ingenuity.

Print onto some paper ripped out of a glossy magazine, load it into the laser printers manual tray and print out the design. Then line it up onto the copper board and shove it (quite hard it must be said) into the office laminator turned up to its 'Hotter than the surface of the sun' setting
Once done soak the paper off and hey presto...A sexy looking PCB

We are going to give it another go now we know it works

Geronimo!!

Well the Parachute has turned up.. It is made out of a lovely 'thin mill' fabric and only weighs in at 11 gms so result. We went for the 24" as we worked out it should give us a decent rate of 5.61 meters/sec and should be a safe landing rate...but looking at it....we need to do some testing but "I think we need a bigger boat"

Flashing lights

Phil noticed that our LED was not flashing on receipt of data, but rather flashing on the absence of data. Whilst not exactly required, I decided to include an inverter circuit so that the LED would operate as expected. It sounds impressive, but it's a very simple circuit requiring no more than a couple of resistors and an NPN transistor.

This has been tested and it works fine. Whether it's a good idea to build it onto the production board, I'm not so sure. It adds complexity to a circuit that although should be simple, we've had enough problems on the stripboard to prove otherwise.

This will be the last you will hear from me until the 21st September as I'm off on a break. Hopefully Phil will be here to keep you upto date on the latest whilst I'm away. See you in a few weeks!

Back to basics...

...back to the breadboard. I've rebuilt the receiver on the breadboard and all appears well. Why the circuit never worked (properly) on stripboard is a mystery, but it confirms that we weren't doing anything very wrong - and that the components are working.

One of the things Andy wanted to work was a flashing LED to show that the device was in fact receiving data. This was lacking from the original design and so never made it to the stripboard version. Now that we are back on the breadboard I've had a chance to try a couple of things, the result of which is... a flashing LED when data is received.

With both circuits fully working, we need to make an effort to get these into their 'production' state. In the meantime we are waiting for our camera to be returned as it died shortly after arriving and before we could even load the new firmware - let alone test it.

Troubleshooting: Day 3

Another frustrating day. Everything that can be tested has been tested, yet we're still no closer to finding out why we get dropped packets when the eval board works perfectly (see yesterdays post).

It's looking more and more likely that the receiver will need to be on a proper PCB. We always knew the transmitter would have to be completely fabbed from scratch as the strip board would be unsuitable. To be honest, once the board is printed, its a lot easier to work with a proper PCB - its just getting to that stage is not completely straightforward.

To make things just that a little bit harder, I'm going to be away from the middle of next week for a fair while. Andy doesn't return until after I leave which means virtually all the electronics work will come to a halt, at least for a few days. Hopefully I'll be able to get enough prepared so that he'll be able to continue with the radio fabbing whilst I'm away!

Troubleshooting: Day 2

The eval kit from Radiometrix arrived today allowing us to work out which board was faulty. It turns out that it is a problem with the receiver which means a more difficult diagnostic process. So far we have tested the Rx module, the IC and the power regulator - all which appear to be fine. I now suspect that the transistor that manages the RS232 to TTL conversion could be faulty - possibly heat damaged in the soldering process. We have learnt that it might be wise to load the Rx module in a SIL carrier - as its a real pain to keep re-soldering.

One bit of good news though - another range test was conducted using our transmitter on the breadboard and the eval receiver board. The transmitter was still inside our building and the helical antenna pointing horizontally rather than vertically. We were also in a highly urbanised area, which we knew would dramatically reduce range. In spite of all this we still managed to transmit an impressive 4500 feet. With so many improvements yet to be implemented (fabbed board, half wave dipole at transmitter end, elevated antenna, etc) we expect to be further impressed in future tests.

Troubleshooting: Day 1

Last night I noticed that the NBEK IC did not have a decoupling capacitor right next to it. Whilst there is one on the Vcc rail, it really is located too far away to be effective at controlling ripple. It was a long shot, but I thought this might actually cure the problem. It didn't.

We've also taken the null modem cable out of the equation as well as the RS232 to TTL converter on the transmitter side.

More kit allowing diagnostics turns up tomorrow.

Missing data

We've hit a snag... What had been working, now seems to have gone a little wrong.

We are currently investigating why we are losing data packets over the radio link. As yet we cannot be sure if this is due to a problem with transmitter or receiver. The only real change has been that the receiver is now a soldered circuit. This is a little unexpected as the fabbed board should make the receiver better, not worse. Another theory is that the transmitter is causing an issue due to it being on a breadboard either because of interference or inductance. Luckily Radiometrix have offered a loan of some evaluation kit which will pin down exactly where the problem is. Once we know which board has the problem we will know how to proceed.

Phil has bet on the receiver being faulty, whereas I think its going to be the transmitter. I hope I'm right as the fix will be simply to fab the board. If Phil happens to be right, that means we need to examine our finished receiver... not something we would want to dismantle!

GPS update #2

The device turning up so soon caught me by surprise and so was completely unprepared for testing. However Phil and myself went up the road and picked up the required components and have now completed the following tests:

1. Plug in and check data is received -PASSED
2. Set to 1200 baud and check data is received - PASSED
3. Disconnect power, reconnect power and ensure data rate still 1200 baud - PASSED

The next test will be to check that we can send (and receive) this over our radio link.

GPS update

As you can see from the photo the GPS device has already arrived! US to UK in a weekend!

GPS ordered & end of week update

A Garmin GPS 15 L has been ordered for testing with our transmitter. We should be able to hook it up to a spare prototype board to program it before hooking it up to the test transmitter circuit. This device is yet another item not easily available in the UK (or the EU for that matter) and has had to be purchased from the United States. Not that I have any problem ordering from the States, but the long lead times as a result of international shipping can be a little frustrating.

Next week we will be testing the camera. Getting deja vu...? I did report that last Friday too, but due to Phil's holiday we have been unable to progress that any further this week. Phil hasn't been completely away from the project though - he has been working on the Zephyrus 1 capsule. Hopefully there will be more to report next week on this.

Andy has been doing further development on the back-end of our tracking solution (as well as adding and tidying the gadgets and layout of the blog). Although the main component is functionally complete, he has set some additional goals beyond what has already been achieved. The new target is a full dashboard - effectively a head-up display for Zephyrus 1. I can't tell you how detailed the HUD will be, but potentially it could allow us on-the-fly predictions of burst point and subsequently landing point. As Andy is away for two weeks, I'm afraid you'll have to sit tight for further information.

Tracking software completed

In a week which has seen a lot of team members off, progress has slowed down somewhat - this slower pace is to be expected for the following 5 weeks due to holidays. This had already been accounted for in the launch date, so no targets have slipped.

Despite this, I'm pleased to report that Andy has completed the tracking software. Anyone that has access to Google Earth and has been given the URL for our tracking page will get live updates of Zephyrus 1's position. The link also works in Google Maps on Windows Mobile devices, although a manual refresh is needed (Google Earth automatically updates).

Launch date

Very much like a NASA shuttle launch, we are unable to give a definate launch date as we are at the mercy of the weather. High winds and/or rain will force us to scrub any launch attempt as would any equipment failure on the day. What we can do, (again like a shuttle launch), is give the earliest date that a launch can take place.

The 'not before' date for Zephyrus 1 is 03 October 2009. Make a note in your diary.

Receiver update

Our new receiver has now been soldered up and tested - and it works! This is largely down to Andy's impressive soldering skills (the IC was pretty much machine quality!) and despite the fact I'd put the voltage regulator the wrong way round - though, in fairness, the Micrel regulator device was counter-intuitive.

Next week we will be begin working on the transmitter, which won't be on stripboard like our receiver, but will be a proper PCB. There are a quite a few reasons for this, but weight and size are a major factor. We will also be taking our first look at the Canon A560 camera and seeing what its capable of.

New board and an update on software

As I suspected, the stripboard could not take the pain of further re-soldering, so a new board had to be acquired. This time the whole board is being laid out first, (as you can see from the photo), and will be soldered in one go. I’m fairly confident that the major components (the IC’s) will have survived – but we won’t know for sure until tomorrow. Lets hope Friday is third time lucky.

Andy has been putting in the hours on the tracking software and the latest news is that it can now error check the data that is received from Zephyrus 1. During the flight it’s likely that the radio range will be close to its limit and, as a result, some information may be corrupted. In that instance, we don’t want to be chasing shadows – we want to know for sure that the data we get back is good. Thanks to Andy’s software, any points plotted on Google Maps will be pre-checked giving us full confidence in where our payload is.

The joys of resoldering...

As I predicted, a mistake had been made. After a resolder and retest it transpires my first fix had caused a short circuit. I've corrected this and checked over the board, which now seems okay. A test will be carried out tomorrow to see if I'll need to get a new bit of stripboard - as further resoldering is probably unwise.

Meanwhile, Phil has been investigating parachutes and Andy is developing tracking software that will, among many other benefits, allow multiple recovery teams access to live location information.

Receiver complete

The receiver is now functionally complete (although the power switch has not been wired) and will hopefully be tested tomorrow. I fully expect to have made a mistake somewhere!

In other news from today, Windows Mobile continues to impress. One of our major concerns is that GPS equipment will fail due to ITAR/COCOM restrictions. Thankfully a free (and powerful) scripting utility for WinMo allows us to restart the GPS whenever we like. I'll cover what we are using, and how we are using it, in a future post. No matter how good the radios are, Windows Mobile is booked on the flight.

Status update

I thought it might be appropriate to show exactly what we have and where we are with the project.

Balloon - FLIGHT READY
Capsule - DESIGN PHASE
Parachute - OUTSTANDING
Phone - FLIGHT READY
Camera - PURCHASED; AWAITING DELIVERY; FIRMWARE TO BE LOADED & TESTED
Transmitter - PROTOTYPE PHASE; FIRST TEST COMPLETE
Receiver - PROTOTYPE TESTED OK; BUILDING PRODUCTION VERSION
Rx Antenna - COMPLETED BUT NOT FULLY TESTED
Tx Antenna - OUTSTANDING

Voltage regulator

The voltage regulator is the first part to get soldered in place. Doing so allows me a chance to brush up on my precision soldering without risking costly components. It's also a good candidate as it can be tested quickly and easily. Everything went to plan and it checked out perfectly providing exactly 5.00 Volts.

A better receiver

Although the testing phase is incomplete, to actually conduct these tests more easily, we need to have a 'finished' receiver. Try holding a breadboard, power pack and laptop still on your lap whilst holding a metre long antenna out of a car window!

The prototypes work, but are fragile and cumbersome. Having the receiver in a single, easy to transport and handle unit with sockets for antenna (BNC) and serial (DB9) will make subsequent test runs much smoother. As you can see here, the work on such a unit is just beginning.

First distance test

The team has completed the first distance test of our equipment and achieved a range of around 500m. Whilst this clearly is a long way short of the required range, we were still reasonably satisfied. I can almost hear your cries of "Why?". There were a number of known issues with our set-up on this first test - these include:

1. Using only a helical antenna on tranmitter, which we already knew to be very poor. To make matters worse, it's not even electrically the correct length due to the way we have connected it to the prototype board. This will not be an issue on the flight as we will either be sending a whip or half-wave dipole (properly connected!). Tests on these types will be run shortly.

2. Our transmitter was well inside a building surrounded by computer equipment - the helical antenna taped to a laptop screen. The building has metal walls, ceilings and floors - unrealistic for our flight, seeing as the transmitter will have clear line of sight and be in clear air.

3. I was holding the dipole incorrectly. This was partly down to the fact I'd forgotten our transmitter wasn't actually in flight. Future tests will ensure it is being held correctly.

4. We're still on prototype boards. Both circuits are far from ideal even on the breadboard - to assist a little with this, I'm hoping to knock up the production version of the receiver over the weekend. The transmitter needs to stay on a prototype board for now - but it might be worth a bit of a shuffle to ensure we aren't causing interference.

With this in mind, we hope to get much further next time.

A better kind of antenna

No testing occured yesterday - instead parts for a better antenna were purchased. We couldn't link up our coathanger version due to lack of the appropriate connecting cable (50 ohm coax). Andy got hold of some last night and Phil bought a 5mm diameter aluminium rod. By cutting this at the appropriate length and sticking it in some 'choc-block' we end up with, what should be, a very good half-wave dipole. We hope to test in the next few hours.

What's next?

As far as we've come, there's still a long way to go. Tomorrow, (or as I write this, later today), we will be conducting the first round of range tests.
These tests, using our prototype receiver and transmitter, will give us our first chance to see what the units are capable of. Part of tomorrows plan involves making a half-wave dipole antenna to go on our receiver, which is essentially just some coathangers cut to the correct length for our centre frequency. Confirming range is an important step to qualifing our hardware for flight - theres little point in putting all this extra weight on board if we lose the signal before the balloon loses GSM. Lets hope for some good results...

Assuming we get the results we require, the next stage will be to purchase a suitable GPS receiver. Some research has already been undertaken in this area, so we are reasonably familiar with what will (and what won't) do the job. Once again, its no easy task. We have many contraints that consumers normally wouldn't think twice about including weight, power use, minimum baud rate and ability to customize NMEA data. Just to make make things that extra bit harder, we also need a device which implements COCOM aka ITAR restrictions properly. Every GPS receiver sold in world has a restriction built-in to prevent a 'home-brew' cruise missile. The exact implementation should shut down the GPS device should it exceed 60,000ft AND be moving at greater than 999 knots. Unfortunately, most GPS developers code their firmware with 'OR' instead of 'AND' - no doubt assuming neither are very likely anyway. The upshot of all this being that as our balloon will be going above 60,000ft, we need to make sure that our device doesn't bug out or we'll never see our payload again!

Still, lets get through tomorrows testing first....

Balloon update

After a successful radio test, what better way to round off the day than to find that our balloon has been dropped off.

Radio Update

Quick update: the radio equipment has been tested and works!

Assembly

This evening was assembly time. Here you can see both prototypes (almost) fully assembled. Andy has purchased the outstanding DIL socket to be installed tomorrow.

Communication: Proof of concept 1

As you will have seen from a previous post, the method for getting telemetry back from the HAB is as follows:

GPS Device -> Conversion to radio data -> Transmission -> (Radio) -> Reception -> Conversion to serial data -> PC -> Google Earth & Internet

Theres a lot going on here and each stage needs careful testing. The very first proofs of concept are:

(1) Plugging in a GPS device and capturing the raw data with hyperterminal
(2) Connecting two computers with a null modem cable and using hyperterminal, (and the settings we expect to be using in our application), send raw data between the machines.

Both of these we would expect to work; there really is no reason whatsoever that it wouldn't. However, in the interest of being thorough the tests needed to be done. You'll be unsurprised to hear that we had no problems whatsoever.

The next task is to assemble the transmitter and receiver modules. Once assembly is complete, we will can retest (2) from above, this time wirelessly. We'll start with the Tx and Rx next to each other and should that work, we'll begin distance testing.

Power & Weight

Zephyrus 1's balloon doesn't have much lifting power. To achieve a satisfactory altitude, the maximum payload weight is just 580 grams. Working to such contraints isn't easy and every gram counts. At the same time, our avionics are going to be demanding on power. Running just a GPS chip alone draws 100mA. That might not sound like a lot, but it'll drain a 9v PP3 battery in about 2 hours. To make matters worse our expected drain is closer to 300mA which will kill it in just minutes.

After finding that the PP3 battery performs so badly, especially under load, it has been decided that AAA size batteries will power our GPS receiver and radio gear. We'll also be using Lithium batteries rather than alkalines as they provide better longevity in high drain applications and as an added bonus they are also significantly lighter. An average AAA battery weighs in at 12 grams - whereas the Lithium counterpart is just 7.6 grams (Energizer L92). Since we need 4 to power our telemetry package thats a saving of close to 18 grams.

Our camera will also be powered by Lithium batteries (probably Energizer L91) as they weigh just 14 grams compared with 23 for alkalines. Since the A560 takes two AA's we will be saving another 18 grams here.

Simply changing from alkaline to Lithium batteries will shave a massive 36 grams off of our payload and come the final weigh-in that could be vital.

5v regulation

We need perfect 5v regulation to our circuit. I've put together the prototype and it works perfectly. As you can see from the photo, you can't do much better than that.

Prototyping

I'm now testing our components whilst waiting for the remaining parts to arrive. As you can see, these LEDs work fine ;-)

Components...

An order has now been placed for a ton of components from RS. This mixed bag of resistors, transistors and capacitors will be the supporting cast in our transmitter and receiver PCBs.

I've come up with a design for a voltage regulator module which will break off +5V and +3.3V rails - whether it will work is a different matter...

Telemetry Update

Somewhat unexpectedly, it would appear that we are making headway on the ability to receive telemetry for at least part, if not all, of Zephyrus 1's journey.

Andy has located transmitter and receiver circuit diagrams which use a chip to encode and decode serial data. This will allow us to connect a GPS device and send its data wirelessly to a computer. We are now pricing components and checking weight constraints.

The next step is to build prototype devices - which will involve butchering one of Phil's GPS devices.

Balloon ordered

The balloon that will lift Zephyrus 1 is now on its way from the USA. The 300 gram balloon has a burst altitude of nearly 70,000 feet and can carry a payload of upto 660 grams when filled with Hydrogen. Since our balloon will be filled with Helium (as we'd quite like to live to launch a second balloon) we're capping our payload at around 500 grams.

Telemetry

Currently the team are investigating the possibility of getting telemetry from our HAB, which is much more difficult than it might sound. Mainly this is down to transmission output power limitations which are enforced in the UK. The small areas of the radio spectrum that are licence exempt require output power to be 10mW or less (on the European mainland that limitation is 100mW).
It is not beyond our capability to be able to send and receive a signal at that distance even with this, somewhat over-the-top, restriction - however it is unlikely that any telemetry hardware will make it onto this first flight. Instead development will continue with the radio hardware as it is something we would like on subsequent flights.

More avionics testing...

An important test of our avionics equipment is the freezer test. The device must run continously for at least 120 minutes with 25 of those being in the freezer.

I have carried out the simulation personally and am pleased to report that the unit passed. The unit obviously lost signal during its time in the freezer, but immediately began returning positional data when removed. I allowed the device to run for some 90 minutes afterward and no problems were detected.

Somewhat impressively the device was not charged after the previous test that Andy ran, so battery life is thankfully not a concern either.

These results convince me that our choice of tracking technology is correct and am confident that it will allow us to locate and retrieve our payload.

Photo/Video System

The team were divided over whether we should be taking just photos or taking video as well. Taking two cameras was obviously an option but adds a lot in weight (and cost). Thankfully it turns out that there is a single camera solution in the Canon PowerShot A560.

For a compact it's a very decent piece of hardware, but the real treat is in an aftermarket firmware which will allow us to run a script on it. This script will potentially be set-up to take a photo every minute, with say 10-15 seconds of video in-between.

Andy directed the eBay 'sniping' operation to win us the Canon A560 a little earlier today with just 3 seconds remaining on the clock. Sorry Bidder 7...

Avionics: Tracking

Once our HAB has been released, we will have no control over where it goes nor can we visually track it. So, if we ever want to see our payload again there needs to be a way of finding out where it has landed. Thats where the tracking component of our avionics come in.

Several different methods have been employed by other teams which vary in complexity, starting from a device which sends texts of its GPS position all the way up to RF modems that provide a constant stream of GPS data back to a base station.

Our solution is a Windows Mobile device running GPS tracking software. The software on the phone gets its location from the inbuilt GPSOne Qualcomm chipset which then sends this data over GPRS to a server. The server translates the data and displays the real time position on Google Maps/Earth.

We don't expect a signal above 3000 feet but we are really more interested in its position once it lands.

Andy tested the device on Thursday by taking the unit on a trip into the countryside. His test proved that even if it loses a GSM signal for a prolonged period - once it regains it the device resumes returning positional data.

Foam drying out...

The foam shell is continuing to dry... An 'off-cut' of the material seems very promising. It would appear to be light, strong and very flexible.

Avionics bay

The 'Avionics bay', if you can call it that, is obviously very important. We need to protect our equipment from the harsh conditions of 'near space' and survive a heavy landing whilst allowing us to take photos and being light enough for our balloon to lift.

Phil is working on a prototype(pictured), made out of expanding foam, which hopefully will meet all the criteria.

Zephyrus. The High Altitude Balloon project.

It seems that everyone is jumping on the bandwagon to get a snap of the third rock from space these days. During our regularly scheduled coffee and a whinge a number of us at work decided to join the party and to finally prove that the Earth isn't flat.

To get 'out there' we need a balloon. A big balloon. We also need a payload of gadgets to track it and to snap us some photos. Most importantly, we need to give the project a name. And we have one.

Zephyrus, meaning "west wind" is the name for our project to go into the stratosphere and beyond...