ProjectHAB | Experiments in High Altitude Ballooning

JOTA 2014 – Two Successful HAB Flights

Posted on October 22, 2014 by Steve Smith

So the plan was for Chris Stubbs to launch on Saturday 18th October and me to launch on Sunday 19th October at Kingston Ridge Scouts Campsite in Essex. Chris was already on site by the time arrived. I was kindly ferried from my home location by Dave Hillwood since I don’t drive and carrying the kit by public transport wasn’t a realistic option. Chris had waited until the day to decide between launching a foil or a latex and he chose a latex due to the conditions. Although the launch was scheduled for 12:30pm, due to last minute schedule changes, we had to launch a little earlier. We eventually launched around 11:00am.

Chris filling his 100g Pawan Latex Balloon

Assembling The Cubs for Launch

When the time came, one of the Scout leaders summoned the cubs with a few short blasts on the whistle. They assembled around Chris whilst he explained to them what was about to happen. I had filled a test balloon to check the wind direction.

Test balloon

Perhaps I needed more gas!

After I first let a better filled test balloon go to check the wind speed/direction, the cubs were led in a count:

5 – 4 – 3 – 2- 1 – Launch!

JOTA1 Launch

Launch Conditions

Chris seemed unconcerned with the prevailing conditions, and justifiably so since it brightened up later on. JOTA1 made good progress. I manned Peter Sipple’s laptop which was connected to a projector and Mike Lynn’s Yaesu FT-817D and Chris used his RTL Dongle and Laptop.

Tracking Station

Due to a hiccup with the mic input on the laptop, we used a USB soundcard dongle to do the job. It worked well and JOTA1’s telemetry was decoded perfectly. Meanwhile, the cubs were once more assembled to release their own balloons carrying tags for their return.

Cubs Releasing Balloons

JOTA1 did very well and flew all the way to the coast of The Netherlands with many Cubs, Scouts and Helpers popping into the balloon tent to check the current position on the tracking page.

JOTA1 Flightpath

JOTA1 Flight Profile

JOTA1 Flight – Object Movie by G8DHE

As you can see from the object movie still, there was a short glitch when JOTA1 restarted and took a while to regain it’s GPS fix. Luckily, it came back and stayed pretty constant for the rest of the flight. We were all really hoping it would make landfall but it didn’t quite make it. Still, a very successful flight and a great taster for everyone at the camp. By the end of the day, conditions were really nice and I hoped that it would be the same on the Sunday for me to launch my foil.

For the rest of that evening, after some dinner ordered from a local takeaway, Chris and I assisted the scouts in building minDUINO kits that I’d got together with the help of RS Components. You will be able to read all about that on my other blog ProjectAVR soon.

I arose early at home the next day to be greeted by cloud and squalls of rain. I wasn’t hopeful for a launch. However, again, Dave Hillwell kindly came and got me and by the time we arrived on site, things were looking up. The clouds were parting and blue sky was visible. Again, Chris was already on site and we set about setting up the receiving station, this time in another tent, and devouring rather nice Bacon Rolls prepared by the Scouts for breakfast.

The idea with JOTA2 was to get it to ‘Float’. This is when the balloon ascends until it reaches the point of buoyancy where the balloon doesn’t burst or leak. This enables it to ‘Float’ for a long distance as demonstrated by Leo Bodnar’s brilliant B-64, as I write, currently on it’s 6th pass around the world past it’s launch point in Silverstone. Once the JOTA2 payload was attached to the foil balloon, kindly supplied by Steve of Random Engineering, I opened up the valve with a straw, the recommended method, and started to fill it. Once the balloon was just about able to lift the payload, Chris suggested we add a small weight. I attached 1.2g of solder on the bottom of the payload. We added some more Helium into the balloon but after testing, it seemed too spritely. Perhaps I’d added a few too extra ‘Stirks’ of gas. I extracted some of the gas with a straw after which Chris and I decided that the ascent rate was just right.

Stirk

Noun, Ballooning

The rough measurement of gas equal to a ‘puff’ required to be added or extracted to/from an arbitrary volume of gas in a balloon envelope totaling exactly the correct amount for a given flight.

Abbreviation: STK. – Origin 2011-; named after A. Stirk

Luckily, we were filling the balloon in a tent so it was an easy job to check and re-check the ascent rate by letting the balloon rise to the ceiling. This was a critical to enable the balloon to get into float condition.

JOTA2 Ready for Filling – Image courtesy of Pete Sipple

JOTA2 filled and ready to go – Image courtesy of Pete Sipple

Because JOTA2 was going to ascend very slowly, it was essential that it miss any obstacles on the site, namely the trees. During the preparations of the event, Mike had told me about a climbing tower that was on site and on the Saturday, after a brief reccy, I decided that it was definitely the platform for the launch. Shortly after 10:00am, I donned a safety harness, not the most dignified of things to put on!

Donning a safety harness

However undignified it was to put on, I soon realised that it was essential to keep me safe. The tower is 11m tall and I wouldn’t fancy that fall. I climbed the tower with the aid of Clive without mishap, albeit inside the tower up a ladder rather than on the outside, and the view was great. Kingston Ridge is about 90m Above Sea Level so we were around 100m ASL for the launch, excellent!

Up on the tower

I fed a line down for the balloon and Chris attached it. I brought it up slowly while Clive made sure the balloon didn’t foul on the footholds on the side of the tower.

100m ASL

By this time the Scouts had assembled down below and once I had detached the line from JOTA2, I waited for a lull in the light breeze. When I was happy, I called for a countdown. Everyone shouted…

5-4-3-2-1-GO!

JOTA2 Launch!

JOTA2 Launch Video – courtesy of Pete Sipple

JOTA2 climbed very slowly and thankfully missed all the trees. I carefully climbed down the tower after grabbing a quick snap on my iPhone.

JOTA2 in the Distance

Almost simultaneously, the Scouts launched their tagged balloons, some of which you can see in the image above, following JOTA2 into the sky.

Chris and I were very pleased with how JOTA2 ascended. It was 1m/sec and lower for most of the time. This was looking good for a Float. As JOTA2 continued, we had many Scouts and helpers coming into the tent for updates on how far JOTA2 had got and how high it was. Most were impressed with it’s progress.

Chris indicates JOTA2’s position

To begin with, there was an issue decoding. Chris reported only one ‘$’ character at the beginning of telemetry sentences. He was also missing some sentences completely. I couldn’t understand this. Although I had reduced the ‘$’ characters from four to two, they should have still showed up. The ‘$’ characters indicate to the decoding software that a sentence is about to start. Chris soon found that the radios Squelch was set high, this was suppressing the beginning of the telemetry signal. Once it was opened up, all was well and we got solid strings.

Early JOTA2 telemetry string “$$JOTA2,10,09:08:51,51.559334,00.435543,88.2,0.52,1,1.41,6*6897”

JOTA2 continued to climb slowly into the afternoon and Chris and I wondered if it would get into a float. By this time, the camp was beginning to wind down and we only had a short time left to run the generator. JOTA2 was just beginning to level out though so we thought it was likely that we’d have our floating payload. Both Chris and I helped dismantling the tent and were very pleased to be presented with a gift for our contribution to the event in a ceremony culminating in a traditional Scouts Oggy.

Mike brought me home and I continued to track JOTA2 from there via Tracking Page. By this time I was very tired but continued to watch as JOTA2 successfully ascended into a nice float and crossed the Northern part of The Netherlands and on into the Baltic. At 18:13UTC, Stations SP1TMN-6 & SM7DSE received the last full telemetry string from JOTA2 having just .75v left in it’s AAA Lithium battery. JOTA2 had almost reached Latvia, more than 1000kM from launch and I’ve no doubt it did fly on and reach landfall.

JOTA2 Flightpath

JOTA2 Altitude Profile

JOTA2 Battery Profile

All in all, two very successful flights over the weekend which, although being fun for Chris and I, successfully demonstrated two types of High Altitude Ballooning to Scouts and adults alike. This was the primary aim.

I’d like to take this opportunity to thank Chris Stubbs for all his assistance over the weekend, and without his guidance, JOTA2 may not have gone into Float. Clive for keeping me safe on the climbing tower. Pete Sipple for his help, loan of Laptop and radio for tracking, photograph taking and images. Dave for getting me to the site. Mike for inviting me in the first place and use of his radio and all of the Scouts, Leaders and Staff at Kingston Ridge Campsite for their enthusiasm and welcome (and Bacon rolls on Sunday!). As you can tell, I really enjoyed the event and I look forward to next year!

JOTA1 & JOTA2 Final Fixes

Posted in Events | Tagged Balloon, Flight, Float, Foil, HAB, JOTA, Latex, Launch, Telemetry, Tracking | Leave a comment

JOTA 2014 Launch

Posted on October 14, 2014 by Steve Smith

Time does wizz by! It’s almost the day of my next launch. I was invited to the JOTA event by Mike Lynn G1KOT in order to launch a balloon and demonstrate HAB tracking to the Scouts & Cubs at Kingston Ridge Campsite this year. Additionally, I’ll be supervising the building of 50 minDUINO v1.6 kits that I’ve put together with the aid of RS Components who kindly sponsored the components. I have supplied the PCBs, boxes and documentation. The aim is to introduce the Scouts & Cubs to micro-controllers and circuit building.

Meanwhile, my friend Chris Stubbs and I are going to release a balloon on each of the days of the JOTA weekend. Chris on Saturday 18th Oct and myself on 19th Oct. The details are as follows:

Callsign: JOTA1
Balloon Type: Foil or 100g Pawan Latex depending on conditions.
Date-Time: 18/10/2014 – 12:30pm
Frequency: 434.300MHz
Mode: RTTY 50n7 with 450Hz shift.
Approx. Lat/Lon: 51.559144, 0.435010 – Kingston Ridge Campsite: http://www.kingstonridgecampsite.co.uk/index2.html

Callsign: JOTA2
Balloon: 36in Foil Pico.
Date-Time: 19/10/2014 – 12:30pm
Frequency: 434.450MHz
Mode: RTTY 50n7 with 450Hz shift.
Approx. Lat/Lon: 51.559144, 0.435010 – Kingston Ridge Campsite: http://www.kingstonridgecampsite.co.uk/index2.html

Anyone wishing to track either or both of these balloons can find instructions here although I’d use the new tracking page instead of the old SpaceNear version.

This will be my third launch (subject to conditions being OK) and I’m very much looking forward to it. I’m going to try and get the balloon into ‘Float’ which is to say, rather than it ascending until it bursts and coming down again, I’m going to send it up at a very slow ascent rate in the hope that it reaches it’s neutral buoyancy point and stays there. This will mean a longer journey for the balloon and a longer time for tracking.

Mike is going to supervise the launch of small latex party balloons too for the Scouts & Cubs. These will have labels on them reading something like ‘If found please return to…’ This will be staggered with the larger balloon launches as not to cause an airborne hazard. Currently on 14-10-2014 the prediction for wind direction looks good. I will check each day up until launch on the CUSF Prediction Website:

JOTA2 Prediction for 19th Oct 2014

So, just some final preparation to go. A last check of the payload and get the bits together.

Wish me luck!

RS Components New Products

Posted in Launches, Payloads | Tagged Balloon, JOTA, Launch, payload, Pico, Tracking | Leave a comment

UKHAS Conference 2014

Posted on July 6, 2014 by Steve Smith

UKHAS Conference 2014 Logo

On August 16th 2014, the UKHAS (UK High Altitude Society) conference will be held at The University of Greenwich’s Old Royal Naval College. The full address is:

Old Royal Naval College,
Park Row,
Greenwich,
London
SE10 9LS

Last year’s conference was a great experience. The talks, which were delivered in the morning, were entertaining and full of useful information. This year will be no exception. I’m particularly looking forward to Dave Akerman & Anthony Stirk’s talk about their new Pi-In-The-Sky board, an expansion board for Raspberry Pi owners to turn their mini computer into a HAB payload with ease. Other highlights include a talk on WebSDR by Philip Crump M0DNY and UKHASNET by James Coxon amongst others.

Philip Crump will also be organising UK Amateur Radio Foundation exams to be taken during the afternoon which will be held along with several workshops to be confirmed.

Anthony Stirk delivering a talk at UKHAS – Conference 2013

All details on the conference and ticket prices are available on the UKHAS website at: http://wiki.ukhas.org.uk/general:ukhasconference2014 It’s a fantastic venue to mix with the significant faces of the UK HAB circle and to pick up valuable knowledge on subjects ranging from HAB through Rocketry and on to Satellites.

If you attend, please find me (I’m hard to miss!) and say Hi!

Steve G0TDJ

Posted in Events | Tagged 2014, Ballooning, Conference, Flight, Programming, Soldering, Tracking, UKHAS | Leave a comment

AVR/Arduino Timing Issue with fresh ATMEGA328p

Posted on July 2, 2014 by Steve Smith

I’d like to draw attention to an issue I’ve experienced building the latest VAYU-NTX v1.04 board. I had previously built one that suffered from the same issue but I ended up very frustrated and this probably contributed to my having a break from Electronics/HAB for a while. Eventually, I stripped the old non-working board for parts (they’re expensive!) so at the time, I never found out what the issue was. I assumed that it was one of the components and I kept them separate from ‘stock’.

Fast forward to last Sunday, June 29th 2014. I was eager to build a payload to update my cobbled together firmware. I had purchased a cheap toaster oven from Currys which I thought would be good for reflow purposes and I wanted to try it out. I had done a few test runs with sacrificial boards to ascertain the time required for the solder paste I had obtained on eBay. It worked well, especially since the solder paste’s profile is almost straight up and down with little discernible soak period.

I carefully laid the components out on the new board after carefully applying the solder paste via the stencil I had made when the boards were fabricated. I placed the populated board carefully in the oven and hand timed the heating, using a further sacrificial board with some blobs of solder paste to confirm the time. I saw the solder melt at around 2:35 and left the board under heat for a further 20secs. I then switched off the oven, very carefully opened the door (after making sure there was adequate ventilation!) and let the board cool down. Much to my delight, the components were soldered perfectly. I finished the board by adding the NTX2 module from the previous board. I was pretty sure this wasn’t the culprit of the last board’s issue since I’d received an RF signal from it.

VAYU-NTX v1.04 Newly Built

Two things to notice; the awfully soldered power header on the right. It works. I’ll replace it at some point. And the two test connections for +VCC and GND on the left that I removed, more on that later.

The time had come to load the firmware so I started up the Arduino IDE and tried to bootload the board. I found that the custom entries in boards.txt I had previously had now gone. When I was building the v1.03 board, I had help from Chris Stubbs who assisted me by defining a custom entry in the boards.txt file in the Arduino software. This enabled the application to download a bootloader into my newly built VAYU-NTXs. I must have overwritten the old Arduino software with a new version, loosing the custom entries. Well, I thought, all I really need to do is set the fuses (Fresh ATMEGA328s are set to run on their internal r/c oscillator). I opened Atmel Studio 6 and set the fuses to: Low 0xFF High 0xDA Extended 0x05. I went back to the Arduino IDE, compiled and then uploaded the firmware; This is where the issue begins.

When powered up, I found the familiar tone at around 434.445MHz. This indicated that the NTX2 was sending a signal. With the current firmware, the signal stays here as a constant tone and then jumps up in frequency once a satellite lock is obtained and starts sending the RTTY Telemetry signal. I waited for 25mins before assuming it wouldn’t GPS lock. This was identical to the issue that the previous board had suffered. At least, I thought, it’s probably not the hardware. The only two components I used from the previous board were the NTXb module and the GPS antenna, all the others were new.

I begun troubleshooting by programming the status LEDs to blink. This proved the ATMEGA238 was alive and working fine. The NTX2b I’d already decided was OK since the RF signal was nice and strong. I tested the GPS module by connecting the TXD output from the test point into a logic analyser and that showed serial GPS data as expected. Was it the layout? The last working board was VAYU-NTX v1.03 which didn’t have the +VCC and GND test points near the GPS antenna. Could these be affecting the GPS reception? I removed them on both sides along with the through hole plating (sorry Mitch!) but that didn’t fix it either. As you can probably guess, I was pretty confused by that point.

After a break, I remembered a phrase on Anthony Stirk’s website “If you’re ever unsure if your radio is working you should step back to this extremely simple code to check the basic operation.” So I heeded that advice and loaded the simple RTTY code (from Pt. II). I was amazed to find it produced a signal but it was remarkably slow. Half speed in fact. DlFldigi (The software used to receive telemetry) couldn’t resolve it at all. Why was this? I had set the fuses correctly. In fact, at that point I double checked them to be sure. Puzzling. Since I couldn’t get DlFldigi to resolve the signal with it’s settings, I dived into the firmware and fixed it from inside. I halved the transmission delay in the code. But, no, this still didn’t fix it. I searched for other timing dependent lines in the code. OF COURSE! The GPS serial speed of 9600 baud. I doubled this to 19200 baud and finally, it worked!

So, after mulling this over, I realised that, for whatever reason, the ATMEGA328 was running effectively at double the speed it should be. It was being treated like an Arduino UNO. Even though I had set the fuses for 3-8MHz external crystal operation. I remembered back to how I initialised the working boards and each of them did have the bootloader installed before overwriting it with the firmware via ISCP. It made no sense to me to do this but after chatting with some of my friends over IRC and via e-mail, I went ahead. Firstly I had to re-create the custom boards.txt entry (Thanks again to Chris Stubbs for his help with this). Chris gave me a copy of his version which I customised further to work with VAYU-NTX. This is the text I ended up with:

##############################################################

vayu.name=VAYU-NTX (3.3V, 8 MHz) w/ ATmega328
vayu.upload.tool=avrdude
vayu.upload.protocol=arduino
vayu.upload.maximum_size=30720
vayu.upload.speed=57600

vayu.bootloader.tool=avrdude
vayu.bootloader.low_fuses=0xFF
vayu.bootloader.high_fuses=0xDA
vayu.bootloader.extended_fuses=0×05
vayu.bootloader.file=atmega/ATmegaBOOT_168_atmega328_pro_8MHz.hex
vayu.bootloader.unlock_bits=0x3F
vayu.bootloader.lock_bits=0x0F

vayu.build.mcu=atmega328p
vayu.build.f_cpu=8000000L
vayu.build.board=AVR_UNO
vayu.build.core=arduino
vayu.build.variant=eightanaloginputs

##############################################################

I then proceeded to upload the bootloader after erasing the chip fully in AVR Studio, just to be sure I started with a clean slate. I then compiled and uploaded the old unedited firmware – EUREKA! After 4mins or so, the board locked and started sending telemetry, just as the older boards had done, and with no false settings needed in the code.

OK What’s going on. How is it that you can set the AVR Fuses to run at a particular frequency and still get an anomalous output? Well, I believe it’s all down to the “vayu.build.f_cpu=8000000L” line in the boards.txt entry. I think that this defines the speed for the Arduino software and all the speeds are referenced from this. Of course, that means that if you set serial to be say at 9600 baud, the Arduino IDE software will effectively set 19200 if you’ve set the board incorrectly (an Arduino UNO running at 16MHz for instance).

OK So I believe the mystery is solved. To program the VAYU-NTX boards successfully, you have to have a custom entry in the boards.txt to make sure the Arduino IDE software sets the correct timing. I have since documented this on the VAYU-NTX page so that anyone building one doesn’t suffer the same pitfall.

Let me know if you have experienced a similar problem or indeed, attempted to build a VAYU-NTX – e-mail to steve(at)projecthab(dot)co(dot)uk

I’d also like to take this opportunity to thank all the guys who helped me work through this problem and led me to the final conclusion. Charlie Robson, David Prentice, Matthew Beckett, Chris Stubbs, Andrew Garrett, Anthony Stirk & Dave Akerman. All of whom contributed somehow.

Posted in Payloads, VAYU-NTX | Tagged board, Firmware, Programming, Telemetry, VAYU-NTX | Leave a comment

VAYU-NTX v1.05

Posted on June 2, 2014 by Steve Smith

It’s been a while since I posted here. I took a (LONG) break from things electronic and HAB. However, I have gradually gotten back into things. I have designed an minimal Arduino™ board, minDUINO, design files available on ProjectAVR. This is an educational board designed for my friends daughter to build and learn about micro controllers.

Meanwhile, here I have identified an issue with VAYU-NTX v1.04. I tried to add an option for two different styles of SMD crystal. The normal HC49 size and the much smaller 5032 size. Unfortunately, I misunderstood how the connections were laid out resulting in a completely unusable set of pads for 5032 type crystals. Luckily, this doesn’t affect the HC49 crystals.

VAYU-NTX-v1.04 and v1.05 Comparison

I have also made a few other changes. I’ve added a potentiometer on the relevant MCU line to facilitate Anthony Stirk M0UPU‘s Domino code. This also has an associated jumper to use the payload in RTTY mode. I also broke out the TXD and RXD connections on the MCU for troubleshooting purposes, added labels for the battery input and tried to give the breakout header, J2 a little more room.

I’m currently working on a re-flow oven conversion for soldering SMD boards. Once this is finished, I will order some VAYU-NTX v1.05 boards and try the oven out. I will then publish all the design files.

Posted in Electronics, Payloads, VAYU-NTX | Tagged board, Circuit, Domino, HAB, payload, va, VAYU-NTX | Leave a comment

Launch Announcement – [POSTPONED]

Posted on January 15, 2014 by Steve Smith

[UPDATE 21/01/2014] Due to the wind direction predictions, I have postponed this launch. I will still be giving the talk at the North Kent Radio Society, just sans launch. Watch for launch announcements in the coming weeks.

All being well, I will be launching a VAYU-NTX v1.03 prototype payload from Bexleyheath next Tuesday (21st Jan). This is as part of a talk I’m doing for The North Kent Radio Society, my local radio club. I thought it best to track an actual payload rather than just showing previous flights in images. The VAYU-NTX payload is programmed for 50bd RTTY on USB at 434.500MHz (+/- a few Hz). The standard 7n2 format is used with a 450Hz shift.

The current predicted path is good, towards the S/SE

Launch Prediction for 21st Jan @20:00

Of course, this is apt to change in the coming days. I will monitor it closely.

I am going to try and get the balloon to go into a ‘float’ this time. This is when the balloon ascends slowly and reaches an altitude where the internal and external pressure equalises, meaning the balloon finds the point of buoyancy. If it does, it will make for a long flight. Although the payload is being powered from a single AAA lithium battery which will only allow for a day or so transmitting. I’d appreciate any help tracking past the initial demo flight.

Posted in Launches, Payloads, Tracking, VAYU-NTX | Tagged Balloon, Flight, Foil, HAB, Launch, payload, Telemetry, Tracking, VAYU-NTX | Leave a comment

HNY 2014

Posted on December 31, 2013 by Steve Smith

It’s been a fantastic year for me. I’ve ‘discovered’ a great new facet to my hobby of Amateur Radio in High Altitude Ballooning. I’ve had lots of fun and made many new friends. One of the many highlights was my visit to Youlbury in Oxford for my very first launch. Although it didn’t really go as planned, it was a lot of fun. I’m hoping to have a bit more success at 2014’s JOTA event. Perhaps the weather will be kinder? (Fingers crossed).

Another great event was the UKHAS Conference held in October. It was great to put many faces to names and to fill in some gaps in my HAB knowledge. Having ‘met’ more HAB enthusiasts online, I look forward to the next conference in 2014.

As for ProjectHAB, All the components have arrived for VAYU-NTX v1.04 and I’ll be constructing it soon whilst documenting the process. There is another project in the wings waiting to be developed, once VAYU-NTX v1.04 is finished. I’m also preparing for a talk that I will be delivering at my local Amateur Radio Club The North Kent Radio Society where I am chairman.

It only remains for me to wish all my friends, new and old, and anyone who reads this

HAPPY NEW YEAR
2014

Posted in Electronics, General | Tagged Altitude, Ballooning, Flight, HAB, High, JOTA, Programming, Scout, VAYU, VAYU-NTX | Leave a comment

Neu VAYU

Posted on December 18, 2013 by Steve Smith

I’m very happy to report that the new VAYU-NTX v1.04 PCBs have arrived along with a solder stencil. The boards and stencil are of the normal high quality from Hackvana (Thanks again Mitch).

VAYU-NTX v1.04 PCBs

Although I enjoy the process of hand soldering SMDs, I wanted to streamline the process a little. To that end, I ordered a Solder Stencil with these boards. I made several modifications to the v1.04 updated board, including the editing of three holes to facilitate use with the Arachnid Labs PCB Fixture Block.

VAYU-NTX v1.04 Solder Stencil

I have left the protective covering on the stencil for now. Once the components arrive for the next build, I’ll document the whole process.

Other modifications to the board are as follows:

Additional surface on the crystal pads to accommodate either a standard SMD crystal package or the smaller 5052 SMD package.
Removal of three redundant resistors and routing directly to the NTX2b module.
The addition of TXD and RXD test points for ‘scoping the GPS module output
The addition of +VCC and GND test points to check the regulator output.

VAYU-NTX v1.03 – v1.04 PCB Comparison

I also tidied up a few of the silk screen positions with additions and deletions as required. You can find the full set of design files on the VAYU-NTX page on this site. Either for self fabrication or a commercial fabrication house. Judging on their past performance, I wouldn’t hesitate to recommend Hackvana as your first port of call for the latter.

[UPDATE 19.12.2013]
I’m chuffed to bits, the daughter boards for VAYU-NTX arrived today. I’m really looking forward to getting a complete VAYU-NTX v1.04 board made up along with a Temp/Humid. board.

VAYU-NTX Daughter Boards VAYU-NTX-MOD1 & VAYU-NTS-MOD2

VAYU-NTX-MOD1 has spaces for specific Temperature and Humidity sensors, with a connection table on the back. VAYU-NTX-MOD2 is a general prototyping board for adding multiple sensors or circuits with all the GPIO lines marked up on the first line of connectors.

Posted in VAYU-NTX | Tagged board, Circuit, Component, Design, Layout, payload, PCB, Soldering, Stencil, VAYU-NTX | Leave a comment

Hellschreiber

Posted on December 17, 2013 by Steve Smith

One of the real pleasures of having Amateur Radio as a hobby is the amazing breadth it covers. There are so many facets, to it. One facet is the transmission modes available to experiment with. My first love in radio was Morse Code which is sent using a mode called CW (Continuous wave). This is very simply sent by keying a transmitter on and off and forming characters by using long and short pulses (dits and dahs). A development from Morse was RTTY (Radio Teletype) which uses two separate tones keyed on and off to represent characters. Following on from Morse and RTTY, Hellschreiber was developed in the 1920’s. This uses a similar technique of sending two tones but rather than forming representations of characters which get translated when received, it sends graphical representations which are printed pixel by pixel on to paper or a screen. It looks very much like a Fax.

Whilst generally browsing the web for useful items, I stumbled upon Mark VandeWettering’s website and an article on getting an Arduino to send Hellschreiber. The code is amazingly small and I wondered if it would work in VAYU-NTX. Although Mark was using an ATTiny MCU, there were no specifics for that chip in the code so I changed the output pin number, compiled and uploaded it.

VAYU-NTX v1.04 FELD HELL Test

I was very pleased to find it worked. An interesting thing about the code is the character set glyph table held at the beginning. I wanted to hyphenate VAYU-NTX in the transmission but there was no ‘-‘ character available. This was successfully added by inserting the line:

{‘-‘, {0x0000, 0x0000, 0x0060, 0x0060, 0x0060, 0x0000, 0x0000}},

at the end of the existing glyph table. Each glyph is made up of a 7×14 pixel grid. It was a simple matter to draw a grid and fill in the cells to produce a hyphen and then break that down into hexadecimal numbers to add to the code. Adding further characters, if required, shouldn’t be very difficult.

What will be difficult, at least for me, is to get the transmission under the control of interrupts. Mark’s code relies on a delay loop which I successfully customised to produce a straight line of text. I would like to send the Hellschreiber out along with the standard telemetry string in RTTY and realistically, that will only be possible using the precise timing of interrupts. I have already experimented with Domino transmissions from VAYU-NTX and it is quite clear to me that timing is everything.

Posted in Payloads, VAYU-NTX | Tagged Code, Custom, CW, Domino, Experimental, Hellschreiber, Morse, payload, Programming, Telemetry | Leave a comment

Comments Active

Posted on December 7, 2013 by Steve Smith

Just a quick update post:

I’ve re-enabled comments, this time with a CAPTCHA device. Comments may be left at will now and I will see how it goes.

Mitch from Hackvana has kindly notified me that the VAYU-NTX v1.04 PCBs have been dispatched. I’ve very much looking forward to seeing them and building a new one up.

I’m currently researching other MCUs to design a tracker with. I’m particularly interested in using a Z80 based chip Perhaps the Z8 Encore! The difficulty is that there’s not a lot of information out ‘there’ online. It seems that the only way to get to grips with Zilog chips is to slog through the rather dry datasheets. Still, I’ve managed to pick up a development board on eBay and I’ll post any developments here.

Posted in General, VAYU-NTX | Tagged Ballooning, board, Circuit, HAB, PCB, Tracking, VAYU-NTX | Leave a comment

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