Tuesday, February 9, 2021

BLT-67 - The inaugural flight of the SS_PicoTrackerFW

BLT-67 was launched on the morning of Tuesday (02 Feb 2021) from NW Houston.  It is the maiden flight of my new picoballoon tracker, the SS_PicoTrackerFW (FW = Feather Weight), coming in around 1.4g board weight, and total payload weight of 7.28g.  The solar cells comprise most of that weight, but I'm working on that for the next launch.  

This new board has been in work for months with many factors driving the final design.  My objectives for this board were: 1) use up the uBlox EVA-7M GPS chips I had collecting dust, 2) be as light as possible, 3) transmit both WSPR (HF) and APRS (2m), and 4) be completely solar powered with no battery or super capacitor required.  I achieved 3 out of 4 (no APRS), but I hope to work that into my next board.  It wasn't that I couldn't get APRS to work, but it requires using the Si5351B chip, and the Arduino library I was using wasn't working properly to set the registers for this chip so...it will happen eventually...more work required.  

The board weighted in ~1.4g without the programming header.  In addition to the uBlox EVA-7M, it uses an Atmel ATMEGA328P-MU microcontroller, Si5351A clock generator, NCP551 LDO regulator, and 3-pole elliptical low-pass filter.  I had planned on using the ST SPV1040 MPPT solar charger chip, but learned I still have things to learn about designing low-power solar-only voltage regulator circuits...  While I think I can get it to work, but I ran out of time and patience, and reverted to the old faithful LDO regulator.  

Ironically, the software that drives this board greatly influenced its design, at least from what pins on the uController were used.  As I couldn't carry forward the code I'd been using for the Pecan Pico boards, I was faced with rolling my own or finding something already in use.  I stumbled upon Michael Babineau's (VE3WMB) OrionWSPR software and while not exactly what I needed, I could certainly modify it to do what I wanted.  OrionWSPR is an EXCELLENT piece of software!  It is well designed, coded, documented...  Mega Kudos to Michael for his work on this code.  I had already decided/committed to use Bill Brown's (WB8ELK) telemetry format so I proceeded to modify the OrionWSPR code to implement the required telemetry format (flight ID and time slot transmission format).  

This telemetry format relies on use of a "Flight ID" and "Time Slot" for proper decoding.   I didn't have a Flight ID assigned to me, but fortunately some had come available, so I requested and received Flight ID (channel) 12 to use for my launches.  This would allow me to have 5 trackers active at any one time, and I had already planned to share these within the South Texas Balloon Launch Team.  If we really need more ID's...well, that would be a good thing to have happen.

So fast forward to today.  BLT-67 has been aloft for one week and appears to be doing OK.  Honestly, this was a test flight and I didn't expect it to be aloft for this long.  I used the "Clear Chinese" party balloons and I wasn't sure we had really sealed them (but apparently Walter, K5WH, did a good job with the iron).  The solar panel frame was a new design as was how I connected, secured, and strain-relieved the antennas.  I really didn't expect it to survive more than a couple days.  And then it drug along the ground after I released it at launch....argggghhhh. 

But here we are.  One week later and it just woke up over Vietnam.  Altitude is a little lower than I would like but still OK.  And the transmitter/antenna are working VERY well with very respectable SNR numbers at the receiver sites, and a record (for me) DX reception by VK2COW of 16685 km (JM21RC to QF44OX) on just 10mW of power.  Wow!!!

I am really quite pleased with this tracker's performance and hope the balloon will carry it back to Texas.  Further is good too, but hopefully one circumnavigation is in its future.

73 de John

Oh, you can track it with these links. 



UPDATE: (09 Feb 2021) The flight of BLT-67 has come to an end after just a week.  The pictures below shows its entire ground track and last reported location (~150 miles NE of Hong Kong).  I would consider this a very successful test flight of the new tracker.  Looking forward to seeing how its next flight goes.

Tuesday, December 1, 2020

BLT-62 Update on Day 28 - End-of-Flight Report

(Updated on 12/9/2020) BLT-62 last reported it position on Saturday, Nov 28th @2138Z from grid square DL56 over western Mexico (about 600 miles WSW of its launch site and ~860 miles from Houston). As it's now been almost 2 weeks without a report, I'm ready to call it end-of-flight for BLT-62. It's been 3 days now but I'm not ready to give  up on it yet as we have seen this tracker not 'wake up' and report for a day, and others have had their payloads go silent for a week or more.  So I'm going to give it another week or so before declaring it down and end of the flight.  

Some flight statistics...
Flight duration: 28 days, 6 hours
Circumnavigations: 1.98 (might have actually made 2 complete trips, if only we had a report on Sunday...)
Flight ground travel: 91,529 km (56,874 miles) - per LU7AA tracking website
Maximum Altitude: between 11,100-12,000m (resolution limit of the ZachTek), although I'm saying around 37,000 feet
WSPR receptions: 3284 WSPR reports received (2963 on 20m and 321 on 30m) from 262 unique stations 
APRS reports: 670 position reports posted by WB8ELK
Grids reported: 103 grids (it flew over more grid but these are the ones reported via WSPR)
Strongest WSPR reception: +24dB on 20m by KR4JV (EM66) while balloon was 1211km (753 miles) away in EL86.
Longest WSPR reception: 7941km (4934 miles) by OE9GHV (JN47) on 20m while balloon was in EL96. (SNR of -24dB)

To the Edge of Space!

Tuesday, November 24, 2020

BLT-62 Update on Day 24

Quick update on day 24 of the balloon's travels.  Only 5 days ago, it was cruising over the middle of the USA completing its first circumnavigation milestone.  It's been fortunate to catch fast wind streams allowing it to make good time on its 2nd trip around the world.  Altitude is holding around 37,000 feet, although it tends to drop a little when in the 140+ mph streams, but to me this just demonstrates they are holding pressure (no leaks) as it is able to rise back to float altitude when in slower winds. 

Here are some screen captures of the balloons current location and winds.  Enjoy!  And thanks to everyone who's been following along on the balloon's travels.

73 de John

Tuesday, November 17, 2020

BLT-62 circumnavigates the Earth in 18 days!

Earlier today, the balloon I launched ~18 days ago made its way back to the USA and crossed the longitudinal line from where it was released.  Whoop!  A few days ago, it was zooming for the California coast but decided to take a detour and spend some time over Hawaii...who can blame it for doing that.  After a few days rest, it caught stream back over the US and here we are.

When you launch a balloon, you hope you've done everything right preparing it for flight.  Tracker configured properly, antenna constructed and securely attached to the tracker, balloons filled to the exact lift you want, tracker securely attached to the balloon.  So many things can go wrong and, as history has shown, they usually do.  But this time, it looks like it all came together and BLT-62 is having a very successful and long (and hopefully longer) flight.  

Here's a screen capture of the whole flight to date.  Looking at the winds aloft, it should head southeast and get into a fairly fast jet stream tonight for hopefully its 2nd trip across the Atlantic.  

Tuesday, November 10, 2020

BLT-62 Balloon Launch & Flight

I've been getting lots of questions about my recent balloon launch so I thought I'd resurrect my Blogspot site and post some information about it.  When I created this post, it was located near 41.5° N / 165° E, about 1600 miles NE of Japan, floating at ~37,000 feet above the Pacific Ocean moving about 150 mph to the ENE.  It woke up Wednesday afternoon (11/11/2020) about 1000 miles off the California coast! Below is a screen capture of its locations and the winds aloft at altitude.

Some details about the balloon and tracker that periodically transits its position. The tracker is a WSPR-TX Pico transmitter from ZachTek (https://www.zachtek.com/product-page/wspr-tx-pico-transmitter). It's solar powered only and transmits a 20mW WSPR encoded message on the 20m & 30m ham bands every 10 minutes. A standard WSPR message consists of a callsign, 4-digit maidenhead grid location, and transmitter power level.  The WSPR-TX Pico uses the power level field to send its rough altitude (see link above for the table to translate power level to altitude).  The antenna is made from 39ga magnet wire attached (lightly glued) to 4 lb. test braided fishing line.  The fishing line connects the transmitter to the balloons and provides strain relief for the delicate hair-thin magnet wire. The tracker (with programming header removed) and antenna weighed in at 11.70g. You may think ~12g is light but my goal is to get a tracker down to ~7 grams (a little more than the weight of a nickel).  The antenna on my previous launch used 36ga magnet wire and I though that was thin.  The 39ga wire is considerably smaller and half the weight of 36ga wire, which allowed reduction of the antenna weight down to 1.17g.  Below are pictures of the tracker (without solar cells obviously) and a comparison of 36ga wire (right) and 39ga wire (left) - marks on the bottom are 0.025"

The balloons used are 36" mylar “party” balloons made by Qualatex (https://us.qualatex.com/en-us/products/12683/?product_type=Qualatex%20Foil%20Balloons). There are two balloons connected in tandem and were filled with Hydrogen but only to the point where they have 5g of free lift with the payload attached.  The fill ports were then sealed with Kapton tape.  You might ask why hydrogen vs helium. Two reasons; cost/availability and performance.  Helium (good near pure helium, not the 80-90% mixed gas you get at the party store) has become very difficult to obtain and very expensive!  Hydrogen is plentiful, relatively inexpensive, and provides more lift per volume of gas.  However, hydrogen is a highly flammable and potentially explosive gas.  If you're reading this and thinking about trying to launch your own balloon, I'd recommend you use helium.  

The transmission protocol used by the tracker is called WSPR (weak signal propagation reporter).  It was developed by Dr. Joe Taylor, K1JT, (former Princeton University professor and Nobel Prize winner). You can read more about WSPR at his website https://physics.princeton.edu/pulsar/k1jt/.  WSPR was created to help monitor HF radio propagation around the world.  WSPR is a forward error corrected 4FSK signal occupying about 6 Hz of bandwidth and transmits 162 symbols in 110.6 seconds. It can be received with a signal-to-noise ratio as low as -34 db, well below what you can audibly hear from a radio speaker. Many amateur radio operators have setup permanent transmitters that are received by a network of receivers (http://wsprnet.org/drupal/). To get my balloon’s position listed on the https://aprs.fi and https://tracker.habhub.org, I asked a fellow balloonatic (WB8ELK) to run a python script that periodically pulls database entries for my callsign (AB5SS) from wsprnet.org and posts them to the APRS-IS server under the callsign AB5SS-14. 

The balloon was launched around 10:00am on October 31st from a friends ranch near Batesville, TX.  After a brief scare, it started to rise (and we started to breath again) and began its journey across Texas, the Gulf of Mexico, Florida, then out across the Atlantic.  It managed to dodge some storms and was predicted to head to the North Atlantic but caught a southerly flow and went over Africa, Saudi Arabia and headed for Nepal.  Then it gave us another scare on Nov 9th as it was going over the Himalayas and we didn't receive any reports that day.  But then it showed up over China on the 10th and now it's over the Pacific expected to travel just south of the Aleutian Islands and hopefully head towards the west coast of the US.  It's been exciting to watch for it every day to see if it's still alive and how far it's gone during the night.  I'm hoping for a circumnavigation (fingers crossed) but am thrilled with its performance so far.  

73 de John

Wednesday, June 1, 2016

Seabrook Intermediate School Balloon Launch

My daughter attends the Science Magnet at Seabrook Intermediate School.  Last week, I had the opportunity to speak with a large group of her teachers and classmates about one of my obsessively favorite hobbies, which is building, launching, and chasing high altitude amateur balloons.  After the talk, we all went to the football field to launch a floater balloon, but had to abort due to a tracker failure (good GPS lock, but it just would not transmit...)  So, we sent a bleacher full of kids back to class and I went home to troubleshoot the problem.  

The Pecan Pico 5 tracker is usually flown with a LiPo and solar cells, but this tracker's onboard power supply had failed and I had kludged together a make-do supply out of a CR123A battery, a 5V up converter & a 3.3V regulator.  Not efficient, but good enough for a few days of service.  The "failure" was all my doing, as I forgot to disable the battery protection code that keeps it from discharging below a certain level.  Once I made that change...boom, the GPS locked and it transmitted in less than a minute.  Now, just have to wait for the weather to cooperate.

After a weeks delay, we finally were able to launch the mylar floater balloon and tracker payload.  We had a much smaller gathering of teachers & students, but everyone was excited...they all love this stuff.  My daughter released the balloon and it rose slowly in the sky, heading North until it was out of site.  We continued to monitor it's flight on http://tinyurl.com/sisballoon and on http://tracker.habhub.org.  A little over 5 hours into the flight, it descended and landed somewhere east of Orange, TX, just short of the Louisiana border.  Maybe it didn't have a Cajun Visa?  Or more likely the thunderstorms in East Texas were too much for the balloon resulting in a slow leak and a much shorter flight that we'd hoped for. 

As background, this all started when I invited two of my daughter's teachers, Chris Lowe () and Joe Miller, to come out to the Wharton Intergalactic Spaceport for the South Texas Balloon Launch Team's BLT-42 flight last August.  They took it all in and even participated in the chase, which was awesome!  Afterward the flight, we thought it would be a great experience for the students to participate in a smaller scale balloon launch at their school. Chris even wrote about the experience on his site. https://sites.google.com/site/seabrooklowe/home/expeditions/high-altitude-balloon-launch

The next flight will be BLT-44.5, another floater, to be launched as part of the Great Plains Super Launch 2016 (http://superlaunch.org) on Saturday, June 18th @ 9:00am.  Right now, only myself and Bill Brown, WB8ELK, will be launching floaters.  Everyone else is launching high altitude latex balloons.  Now, I just need to finish building the payload and write my presentation :)

73 de John

South Texas Balloon Launch Team

Sunday, May 29, 2016

I'm planning to attend the Great Plains Super Launch 2016 this year in Granbury, Texas (http://superlaunch.org) for the first time and I'm really looking forward to it!  Previous GPSL events have appear to be well attended and had great presentations!  On Saturday morning, many are planning on launching balloon missions, most are latex balloons, but I'm planning on launching a floater balloon.  It will be a 36" Qualatex helium filled balloon carrying a Pecan Pico 5 tracker configured with LiPo battery & solar cells for what is hopefully a long duration flight.  More to come on that in future posts, but it will look something like the one we launched at the Greater Houston Hamfest this year (picture below).

73 for now, de John