Flight Wisp1c_6

Flight Wisp1c_6

Changes

• Using different solar cells.  
• These are more square and seem a little less fragile.

• Changed transmissions to 20m only at 10 minute intervals.
• 30m on flight Wisp1c_5 was nearly useless.
• Balloons stretched to 0.4psi prior to launch.

Initial prediction

Launch

 Setting up the tracker on the roof to assure everything comes up and transmits.

Nice and sunny up here.

Just about to let it go.  Nice still air.

And we're off.....

Day 1

The flight was disappointingly short.  It was on track moving southeast.  It got to Binghamton at about 23,000 feet and simply disappeared.  There was no further telemetry.  It suffered some kind of catastrophic failure.  My guess is that a wire dislodged from a solar cell, causing the tracker to lose power.

Flight wisp1c_5

Flight Wisp1c_5

Preparation

My wife assisted, and we tried braiding two strings with one strand of 36ga magnet wire for the antenna and counterpoise this time.  It came out at the same weight (1.8g) as a single strand with the wire, and a ton of nail polish.

This time, Following Dave/VE3KCL's advice, I ran a little tape up onto the two balloons as I joined them.  There is less stretch near the edges than there is in the center, so hopefully this won't be a problem.  I also ran a strand of backup tether between the two balloons, just in case the tape lets go.

Here's how the two-balloon configuration looked, just prior to launch.

Testing the tracker, just prior to launch.

Specifications

Tracker: wisp1c_5
Bands: Alternating 20m / 30m WSPR, gatewayed to APRS: KD2EAT-15
Power: Solar only
Weight: 14.5g
Free lift: 5g

Launch

There was a touch more breeze than the launch for wisp1c_4, but not bad.  This puff relaxed, and the balloon went more upward.   I ended up letting it go over the ledge to my right.  The tracker briefly went below roof level, and then climbed away.   Roof launches make life SO much easier!

Day 1

The initial climb to float altitude worked beautifully.  We achieved float within a few kilometers of predicted.

Mark Conner / N9XTN shared the Ensemble model for the flight.  Its colorful tendrils look pretty good!

End of Day 1

Day 1 ended on a sour note.  After passing over the Boston area, it appears that propagation really went to hell.  We hadn't heard much on 30m through the eastern half of Massachusetts.  It went completely silent, and then we lost 20m.  As a result, we had little telemetry in the final hours of daylight.

The final full packets were received here, off the coast of main.  Things looked solid with the altitude at just over 30,000 feet and the supercap and solar doing well.   We were in grid square FN51wt. Then it went silent.

We did receive a few spurious telemetry packets.  This last one was received at 6:22pm EDT:

2016-07-06 22:22 | QO6LO    | 10.140148 | FN61 | +43 | K9AN       | 30

We were in grid square FN61lo, 93km further East on a heading of 104 degrees.

Presuming the final altitude didn't change by 1000 meters or more, the final telemetry was:

CallSign	KD2EAT
GridSquare	FN61LO
Flight ID	16
Altitude	9222
GPS LOCK	Y
Sats	6
Solar V	1.00
Batt V	4.60
OAT	5.0

That's quite consistent with the data we were receiving throughout the late afternoon.

We'll hold tight and hope it wakes up in the morning to better band conditions!

Day 2

It's alive!

As the afternoon wore on, the band conditions improved a little, and we received more packets.  30m was still dead, but 20m was improving.  In mid-afternoon, we approached this storm, which has some pretty high clouds.  Crossing our fingers!  That green color indicates clouds at nearly 40,000 feet, well above our cruising altitude.

Propagation improved on 20m near the end of the day.  The balloon looked strong and stable at the end.

At the current pace, I imagine the balloon will wake up at The Azores!  It's definitely moving slower than the last balloon.

Statistics on GPS performance are below.  I would venture to say that >something< is wrong with this GPS.  I need to do more ground testing to validate that it's not a software problem.

Day 3

We ended Day 2 at grid GM86ep and awoke on Day3 at HM26ou.  We covered a distance of 755 kilometers overnight.  We ended the day at HM58si, for a distance traveled by day of 583 kilometers. So, over about 24 hours we covered 1338 kilometers (55.75 kph, or 34.6 mph).

Here's the initial start, with the prediction from Day 3.

Here we are at the end of the day, with a revised prediction.

Thankfully, it looks like we edged past that front of weather without difficulty.

Though the bands were bad again, we got enough telemetry to see that the envelopes are continuing to stretch.  We were at 9333 meters for most of the day, with a few packets at 9444.  I expect we'll have quite a few at 9444 tomorrow.

The weather ahead still looks clear.  Barring any unforeseen disasters, we should be back on the air tomorrow with the sun.  Sunrise in the Azores is at 6:29 GMT (2:29 EDT).  It generally takes about 90 minutes for the sun to rise high enough for the packets to flow.  I'd expect the first packets around 4:00am, EDT.

Mark Conner / N9XTN ran a prediction this afternoon.  Let's hope we don't follow the green!

Day 4

Day 4 started out well, with pretty good reception on the bands, and wind velocities increasing.

The day ended over the Bay of Biscay.  We didn't follow the prediction very well, but at least we're moving faster!

The weather looks good going into the night cycle.  I expect it'll be near Paris in the morning.  Sunrise is at 6:30 Paris time, 12:30am EDT.  It takes about 90 minutes for the sun to rise high enough to come online, so I'd expect packets around 2:00am.   (Note: It ended up being 1:53am.)

Bogus Altitudes

I noticed a bogus altitude on APRS, and found it in the data coming into my "aprs2wspr" script today. The "thousands of meters" field is stored in the DBM value in the first of the two telemetry packets.

Jul 09 10:39:06 [INFO] 2016-07-09 14:36 KD2EAT 14.097059 IN33 +50 DF2JP 20m

Note the "+50" DBM value.  They're normally "+30".   This had happened a few times in flight.  I wasn't sure if this was an artifact of the tracker sending bad data, or whether the receiving station copied the data badly.   Unfortunately, in the instances that I researched, only ONE station had received the packet, so I couldn't tell.  Today, however, with band conditions improved,  I was able to confirm that the tracker is sending the incorrect data.

2016-07-09 14:36	KD2EAT	14.097056	-22	0	IN33	100	PI4THT	JO32kf	1767	50
2016-07-09 14:36	KD2EAT	14.097073	-26	0	IN33	100	PD0DH	JO21fv	1603	48
2016-07-09 14:36	KD2EAT	14.097059	-18	0	IN33	100	DF2JP	JO31hh	1710	53
2016-07-09 14:24	KD2EAT	14.097013	-26	1	IN33	1	DF1RN	JO30br	1653	54
2016-07-09 14:24	KD2EAT	14.097057	-17	0	IN33	1	F5OIH	JN06ci	1090	68
2016-07-09 14:24	KD2EAT	14.097058	-27	0	IN33	1	F5LHF	JN25em	1397	75

Note that the previous packets showed "1 watt" (30 dbm) of output power, but this one showed "100 watts" (50 dbm) at all receiving stations.

So, the tracker is definitely sending bogus data.  The next question is whether it's the GPS providing the bogus data, or something with my code.  This will take a bit more research.

Day 5

We woke up on schedule at 1:53am.  We were received well on both bands and moved at about 40mph throughout the day.

We covered great ground, and ended the day with one toe into the Czech Republic.  Speeds were good all day, and GPS and radio performance were awesome.  Still, there was one very obvious watchdog reset in the data.  

Day 6

Day 6 started out right on time.  The first beacon arrived about 12:04am EDT.  Today was exceptional for two reasons.  First, we passed through our first Geofenced area - Romania.  As can be seen on the map below, we didn't beacon at all while inside the borders.  It worked perfectly!  Woo hoo!  We got VERY lucky, as it was growing dark as we left Romania.  The tracker literally uttered two packets and shut down for the day.  Given the proximity to sundown, I was shocked it even beaconed.

The second exceptional thing about the day was the performance of the GPS and reception.  The GPS never failed to get a lock on time, as shown by the reception data.  Also, We had 100% reception of packets on 20m while we were beaconing.  30m wasn't bad either, at about 61% reception.

The weather ahead looks scary, but the tracker is forecasted to take a major dip south and do a loop over the Black Sea.  Hopefully, we'll survive whatever that is.

Day 7

We woke up as expected in the Black Sea, and executed a Loop-de-loop.   The tracker had major problems today with late GPS locks, GPS resets and at least one watchdog reset.  In Wisp2, I'm going to wire in a RESET line for the GPS and zap it if we have this kind of locking trouble to see if that improves matters.  Even the soft resets didn't seem to last for long.

The weather as we come toward wakeup time looks pretty grim.  Also, the balloon was headed back to Romania for a while, which means it will be geofenced as it hits this weather.  It's going to be another nail-biter.

Day 8

We came through the weather just fine, and managed to clear Romania in plenty of time to beacon this afternoon.  I ran a new prediction which is in yellow.

I also ran a hysplit with predictions for the next few days.

The GPS seemed to work VERY well today, and as usual, 30m was a pretty worthless band to transmit on.

Steady on!

Day 9

We awoke on schedule on Day 9 and had an unremarkable day moving into Russia.  The altitudes crept up a little near the end to 9666 meters.  The GPS had a few glitches today, but it appears that the software resets were sufficient to bring it into line.   The 30m band continues to disappoint.

Day 10

We are doing a walking tour of Russia, it seems.  For much of the day, the tracker was traveling under 20 kph.  The GPS was pretty stable, but we heard nothing on 30m all day.

Day 11

We awoke with the sun and beaconed once, and then weren't heard for a bit.  Altitude looked great, at 9555 meters.   Moving slowly.  Finally hit Kazakhstan today!

Day 12

Speed has picked up.  We averaged about 60 mph through the day, though the day, though propagation was lousy, so we didn't get a lot of data.  We seemed to go straight down the middle of the Caspian sea.

Day 13

Our rugged little tracker is getting FAR away from any stations to receive it. We got a total of ONE packet last night. It was the second telemetry packet, and not the first packet. Due to a vaguery of the way the scripts are written, that means it didn't update the map. I just drew in where the single data point was located, along with a conjecture of the route in purple. The altitude was down to 9222 meters, but it's still serviceable. Let's hope for better reception tonight!

Day 14

No packets on day 14.  It's possible that it's just not close enough to anyone to be heard.  The bands have been bad for the last few days.  Below is a map showing the one and only site that heard the telemetry packet the other day.

Day 15

No packets heard at 4+ hours into daylight where the tracker would likely be.   I'll keep an eye out for a few more days.  Prepping for another launch this coming weekend.

Daily Statistics

Day	Band	Received Packets	Lost Packets	Percent Received	GPS Locks Missed	Probable GPS Resets	Probable Watchdog Resets
1	20	89	15	85.6	7	1	1
1	30	52	52	50.0
2	20	50	58	46.3	16	4	1
2	30	4	102	3.8
3	20	49	69	41.5	15	5	1
3	30	0	118	0
4	20	71	23	75.5	25	13	1
4	30	11	79	12.2
5	20	124	4	96.9	3	0	1
5	30	77	45	63.1
6	20	84	0	100	0	0	0
6	30	49	31	61.2
7	20	76	18	80.9	36	26	1
7	30	41	49	45.6
8	20	63	7	90.0	2	0	0
8	30	5	59	7.8
9	20	115	15	88.5	5	2	0
9	30	12	114	9.5
10	20	80	120	66.7	4	1	0
10	30	0	120	0
11	20	61	63	49.2	9	1	0
11	30	0	124	0
12	20	23	69	25.0	9	6	0
12	30	0	92	0
13	20	1	1	50.0	0	0	0
13	30	0	0	0

Wisp1 output power

Wisp1 output power

So, Alan/W7QO encouraged me to measure the output power of my Wisp1 board.  He was concerned that the Low Pass Filter might be reducing my output power. I hadn't made measurements since I was prototyping with an Adafruit Si5351 board. so it seemed like a good idea.


The LPF configuration is as I planned previously.

I ran a measurement of the output and found this:

It looks like 780 millivolts, peak to peak.  I used the calculations, as in the previous blog post, and came up with an output power of 1.52 milliwatts.  UGH!

I removed the LPF, pi filter (2 caps and inductor) and just put a 0 ohm resistor across the inductor pads.  The output power was much better.

It showed 1.90v peak 2 peak.  That yields 9.02 milliwatts without the LPF.  MUCH nicer.

Given the low power we're talking about with these boards, I'm going to  go ahead and skip the LPF at output.  At some point, I should go through the filter formulas again to see why I'm attenuating badly at 14 MHZ.

Antenna construction

Antenna Construction

Just a quick note on how I'm building the antenna for the Wisp trackers.

I previously blogged an analysis of the weight and length of the antenna wires I want to use.  I opted for the 36ga wire, which is very light, delicate, and tends to bunch up if uncoiled.  Traditional wisdom has been to attach the counterpoise wire with little bits of tape every few feet to the tether string going up to the balloon.  I understand that some people put a tiny bit of tape on the very end of the antenna side, just to help pull it downward.

Alan Adamson / W7QO tried an experiment that worked quite well, and I've adopted it.  He suggested using nail polish as a glue to hold the string and wire together.   It's "strong enough", and does not add much weight at all.  Here are the materials I used for both my counterpoise and antenna.

I simply cut a length each of the (100% rayon) thread and the wire.  I tied them together at one end. Then, I bound them with the nail polish using my fingers.  I dabbed a little polish between thumb and index finger, and ran the string and wire between, twirling them a little to get them to stick together and wrap around each other a little.  I would go up and down about 2 feet of wire, wind it onto the spool, and repeat.  

Here's what an end looks like.

Flight: wisp1c_4

Flight wisp1c_4

My new 0.8mm boards came in from Hackvana.  I did my testing, and two flights on my OSHpark RevB boards.  RevC changes were all cosmetic - cleaning up traces, etc.  I was confident enough that I just went ahead and ordered the slightly modified boards in bulk for flights.

First step: Make a batch of boards

I ordered them in panels of 3.

Finished product, out of the oven.

Nice and light!

Prepping for flight

Testing went smoothly.  I had to clean up some solder bridges on the processors, and one bridge on a solar chip.  Once that was fixed, all 3 boards passed all diagnostic checks with flying colors.  I numbered the boards 4-6, and prepped number 4 for flight.

Without antennas and tape, it comes in at 10.6 grams.

I built an antenna and counterpoise, as i had in the past with thread and 36ga wire.  I attached them to small lengths of guitar wire for strain relief.

I implemented an "elegant solution" (ok, kludge!) to keep the counterpoise away from the GPS chip antenna.  The two lines going to the tracker near the chip are just thread.  The thread/wire counterpoise line is secured above and away a bit.

Kapton tape FTW.  I put a bunch of strain relief on the wire connections to keep them from being stressed and flexed near the attachment points,

The twin balloon assembly looks like this.  I used Tyvek tape to attach the upper to the lower balloon.

These two balloon pictures aren't from this flight, but give an idea of what the balloons look like when assembled.

 Launch

 It was a gorgeous day with clear skies and 5mph winds.  The tracker floated straight up from release and hovered nearby as it climbed.  I nearly forgot to take a picture.  It's off in the distance here.  If you zoom in, you can make out the tracker 17 feet below the balloons, and the antenna dangles below that.  There is a small square of tape at the bottom of the antenna.  You can just barely see it when zoomed in.

Flight: Day 1

 The first day of flight followed the predictions nicely.  The zigs and zags are from missed telemetry packets.  The envelope reached float at around 29,500 feet.  Near the end of the day, the balloons stretched a little, and opened up to around 30,000 feet.

Flight: Day 2

 The tracker woke up on schedule.  It was a nail-biter as it was flying right into the storm below.  On top of that, the bands were awful.  Propagation sucked all day, so very few packets came in until about 4:00pm.

The day ended with the tracker starting to make the curve southward.  By this point, the balloon was fairly consistently over 30,000 feet.  It was traveling at over 100mph.  The weather looked clear.  It looked optimistic for Day 3.

Flight: Day 3

We awoke over France, as scheduled.  That's a new Personal Best for me!  :-)  It was still right on the predicted track.  The balloons stretched a bit more.  The balloon peaked at 34,000 feet for much of the day.  Speeds seemed to hold around 30-40 mph.

As the day wound down, it flew into a pretty large storm.  The dramatic tension will be high as I wait until tomorrow morning to see if we're still there!

Flight: Day 4

Balloon down!   I awoke this morning to find beacons coming from the balloon at nearly ground level.  

The last pair of packets BOTH received were on 30m.

Jul 03 04:16:13 [INFO] 2016-07-03 08:14 KD2EAT 10.140153 JO83 +0 SM0EPX/RX2 30m

Jul 03 04:16:13 [INFO] 14/16/18/KD2EAT JO83 0 0

Jul 03 04:19:14 [INFO] 2016-07-03 08:16 QU6VKY 10.140151 JO83 +23 SM0EPX/RX2 30m

Jul 03 04:19:14 [INFO] 16/QU6VKY 23

Jul 03 04:19:14 [INFO] 16 KD2EAT JO83VK 6 0.6 5 5 0 0 0

Jul 03 04:22:15 [INFO] KD2EAT-14>APRS,TCPIP*,qAS,KD2EAT-1:!/3LhZR{;wO!!Y/A=000000 0 QU6VKY 23 30m|"zWw'W?U!'!!!!|

This telemetry data decodes as follows:

Grid Square: JO83vk

Altitude: 0m  (between 0-111 meters)

Satellites: 6

Solar volts: 0.6v

Battery volts: 4.80

Temperature: 5c (really means 5c or ABOVE.  This is max temp we report.)

We subsequently received one more telemetry packet, without the first packet.  It was identical.

Looking at the elevation in that area, it appears it's 138m.  So, we're very close to ground level in that vicinity.  

This is the satellite view of the landing area.

The data is a little curious.  We started receiving packets at 07:14 UTC.  Given the daylight overlay I saw on spacenear.us, I would have assumed the tracker would have had daylight a good bit earlier.

Given that it came down, the big question is "why?".  We had significant weather in Germany the night before, but it didn't go down "hard", or it wouldn't have traveled as far as it did.  My guess is either a catastrophic balloon failure on one of the envelopes, or perhaps the upper envelope simply came off.

Local hams have been contacted via a Balloon forum, and they may attempt a recovery.  In the meantime, here is the final track we followed, beside the original prediction made on launch day. That's pretty darn good, for 4 days out!