Live tracking
01-Apr-2020 update
29-Mar-2020 update
Day13 update: 19-Feb-2020
Day5 update: 12-Feb-2020
Day3 update: 10-Feb-2020
Day2 update: 09-Feb-2020
Day1 LAUNCH: 08-Feb-2020
Launch photos

This is the first test flight of the new U4B tracker. For details see below.

U4B-1 was launched by Dave VE3KCL at approx 2030Z on 08-Feb-2020. The transmitter callsign is VE3OCL and telemetry channel 03 (in the old system way of looking at things). Transmissions are on 30m only. U4B-1 completed a circumnavigation on 14-Feb-2020 and then headed so far North that it was not heard from again for over 5 weeks. In the map below, the colour coding is as follows:

  • LIGHT BLUE: First circumnavigation lap
  • DARK BLUE: NOAA Wind projection for the likely path from 19-Feb-2020 to 23-Feb-2020
  • RED: New path from when U4B-1 transmitted starting 28-Mar-2020

NOTE: The total distance traveled is meaningless because U4B-1 spent so long out of contact that we don't know where it went. 

Live tracking

01-Apr-2020 update

U4B-1 sent some reports today and moved very slowly. The wind forecast indicates it should be operating in the next few days and will turn south.

29-Mar-2020 update

After no sign of U4B-1 for more than 5 weeks, U4B-1 suddenly appeared again on Saturday 28-Mar-2020 with a single WSPR report from somewhere around Banks Island, Canada (latitude 73-degrees North). U4B-1 must have been so far North for these 5 weeks, that there was insufficient sunshine for the solar panels to power the tracker. The single report on 28-Mar-2020 has poor accuracy since it was just the standard WSPR packet with 4-character grid square locator.

U4B-1 operated for a little over 2 hours on Sunday 29-Mar-2020, generating several WSPR reports and telemetry reports. Four complete packet pairs (standard WSPR report, and telemetry packet) were received; the 4 map points for 29-Mar-2020 are therefore with full precision. 

On the map (above), the light blue line is the first lap; this also had sporadic reporting because the path went far North for many days (see below); the thin dark blue line is the NOAA wind projection for the few days following the previous last report on 19-Feb-2020; the RED path is the new path generated 28-Mar-2020 and 29-Mar-2020. 

The wind projection (below) suggests we may hear from U4B-1 again on 01-Apr-2020. 

Day 14 update: 19-Feb-2020

U4B-1 showed up on cue, it is travelling back North again... it will probably be sleeping in the dark for some days now...

Day 13 update: 19-Feb-2020

Nice news today, U4B-1 turned up in Canada, somewhat North of its starting location (Toronto); the altitude is lower than expected which may indicate a balloon inflation or stretching issue. U4B-1 has almost completed one circumnavigation! From here, the wind projection unfortunately indicates a North path again, which will mean more quiet days in the dark. It may show up briefly tomorrow.

Note that some of the points in the path in the above map were added manually (around Japan), there were no reception reports from this area; the points were added because otherwise the Google map draws a line straight back from Germany, West to Canada... which is NOT what happened. Note that the total distance quoted on the map is also inaccurate, and for the same reason: it calculates the "short path" from Germany back west to Canada, not the long path via Japan and the Pacific.

Day 5 update: 12-Feb-2020

As expected, there were no more updates since 10-Feb-2020. The wind projection shows U4B-1 travelling far north for many days, it may show up again over Japan in 3-4 days, or it may not. 

Day 3 update: 10-Feb-2020

U4B-1 crossed the Atlantic very fast indeed in strong jetstream winds, making it across Germany too still around 1.5 days from launch. Note that U4B-1 now heads North (see forecast below) and there will be insufficient winter sunlight up there, to power the transmitter. Therefore we do not expect to hear from U4B-1 again for a few days, then it should show up over Japan. 

Day 2 update: 09-Feb-2020

U4B-1 did indeed wake up at the anticipated time and in the anticipated place. Note that due to the short winter days and hence low solar angle, at this latitude there are only about 2 operational hours per day. 

Day 1 LAUNCH: 08-Feb-2020

Due to the late afternoon launch (the only possible weather window) there were no transmissions before sunset, the sun was already too low in the sky to operate the tracker using the limited energy hitting the solar panels. 

Launch photos

"She went up at about 2030 gmt but the sun was a bit too low for a start 18 degrees ... am looking for a possible show at 1500z tomorrow off the coast of Newfoundland... if all goes well. Sky was clear so I suspect it could get up to float without a cloud screwing things up. It was a rush job ..usually I test the balloons for a few days to see how the leak or not... this was stretch fill with helium and launch....."


This is the first test flight of the new U4B tracker. U4B-1 was assembled by Dave VE3KCL, and launched by Dave VE3KCL on 08-Feb-2020. This YouTube video explains the features of the U4B tracker. 

U4B-1 is flying without any batteries or ultra-capacitor; only the raw solar cells are operating the tracker. 


Tracker: 4.4g
Misc.: 0.1g
Antenna: 0.9g
TOTAL: 5.4g

There are two balloons used, with 8 grams of free lift per balloon; the balance for each balloon is 10.7g. 

This is the actual complete BASIC program which is operating on U4B-1. Note that not all of the lines are useful or sensible, lines with a PRINT statement for example, output debug info to the serial port and of course no terminal is monitoring that during flight. This program was created to allow a lot of ground testing of the U4B. 

2 LET C = 31
4 FOR A = 1 TO 5
7 IF BT < 3100
8 SLEEP 10 1
9 GOTO 4
11 GOTO 18
18 LET R = I2CR 144 0
20 LET T = I2CR 146 0
40 LET FR = 26999850
45 OUT 9 0
50 GPS 200 "$PSIMNAV,W,3*3A"
51 GOTO 53
52 OUT 9 CL
53 SLEEP 10 3
56 CW 0 10140420 12 0 "_VE3OCL"
57 CW 2 10140420 4 10 "TT"
65 GOTO 18