Extracting useful data from Spirit of Knoxville

LVL1 here takes a detailed examination here of several balloon flights to understand more fully what happened to them during their flight. We will use the generous open-source contributions of the UTARC/SNOX balloon group to bootstrap our effort, to carry the torch not really any more upward, and definitely not lower, but decidedly onward.

SNOX II landed just 20 minutes after launch, having a ruptured balloon envelope, and will not be analyzed.

SNOX III launched with a faulty GPS, which provided almost no useful telemetry, and its flight path was determined only roughly by VHF radio-triangulation until it left the US coast. After that contact was lost, as the flight computer never turned on the HF shortwave radio, because it used lat/lon position to know when to turn that on, and it had no GPS data to determine position.


Background SNOX I was the first full size ZP balloon launched in the formerly called Icarus UTARC Balloon program. With this flight, the program was officially rebranded “Spirit of Knoxville”, as it had all a flight hardware system fully capable of crossing the atlantic. The SNOX hardware design would remain nearly unchanged from this flight to the end of the program. The most important improvements from here on were to be made in software in the flight computer and on the ground.

SNOX I telemetry contains multiple sheets of data. The first two sheets are raw NMEA standard data from the GPS, which was sent over VHF radio while over the continental USA. After departing the US coast, the HF radio began to transmit data, indicated by the “DTRC” sheets.

Original Data/Doc Links

SNOX I Raw Telemetry (note there are multiple sheets, see above explanation)
SNOX I Flight Prep Notes and Post-flight Analysis


This was the most successful of the Spirit of Knoxville missions, travelling 3300+ miles over 40 hours.

New Analysis

Simple PLotting of SNOX IV Telemetry

SNOX IV Normalized

The linked plots detail the mean of non-convective cloud coverage (%) for the SNOX IV flight. Time is UTC. I chose to plot at 300 mb because the jet stream averages at 300 mb in the winter.


SNOX IV mean non-convective cloud coverage (%) 300 mb

Original Data/Doc Links


This flight failed prematurely and landed in the Eastern USA.

Original Data/Doc Links

SNOX V HF Over-the-air Telemetry Format Dictionary Note: the content will be the same as the Raw Telemetry link here, however this dictionary references the actual over-the-air character stream, which has much additional formatting than the provided Raw Telemetry link below.
SNOX V Raw Telemetry and volunteer listener callsigns (note there are multiple sheets)
SNOX V Flight Computer Firmware in PBasic, for the PIC18 microcontroller.
SNOX V Flight Prep Notes and Post-flight Analysis

The linked plots detail the mean of non-convective cloud coverage (%) for the SNOX IV flight. Time is UTC. I chose to plot at 300 mb because the jet stream averages at 300 mb in the winter. SNOX V mean non-convective cloud cover (%) 300 mb

Flight Algorithms:

  1. Vertical Velocity Calculation
    1. Points taken in moving average: 10
    2. Interval between points: 10s

Telemetry Tracking Network: DTRC

How the Live Web Tracking Application Worked Article by Mike Coffey (mike at mcoffey.com), DTRC programmer
Distributed Tracking and Relay Client site

analysis/snox.txt · Last modified: 2018/07/29 17:58 (external edit)
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