Sensors & Telemetry
Turning measurements into understanding.
Course
How sensors measure the world, how numbers become packets, and how engineers read telemetry to see what a spacecraft is doing.
Before you start
- Reading graphs
- Averages
Learning objectives
- Explain how a sensor turns something physical into a number
- Read a telemetry chart and spot when a value leaves its normal range
- Tell the difference between noise and a real change
By the end you can
- Can read a telemetry chart with confidence
- Knows that every number has a unit and an uncertainty
Before you start
- Foundation level of this track
- Straight-line graphs
- Basic programming
Learning objectives
- Apply the sampling theorem when choosing a sample rate
- Calibrate a sensor with a straight-line fit
- Design a telemetry frame and calculate the data rate it needs
- Use limits with persistence to avoid false alarms
By the end you can
- Can design telemetry that answers engineering questions
- Can explain the false-alarm trade-off
Lesson plan
Lessons · Ages 14–16
Sensors
- Temperature, pressure, light, motion
- Units and ranges
From voltage to number
- Analogue and digital
- Resolution
Telemetry
- What a packet contains
- Time stamps
Reading the chart
- Normal ranges and limits
- Noise and averages
- Trends
Hands-on activities
- Record a light sensor or phone light meter through a day and plot it
- In Survive the Eclipse, read the battery chart and find the exact moment the satellite enters shadow
Challenge: Read the Telemetry
A simulated telemetry log contains one abnormal period. Find it and explain what probably happened.
Pass criteria
- Correct time window identified
- Explanation names the measurement and the limit it crossed
Physics and mathematics
Show the 2 equations
x̄ = (x₁ + x₂ + … + x_n) ÷ n
same as the measurement
Averaging several readings smooths out noise.
step = range ÷ 2ⁿ
same as the range, n = number of bits
A 12-bit reading of 0–3.3 V changes in steps of about 0.8 mV.
3D models
- CubeSat telemetry overlay (available: Survive the Eclipse)
Lessons · Ages 17–18
Sampling
- Nyquist rate
- Aliasing
Calibration
- Offset and gain
- Least-squares line
Frames and links
- Headers, payload, checksum
- Bit rate
Monitoring
- Limits and persistence
- False alarms versus missed detections
Hands-on activities
- Calibrate a temperature sensor against two reference points and report its error
- Write a frame format for six channels and calculate the downlink time per orbit
Challenge: Frame and Flag
Design a telemetry frame, then write a limit check with persistence that catches a real fault but ignores single noisy samples.
Pass criteria
- Frame decodes correctly field by field
- The check flags the injected fault
- No false alarms on the noisy but healthy log
Physics and mathematics
Show the 3 equations
f_s > 2 × f_max
Hz
Sample faster than twice the highest frequency in the signal, or it will be misrepresented.
y = a × x + b
a gain, b offset
Fit a and b from known reference points.
R = channels × samples per second × bits per sample
bit/s
Add the frame overhead before comparing with the link.
3D models
- CubeSat with live simulated telemetry (available: Survive the Eclipse)
- Propulsion pressure monitoring (existing: Advanced Rocket Propulsion Digital Twin)
Classes and workshops
Online
Interactive mission and tutorials now; live online classes planned.
In person
No offline workshop is planned for this track yet; its activities can be done at home or in a school lab.
Existing tutorials for this track
- CubeTwinCubeSat energy digital twin: sunlight, battery, faults, safe mode.
- Satellite Explorer 3DA 6U Earth-observation satellite in interactive 3D.
- Advanced Rocket Propulsion Digital TwinPressure monitoring, fault detection, diagnosis and prognostics.
- UFlight 3DAn electric aircraft's sensor networks and health monitoring.
Eligibility, independence and privacy
- Independent initiative. Space Academy is part of an independent ISHAVASYAM.ORG education initiative. It is not affiliated with, endorsed by, or run on behalf of ISRO, IN-SPACe, NSIL or the Department of Space.
- No competition eligibility. Learning here does not register anyone for, or make anyone eligible for, any national or international competition. Each competition's organisers set its rules and eligibility.
- Simulated and illustrative. Interactive missions use simplified models and simulated, illustrative values. They are labelled as such and are not flight data.
- Ages. Written for learners aged 14 to 18. Anyone may play the self-paced missions; enquiries from under-18s need a parent or guardian.
- Privacy. Missions never ask for a name, school, age or contact details. Progress is stored only in this browser and can be cleared at any time. This site uses Google Analytics to count page visits and mission steps. Some of the site's existing tutorials ask visitors to sign in with a Google account. If you are under 18, check with a parent or guardian before signing in.