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West Virginia University · Radio Astronomy Instrumentation Laboratory DSPIRA Lessons

Digital Signal Processing in Radio Astronomy

Build a radio telescope. Point it at the Galaxy.

51 free lessons. Fold the antenna from insulation board and solder your amplifier. Then use the telescope to measure the Milky Way's rotation. The high school teachers who wrote these did all of it first.

Start at lesson one See all 51 lessons

Curriculum

The seven modules

Work through the modules to progress from a flat insulation board to a Milky Way velocity curve. Or take any one on its own; most stand up as a couple of weeks of classroom material.

  1. A finished horn telescope on its wooden stand in a field.

    Module 1

    Horn Construction

    Foil-faced insulation board, aluminum tape, dimensional lumber, and a paint-thinner can for the throat. The finished stand is 75 cm across, so it fits through a classroom door.

    All 5 lessons

  2. A soldering station set up for assembling the low-noise amplifier.

    Module 2

    Receiver Electronics

    The amplifier is what decides how good your telescope is, so it is the part worth taking time over. Build the DSPIRA board for about $30 in parts, or buy one ready-made and get on with the observing.

    All 5 lessons

  3. A GNU Radio flowgraph for the DSPIRA spectrometer.

    Module 3

    Software Setup

    Ubuntu, GNU Radio, and the DSPIRA blocks. The flash-drive route turns any Windows machine into a spectrometer without touching its hard disk.

    All 11 lessons

  4. Two observers running a horn telescope from camp chairs in a field.

    Module 4

    Observing

    It works in daylight, in the rain, and from a school car park. All it needs is open sky and somewhere to sit.

    All 10 lessons

  5. A spectrum with the 21 cm neutral hydrogen line standing above the noise.

    Module 5

    Digital Signal Processing

    Six labs build a GNU Radio spectrometer one block at a time. Topics include sampling, Fourier analysis, filters, and correlation. Correlation turns two horns into an interferometer.

    All 8 lessons

  6. Horn telescopes and a lit tent under a field of stars at Green Bank.

    Module 6

    Astronomy

    The part it is all for. Learn where to point and how hydrogen appears at 21 cm. Use a rotation curve to investigate dark matter.

    All 8 lessons

  7. Students setting up a horn telescope in a school parking lot.

    Module 7

    Community Labs

    Schools, clubs, and students extend the curriculum with their own hardware. Projects cover cosmic rays, motorized mounts, and comparisons with published measurements.

    All 4 lessons

What the telescope is

A horn telescope has three parts. The antenna is a pyramidal horn folded from foil-faced insulation board. The stand uses dimensional lumber. The back-end electronics combine a low-noise amplifier with a software-defined radio dongle. Parts cost a few hundred dollars. A hardware store and a couple of online suppliers provide everything needed.

It detects neutral hydrogen's 21 cm line in the sky. Use this signal to map hydrogen in the Milky Way and measure the galaxy's rotation.

A pyramidal horn antenna of foil-faced insulation board, mounted on a wooden cradle and stand in a field.
The whole instrument: horn, cradle, stand and feed can.

Where these came from

DSPIRA was a National Science Foundation Research Experiences for Teachers site at West Virginia University. It ran with the Green Bank Observatory. Over three summers, fifteen high school teachers built these telescopes and learned their signal processing. They observed at Green Bank, then wrote lessons based on their experience.

The cohort programme concluded in 2019. The lessons are still here, still free, and still maintained. More about the programme.

The Milky Way over the Green Bank Observatory site, with DSPIRA written in the air by a hand-held light.
Green Bank, West Virginia, where the cohorts observed.

Beyond the lessons

Also here

  • Telescope kits

    Educators and community organizers can request a starter kit. It supplies the hardest-to-source parts: an SDR dongle and a 21 cm amplifier.

  • Who these are written for

    Every lesson is tagged for school teachers, students or hobbyists. This is the same 51 lessons sorted by who they were written for.

  • Associate research labs

    Classrooms and hobbyist groups that have taken this hardware and these lessons and built their own programmes on them.

  • LightWork Memos

    An informal numbered memo series on citizen science with radio telescopes, covering design, construction and operation.

  • The forum

    Questions, build reports and troubleshooting, on the project’s GitHub Discussions. Threads go back to 2020.

  • Contribute a lesson

    The whole site is Markdown in a public repository. This is how to add your own lesson to it.