Cohort archive

2017 The first summer

Nine teachers spent six weeks learning digital signal processing, building a radio telescope each, and taking it to Green Bank.

9 teachers
5 states
6 weeks
Morgantown + Green Bank

A horn antenna built by DSPIRA teachers set up on the grounds of the Green Bank Observatory — A teacher-built horn antenna at the Green Bank Observatory.

Who was here

The 2017 cohort

Nine teachers came from five states. All teach science in grades 8 through 12. Each returned home with a working radio telescope.

The 2017 DSPIRA teacher cohort assembled outdoors — The 2017 cohort.

Jamie Avalos TX
Howard Chun RI
Denise Gipson WV
Eric Goff WV
Wendy Lee WV
John Makous NC
Adam Osborne WV
Shane Price WV
LaShonda Torbert MD

Foundation

The program prepared teachers to run digital signal processing projects with their students. Four weeks of daily lectures first built foundations in astronomy and DSP.

Astronomy topics included the celestial sphere, astronomical and solar time, Kepler's laws, and the H–R diagram. Lectures also covered galaxies, cosmology, dark matter, and galaxy rotation curves. The signal-processing track followed an undergraduate DSP course. It progressed from signal basics to the fast Fourier transform.

Hands-on learning

Every lecture was followed by a lab. Software-defined radio made abstract DSP concepts tangible. GNU Radio is free, open source, and compatible with inexpensive radio hardware. The lab uses the same tool on research instruments. The structured labs ended with each teacher writing their own software spectrometer — a component every radio telescope needs.

Then they built the telescope. Teachers soldered low-noise amplifiers from small components. They fabricated horn antennas using materials and tools available at hardware stores. The horns were built in the industrial design workshop at WVU.

The whole group got their LNAs working, several of them having never soldered before. The horn construction turned into an assembly line. Each teacher combined a spectrometer, LNA, and horn into a working telescope. This was completed during the four weeks in Morgantown.

GNU Radio — free, open source, and the same stack the lab uses on real instruments.

A surface-mount amplifier component a couple of millimeters across, balanced on a fingertip above a printed assembly sheet — The amplifier parts are a couple of millimeters across. Several teachers had never soldered before.

Two teachers working a metal cylinder into shape at a bench in the WVU workshop — Fabricating the feed, in the industrial design workshop at WVU.

A completed horn antenna on its wooden mount standing in a field under a blue sky — The finished article. Horn, mount, amplifier and spectrometer — four weeks, from nothing.

Field experiments

The horn antennas were tested in Morgantown, then taken to the Green Bank Observatory.

At WVU

Several tests confirmed the telescopes worked before they traveled. LNA performance was measured in the lab, with the noise figure taken inside the Faraday cage in the RF room. A trial observing run with one of the horns was conducted on the roof of the Engineering Sciences Building.

At Green Bank Observatory

The last two weeks were spent on site. Teachers completed the observatory's outreach activities, including training on the 40 Foot telescope. They routed its signal through an SDR dongle into their GNU Radio spectrometer. They also processed the Green Bank Telescope's intermediate-frequency signal with their spectrometer. They compared its output with the VEGAS back end.

Mostly, though, the time went on planning and executing observations with the horns. The teachers wrote their own observing plan to map the whole sky. Hot-cold measurements established horn-system gain and temperature. Teachers continued improving probes and LNAs in GBO's electronics lab. Workshops taught reduction of the spectrometer's data.

Bench test equipment in the WVU RF room showing a measurement on red LED displays — Measuring the noise figure, in the RF room at WVU.

Hot–cold measurements, to get the system temperature of the horn.

A horn antenna set up on the rooftop of the Engineering Sciences Building at WVU, the valley stretching away behind it — The trial run, on the roof of the Engineering Sciences Building.

The 40 Foot telescope sign at the Green Bank Observatory with the dish standing behind it — The 40 Foot, whose signal the teachers routed through their own spectrometer.

Four horn antennas on wooden mounts lined up on the grass outside the Green Bank Science Center, with the Reber Telescope towering behind them — Four horns on the lawn outside the Science Center, under the Reber Telescope.

Two teachers working by lamplight with horn antennas beneath the Reber Telescope against a deep blue dusk sky — The same spot at dusk. Mapping the Galaxy took the observing into the night.

Students and lessons

The visit overlapped with the PING summer camp. Teachers tested their material with its students. They developed and taught DSP activities for school-age children. These became the first DSPIRA curriculum materials.

In the classroom. Introducing PING campers to digital signal processing.
Group exercises. Every module ended in one.
Sampling discretely. Sampling and quantization — the cornerstone of the whole subject.
Campers working through one of the activities.
On encoding. A basic exercise in digital encoding.
An outdoor activity. Filtering, outside the Green Bank Science Center.

What it opened up

Teachers gained research experience in engineering and radio astronomy. The summer also demonstrated opportunities for amateur radio astronomy. The inexpensive design uses common materials, including home insulation and paint thinner cans. Curious builders can start with readily available supplies. It also means a teacher can build more telescopes back at their own school without much logistical burden.

And these simple systems can do more than one thing. An array of horns supports time-domain radio astronomy. Undergraduates in the 2018 cohort pursued this possibility.

Four teacher-built horn antennas lined up side by side on their wooden mounts as a small aperture array — Four horns as a small aperture array — the starting point for the next summer's pulsar work.

Everything they used

Use the lessons online

50 lessons covering the astronomy, the hardware, the signal processing and the labs—free and maintained by the DSPIRA community.

Open the lessons site