# The Completely Hackable Amateur Radio Telescope (CHART) Project

Lindsay M. Berkhout1, Adam P. Beardsley2, Daniel C. Jacobs1, Raven
Braithwaite1,
Bryanna Gutierrez-Coatney1, Arib Islam1, Ahlea Wright2
1School of Earth and Space Exploration, Arizona State University, Tempe, AZ,
USA
2Department of Physics, Winona State University, Winona, MN, USA E-mail:
<EMAIL_ADDRESS>
# The Completely Hackable Amateur Radio Telescope (CHART) Project

Lindsay M. Berkhout1, Adam P. Beardsley2, Daniel C. Jacobs1, Raven
Braithwaite1,
Bryanna Gutierrez-Coatney1, Arib Islam1, Ahlea Wright2
1School of Earth and Space Exploration, Arizona State University, Tempe, AZ,
USA
2Department of Physics, Winona State University, Winona, MN, USA E-mail:
<EMAIL_ADDRESS>
###### Abstract

We present the Completely Hackable Amateur Radio Telescope (CHART), a project
that provides hands-on radio instrumentation and design experience to
undergraduates while bringing accessible radio astronomy experiments to high
school students and teachers. Here we describe a system which can detect 21-cm
emission from the Milky Way which is optimized for cost and simplicity of
construction. Software, documentation, and tutorials are all completely open
source to improve the user experience and facilitate community involvement. We
demonstrate the design with several observations which we compare with state-
of-the-art surveys. The system is shown to detect galactic 21-cm emission in
both rural and urban settings.

##  1 Introduction

The Completely Hackable Amateur Radio Telescope (CHART) Project provides a
platform and tutorials for amateur radio astronomy, with the intent of
broadening access to radio science at the secondary school and early
undergraduate level.

A radio telescope is an excellent educational or amateur astronomy project for
several reasons. Optical astronomy is popularized by high profile telescopes
such as the Hubble Space Telescope or the James Webb Space Telescope [1] and
there are multiple paths for an interested amateur to obtain their own
backyard optical telescope. However, optical observations are best done under
clear skies from dark rural locations, and most people live in cities where
air quality can be low or clouds are common. About 80% of North Americans
cannot see the Milky Way from their homes [2]. On the other hand, while cities
also pose noise challenges, with careful design it is possible to see the
Milky Way at radio frequencies from even a large city. Additionally, radio
frequency observations can illuminate different properties of astronomical
objects that cannot be observed with low-cost optical instruments, such as
Doppler shift from motion and spectral properties of galaxies. Lastly, in a
benefit particularly useful to k-12 schools, radio observations can be
performed in the day time when class is in session.

Though several previous projects have described amateur-grade systems using
consumer grade electronics, the part selection, signal processing, and
software analysis details are usually left to the user. This increases
barriers to participation for those with less technical experience. Here we
describe a radio telescope kit which, through a combination of documentation
and testing, can be built by a typical high school science teacher or someone
with similar experience.

The base platform targets measurements of the 21-cm line of neutral hydrogen.
Low cost, easy to obtain materials are used for the design, and the open
source system design and software are available
online111https://https://astrochart.github.io/. The total cost currently runs
at about $300 of materials, with efforts being made to reduce this further.
The design is “hackable" in the sense that enough documentation is provided
for users to make improvements or branch out in new directions. The project is
also educational for undergraduate students at participating universities who
do most of the development work. This contributes further to CHART’s
educational goals helping the next generation of astronomers get hands-on
experience with instruments as well as improves representation at the
interface for kit users.

Here we demonstrate CHART with a short primer on our object of choice (Sec.
2), a description of the hardware and software design (Sec. 3), and example
observing sessions in multiple settings (Sec. 4). We end with a short
discussion on the classroom use of CHART (Sec. 5).

##  2 Observing the 21 cm Line

Atomic neutral hydrogen emits a spectral line when the electron transitions
between two hyper-fine levels of the ground state. This “spin-flip" transition
occurs when the proton and electron spins go from being aligned to anti-
aligned, emitting a photon with rest wavelength 21 cm, or frequency 1420.4
MHz. For neutral hydrogen clouds in the Milky Way and nearby galaxies, an
observed deviation from this frequency is a Doppler shift caused by motion,
and can be mapped directly to a velocity for the observed gas.

The electromagnetic energy at this particular part of the spectrum can easily
penetrate through cosmic dust and Earth’s atmosphere, making it an easy target
for ground observations. 1420 MHz is in a protected frequency band for radio
astronomy, encompassing 1400-1427 MHz in the United
States222https://www.ntia.doc.gov/files/ntia/publications/2003-allochrt.pdf,
and therefore should not be subject to radio frequency interference (RFI) from
other sources. For these reasons, radio astronomy with the 21 cm line is an
ideal tool for students to learn about emission spectra, galactic motion, or
even evidence for dark matter with rotation curves [3].

Galactic hydrogen has been observed many times with many instruments,
beginning with Ewen & Purcell in 1951[4], and followed by a number of more
recent surveys [[, e.g.]]smoot, salsamap,surveycomp. Recently hobbyist
interest in 21cm radio science has picked up, and there are many avenues to
participate at the amateur level, such as the Society for Amateur Radio
Astromomy (SARA) grants 333https://www.radio-astronomy.org/grants, the
Goldstone Apple Valley Radio Telescope [8], and the SALSA project [9], but
these opportunities often either assume pre-existing radio science literacy or
provide access to a telescope for use, where one does not design or build
their own instrument. There is still a significant gap to bridge between the
amateur radio astronomy community and high school level physics and astronomy.

Regarding 21-cm amateur measurements specifically, there are a number of
projects with similar goals. Each project takes a unique approach with
differing goals and learning outcomes, and we include a few of the most
similar works here. The Digital Signal Processing in Radio Astromomy (DSPIRA)
444https://wvurail.org/lightwork/ project focuses on teaching signal
processing and fourier analysis in this regime. The Physics Open Lab website
reports measurements of the Milky way made with an amateur telescope
555https://physicsopenlab.org/2020/09/08/milky-way-structure-detected-with-
the-21-cm-neutral-hydrogen-emission/. The PICTOR telescope
666https://pictortelescope.com/ offers measurements of the Milky Way from a
remote setup. The BHARAT [10] telescope uses a similar off-the-shelf principle
to construct an amateur telescope for use in undergraduate labs.

The CHART project aims to build on these initiatives by targeting its content
towards secondary school teachers as an audience, and providing detailed, open
source materials and code. The project is organized as a "follow along" set of
tutorials taking a user from building their own horn to a rotation curve
constructed with their data. We use accessible materials for building a low-
cost instrument and expect no pre-existing radio science expertise.

Figure 1: The full system diagram for a CHART setup. Electromagnetic radiation
enters the horn, and is picked up by the probe inside the waveguide. The probe
connects to a combination noise amplifier (LNA) and filter via coaxial cable.
The LNA/filter connects to an RTL-SDR software defined radio which is read out
by a Raspberry-Pi processor. The RTL provides power to the LNA as a DC bias on
the RF cable. A monitor is needed to view the Pi interface, and battery power
is needed for both the Pi and monitor.

##  3 System Design

A summary of a fully tested example system is included in figure 1. Due to the
intended reconfigurability of CHART, many substitute components and designs
could be used. This iteration is suggested as an easy, low-cost starting
point, and has been well tested by the project participants. The design has
been optimized to minimize part count which improves portability and ease of
setup.

###  3.1 Feed-Horn and Antenna

The design of the CHART front-end was optimized for observations at the rest
frequency of neutral hydrogen, as well as cost-effectiveness and ease of
construction. A feed-horn and antenna configuration was chosen as it can be
easily constructed from aluminium wrapped cardboard and a length of wire.

The purpose of the feed horn is to provide directional gain, acting as a
"funnel" for the desired radiation. The dimensions for the horn were chosen
using electromagnetic simulations. The optimized parameter was the beam
directivity, or the concentration of an antenna’s radiation pattern in a
particular direction, at 1420 MHz.

Figure 2 shows the dimensions of the horn used for the measurements in this
paper.

A wire antenna of length 6.3 cm is soldered into a coaxial connector and
installed in the side of the waveguide (the rectangular portion at the bottom
of the horn), using a soup can lid as a structural support and grounding
point.

A photo of the fully constructed front end is included in figure 3.

Figure 2: The dimensions and template for the CHART horn construction.

###  3.2 Electronics

The analog signal chain filters out unwanted signals and amplifies the
radiation picked up at the antenna.

A few different amplification and filtering schemes have been tested. The
current suggested hardware based on performance, cost, and ease of use is a
Nooelec brand combination bias-tee enabled low noise amplifier (LNA) and
filter. The Nooelec module combines both the filtering and amplification into
one component and is easily obtained for minimal cost from consumer outlet
targeted sellers, and combines both the filtering and amplification into one
component.

Additionally, the module can be powered using a bias-tee, meaning it can be
powered by a USB radio over the RF coaxial cable instead of needing a separate
power source.

The module has a good performance with about 40 dB of gain over 1375-1450 MHz
and a noise figure of 1.05dB or 79K. The attenuation outside of the 65MHz
pass-band is between 40 and 60dB.

Figure 3: A fully constructed CHART horn on an observing trip at a weeklong
workshop for High School teachers at Winona State University. The CHART
documentation kit includes instructions for making a pyramidal horn made from
cardboard and tin foil, as well as for setting up the electronics and
software.

###  3.3 Mixing and Digitization

The output of the amplified and filtered analog signal is mixed down to a
lower frequency and digitized. The digital voltage samples are read out by a
computer, transformed into a spectrum, and averaged.

Here we have used the "RTL-SDR Blog V3," a popular hobbyist software defined
radio which is based on the RTL2832U and Rafael Micro R820T2 chipsets. The
RTL-SDR model is a USB dongle that can be obtained for approximately $30. It
includes a tunable mixer, adjustable gain blocks, digitizer, and bias-tee for
powering an external amplifier. The frequency range of operation is 24 – 1766
MHz, although with direct sampling can go as low as 500 kHz, and the maximum
sample rate (without dropped samples) is 2.56 MS/s.

We use a Raspberry Pi to process the samples from the SDR, and our tutorials
include simple instructions to install and configure the necessary software.
This setup provides easy to setup and low cost computing and file storage
until the data can be transferred onto a personal computer or server, although
any machine that can support a USB SDR and the GNURadio software described
section 3.4 could be substituted for the Pi.

###  3.4 Software

The open source and free GNURadio777gnuradio.org provides the basis of our
data collection. One can use GNURadio’s graphical user interface (GUI)
directly, building a signal processing flowchart to acquire a spectrum and
write it to a file. We have also written wrappers to streamline the data
collection in our open source software package888https://github.com/astrochart
– either in a Linux command line mode, or our dedicated GUI. This is simpler
to run, but it does obscure the data taking flow from the user.

The data taking options allow for flexibility depending on the need and
expertise of the user. Those who work directly with GNURadio will interact
with the engineering aspects of radio instrumentation and learn more signal
processing. For those who are more interested in the astronomical analysis of
the data, the CHART software provides a quicker method of obtaining data. A
custom python package provides analysis functions. Functions include
coordinate conversions, bandpass calibration, and plotting in a Doppler
velocity frame.

###  3.5 Tutorials

To make the platform as user friendly as possible, and to provide usability
for the widest range of experience levels, detailed tutorials are available on
the CHART website. There are videos and text walkthroughs of the full system
setup.

As this setup is reasonably complex and users are not expected to be familiar
with advanced computing and coding, the tutorials also cover setting up the
Raspberry Pi computer, basics of the Linux operating system, and use of the
software. Analysis of the collected data is demonstrated in a Jupyter
notebook. This notebook can be run directly on the Raspberry Pi, on any
personal computer, or on a community server described below.

###  3.6 Data Storage and Analysis Server

We created a Microsoft Azure server to store data and perform analysis to
facilitate community engagement, data sharing, and ease of use. For the pilot
implementation, we allocated a virtual machine with 8 CPUs (3rd generation AMD
Milan), 32 GB RAM, and a 128 GB hard drive with the option to expand as
needed. This should comfortably meet the needs of about ten users.

Participants can contact us to acquire an account on the server. With an
account, users can upload their data directly from the CHART observer GUI. The
server accepts the data upload and adds it to a database which includes
metadata about each observation (e.g., location, date, observed frequencies).
All uploaded data is visible to all users so they can easily exchange
observations and compare results.

Once uploaded the users can look at their data in a
JupyterHub999https://jupyterhub.readthedocs.io/ instance running on the
server. User accounts are created with all necessary software for data
analysis, including the CHART python package, and an example analysis Jupyter
Notebook which users can use as a starting point and serves as a self-
documented tutorial. This setup avoids initial setup difficulties which often
pose a source of friction for new users.

##  4 Example Observations

While unwanted radio frequency interference (RFI) can be filtered out with a
number of analog and digital techniques, interfering signals common in urban
environments can be loud enough to cause distortion in the signal chain which
can alter the astronomical signal irrecoverably. This makes doing radio
astronomy in populated areas more difficult, but not impossible. Results are
presented here for two places with differing population densities. This setup
has been tested by students in near Winona State University in Winona,
Minnesota and in downtown Phoenix near Arizona State University.

Figure 4: An artist’s concept showing principle structures of the Milky Way
and illustrating observed sight lines. The labels of the sight lines
correspond to the locations of our observations in sections 4.2 and 4.3. Image
credit: NASA/JPL-Caltech/R. Hurt (SSC-Caltech) with this link:
https://www.nasa.gov/jpl/charting-the-milky-way-from-the-inside-out.

Figure 5: A user’s view from the Stellarium web simulator of the sky above the
Winona, Minnesota observing location at the time of data collection. The
circle corresponds to the center of the pointing labelled as $l=117.75$ in
figure 4. The size of the circled area approximates the CHART beam size.

###  4.1 Methods

Observations were conducted by several groups of undergraduate students.

In each observation the time and orientation were noted. Neutral gas in the
Milky Way is distributed mostly within a thin disk that is co-located with the
optically visible galactic plane. Because the solar system is located within
this disk, any line of sight across the sky will contain galactic HI [11]. In
most cases orientations were chosen towards the galactic plane to maximize
detection probability, as the signal is strongest there. Observations included
a wide scan across 20 MHz (2 MHz at a time due to the limits of the SDR)
surrounding the 21cm line to assess the interference environment.

The center of the telescope pointing was determined by estimating the right
ascension and declination of the horn pointing from measured azimuth and
elevation. This was then converted to galactic coordinates, and the pointings
will be labelled as such. In galactic coordinates, $l$ is the galactic
longitude and $b$ is galactic latitude; degrees away from the galactic plane.
Figure 4 shows the line of sight for the galactic longitudes ($l$) used in our
analysis. An example view on the sky of one of the pointings shown in figure 4
is included in figure 5. This snapshot is from the Stellarium
software101010https://www.stellarium.org, and approximates the area on the sky
and location encompassed by one of our pointings. All measurements were taken
with the horn described in section 3, which has a beam width of approximately
25 degrees.

Post observation, the data must be preprocessed for analysis. Many of our
analysis choices were motivated by desire to compare our results to known
neutral hydrogen profiles from the Milky Way. We chose to compare to the
Leiden/Argentine/Bonn (LAB) survey [7]. The LAB survey used the Dutch 25m
telescope in Dwingeloo and the Argentinean 30m telescope in Villa Elisa to map
the neutral hydrogen in the Milky Way.

In order to compare to the LAB survey directly, we take a few processing
steps. We must remove effects imposed on the astronomical data by our CHART
system to calibrate the data to brightness temperature units, as well as
transform to a common reference frame of motion to match the survey reference
frame choice.

First, we remove the instrumental effects. The CHART system itself imposes
some characteristics onto our true sky signal, namely a multiplicative gain
(e.g. from the antenna and amplifiers) and an additive noise (predominantly
thermal noise from electronics). Most components in our system have a gain and
noise profile that is relatively constant over the frequencies of interest.
The one notable exception is the bandpass of the anti-aliasing filter in the
Software Defined Radio, which prevents unwanted frequencies from aliasing into
the data at the digitizing state. However, the filter varies strongly as a
function of frequency and imposes an undesirable shape onto the spectrum. We
measure this bandpass shape using an "off tuning" away from the 21-cm line
where we expect no astronomical signal, and divide it out of the data.

After the bandpass shape is removed from the data, we assume that the other
contributions to gain and noise are linear in frequency in a small range
around the 21-cm line. Then, mathematically, we know how these terms relate to
the true sky. A two component model for the analog system is described by Eq.
1 which relates the measured spectrum ($d(\nu)$) to the true sky ($m(\nu)$)
via an unknown multiplicative gain ($g$) and an unknown additive noise level
($n$) that are constant across the spectrum.

$d(\nu)=g\cdot m(\nu)+n$ (1)

We calculate $g$ and $n$ for the CHART data by using a model for the true
brightness temperature ($T_{B}$) of the 21cm sky ($m$) in units of Kelvin (K).
For this true sky model, we use a data-based simulation of the expected 21 cm
spectrum from the EU-HOU project, using their web simulator
111111https://www.astro.uni-bonn.de/hisurvey/euhou/LABprofile/index.php. The
simulator uses data from the LAB survey and allows the user to input their
telescope field of view and observing coordinates to estimate what their
expected spectrum should look like. The simulator has a maximum beam width of
20 degrees, which is smaller than the CHART horn beam by about 5 degrees, but
provides a reasonable approximation of the field of view.

First we estimate the noise level by choosing a frequency where the model
predicts no 21cm emission and is free of interference, allowing us to
approximate ($d(\nu))\approx n$. Then we assume this noise is the same across
all frequencies, so we can then calculate the gain term ($g$) where the model
is largest ($g\approx(d(\nu)-n)/m(\nu)$).

We then apply these parameters across the spectrum. This method turns the
uncalibrated CHART data into brightness temperature units. Now the data are on
the same scale as the model, and the profile shapes can be compared directly.

After we remove the effects imposed by our instrument, we must convert our
data to the kinematic reference frame used by the LAB survey. The velocity at
local standard of rest (VLSR) observing frame is used. The LSR follows the
mean motion of material in the local Milky Way, defined as stars in radius 100
pc from the Sun [12]. This frame has two parts: the motion of the Sun relative
to the LSR, and the orbital motion of the Earth. We use the ‘astropy‘ software
package for this conversion [13], and apply the computed doppler shift for our
location, observation time, and line of sight to the frequency axis.

Figure 6: _Top:_ The uncalibrated CHART data for galactic coordinates
$l=117.75^{\circ}$ and $b=-3.25^{\circ}$. The individual spectra represent
separate 2 MHz tunings of the SDR. The spectrometer scans across the frequency
range in 2 MHz tunings, with a step of 1 MHz so that there is some overlap
between tunings. The repeating structure in every tuning is due to the anti-
aliasing filter of the SDR. _Bottom:_ Calibrated data after dividing out the
bandpass, subtracting noise, and correcting for the overall gain.

The raw, uncalibrated and uncorrected data for the sight line of
$l=117.75^{\circ}$ taken in Winona, Minnesota is included in figure 6 (top).
The shape of the spectrum is dominated by the anti-aliasing filter which is
applied to each 2MHz tuning. This shape is divided out in the calibration
post-processing step. Sporadic RFI can be seen in a few tunings, and the 21cm
line is visible slightly to the left of the rest frequency indicated as a bold
vertical line. The whole frequency range has a slight slope caused by the
uneven spectral response of the electronics. The vertical axis units are
arbitrary and have no correspondence to a physical unit before calibration.
Fig. 6 (bottom) shows the result of the calibration process. There is still an
overall ’u’ shape to the bandpass as we do not correct for second order
effects when removing noise, but as the 21-cm emission occupies a small
fraction of the bandwidth in the observation, we do not worry about removing
effects outside of this range.

###  4.2 Results from Winona, Minnesota

Figure 7 shows the velocity profile for three different sets of galactic
coordinates, following the corresponding lines of sight in figure 4. The data
was taken near Winona State University in Winona, Minnesota. The CHART data is
plotted against the LAB survey simulation for the same set of galactic
coordinates.

Figure 7: Subfigures show a radial velocity vs brightness temperature
measurement taken for 3 different sets of galactic coordinates, rounded to the
nearest quarter degree. The coordinates follow the line of sight in figure 4.
The data labelled "CHART" correspond to the profile from our CHART telescope,
and the "Model" is calculated with the EU-HOU web simulator.

Our data largely agree with the simulation results for the selected galactic
coordinates. The locations of peaks in the spectra are well matched between
our data and the survey simulation data. There is minor variation in the
shapes of the profiles, which could result from a variety of factors. Likely
culprits are pointing accuracy errors or variation in the field of view of the
data and models. Pointing accuracy is limited by the observer’s ability to
estimate the coordinates of the center of their pointing with a protractor and
phone compass, and the beam size and shape is not exact between the EU-HOU
simulation and the real horn.

###  4.3 Results from Phoenix, Arizona

This section presents a more challenging RFI test environment than the
previous test location. Measurements were made in near the city center in
Phoenix, Arizona, and were taken in the day time. In this location we expect
interference at frequencies close to the HI band (including cell phones, FM
radio, and other transmitters) at levels strong enough to overcome the
bandpass filter and possibly to saturate the amplifier.

Figure 8: Observed Brightness Temperature (TB) spectrum as compared to the
simulation, with a pointing of galactic coordinates $l=72^{\circ}$,
$b=0^{\circ}$. This follows the $l=72^{\circ}$ line in figure 4. This data has
been masked and filtered in the Fourier domain. The observed data peak width
and center appear to be well matched to the model. There is a ripple across
the data on the level of the high negative velocity clouds, so the match of
the non-zero velocity peaks cannot be determined from this data.

The data was taken at galactic coordinates $l=72^{\circ}$ and $b=0^{\circ}$,
following the $l=72^{\circ}$ line of sight in figure 4.

For this data, a few extra analysis steps were taken to remove contaminants.

Using a reference pointing with the horn covered, the data was masked for the
contaminants that show up in both the control data and the sky data. We know
sources that show up with the horn covered to be self or environmental
interference rather than astronomical in nature, and can safely remove them
from the data. We also applied a Fourier domain filter to remove any frequency
dependent systematics.

The filtered and calibrated signal is seen in figure 8. The data appears well
matched in width and peak to the simulation. The noise level of this data is
high, so we do not interpret the negative velocity peak as a true match. There
is a ripple across the band on the level of this peak, as seen in the bump at
positive velocities of 75 km/s. However, the main lobe of our emission line
seems to be an excellent fit and is well above the noise level of the ripple.

##  5 Using CHART in the Classroom

At the time of this manuscript, CHART has been used in the classroom at the
undergraduate and High School level.

Undergraduate students take responsibility for many of the development and
testing parts of the project. This offers students an easy entry point to
research, as the topics we teach with CHART (antenna design, signal
processing, etc.) are essential to understanding research with larger scale
experiments. To this front, we host summer undergraduate internships at
Arizona State University (ASU) and Winona State University (WSU) that focus on
CHART. We have also taught an entry level week-long workshop in Spring 2023,
attended by 30 undergraduate students, as well as a Spring 2021 semester upper
level course which registered 12 students at ASU.

At the High School level, CHART has been used at WSU for a week-long Summer
workshop. The workshop brought four teachers, mostly from the areas
surrounding Winona, to WSU and covered the introductory science, radio
instrument construction and building, and observing and data analysis for the
project. All participants were able to successfully detect galactic hydrogen,
and left the workshop with the provided components for future use.

Quantitative details of the impacts of the project on students & educators
will be left to the work of a future study.

##  6 Conclusion

The CHART platform offers a classroom accessible method for students and
educators to get involved in radio astronomy. Here we have demonstrated
detection and analysis of the 21-cm line from local neutral hydrogen using a
cardboard horn, low cost electronics and freely available software.

The base platform can be modified and extended by advanced users. Future
directions include further analysis to create galactic rotation curves
demonstrating the necessity of dark matter and alternative radio targets at
other bands. With some component changes, the platform is easily extensible to
other projects including solar observations, radio Jove (Jupiter), pulsars,
and Cosmic Microwave Background (CMB) observations. Additionally, with
multiple CHART systems, interferometry is possible.

The documentation and construction of this project is designed to be easily
accessible to secondary school level educators.

CHART has been used at summer workshops for High School teachers, as well as
by local teachers in the areas surrounding participating universities. We also
engage undergraduates in the project through research involvement and
coursework. We hope to expand project engagement even further as the
documentation and science results grow.

## Acknowledgements

LMB acknowledges that this material is based upon work supported by a National
Science Foundation Graduate Research Fellowship under Grant No. 2233001.

APB acknowledges support from an NSF Astronomy and Astrophysics Postdoctoral
Fellowship under award AST-1701440, and a grant from the Mt. Cuba Astronomical
Foundation.

APB and AW acknowledge support from NSF grant AST-2108348.

DCJ acknowledges NSF CAREER, grant #2144995.

For the modeling data in this paper, we acknowledge the EU-HOU project and the
Comenius grant.

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