[Music]
welcome back to the open hardware
minicon so next up we have a
presentation about open hardware weather
radar and our speaker is tisham who you
may have seen previously at an open
hardware mini conf he did a very
interesting talk about energy monitoring
and
if my memory is correct tish you were
using fpgas for that project i think is
that correct
i got to a stage where i was like
experimenting with them yeah this has a
fair bit of fpgas in it as well
okay great so
following on from questions after that
last session about what are applications
for fpgas perhaps
this is an example i'm very interested
to see this presentation so tish take it
away
thank you thank you um yeah so my slides
are up uh so i uh
i'm tisham i
build things for fun and this is one of
the things i built and
i'll start
before i introduce myself i will start
with an acknowledgement to the country
i'm presenting today from the land of
the ghana people of the adelaide plains
and i acknowledge their
people the past present and current
and the connection to the land and water
is very crucial to life
and this presentation even though it's
about hardware it's really about water
and we'll see a lot of that going
through and yeah enjoy
so i started
building this project
many years ago there's a little bit of a
timeline here but uh slowly been
chipping away at it and
i'm at a stage where i need help and
this is in addition to what you have
done and learned it's also about getting
this out to the community and getting
interest in hardware
in rf frequencies
bigger
and looking at water that's right
so there's a bit of a flow of the ideas
i my mind works in a very random
branching fashion and i have to
backtrack and linearize it our
presentation by its very nature is very
linear so i've tried to put down all of
the different ideas that are
going to be talked about in a linear
fashion
so i will talk a bit about the history
of weather radars where they come from
it's a bit of a superpower seeing things
in radar uh we don't really have extra
vision or super people these days but uh
radar is the closest you can come to
extravision seeing through walls and
clouds into into the what's behind
uh talk about a bit of ocean in the sky
and how the radar interacts with the
moisture
some stuff about solid state radars and
where things are at in the commercial
industry in this arena a bit of project
timeline of my and my partner gashini's
work on this so i didn't do all this by
myself i had a lot of help
and all of the rest of it is around
how iteratively you try to solve
problems i was watching
john's presentation on dealing with
issues that you come about when you're
trying to make hardware
some of the issues when you're trying to
get a new idea of the ground or even
bigger their business issues and making
people understand that this is actually
worth doing
uh and then there is a funding issues uh
is what i'm referring to and a couple of
technical issues around now casting and
qpe which stands for quantitative
precipitation estimation
and then we get to
the actual idea or the prototypes i have
or been working on for uh phased array
radars
and
and this is not a brand new idea it's
just becoming easier and easier to do
with the advances in availability of
hardware
uh easier for novices and people just
sitting in their living rooms to do i
guess outside a lab
and sky's ahead hewani is the project
name hiwa means that what's in the sky
what's the weather like in swahili
so the sky is ahead for this project and
all of the turbulence that would be
experiencing or been experiencing
so yeah so the there's a fair amount of
slides there's a lot of words uh some
pictures so i'll just go through it and
i will keep an eye on the time
so the
microwave part of the electromagnetic
spectrum is what we're talking about and
it's a finite resource
and we have governments uh
licensing our spectrum
at very very high rates and our modern
civilization like me talking over wi-fi
right now
is tied together by this part of the
spectrum and only very few people work
on it understand it it's pretty black
magic
yeah so that's that's sort of the very
interesting area to work in
a bit of history of how how these things
came about
the radios were invented and then the
radar itself came from
what was a request for a death ray to
spray something into the air and take
down aircraft during the second world
war uh and the uh
the radar installations came about i
became aware in my life journey about
radars through reading this book the
grand slack
by a french free air force pilot pia
customer who later became a politician
who talked about the radar that was
being used in the air force during the
second war
uh so yeah so that from war after the
war ended there was a lot of radars
available and uh there were what was the
clutter in the wartime radar uh became
signal in that this radar is being used
for civilian purposes to observe
precipitation
rain surplus military radars form the
seed of weather observation radars
so there's an ocean in the sky
uh we have so many oceans that my son
reads about you know uh the arctic the
antarctic the
south the north atlantic south atlantic
there is also an ocean in the sky
all of the evaporation from all of the
oceans gathers in the sky and a lot of
our
uh biosphere depends on that ocean in
the sky falling down on the land
and the
the reason that we have things like
wi-fi are due to the weird dams that the
water molecule does when excited with
frequencies at this uh this this yeah
with these frequencies and absorbing it
sucking it up and sometimes reflecting
some of it
and we end up with this unlicensed bands
where no people don't want to use it and
we use it for things like wi-fi and the
ism bands
the benefits of the weather observation
i will go into more detail but it's it's
uh affects both the benefit side that we
grow crops and have drinking water
uh to the risks we have i was living in
canberra and uh thousands of cars were
turned into
what my friend kelvin refers to as golf
balls by the meteors
hydro meteors not that not the space
kind
so uh i have seen this i i learned
french in school so i've seen this
saying in english you know one man's
fish is another man's poison it didn't
really make sense until i learned french
is that poison is actually fish
and the
this is because what i refer to as the
attenuation due to their resonance with
water at these frequencies and this is
what you can use for uh
for the microwave observation of
precipitation
so the given coming from the target
observation radars you have lots of
other types of target observation radars
some of them are marine radars and they
can be
turned into weather radars with
modifications
but you require specialist labs to make
those modifications and uh yeah they're
not quite easy to get you need a whole
truck and it's big so this one is not uh
like a
small low frequency so high frequencies
it depends a big antenna they're quite a
bit set up
but quite quite interesting things you
can do with all of the target
observation right now so that's sort of
history of where we are
sort of moving forward to the last 10 or
20 years we have seen uh
things
become more even more compact gallium
nitride is uh used for the power of the
fire solid state instead of magnetrons
which were used in the earlier radars
and were not very disciplined in their
frequency generation
to have a little list of various
military modern solid-state radars
and then the civilian solid state radars
are available too but they still use a
spinning antenna
uh so i have a few small list of
civilian solid-state radars that are
just been entering the market over the
last five years or so
um yeah
i actually went out to the marina to
take a picture of one
in adelaide my yeah
during a family beach time i'm just
staring at radars at the marina
so yeah so this is a project timeline of
me being becoming involved in this
project working through various
challenges deploying hardware in on the
field uh doing our first presentation on
it so i started working on it uh with my
friend kashini around 2018
i visited kenya we'll talk about that in
a minute and uh we deployed sensors uh
we sort of i give a first public
presentation about it in baikonu mostly
on the devops and the high software side
of it and the infrastructure side of it
of getting the data together and
sort of disseminating it
over
nairobi
uh so nairobi hasn't had a weather radar
in the last
30 or so years before that in a place
called current there was a big radar
installation
and it became such that there was no
expertise obviously in maintaining this
a big piece of hardware and it became
unmaintained and there the government
has been trying to do
a new budgetary required request to set
up a new one and they refund to do a one
big lumpy one you end up with millions
of dollars and uh sub-saharan country
just doesn't have the room to pull it
off
uh so yeah so that's sort of we saw a
need and we ideated we deployed stuff we
talked about it i talked about it um
vishing is a very private person uh he
doesn't like talking about these things
too much
uh the
i've been trying to stabilize stuff over
the last year i've taken various breaks
between jobs and written a bunch of code
to improve the stuff from how it was run
some serverless now i'm sort of working
again on the hardware side
to create
new versions which are cheaper easier to
deploy require less maintenance
are more open compared to what we have
now
uh and sort of uh maybe in a few years
maybe hardware is hard
someone will pay us for it or
there will be a big market where
everyone is making them and we can buy
them cheaper than we can make them
ourselves which is sort of even though
the gray market for arduinos is huge
this day is in aliexpress
it's great for people in other parts of
the world like say india or kenya
is a financially really good
option for a cheap hardware to become
available that people can learn outside
outside
of what they can afford yeah
so uh so this is sort of the loop
again i'm reminded of john's talk of uh
prototyping trying something out
sharing about it getting some learning
new things getting feedback
refining your ideas and trying going
again
just keep doing it the cost of iterating
on hardware is higher time costs are
higher
it's a slow cycle so you make small
changes and you put on
yeah instead of getting a new stencil
made you put on captain tape where you
need to hack things together have
botched wires
it's a it's how hardware is done uh
it's not pretty i was iterating on my
background this morning to get it in the
good white balance it's a real world
changing the real world is hard
so i have to run off and get some you
know uh dark paper to fix it and i could
have done two in software but uh i'm a
hardware person i guess
so yeah so one of the challenges we had
was uh getting started bootstrapping and
getting a little bit of money to get
started uh so
the top picture is me and my friend
kishini and my tattoo which are like
local
small minivans typically
toyota toyotas
uh that take people around at the back
of it we are going going to some place
called lamu which is like a few
kilometers from the somali border and is
famous for kidnapping tourists but
anyway
and then we sort of put this idea
together so yushini is super smart he
went to mit he got into some got some
contacts
uh the major of them was greg greg
runs the microwave sensing course at mit
i've got a few props here so one of the
courses that greg runs uses containers
to build a small short range
radar which you can generate images from
using synthetic apertures you should
check out it's an open course you should
check out that stuff that greg has
um yeah and he advised us
we needed some money to build some stuff
so
ray stata who is the founder uh and
for a while the ceo of analog devices
uh a very high-speed analog sensing uh
instruments maker
he talked to us said what are you
planning to do in three years we wrote
down on one page he spoke to us for five
minutes
and he gave us
a bit of money to do do some crazy
things try out some crazy things
um so yeah so that was how we got
started on this idea
uh so the upsides that we did sell to
people was uh you know the rain is uh
uh is i is vital for how we grow food
the upsides of knowing predicting when
it will be
are you going to get decent amounts of
it so you can see the graph of the
rainfall versus food production here due
to rainfall agriculture
and then on the flip side the damages
caused by unexpected precipitation
events
are there there's a very good site from
noaa called billions
and you can see billions of dollars of
losses due to weather-related events
flooding hail that the us experiences
yeah so there is a good case for doing
it we can't really control the weather
we can observe and move people to safety
uh so that's one of the things you can
do or you can estimate insurance losses
or risk of looking forward insurance
works on the principle of the insurance
industry knowing the risks slightly
better than the people being insured and
benefiting of that gap
um yeah so that's sort of the benefits
of better precipitation observation
so that's the first part of getting
going and getting some funding in and
convincing people that this is worth
doing maybe uh
it's already being done by states like
the nation states uh in the western
world
it's just uh
it's worth doing for a place like africa
as well
so the next challenge which i guess
came as
creating something cool
the project started we got the idea
initially when i was like watching
soccer it's uh premier league is pretty
big and in kenya i was watching soccer
at a pub
and whenever the rain would come the
satellite broadcast would like fade away
due to rain fade obviously and i was
like oh it's gonna i know where the
satellite is it's probably gonna rain in
five minutes and other people watching
that thing with me at the bar were like
how are you doing that
so that sort of
that sort of five minute prediction is
easier but uh if you want to do 90
minutes and so you'll take years of
research to do it so first of the
challenge one of the challenges we
looked at was now casting
and that requires a large sampling
window and uh creating a grid of this
sensors
uh i have in here uh radar data
simulation and now casting paper from
one of the many research papers going
around this one in particular one is in
catalonia
uh so we got to some stage we got to uh
sort of 20 minute window now casting
approach i'm just gonna talk a little
bit more about the the way it works in
uh in a properly deployed scenario so
you need typically you lean big lumpy
radars like uh the bureau of meteorology
has
in various different wavelengths each
with their own advantages
uh bureau of met in australia has things
with up to 200 kilometers in coverage
after that the curvature of the earth
again as we will discuss um you know
just a slight couple of slides down uh
starts affecting the big lumpy radar
uh you can also have what i call the pie
in the sky very high high risk
systems which can blow up regularly so
one of the some of these meteorological
satellites have blown up while being
launched
so you put you make a baby for years and
it costs millions and then you put it on
a firecracker and you try to send it to
space it's it's a high risk venture but
no it's still doing it
and then uh sort of uh the or the whole
big picture uh requires some of this for
stitching the things you're seeing on
the ground it gives us a good big
picture of you
uh this is sort of the history of the
various meteorological satellites that
are going have been up
my i love this last one it's a very uh
the severi uh has a spinning
uh approach with a mirror for observing
the hemisphere getting a disc image uh
there is an animation on the umed sat
website of how severe composites this
image is really really cool it's really
cool with a spinning mirror
and then you can have this sort of
honeycomb approach which is what we
aimed for in our project uh in putting
together cell of uh networks depending
on density depending on the
importance i guess from a human
perspective so you don't want to have
lots and lots of dense expand radars in
an area where there are not many people
a 200 kilometer one would be fine so
this sort of approach is quite common in
weather simulations there is one of
those models i was looking at called
empass
uses a multi-grid approach rather than
an even grid it uses a multiple
different density grids to create create
a
lower data volume but still quite
accurate with the model with a
simulation model
uh so many many years ago uh well i was
still doing my phd one of the other
projects also being run out of my lab by
my
pg supervisor doug gray was this thing
called the ren
uh so this was run out of the adelaide
university uh i'm not quite sure where
it is at i've been out of the lab for
many years now
but it sort of also inspired the work we
did was to wear the radar experimental
network which was essentially the same
idea taking small radars and then
joining them together into a into a
network to get rid of what the what
bureau of metrology talks about the
earth curvature effect of the big lumpy
radar
so it gives you better microclimate
estimations higher resolutions temporal
spatial
and uh yeah takes care of takes care of
the curvature the earth is not flat
uh the rend project was supported by
raytheon's phased array radar
which is not again commercially
available
uh so yeah so that
again
my attempt at this ongoing is to develop
something that is not a military system
and is fairly open so that we can
create more of them
uh so the other challenge is uh what i
had in my uh stream as a qpe
quantitative precipitation estimation
uh the qp challenge for is addressed in
say i have a paper this uh this as a
reference paper relatively recent a year
or so ago from taiwan
um
is a you need lots of ground truth
because the rain moves around by the
wind uh and where you observe it in in
the space may not be where it lands
uh but the source data available to
perform qpe over africa is very sparse
and they don't agree with each other
there are various data sources that
tahmo temps at
the a couple of weather models guests
ecmwf
their resolutions are very different to
the sensor that we are using
and
the inversion problem
becomes interactable without good data
to tie to the taiwan paper which was
fairly successful uh is
uh
uses a network of thousand stations
uh for automated weather stations so
there is another piece of hardware that
needs to be built and
made much more commodity which is
automated weather stations
um um this is an open hardware mini
console it's another another prop for
another piece of hardware that needs to
exist to solve this problem better
the another fun fact about taiwan
apparently part of the
silicon supply chain issue is due to
reduced rain in the mountains of taiwan
reducing supply of fresh water
so
if you are not seeing chip shortages
there is the rain is causing it less
rain is causing
uh so the the the
in uh absence of the ground rules so one
of the things i looked at is and i would
like to introduce here is this concept
of precipitation air rcs
oh that's a duplication
radar rcs it's just rcs
radar cross section
i have to fix up the slide but anyway
the teardrop shape that you have in all
of the
emojis of rain is not true the rain
doesn't form a teardrop it forms this
thing which is like an inverted goblet
which comes to
closest to the teardrop shape
uh when it gets pretty big but it never
is a teardrop it looks like a flattened
ball it looks more like an orange when
it's falling down due to the pressure of
the air on on the raindrop only when
it's very small it's a sphere because
the surface tension of the water but as
it as it gets bigger and due to the wind
velocity it starts distorting
the its shape is never a teardrop which
is quite interesting
um and then the the other type of rcs
you have to get is for the hailstones i
was discussing about in canberra uh the
this is a pretty funky one i like it
because it looks almost like a virus
this one is created by by the super
cooled water spinning and pushing off
little cones as it spins and those cones
freeze into place and uh
but usually it's like a water ice mixed
with sometimes air bubbles in it so
you're creating the dielectric for
hydrometeors is quite hard
um anyway so it's a it's another
interesting precipitation if you want to
compute rcs uh using simulations instead
of using uh ground station data
and the other one type of rcs
precipitation form is fox which you can
just use small spheres uh to calculate
i've been experimenting with another
open source software project called meep
from mit also
which looks at this uh quite cool uh it
has a python api you can create objects
and then throw radar at it to see what
the backscatter looks like just click
cool
and this is my favorite good looking one
uh that i have added here a sample for a
concocts uh
fractal based uh
notebook for creating ice crystals that
grop learning has it's very cool i had a
lot of fun playing around with it
uh yeah so sometimes it's just fun uh
doing some of these things and looking
at the shapes that water forms
so this is the open hardware radar
presentation i'm fairly into my time
but i will i'll go over it
i have bits of kit to show
so the idea is essentially instead of
having a big antenna that spins like we
saw in the other one of the historical
notes
you create a panel with lots of antennas
in it and you can steer in one direction
not physically but electronically
so it requires a bunch of software
defined radios frequency doublers
in my case because i only have like five
six gigahertz radios
uh power amplifiers antenna arrays those
are the basic building blocks there's a
nice write up this image is from toshiba
research on this again as i said most of
this stuff happens in the lab and it's i
would love to see it moving towards open
hardware community and becoming much
more commonplace
so these are the couple of things i've
tried there's an fpga here an ultra
cyclone four
lime sdr i have a few of these
uh i'm trying to get one of these blade
rf's
they're quite expensive this also has an
fpga but next generation up from the
lime sdr the second five fp here
um there is a frequency doublers which
uh i contacted lyme sdr about and they
said tire one customer has bought all of
them so it's not available so i love to
see what this tier one customer is doing
so i have a pcb here
which is essentially the pc we have in
the slide um with feed it has frequency
doubling output feeds and
transmit and receive channels i'll be
quite interesting to see how how we go
uh the next one is the
uh
like a passive frequency doubler so this
one has an active chip on it
but this one is a passive frequency
doubler which
which you can get as well but you have a
bit of signal loss i have ordered a
couple of these to experiment with as
well
uh so then the next part is the hardest
to get stuff because you will be
spraying real power into the air as the
power amplifiers so stay within low
powers
um
60 watt amps you cannot get because you
need to sign 10 000 forms to say you're
not gonna do anything naughty with them
uh but 35 watt or so maybe you'll still
have to sign forms and you can get those
uh again power amplifiers
and then this is a fun bit like i was
talking about the in the can array so i
was been messing around creating antenna
arrays there are existing designs you
can get of the mimo antenna arrays uh
you can at 5.8 gigahertz you can pick up
your standard wi-fi antenna arrays and
work work with those
uh so this is like
created using uh freecad and i'm
planning to put some antenna designs uh
off the shelf and my own into fico which
is a tool i used uh for uh mems based
antenna simulation to see how they
behave
uh this is what a realistic antenna
would look like uh for sending and
receiving and so on
uh so yeah so that's sort of uh the last
part of the open hardware approach that
i'm working on i don't have completed
hardware i have got like lots of parts
i've got like a bunch of cables to put
into my rubber ducks
uh but i haven't got a full built yet
but i would love to see people contact
me and collaborate on that
so the skies ahead are pretty turbulent
for our project we have sort of run
through the angel funds that we had
doing learning various things
experimenting
uh funding for building something in
africa is challenging people don't seek
any clear path to revenue
operating with these things outside of
cleared lab
in a western world is challenging a
little bit
so that's that's quite interesting in
balance in africa we can reach out to
people i have seen the head of the
meteorological department uh
assistant director or in kenya and
pitched our idea and got some support of
some some push back and corruption as
well
but yeah so it's that will be a higher
bar to do in australia
the operating environment in africa is
difficult building hardware getting
stuff shipped in is difficult
and i would love to see open source
hardware and software community jump in
with their resources to put together a
good set of things that can be that can
be relatively affordably built into a
large array so to in order to build a
antenna array like this you would
require hundreds of fpr's
not hundreds yeah perhaps under this
yeah
when in my lab also in the lab we built
a 100 antenna gps passive radar so you
could bounce gps of an airplane and see
use that as a radar so it requires a lot
of a lot of
rf rf signal chain stuff
yes i would love to see the open source
hardware and software community dive
deeper into the rf land
and thank you for listening i'm happy to
take questions uh i think that went went
well for a reasonable amount of time
i was i've been making this presentation
after john asked me to do it over a few
few weeks and i was hanging out whenever
i would have free moment i would hang
out
and one of the people who saw me writing
this presentation wrote me a poem so i
have it in there
oh that's great thank you tish that was
very interesting
now we're pretty much on the limit for
time here but we do have a couple of
questions which hopefully
will be brief
and the first one is calling back to
what you were just mentioning a moment
ago
um you were talking about gps
reflectometry and one of the questions
from in the chat is do you do any work
with passive reception of reflected
noise the rf component of rain noise can
be received but i don't know how
directional it is fairly broadband
yeah yeah so some of the ideas are there
for using rain fade as well
so if you have a good number of cell
towers or things like that or you can
measure the rain fade using passive
received mode only and then you have to
again go back and invert all of that in
the actual body of the rain and the
reflectivity is scatters so you have to
do it's a quite a difficult inversion
problem if you have control over the
radiator it's an easier easier problem
to solve
okay
and another question is do any of the
marine radars work with linux
ah that's that's a that's a good
question so uh the marine readers ship
with their own hardware uh so some of
the you have to break into the signal
chain i spent an amount of time sitting
on um wireshark uh they have ethernet
going over the protocols and stuff uh i
haven't opened uh any of that yet it's
not very
i'm not sure what the
legal ramifications of reverse
engineering these things is yet i don't
have i'm
yeah so
they work over ethernet so once a driver
is built and the ethernet protocol is
reverse engineered you could make them
work
okay i would love help there sen if
please privately send me something else
and do some wireshark capture packets
yeah
um
there was
we are really pushing for time but no
two more quick questions one is would
these radars be useful for people
running solar power plants
interesting uh so if you have want to
see real time quick response so if you
want to see rain clouds arriving over
the horizon beyond the predictions that
bureau of med provides you
then you would want to do this yourself
bureau of met i have spoken to jaya from
after my previous presentation at
birofmet and bureau of met is about to
release after many years of research uh
like 90 minute now casting uh service
which they'll it takes them five minutes
to assimilate and run the radar and then
they can look forward 90 minutes which
is fairly accurate so maybe rather than
hosting your own uh in australia
especially you could use the bombs bomb
is an excellent science agency you could
use bomb service
yeah okay um well we better wrap it up
but just before you go
if people want to follow up on this and
they want to learn more about your
project is there a particular place they
should look
um there is a twitter bot that we built
as part of this uh called heroin aka
which has been gone silent i haven't
been able to maintain it um so you can
look at hawaiian k's previous updates
over nairobi so hewani is what is in the
air k in kenya so it gives tweets out
the rain in nairobi
and you can also reach me on twitter on
what nick is the social media i'm most
active in
yeah great that's fantastic well thanks
tish i really appreciate you coming
along and
this has been a very interesting thing
and a couple of people in the chat also
mentioned i really liked the imagery of
the ocean in the sky that you mentioned
at the start
thank you
okay thank you see ya
bye