[amsat-bb] doppler shift

John john at amber.org.uk
Fri Jan 5 08:34:38 UTC 2018

Wow. Just wow! I bet they loved that.

Our experience was somewhat different, mostly because it was total luck. I'd
just finished talking to the two cub-scouts (8-10 years old) and their
leader who were sat with me, in one of the last sessions of the day before
they were due to leave. I'd done a bit of explanation about satellites, the
ISS, mentioned Tim Peake (we're British after all, and pretty much every kid
had heard of him) along with a little bit more about all that good stuff. I
glanced at my screen, as I didn't have any ARISS schedules to hand, and saw
that the ISS was about to come over the horizon, so I said to them "if you
want to try to listen and see if we hear anything, I'll show you how it
works". I set the expectation at zero, and they said "yeah, why not".
Tracking starts, and nothing heard initially, but then a dead FM carrier...
They didn't know what that was but heard a change in the sound. Then they
heard the ISS calling down to a ground station, but didn't understand the
callsigns. They did, however, understand the words "calling from the
International Space Station". Bearing in mind this was the first time I'd
heard the prelim calls (the ISS hadn't quite appeared over the Italian
horizon at that point I don't think), I was still working out what was going
on myself, but immediately shouted for the rest of the visitors who were on
site to join us. The two cub scouts sat by me still hadn't picked up their
jaws at this point - the thud was probably about as loud as your guys' jaws
hitting the deck too - but then everyone else piled in, and duly listened to
the entire contact, despite not one of them understanding a single word as
from that point on once contact had been made, it was all conducted in

By the time the parents had come to collect their children an hour later or
so, video footage had been shared by one of the leaders into the Whatsapp
chat they run with their childrens' parents, and most parents had seen/heard
about it - they were talking about it on the way in to collect their
children, and the children themselves didn't stop talking about it - I'm
lead to believe it was the biggest surprise of the weekend, and the most
memorable moment for them!

For me, that ten minute pass was the highlight of the weekend, and if
nothing else, it made it all well and truly worth it, especially since I was
using two completely unknown and untested beams, a rotator kit I'd had in
pieces on my lap two weeks prior resoldering connections inside, rebuilding
motors and bearings for, and a radio I'd only owned for 3 months and had
barely played with. It was most definitely "a bit of a lash-up", but it
worked, we got the contacts we wanted (ie any at all), and the young people
throughout the weekend got a bit of a better idea about radio, AMSAT and so
on. We did keep a couple of 2M tape measure receivers handy too, so we could
demonstrate the simple end of the scale, but that made it even better.

You should have heard some of the guesses for the size of the automated
birds though - none of them ever imagined a cubesat can be as small as they

73, and a firm left handshake,
John (XLX)

-----Original Message-----
From: George Henry [mailto:ka3hsw at att.net] 
Sent: 05 January 2018 05:18
To: 'John' <john at amber.org.uk>; 'Nick Hart' <nickhart at usa.net>
Cc: amsat-bb at amsat.org
Subject: RE: [amsat-bb] doppler shift

Several years ago, when the ISS repeater was still working, I was doing a
satellite demo for the scouts under the K9BSA callsign, working stations
right and left with 20 - 25 scouts gathered around the rig, when astronaut
Mike Fincke picked up the mic and said "hello to the scouts from the
International Space Station, NA1SS!"

I swear, the collective "thud" of the scouts' jaws hitting the floor could
be heard for miles...

George, KA3HSW

-----Original Message-----
From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of John
Sent: Thursday, January 04, 2018 1:46 PM
To: 'Nick Hart'
Cc: amsat-bb at amsat.org
Subject: Re: [amsat-bb] doppler shift

Hi Nick,

It all depends on the knowledge and skillset of the scouts in question. My
last significant AMSAT demo was done during JOTA, and at that point we had
between 100 and 150 young people come through the shack doors throughout the
weekend. We didn't have a huge amount of time to explain everything or go
really interactive with the control or tracking, and to be honest most of
them were amazed enough that they could hear voices coming back from space,
so when we listened in to one of the Italian ARISS contacts, they were even
more thrilled! My trusty FT-847, SatPC32, ERC-M interface and Kenpro KR5600
did the job nicely, we made quite a few QSOs, and we got to listen to a full
ISS pass - something the 80 odd people who poured into the shack when it
started will likely not forget for a long time yet.


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