ARLA/CLUSTER: Astronauta Luca Parmitano (KF5KDP) contacta desde a ISS

[João Costa > CT1FBF]

Astronaut Luca Parmitano KF5KDP making ham radio contacts

ESA astronaut Luca Parmitano KF5KDP has been making random voice
contacts from the International Space Station (ISS) to other radio
amateurs on Earth on 145.800 MHz

When the astronauts put out  a CQ call, in range of Europe and Africa,
they transmit on 145.800 MHz FM but operate “split” listening for
replies 600 kHz lower on 145.200 MHz. If you are lucky and hear them
calling CQ just remember to activate your rigs repeater shift to
ensure you reply on the correct frequency. You should never transmit
on 145.800 MHz.

The International Space Station is traveling around the Earth at over
28,000 Km/h. This high speed makes radio signals appear to shift in
frequency, a phenomenon called Doppler Shift.

This Doppler shift will cause the ISS transmit frequency of 145.800
MHz to look as if it is 3.5 kHz higher in frequency, 145.8035, when
ISS is approaching your location. During the 10 minute pass the
frequency will move lower shifting a total of 7 kHz down to 145.7965
as the ISS goes out of range. To get maximum signal you ideally need a
radio that tunes in 1 kHz or smaller steps to follow the shift but in
practice acceptable results are obtained with the radio left on
145.800 MHz.

In the UK we use narrow 2.5 kHz deviation FM but the ISS transmits
using the wider 5 kHz deviation used in much of the world. Most rigs
can be switched between wide and narrow deviation filters so select
the wider filter. Hand-held rigs all seem to have a single wide filter
fitted as standard.

You can receive the ISS outdoors using a 2 metre hand-held with its
helical antenna but a 1/4 wave whip will give far better results.

Cor PD0RKC reports “On Monday, August 5, 2013 I had a short contact
with Luca, anyone made an audio recording? Please send it to my e-mail
address see QRZ.com. Thanks in advance!”

For the current status of the amateur radio stations on the ISS see
http://www.issfanclub.com/