Under jul och nyårshelgerna planeras ett antal aktiviteter från och kring ISS:
+ December 21-26 – we plan to support the Crossband repeater mode
with a
twist. Our intent is to configure the radio for 145.99 MHz
uplink including
PL tone of 67.0 and 437.80 MHz down. This will
be performed in low power
mode.
+ December 22 – Expedition 18 Commander Mike Fincke and
Flight
Engineer Yury Lonchakov plan to perform a spacewalk. As
per
standard procedure, the ISS ham radio system will be turned off
for
the EVA.
+ December 28-January 3 – we plan to reconfigure the
Crossband
repeater for a special experiment. This will be a test of
our
L-Band uplink capability, which, to date, has not been proven
out.
Plan for an uplink of 1269.65 MHz and and downlink on the
standard frequency
145.80 MHz using low power. Given the subtan-
tial cable losses of the L-band
system, we hope some “big guns”
are able to penetrate through, keep up with
doppler, and make
the connection.
+ And at times, especially during
the weekends, you might see some
SSTV operations if the crew is
available.
ARISS US Hardware Manager Lou McFadin, W5DID provided a
summary of expected parameters for those considering trying to make a
contact with the ISS on L-band to VHF crossband repeater experiment
planned for December 28 to January 3.
Lou reported, “The measured
sensitivity of the L band receiver on
a D700, as the radio aboard the ISS, is
-105dBm for full quieting.
The cable loss from the radio to the antenna is
9.3db. The antenna
gain is zero db. The polarization is
LHCP.”
Extending the calcuations to cover the entire system path, Lou
said,
“The path loss at the horizon on L band is -160dB. That means
the
required EIRP for a full quieting contact at the horizon is 65dBm.
The
path loss decreases by 15dB at 80 degrees elevation so that means
you can get
full quieting with 50dBm in that case. To further elaborate
if you use a 20dB
gain antenna (a small dish), it is estimated that
you can complete a QSO with
32 watts at the horizon or 1 watt at 80
degrees elevation.”
The
planned operating frequencies include:
Uplink: 1269.650 MHz FM
Downlink:
145.800 MHz FM