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1993-11-21
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Shuttle Amateur Radio EXperiment (SAREX)
STS-55 Antenna Test
INTRODUCTION:
Here's a great opportunity for schools and hams in the
southeastern United States.
Shuttle mission STS-55 is scheduled for launch on April 24, 1993.
During the flight, Motorola Amateur Radio Club members in Florida
will conduct a test to assess the performance of two different
SAREX antennas in space. Each participant in this experiment
is supplying valuable information to the project!
During Orbit 61, the Shuttle crew will transmit a signal on
145.55 MHz using the SAREX antenna positioned in its normal
orbiter window. For Orbit 62 they will transmit again on 145.55
MHz, this time using an external German SpaceLab antenna in the
cargo bay of the Shuttle.
Your mission is to measure the signal strength (S-meter reading)
and the time of Acquisition Of Signal (AOS) and Loss Of Signal
(LOS) of the Shuttle's transmissions at regular intervals
during both of these orbits.
(For more information on STS-55 and the Antenna Test, please see
February 1993 QST, page 42.)
GETTING STARTED:
1) Determine what time to listen for the transmissions. STS-55
is scheduled for launch on April 24, at 14:52 UTC. If the launch
is on time, the Shuttle will near North America during Orbit 61
on April 28, at 08:55 UTC, and Orbit 62 at 10:29 UTC.
The Orbit 61 pass occurs 3 days 18 hours and 3 minutes after
launch (this is known as 3/18:03 MET - Mission Elapsed Time).
The Orbit 62 pass occurs at 3/19:37 MET. If the launch time is
delayed, simply add the actual launch date/time to the MET values
(see table below) to get the new Orbit 61 and 62 times. This is
explained in more detail in the section labeled "MISSION ELAPSED
TIME."
Table 1
(using a launch date and time of April 24, 14:52 UTC)
Launch 00/00:00 MET or Apr 24, 14:52 UTC
Orbit 61 03/18:03 MET or Apr 28, 08:55 UTC
Orbit 62 03/19:37 MET or Apr 28, 10:29 UTC
2) Synchronize your watch to WWV or any precise time source (you
may phone WWV at 303-499-7111). It is important to make sure
that the times you record are as accurate as possible. Record
all times to the exact second.
3) Begin listening for the Shuttle a minute or two before the
scheduled start of Orbit 61. The receive-only frequency is 145.55
MHz.
As soon as you start hearing the transmissions, record the time
to the exact second. This is the Acquisition Of Signal (AOS)
time.
Next, begin recording the signal strength of the transmissions at
regular intervals. The Motorola Amateur Radio Club recommends
that you record the signal strength every 15 seconds. Signal
strength may be reported in S-units or the number of bars on a
bar graph meter or simply estimate the signal quality ("sounds
like 20 dB quieting", etc.). Record the time and signal strength
readings as accurately as possible on an Orbit 61 Data sheet.
Take as much data as possible.
(Stations with advanced capability and equipment, such as a
calibrated receiver, can report signal strength in dBm or
microvolts. Please attach a description of the method used to
calibrate the receiver, and antenna and feed line gains and
losses.)
Finally, record the time when you lost the signal to the exact
second. This is the Loss Of Signal (LOS) time. (The maximum
time between AOS and LOS is approximately 8-10 minutes.)
4) Repeat Step 3 for Orbit 62. Do not forget to record the
exact AOS and LOS times. The AOS and LOS times are just as
important as the actual signal strengths, so stations with no
S-meter are still supplying important information. Log all of
the data on an Orbit 62 Data sheet.
5) Return station information form and all data within 10 days
after the experiment to ARRL, SAREX Antenna Test, 225 Main
Street, Newington CT 06111.
Thank you for your participation!
MISSION ELAPSED TIME:
How do you plan for timing Orbit 61 and Orbit 62 when you only
know an approximate launch time? The best planning tool is
Mission Elapsed Time (MET). That's what NASA uses to schedule
crew operating schedules.
With MET, you start counting time at liftoff. Think of it this
way: During countdown, the clock moves backward ("T minus 10, 9,
8 seconds, and all that). At the moment of liftoff, the clock
starts moving forward.
As an example, let's say the actual launch time is April 24 at
14:00 UTC. Since Orbit 61 nears North America at Mission Elapsed
Time 3 days 18 hours and 3 minutes (3/18:03 MET), then add this
to the new launch time:
Apr 24 14:00 UTC +
3 days 18:03 MET = April 27 at 32:03 or April 28 at 08:03 UTC
As a result, for a April 24 launch at 14:00 UTC, Orbit 61 will
occur on April 28 at 08:03 UTC.
Because of launch delays, MET is the only reasonable way to
figure time during a mission.
W1AW will broadcast bulletins during the mission announcing the
actual launch time and Orbit 61 and 62 times for this experiment.
DATA (Sample forms, etc.):
Please provide the following information which will be necessary
for us to accurately analyzed all of the data.
NAME-
CALL-
ADDRESS-
PHONE (DAY)-
PHONE (NIGHT)-
Station Information
(attach additional sheets if necessary.)
LATITUDE-
LONGITUDE-
ELEVATION-
RADIO-
ANTENNA- (Please include the type, gain, polarization, and
height.)
(If you are using an HT receiving on a portable antenna (rubber
ducky) make sure to keep the receiver and antenna in the same
location and in a fixed position during the duration of both
orbits.)
Are you using a steerable satellite tracking antenna?
Detailed equipment configuration- (include accessories such as
preamps, external meters, calibrated signal generator, ....)
* Return this information and all data within 10 days after the
experiment to ARRL, SAREX Antenna Test, 225 Main Street,
Newington, CT 06111.
ORBIT 61 DATA-
ACQUISITION OF SIG. (AOS) DATE: TIME (UTC):
LOSS OF SIGNAL (LOS) DATE: TIME (UTC):
ORBIT 61 TABLE
TIME (UTC) SIGNAL STRENGTH NOTES
1
2
3
etc...
ORBIT 62 DATA-
ACQUISITION OF SIG. (AOS) DATE: TIME (UTC):
LOSS OF SIGNAL (LOS) DATE: TIME (UTC):
ORBIT 62 TABLE
TIME (UTC) SIGNAL STRENGTH NOTES
1
2
3
etc...
(end)