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1994-03-20
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SB SAT @ AMSAT $ANS-071.01
W3IWI EXPLAINS SAT PROPAGATION
HR AMSAT NEWS SERVICE BULLETIN 071.01 FROM AMSAT HQ
SILVER SPRING, MD MARCH 12, 1994
TO ALL RADIO AMATEURS BT
BID: $ANS-071.01
W3IWI Explains A Propagation Phenomenon Observed By IT9XXS
Giovanni Mazzola (IT9XXS) posed a question about a propagation phenomenon
he has been noticing on KO-23, KO-25, UO-22 and other digital satellites.
He reported that he has regularly observed that at the end of the pass,
when the satellite is between 0 and -2 degrees elevation, the signal
exhibits three strong peaks. During the pass it may be S4 but when the
three peaks in signal strength occur, they are over S9. After that he
loses the signal altogether. He notes that he has a good horizon, looking
out to the sea to the north.
Ton Clark (W3IWI) offers the following explanation: What IT9XXS is observ-
ing is classic and very predictable. It is the result of two physical
effects: atmospheric refraction and "Lloyd's Mirror" reflections.
The earth's atmosphere bends the signals so that your "radio" horizon is
below the physical horizon. The refractive index of the air is about 300
parts per million different from unity depending on the temperature and
water vapor content of the air. This is precisely the reason that most
line-of-sight computations of terrestrial paths increase the effective
radius of the earth by about 1.33. Under some tropospheric conditions
like when the temperature increases with height and/or when anomalous
water vapor content is present, ducting can occur and VHF/UHF paths may
extend to thousands of kilometers. This is especially true of over-water
paths like the frequent duct that occurs between southern California and
Hawaii or between Italy and Spain. Since the path in question is over
water, this is probably the reason signals are received from the satellite
when it is below the apparent horizon.
The second effect that is occurring is a reflection of the signals from
the water, so the antenna is receiving two different signals. In optics
this is often called the "Lloyd's mirror" effect. When the signal is
reflected, its phase is changed by 180 degrees, so the direct and
reflected signals arrive at the antenna out of phase and cancel at
the horizon. At other elevations, the two signals traverse different
paths so the phase difference of the direct and reflected signals varies,
and the signals may either add constructively (increasing the signal
strength) or destructively (causing a null). If the angles at which maxima
and minima signal were known, it would be possible to compute the height
of receiving antenna above the level of the sea (reflector).
This reflection effect was first seen in about 1947 when some Australians
observed the radio "star" Cygnus-A from an antenna atop a sea cliff. The
fact that they observed deep nulls allowed them to demonstrate that Cygnus-
A was a compact object, smaller than a few arc-minutes in diameter and not
a large-scale feature of the previously discovered radiation from our
Milky Way galaxy. This work was done at VHF frequencies not far from our
2M amateur band.
[The AMSAT News Service (ANS) would like to thank Tom Clark (W3IWI) for
this explanation and IT9XXS for posing the question.]
/EX
SB SAT @ AMSAT $ANS-071.02
STS-59 SAREX INFO
HR AMSAT NEWS SERVICE BULLETIN 071.02 FROM AMSAT HQ
SILVER SPRING, MD MARCH 12, 1994
TO ALL RADIO AMATEURS BT
BID: $ANS-071.02
N5QWL Provides A "Fact" Sheet For The Upcoming STS-59 SAREX Mission
Shuttle Amateur Radio Experiment (SAREX) Fact Sheet
STS-59 Space Shuttle Endeavour
When: Planned Launch April 7, 1994 at 12:07 UTC for 9 days of 2M
operations.
Where: Earth Orbit. Altitude 220 kilometers, with radio coverage of
latitudes from 70 degrees North to 70 degrees South. We are in
one of the lowest altitude orbits ever flown by the shuttle, so
pass times will be shorter than usual.
Operators: Dr. Jay Apt (N5QWL) and Dr. Linda Godwin N5RAX. N5QWL is the
commander of the Blue Shift aboard Endeavour and will
operate the shuttle systems during the "night" shift, while
N5RAX is the Payload Commander, responsible for overall
operation of three large radars in the shuttle's cargo bay
during the "day" shift.
Modes: FM Voice
VOICE CALL SIGNS: N5QWL and N5RAX
Packet (Beacons giving daily mission activities daily if we get
a chance, and robot QSOs -- successful connects will be issued a
contact number by the robot) PACKET CALL SIGN: W5RRR-1
Frequencies: We will operate split.
PLEASE DO NOT TRANSMIT ON THE DOWNLINK FREQUENCY!
VOICE: Downlink (shuttle transmits) on 145.55 MHz
Uplink (ground transmits) on 144.91, 144.93, 144.95,
144.97, and 144.99 (except over Europe) - we'll listen
on those 5 frequencies to spread out the pileup a bit.
Uplink for Europe only: 144.80, 144.75, 144.70
Successful QSOs on voice will be facilitated by using
standard international phonetics for your call sign.
We will not answer any stations using non-standard
phonetics. Use your entire call sign -- we log with an
audio tape recorder. Do not use our call sign --
passes are very short, and we want to work as many
folks as possible.
PACKET: Downlink (shuttle transmits) on 145.55
Uplink (ground transmits) on 144.49 (worldwide)
If you can, decrease your radio's deviation to 3 KHz (most are
initially set at 5 KHz) and compensate for the Doppler shift. If
you cannot, wait until a minute or 90 seconds after we come over
your horizon to transmit -- that will put you within our IF. If a
station transmits without following these suggestions, we just hear
what sounds like a noisy carrier. The above applies to both voice
and packet.
QSL via: ARRL, ATTN: STS-59 QSLs, 225 Main Street, Newington, CT 06111,
USA. Include a self-addressed stamped envelope (SASE). Non-US
stations include a self addressed envelope with $0.50 of US
postage affixed or appropriate IRCs. Include the Callsign worked,
Date, UTC, Mode, and Frequency. For packet contacts, include the
QSO number issued by the robot. SWL QSL's: Include the Callsign
heard, Date, UTC, Mode, and Frequency.
Information during the mission: AMSAT bulletins, Compuserve, Genie,
Prodigy, local packet bulletin boards,
ARRL bulletins, and HF voice from NASA
Johnson Space Center ARC, Houston, Texas,
W5RRR, or NASA Goddard Spaceflight Center
ARC, Greenbelt, Maryland, WA3NAN,
frequencies listed below.
W5RRR may be found on or near: 7.215, 14.280, 21.360, and 28.400 MHz.
WA3NAN retransmits NASA Select Audio and SAREX bulletins simultaneously on
or near 3.860, 7.185, 14.295, 21.395, and 28.650 MHz.
The NASA Info BBS at Johnson Space Center, Houston, will also carry
Keplerian elements and SAREX bulletins. (713) 483-2500, 1200 baud,
8-N-1. At the "ENTER NUMBER:" prompt, type 62511 <return> and log onto the
BBS. The Keps and bulletins will be in the welcome message. Disconnect
rapidly to facilitate access by others.
Operations Notes: If you have a packet QSO number issued to you by the
robot, don't try to get another one! Our on-board
program drops the duplicates anyhow, and all you
are doing is making it harder for the other folks. We'll
issue you a QSL card if you appear in the "heard" list on
the TNC and we have issued you a QSO number...that's a
2-way contact, AND REMEMBER, THIS IS ONLY A HOBBY!
N5QWL will be asleep over most USA passes, and N5RAX will be busy with
assigned duties for most daylit US passes, so try us on packet over the
USA if the sun is up. Remember, our packet call sign is W5RRR-1. We'll
try to work voice (1) when we are not otherwise engaged, and (2) at night
or when the ground is cloudy (we are generally busy taking pictures of the
Earth during clear daylight passes).
If I can get to it, I'll activate the SAREX about 3 hours into the mission;
deactivation will occur at about 8 days, 17 hours after launch (unless we
get a one-day science mission extension, then it will be deactivated at
about 9 days, 17 hours after launch).
Prelaunch Keplerian Elements, courtesy of Gil Carman (WA5NOM) of the JSC
ARC):
STS-59
1 00059U 94097.74947238 .00221188 00000-0 11303-3 0 70
2 00059 57.0053 276.3038 0009259 269.9963 90.0094 16.19806752 56
Satellite: STS-59
Catalog number: 00059
Epoch time: 94097.74947238 = (07-APR-94 17:59:14.41 UTC)
Element set: 007
Inclination: 57.0053 deg
RA of node: 276.3038 deg Space Shuttle Flight STS-59
Eccentricity: .0009259 Prelaunch Element set JSC-007
Arg of perigee: 269.9963 deg Launch: 07-APR-94 12:07 UTC
Mean anomaly: 90.0094 deg
Mean motion: 16.19806752 rev/day G. L. Carman
Decay rate: 2.21188e-03 rev/day^2 NASA Johnson Space Center
Epoch rev: 5
Checksum: 327
[The AMSAT News Service (ANS) would like to thank N5QWL for in this
bulletin item.]
/EX
SB SAT @ AMSAT $ANS-071.03
AO-13 OPERATIONS NET SCHEDS
HR AMSAT NEWS SERVICE BULLETIN 071.03 FROM AMSAT HQ
SILVER SPRING, MD MARCH 12, 1994
TO ALL RADIO AMATEURS BT
BID: $ANS-071.03
Current AMSAT Operations Net Schedule For AO-13
AMSAT Operations Nets are planned for the following times. Mode-B Nets
are conducted on AO-13 on a downlink frequency of 145.950 MHz. If, at
the start of the OPS Net, the frequency of 145.950 MHz is being used
for a QSO, OPS Net enthusiasts are asked to move to the alternate
frequency of 145.955 MHz.
Date UTC Mode Phs NCS Alt NCS
19-Mar-94 1730 B 073 W5IU WA5ZIB
26-Mar-94 2130 B 084 WA5ZIB W5IU
Any stations with information on current events would be most welcomed.
Also, those interested in discussing technical issues or who have questions
about any particular aspect of OSCAR statellite operations, are encouraged
to join the OPS Nets. If neither of the Net Control Stations show up, any
participant is invited to act as the NCS.
AO-13 ZRO Tests For March 1994
The following schedule of Mode "B" tests were chosen for convenient
operating times and favorable squint angles. The tests can be heard on
145.840 MHz. Andy McAlister (WA5ZIB) will conduct all the tests. Mode
"JL" tests will no longer occur due to the failure of AO-13's 70CM trans-
mitter.
Day Date (UTC) Time Areas covered
Saturday Mar. 19, 1994 1930 UTC NA, SA, Europe, Africa
Saturday Mar. 26, 1994 2315 UTC NA, SA
Note that the dates and days are shown in "UTC". Any changes will be
announced as soon as possible via the AMSAT HF and AO-13 Operations
Nets.
All listener reports with date of test and numbers copied should be sent to
Andy MacAllister (WA5ZIB), AMSAT V.P. User Operations, 14714 Knights Way
Drive, Houston, TX 77083-5640. A report will be returned verifying the
level of accurate reception. An S.A.S.E. is appreciated but not required.
/EX
SB SAT @ AMSAT $ANS-071.04
WEEKLY OSCAR STATUS REPORTS
HR AMSAT NEWS SERVICE BULLETIN 071.04 FROM AMSAT HQ
SILVER SPRING, MD MARCH 12, 1994
TO ALL RADIO AMATEURS BT
BID: $ANS-071.04
Weekly OSCAR Status Reports: 12-MAR-94
AO-13: Current Transponder Operating Schedule:
L QST *** AO-13 TRANSPONDER SCHEDULE *** 1994 Jan 31-Apr 04
Mode-B : MA 0 to MA 90 |
Mode-BS : MA 90 to MA 120 |
Mode-S : MA 120 to MA 145 |<- S transponder; B trsp. is OFF
Mode-S : MA 145 to MA 150 |<- S beacon only
Mode-BS : MA 150 to MA 180 | Blon/Blat 180/0
Mode-B : MA 180 to MA 256 |
Omnis : MA 230 to MA 30 | Move to attitude 240/0, Apr 04
[G3RUH/DB2OS/VK5AGR]
FO-20: The following is the current schedule for transponder operations:
ANALOG MODE:
23-MAR-94 7:52 -TO- 30-MAR-94 8:15 UTC
DIGITAL MODE: Unless otherwise noted above.
[Kazu Sakamoto (JJ1WTK) qga02014@niftyserve.or.jp]
RS-10: Still operating normally for ZS6AOP. The usual regular stations are
often found working thru the satellite as well as the "odd" new
comer. Reports of copying the beacon while well below the horizon,
over the South Pole on south-to-north passes with good signal
strengths have been coming in. Hopefully, with more stations
becoming active there will be some real long distance sub-horizon
contacts soon. [ZS6AOP]
RS-12: RS-12 is currently operating in Mode K. The uplink passband is
21.210 - 21.250 MHz with downlink on 29.410 - 29.450 MHz. The
transponder is non-inverting USB or CW, i.e., if you are on 21.225,
then listen on 29.425 +/- the doppler shift, adjust your transmit
frequency as you work the satellite to keep the downlink frequency
constant. The beacon frequencies are 29.408 MHz or 29.454 MHz. The
Robot operates on 29.454 MHz. The uplink frequency for the the
Robot is 21.129 MHz. When the Robot is not operating, this freq-
uency pair can also be used for general QSOs.
[KB8FGC @ KC8TW.#swoh.usa.na]
AO-21: This OSCAR sends down beautiful signals, 59+ signals about 90% of
the time. Along with DOVE, ZS6AOP can recommend AO-21 to anyone who
wants to start capturing and examing telemetry using basic
equipment. [ZS6AOP]
AO-16: Operating normally. [WH6I]
LO-19: Operating normally. [WH6I]
IO-26: Operating normally. [WH6I]
KO-23: Operating normally. [WH6I]
KO-25: Operating normally. KO-25 has a number of new earth images this
past week. So far WH6I notes that he has not seen any pictures that
were particularly interesting to him. [WH6I]
AO-27: There is no particular schedule transponder schedule per se, and the
way it works is that amateur radio section of the satellite has only
solar cell illumination to power it so as to not strain the drain of
on board battery power on the commercial side. Therefore, if your
using ITRACK OR QUICKTRACK watch the sun terminator (sun darkness
line) when it crosses into the light, the Analog repeater turns on
but not until it is in sunlight. N4OUL's own experience is that he
has worked it with a hand held ICOM-2AT on low power 2.5 W into 4
el 2M antenna and was full quieting stateside. Also VE3BDR worked
it with a portable low power with a mag mount. Uplink on 2M is FM
at 145.850 MHz and downlink on FM at 436.800 MHz. [N4OUL]
The AMSAT NEWS Service (ANS) is looking for volunteers to contribute weekly
OSCAR status reports. If you have a favorite OSCAR which you work on a
regular basis and would like to contribute to this bulletin, please send
your observations to WD0HHU at his CompuServe address of 70524,2272, on
INTERNET at wd0hhu@amsat.org, or to his local packet BBS in the Denver, CO
area, WD0HHU @ W0LJF.#NECO.CO.USA.NOAM. Also, if you find that the current
set of orbital elements are not generating the correct AOS/LOS times at
your QTH, PLEASE INCLUDE THAT INFORMATION AS WELL. The information you
provide will be of value to all OSCAR enthusiasts.
/EX