Ham Radio/Ham Radio CD-ROM (Emerald Software) (1995).ISO/news/amsat219/amsat219.txt

Text File | 1988-08-08 | 24.3 KB | 482 lines

SB ALL    @ AMSAT  $ANS-219.01
AO-13 Showing More Good Signs

HR AMSAT NEWS SERVICE BULLETIN 219.01 FROM WA2LQQ
WARWICK, NY  August 06, 1988
TO ALL RADIO AMATEURS BT

With more than two week's experience on the new AMSAT OSCAR 13, the number of
users on all modes is increasing as is their apparent satisfaction.  Veterans
and newcomers alike are praising the new satellite even as it remains in the
engineering phase prior to its official turnover for general operations. The
condition of the satellite continues to be excellent and, except for an
apparent glitch in the RUDAK packet system, optimism prevails.

Modes B and J have been widely applauded for their performance.  Their
sensitivity seems to be excellent. Although there seem to be few times when
the officially recommended uplink power levels suffice, this clearly is
attributable to transponder loading and the realization of a typical power
escalation scenario.

Higher than the officially recommended uplink power levels are apparently
being used by most Mode B and J users.  There is thought to be a power
escalation cycle that is initiated or accelerated by a few stations who have
wholly inadequate receive systems. All users MUST be aware a preamp is
essential for all AO-13 modes.  Operating without one is a prescription for
failure. Operating WITH a good preamp (preferably at the antenna) can convert
all the modes (especially L) from a strain to a plain joy.

Perhaps the biggest turnaround in user opinion has occurred in the Mode L
domain.  When first turned on July 24, Mode L was thoroughly panned by U.S.
users. Based on what they saw, U.S. users were wondering what European Mode L
users where cheering about. It was subsequently learned European Mode L users
enjoyed a very strong uplink advantage in the first few days of its operation
as a consequence of the squint angle of the satellite; the offset angle
between the Mode L uplink antenna and the uplinking station.  Analysis now
shows a squint angle greater than 10 or 15 degrees to be anathema for good
Mode L QSOs.

Another confusing element, which strongly abetted the gap between U.S. and
European reports on Mode L performance, was the discrepancy between previously
published Mode L frequencies and the ACTUAL Mode L frequencies.  For reasons
not yet clear, the frequencies previously published by AMSAT-DL and
re-iterated by AMSAT-NA and in various U.S. publications have proven
erroneous. (The Mode B and J frequency discrepancies are inconsequential; Mode
L frequency disparity is substantial.

The combination of amplitude and frequency discrepancies led many U.S.
satellite users to conclude Mode L had actually failed entirely. Few could
even find their downlink at all using all the power they had available to
them.

Fortunately, the big swing in opinion came like a whipsaw last week as Mode L
showed off its best to the West.  Favorable squint angles have come to the
U.S. and Mode L users there have changed their views entirely; have been
showing up in droves on the new mode.

And, as may be characteristic of U.S. amateurs, they vote with their
pocketbooks.  When they like something, they support it with equipment
purchases.  Equipment dealers report an unprecedented run on 24 cm equipment;
a sound vote of confidence in Mode L if there ever was one!

With the excellent conditions, analysts too have had a good chance to measure
the actual Mode L performance.  The results show what to expect under ideal
conditions and what to expect otherwise.  The resulting numbers suggest AO-13
Mode L is now working better than AO-10 Mode L ever was expected to!
(Specific data in a separate bulletin).

On a slightly less positive note, AMSAT-DL workers report there is a problem
with RUDAK, the packet digipeater developed in Munich.  When attempting to
bootload from the PROM, the RUDAK CPU runs for a while but then hangs up.  The
10 byte loader module will not allow a special program to be loaded into RAM.
It is now recalled from the thermal vacuum tests that the PROM (a fusable link
type) was then found to be temperature sensitive. AMSAT-DL is evaluating ways
of warming the RUDAK module.  One scheme being considered calls for energizing
the module next to RUDAK, the LIU (Liquid Ignition Unit).  This will warm up
RUDAK considerably and may solve the problem they say.

In sum, AO-13 continues to provide excellent performance on all its linear
transponders.  The RUDAK is being investigated for a possible thermal
malfunction and Mode S may be activated next month. New and veteran satellite
users alike are singing the satellite's praises and apparently thoroughly
enjoying the new bird!  Equipment dealers are being swamped with 24 cm
equipment orders and there seem few remaining open questions on what Mode L is
capable of.

/EX
SB ALL    @ AMSAT  $ANS-219.02
Tests Prove AO-13/L Superior

HR AMSAT NEWS SERVICE BULLETIN 219.02 FROM WA2LQQ
WARWICK, NY  August 06, 1988
TO ALL RADIO AMATEURS BT

On-orbit AO-13 Mode L performance tests completed last week strongly suggest
it is working well indeed; better even than its predecessor (AO-10 Mode L) was
expected to work by a couple of dB.  The tests also have shown the range of
conditions experienced by Mode L users and how to choose the best times to
work the new mode. The key to success on Mode L is now clearly shown to be
closely coupled with the positioning of the satellite's Mode L 24 cm uplink
receive antenna.

As expected, under poor conditions copious uplink power is required.  Many
tens of kilowatts (EiRP) will be insufficient under the worst conditions.  But
under good to ideal conditions, very moderate power levels will provide
satisfactory results.

The key to Mode L success, analysis this week has shown, is that users must
pay close attention to the pointing or squint angle of the satellite's 24 cm
helix uplink antenna.  Under good conditions, an approximate 2 hour sub-window
of optimum Mode L time will exist within the general Mode L window for a given
QTH.

About half the total Mode L time is the prime Mode L sub-window where the
squint angles are 10 degrees or less. According to Mode L operator John
Gayman, WA3WBU, when squint angles get much over 10 degrees, Mode L uplink
power requirements skyrocket.

Thus it's important to determine the timing of that prime sub-window when your
QTH will fall within that acceptance cone. AMSAT's QUIKTRAK program computes
the positioning of the cone based on the satellite's attitude in Bahn
coordinates, its current position on orbit and your QTH.  The PA (pointing
angle or squint angle) parameter is output by QUIKTRAK.

Under thoroughly ideal conditions, it now appears a Mode L uplink of 29 dBW
(about 800 watts) EiRP will produce about a 10 dB signal to noise ratio in a
2.4 kHz channel when received on a system with an approximate 50 degree Kelvin
system noise temperature at or near to apogee. (Figure of Merit = -2 dB/K).  A
50 degree K, 435 MHz receive system might consist of a 0.6 dB noise figure
preamp behind a 15 dBic RHCP antenna and a standard, modern SSB UHF receiver.
(CW signal performance is proportionately better).

However, under most practical operating conditions, more uplink power will
certainly be required on Mode L.  Factors increasing Mode L uplink power
requirements include polarization losses (3 dB penalty for running linear
polarization instead of Right Hand Circular Polarization); squint angle
(penalties mount very fast beyond squint angle of 10 degrees); increased path
losses; increased absorption at low elevations angles; heavy transponder
loading; local impediments (trees; houses), etc.

Based on these preliminary estimates, it now appears 33 dBW (2 kW) EiRP is the
lowest PRACTICAL level Mode L SSB users should expect to be regularly
successful with. For higher reliability, that is for your ability to work well
when combining penalty factors as described previously, another 5 dB or more
should be available. Based on these tests then, 38 dBW (6.3 kW) EiRP can be
expected to produce good SSB results under most (but definitely NOT all)
operating conditions.  Obviously, if one wants to work under the most adverse
conditions with strong, compound penalty factors, much more power will be
needed.

The 38 dBW level seems, however, to be a reasonable compromise between
performance, reliability, cost and physical structure.  For example, 30 watts
applied to the feed of a pair of 20 dBi loop yagis will produce about 37.3 dBW
5.4 kW) EiRP including losses; sufficient for good SSB QSOs under most
conditions and excellent for CW under most conditions.

Comparing AO-13 Mode L and AO-10 Mode L, it now appears the actual measured
performance of AO-13 Mode L exceeds the expected performance of AO-10 Mode L
by 1 to 2 dB.  (Of course AO-10 Mode L never actually achieved its potential
performance by a factor of at least 10 dB).  By contrast, AO-13 Mode L is
coming close to its corrected specs.

/EX
SB ALL    @ AMSAT  $ANS-219.03
AO-13 Ops Sked and Freqs Update

HR AMSAT NEWS SERVICE BULLETIN 219.03 FROM WA2LQQ
WARWICK, NY  August 06, 1988
TO ALL RADIO AMATEURS BT

AMSAT OSCAR 13 continues under engineering jurisdiction and has not yet been
officially released for full operations. Spacecraft controllers and engineers
have been meeting in Marburg, West Germany to evaluate spacecraft systems
performance to date and to plan general operations for the near-term and
mid-term future.  They have agreed on the following revised schedule said to
be effective until September 21 but subject to change for continued testing.

            Revised Operating Schedule: V3.0 6Aug88
  +---------------------------------------------------------------+
  |  Mode  |  From  |   Thru  |       Remarks        |  Duration  |
  |        |(Inclus)| (Inclus)|                      | MA  Minutes|
  |========|========|=========|====================================
  | Off    | MA 241 | MA  002 | Solar eclipse window | 18   48.3  |
  | Mode B | MA 003 | MA  099 |                      | 97  260.2  |
  | Mode L | MA 100 | MA  180 | Mode JL optional     | 81  217.3  |
  | Mode B | MA 181 | MA  220 |                      | 40  107.3  |
  | Mode B | MA 221 | MA  240 | With omni antennas   | 20   53.6  |
  |--------+--------+---------+----------------------+------------+
  | Mode S |        |         | Commence September(?)|            |
  | RUDAK  |        |         | Testing; ops pending |            |
  +--------------------------------------------------+------------|

The current attitude is approximately BLON=180, BLAT=0.

The updated frequencies, based on in-orbit tests and corrected for Doppler
shift, to within 1 kHz, are:

 Mode B: the sum of uplink and downlink frequencies equals a constant 581.398
 MHz. At Mode B mid-band, 145.890, the required uplink is 435.508 MHz.

 Mode J: the sum of uplink and downlink frequencies equals a constant 580.413
 MHz. At Mode J mid-band, 435.965, the required uplink is 144.448 MHz.

 Mode L: the sum of uplink and downlink frequencies equals a constant 1705.356
 MHz. At Mode L mid-band, 435.860, the required uplink is 1269.496 MHz.

/EX
SB ALL    @ AMSAT  $ANS-219.04
Surrey/UK Colloquium Summary

HR AMSAT NEWS SERVICE BULLETIN 219.04 FROM WA2LQQ
WARWICK, NY  August 06, 1988
TO ALL RADIO AMATEURS BT

Over 160 persons from 19 countries attended the 3rd AMSAT-UK/UoSAT Space
Colloquium held at the University of Surrey last weekend (29-31 July).
International speakers presented 20 papers on diverse topics, covering:

 Geostationary AMSAT Phase 4 spacecraft designs
 AMSAT Phase 3D spacecraft design
 UoSAT-C, D and E spacecraft technologies
 Amateur Radio using High Altitude Balloons
 AMSAT OSCAR 13 spacecraft orbital commissioning and operations
 UoSAT-1 & 2 spacecraft orbital operations
 The Chinese Space Program
 Digital signal processing techniques for amateur satellite communications
 Packet Radio Satellites
 Soviet/Canadian Transpolar SKITREK Future Soviet amateur radio satellites

Among the many radio amateurs who attended were Jan King (W3GEY), Karl Meinzer
(DJ4ZC) and Leo Labutin (UA3CR). Leo was particularly welcome and read a paper
describing the SKITREK project and spoke on future Soviet satellite plans.

The Colloquium was preceded by a one-day Satellite Technical Workshop devoted
to detailed discussions of advanced amateur satellite techniques and a one-day
co-ordination meeting sponsored by the Radio Society of Great Britain focusing
on funding, frequency allocation and educational matters.

Colloquium Proceedings, comprising 16 of the papers presented, were sold out,
However, additional copies will be available shortly from AMSAT-UK.  The
sponsors send their thanks to all who visited UoS last week and who made the
Colloquium such a success! (Bulletin per UO-11 BBS; tks UoS)

/EX
SB ALL    @ AMSAT  $ANS-219.05
UO-11 DCE Linking Strides

HR AMSAT NEWS SERVICE BULLETIN 219.05 FROM WA2LQQ
WARWICK, NY  August 06, 1988
TO ALL RADIO AMATEURS BT

The UO-11 DCE (Digital Communications Experiment) packet radio gateway network
continues to grow. ZL1AOX, VK5AGR, GB3UP and ZS6SAT are passing messages for
large packet radio user networks in New Zealand, Australia, the UK and South
Africa.  A new station, ZL5BA, is located on Ross Island in the Antarctic.
The operator there (SoJo) is working at a Greenpeace scientific base. He will
use his DCE station for recreation and to send health & welfare messages home
for the others at his base.  ZL5BA was activated on 29 July and is providing
an interesting insight into the coverage received by polar stations from a
polar orbiting satellite.  He sees UO-11 on almost every pass although some
times of day provide higher elevations than others.

Surrey plans to commission a USA gateway soon.  The station is N6IIU in the
San Francisco area.  This station is located in a Red Cross headquarters which
already houses an emergency communications station and a packet BBS.
Discussions are also under way with an East Coast USA amateur.  Meanwhile, a
gateway in West Germany is also almost ready to go.  DB2OS, one of the AO-13
control operators, will bring DCE access to the well-developed European packet
radio network.  When the USA and Europe are on line, the DCE will be able to
link together all of the major amateur radio packet networks worldwide.
(Bulletin per UO-11 BBS; tks UoS)

/EX
SB ALL    @ AMSAT  $ANS-219.06
RS-5, RS-7 Dead Report Avows

HR AMSAT NEWS SERVICE BULLETIN 219.06 FROM WA2LQQ
WARWICK, NY  August 06, 1988
TO ALL RADIO AMATEURS BT

Recently, Leonid Labutin of Moscow, a prime mover in the Soviet Radio Sputnik
(RS) program, said that on July 15 the first western amateur visited the USSR
RS command station RS3A in Moscow.  Danny Kohn, SM0NBJ, of AMSAT-SM, visited
UA3CR during his recent stay in Moscow. Danny interviewed the chief operator
there, Leo Maxakov, RA3AT, made tape recordings and took pictures.

According to Nico Janssen, PA0DLO, upon Danny's return to Stockholm, he
promised to make an extensive report on his visit to RS3A. One of the
interesting things he has already told the European AMSAT Net (on July 23)
was, that according to the operators at RS3A, the old RS satellites, RS-5 and
RS-7, are definitely out of operation now. RS3A has gradually lost control
over these last two active RS satellites of the RS-3 to RS-8 series. They are
convinced that the batteries in RS-5 and RS-7 are dead so no new activities
can be expected from these satellitese. RS-3 through RS-8 were launched
together on December 17, 1981.

/EX
SB ALL    @ AMSAT  $ANS-219.07
Absurd FCC 220 Move Shocks AR

HR AMSAT NEWS SERVICE BULLETIN 219.07 FROM WA2LQQ
WARWICK, NY  August 06, 1988
TO ALL RADIO AMATEURS BT

Amateur Radio was badly shaken last week when on August 4, the FCC adopted a
report and order in general docket 87-14, the proposal to reallocate the
220-222 MHz band to the land mobile service.

According to the ARRL, in balancing the impact on existing users, emergency
communications, and future amateur growth against land mobile requirements,
the Commissioners concluded that the reallocation was in the public interest
despite overwhelming opposition.

Wishing to reassure amateurs of its strong support for the service, the FCC
emphasized that the remaining 3 MHz of the band, 222-225 MHz, would be
available to amateurs on an exclusive basis, thus removing the cloud that has
hung over the status of the band for many years.  The effective date of the
reallocation will be announced later.

ARRL continues to oppose the reallocation, and will pursue all available means
to reverse the commission action.

AMSAT emphasized other bands of even greater import are similarly vulnerable
and urged support of its landmark Phase 4 Geosynchronous Satellite Program to
deflect further frequency grabs especially at 1.3 GHz and up.

/EX
SB ALL    @ AMSAT  $ANS-219.08
Short Bursts

HR AMSAT NEWS SERVICE BULLETIN 219.08 FROM WA2LQQ
WARWICK, NY  August 06, 1988
TO ALL RADIO AMATEURS BT

The annual meeting of the Central States VHF Society took place in Lincoln
Nebraska the weekend of July 22-24.  According to Bill Tynan, W3XO, quite a
number of AMSAT Members were on hand.  They included AMSAT Regional
Coordinator Keith Pugh, W5IU, who accepted a donation from CSVHFS on behalf of
AMSAT.  Keith got the "customary" $400 check plus a $200 "Well Done" bonus for
the success with AO-13.  AMSAT expresses its thanks to the CSVHFS for these
kindnesses.

The current AMSAT fund raising drive initiated by a letter to all domestic
AMSAT members is quickly becoming the most successful in AMSAT history only 3
weeks after it was kicked off.  Those who donated $20 or more to the fund will
be receiving their free, handsome all-OSCARs frequency guide in the mail soon.
The frequency guides, including the latest AO-13 frequency updates, are now in
production and will be mailed to all qualified donors before the end of
August.  There is still time for those who haven't already done so to mail in
their donations in the envelope supplied and receive their frequency guide
free before supplies are exhausted.

AO-13 "First Day Club" logs, certificates and QSL cards are being processed
and should be mailed to all qualifiers by mid-September.

Here is the current AO-10 operating schedule:
 August 1  - August 15: Mode B  MA 30 to MA 240
 August 16 - Further notice: Out of Service
AO-10 is showing some signs of the anticipated seasonal power-down.  FMing has
been heard and the beacon has appeared to be under low-power duress.  Please
do not use AO-10 if you observe these symptoms which are expected to become
more common in the next few days. The satellite will be unavailable for use
beginning August 16 because of predicted insufficient solar illumination and
reduced battery charge.

JARL says it will soon begin work on another flight model of JAS-1 with an eye
towards launching a second OSCAR after a long hiatus since the launch of JAS-1
(FO-12).  Efforts with JAS-1B will focus on improving the satellite's tight
power budget and antenna directivity in order to obtain a flatter pattern for
better performance.

Here is the FO-12 operating schedule.
Mode  From (UTC)
----------------
JA  Aug 06  0845
D       07  0751
JA      11  0617
D       12  0724
JA      13  0630
D       14  0536
JD      18  0603
DI      19  0712
JD      20  0415
DI      21  0523
JD      25  0348
DI      26  0457
JD      27  0606
D       28  0511
JA      30  0120
D   Aug 31  0228
JD = Digital mode
JA = Analog mode
D  = All systems off
DI = Systems off except CPU and memory

The transponders will be off at other times. The actual operating schedule may
change due to unexpected situations such as variations in available power.
Mode JA Beacon: 435.795 MHz. Mode JD Beacon: 435.910 MHz.

/EX
SB ALL    @ AMSAT  $ANS-215.01
AO-13/L Perspectives Improve

HR AMSAT NEWS SERVICE BULLETIN 215.01 FROM WA2LQQ
WARWICK, NY   August 2, 1988
TO ALL RADIO AMATEURS BT

AMSAT OSCAR 13's linear transponders, Mode B, J and L have been putting in
regular service for more than a week now and, while Modes B and J have been
drawing rave reviews, Mode L reports from U.S. users were not quite as rosy.
Since August 1, however, U.S. Mode L users have gotten to see the satellite
from a different perspective in both a literal and figurative sense.  The
result is a renewed optimism in Mode L functionality.

During its first week of operation beginning July 24, would-be Mode L users in
the U.S. were discouraged by poor results and confused by optimistic reports
originating in Europe.  Many couldn't even find their downlinks.  This has
been determined to be the result of two factors: 1. The Mode L translation
frequencies previously published have been invalidated (probably by a change
in an electrical parameter in the transponder) so many were listening on the
wrong frequency and 2. Perspectives on the satellite from the U.S. were poor.

Last week European Mode L users were looking "right down the barrel" of the
satellite's Mode L receive antenna and had good results. In contrast, U.S.
Mode L users were pounding against the side of the satellite outside the
narrow Mode L uplink beam. Now that U.S. users are well-situated in the beam,
reports from U.S. Mode L users are much more positive.

According to AMSAT officials, recent tests on Mode L indicate its performance
is actually quite good; even better than AO-10 was expected to be had it
worked properly.  AO-13 is exceeding the expected performance of AO-10 Mode L
by a dB or 2 they said.  Whereas uplink recommendations for AO-10 Mode L were
in the 3 kW EIRP range, it now appears a good, if not booming, SSB QSO can be
had under good conditions with 2 to 3 kW (33 - 34.8 dBW) EIRP or with 1.5 to 2
kW (31.8 - 33 dBW) EIRP under ideal conditions. These values can be reduced by
another 3 dB if right hand circular polarization (RHCP) is used on the uplink
instead of linear polarization. Under transponder loading, however, the
required uplink power will obviously go up.

In sum, under totally ideal conditions (boresighted, RHCP and alone on the
transponder), about 800 W (29 dBW) EIRP will be adequate for a reasonably good
SSB QSO.  Under less than ideal conditions, you'll need more power.  It would
be a good idea to have another 6 to 8 dB in reserve.  Thirty watts to a pair
of 20 dB loop yagis will yield about 37.3 dBW (5.4 kW) EIRP including splitter
losses.

So AO-13 is in fact doing quite well!  And last week's optimistic reports by
G3RUH and other Europeans have been largely corroborated by subsequent reports
from U.S. users.

The key to the renewed optimism is the realization that there is an additional
constraint on Mode L use beyond that of the Mode B and J transponders.  That
additional constraint is the satellite's 24 cm uplink antenna beamwidth.  Its
fairly narrow beamwidth (-3 dB value is 49 degrees), combined with the
beamwidth of the 70 cm downlink antenna means one needs to be fairly close to
"boresight" to do well on Mode L.  But now that that fact is recognized, Mode
L users can take it into account in planning their use of this powerful mode
and be successful.

Mode L is not just a higher frequency Mode B, AMSAT officials point out.  When
planning Mode B operations, one simply checks to see if the satellite is above
the horizon and if the Mode B transponder is scheduled to be on.  With Mode L,
they point out, there is an additional consideration: Where is the narrow 24
cm footprint relative to you?

The angle between the boresight and your QTH is often called the squint angle.
In AMSAT's QUIKTRAK program it's called PA or pointing angle.  Using QUIKTRAK,
one can readily determine when the PA is sufficiently low so as to facilitate
Mode L QSOs.  Best results occur when PA is less than about 10 degrees. When
using QUIKTRAK, be sure to set STABTYPE to 0 to get the pointing angle
function to work properly. Current Bahn coordinates are about BLON=180,
BLAT=0.

Now that both the Mode L frequency translation matter and the squint angle
issues have been resolved, Mode L use in the U.S. is expected to skyrocket.
Equipment suppliers already report unprecedented activity in 70 and 23 cm
equipment and attribute this largely to a huge ground swell of interest in
AO-13.  AMSAT says it's preparing numerous special event activities on Mode L
including the return of the popular ZRO Test and Technical Achievement Awards
Program. Stay tuned.

/EX