[amsat-bb] Concise Guide to Working the Easy Sats - includes UO-14

[Mike Gilchrist <kf4fdj@xxxxxxxxx>]

A Concise Guide to Working the Easy Sats

This document should be considered a WIP (Work In Progress).  In reaction 
to many questions regarding how to work the easy sats, this effort was 
born.

Mike Gilchrist, KF4FDJ -- February 28, 2000 -- Fort Myers, FL



THE ACTIVE BIRDS

Now that MIR is silent, there are currently 4 satellites that fit the 
category of easy sats.  FO-29, when in digitalker mode, AO-27, for daylight 
passes over the Northern Hemisphere, SO-35, or SUNSAT, when the operators 
turn the device on, which is usually weekend daylight passes over Europe 
and North America, and UO-14, which is usable during all passes visible to 
the operator.

The FO-29 digitalker transmits on a frequency in the 70-cm band.

AO-27 is a mode J FM bird.  Mode J is 2-meters up, and 70-cm down.

SO-35 is also an FM bird, and is usually operated in mode B, but can also 
be operated in mode J.  Mode B is 70-cm up and 2-meters down.

UO-14 was launched as a digital workhorse.  It managed to carry digital 
traffic half way around the world for medical staff working in 
communication challenged third world countries.  The torch, and duties were 
passed to UO-22.  Since that time, the bird has been sending telemetry, 
until February, 2000, when the control operators toggled the bird to mode J FM.


WHEN AND WHERE TO POINT

Since all these birds are low earth orbit satellites, most passes will be 
between 6 and 18 minutes in duration.  Timing is critical in working any 
amateur satellite.

Since these birds are all considered weak signal, you must know when the 
satellite will pass over your location, and where in the sky to point your 
antenna.  You will need a program to generate predictions of when the 
satellite is "visible" to you.

An excellent place to find downloadable software for real time tracking of 
satellites, and other information on the amateur satellite program in 
general, is:

http://www.amsat.org

I believe WINORBIT 3.6 is one of the better programs available for 
beginners using PC type computers.  Mac users should look at MacDoppler, 
available from the AMSAT site, or from the developer’s site:

         http://www.dogparksoftware.com/Macintosh_Amateur_Radio_Pr.html

Both of these programs have proven to be Y2K compliant, and load 2000 
Keplerian coordinates with no problem.

Be sure to download the latest Keplerian coordinates if you download a 
tracking program.  Each prediction program needs these coordinates to 
determine where the satellites are, and to help you determine when the 
satellite will be over your horizon.  Another casual approach, is to use an 
online prediction site, such as:

      http://acsprod1.acs.ncsu.edu/scripts/HamRadio/sattrack

This site will generate pass predictions for a selected satellite.  Be 
aware, that as of the time this article was written, this site is using 
stale Keplerian coordinates, and might not give absolutely correct 
positions for the satellites.  They might be off by close to a minute.  If 
I encounter a similar site with more up to date coordinates, I will modify 
this text accordingly.



THE DOPPLER EFFECT

Since LEO (Low Earth Orbit) satellites travel at high velocity, radio 
signals arriving at and moving away from the satellite are subject to a 
perceived change in frequency.  This phenomenon is called Doppler shift.

Much as a passing car with horn blaring will seem to change pitch the 
moment it passes an observer, satellite communications are subject to the 
same effects.  While listening to a signal from a satellite that is 
approaching your position, you will receive the signal slightly higher than 
the actual transmitted signal.  As the satellite moves away from you, the 
received signal will be found lower in frequency than the actual 
transmitted frequency.

The opposite effect is seen on an uplink signal to a satellite.  If the 
bird is approaching you, your transmit frequency will be slightly lower 
than the frequency the satellite receiver hears.  Likewise, as a bird 
recedes from your position, you will need to transmit higher in frequency 
to compensate for the Doppler effect.

Doppler shift is more pronounced the higher the transmitted frequency.  As 
a rule of thumb on the LEOs, the maximum 2-meter Doppler shift is around 
3.5 kHz, while on 70-cm, it may be close to 10 kHz.

The Doppler frequency shift is most pronounced as the satellite makes 
closest approach to your position and then moves away. Passes low on the 
horizon will have less Doppler shift than a pass closer to your zenith.

Most readers of this document will be using a handheld scanner or an HT to 
listen to, or work the easy sats.  Since these devices are generally only 
capable of being tuned in 5 kHz increments, you will have to program a 
series of frequencies into your rig.  Under each section for a particular 
bird, I have included a list of frequencies tabulated, mindful of this 
limitation.



LISTENING TO THE FO29 DIGITALKER

The digitalker on FO-29 is a digital loop announcement, which makes the 
same announcement over and over. You will hear, "Ho- ho'kke'kyo, this is 
JAS two."   The first part is the song of a bush warbler.  JARL (Japanese 
Amateur Radio League), plans to cycle digitalker, mode JA, and mode 
JD.  The digitalker message is subject to change.  Check announcements on 
the BB for a mode schedule and other details.

Since FO-29 transmits in FM mode while in digitalker, any FM or multimode 
receiver capable of tuning the 70-cm ham band should be able to detect the 
signal.

Digitalker operation dedicates most of the power budget of the satellite to 
the FM transmitter, instead of spreading it across a mode JA transponder. 
It is a very strong signal!  It is possible to hear the satellite with a 
handheld scanner or transceiver, and a stock "rubber ducky" antenna.  Most 
70-cm base stations, or scanner listening posts, with fixed antennas, 
should also be able to tune the signal.

If you are using a handheld device, you will need to rotate the rig (and 
antenna) for the best orientation.  Experience shows that horizontal 
polarization, with the axis of the antenna perpendicular to the satellite 
gives the best reception.  Experiment!

The transmit frequency is 435.910.  Of course, you will have to compensate 
for Doppler shift.  Just remember you will tune a little higher in 
frequency as the satellite approaches your position, and a little lower in 
frequency as it recedes.  You will always be tuning higher in frequency 
when the satellite comes over the horizon.  Make sure you have your radio 
set to tune small increments, as increases and decreases in Doppler are 
gradual.

Here are the frequencies you should program into your rig:

435.920
435.915
435.910 Mid Pass
435.905
435.900

The digitalker presents an easy opportunity for hams and non-hams to have 
their first taste of real time reception of signals from space.  Use this 
opportunity to show a kid, or a terrestrial ham how easy it can be to tune 
a satellite.  This opportunity is excellent for scout meetings, monthly ham 
meetings, schools, or any place where inquisitive persons congregate.



WORKING AO27

As previously stated, Oscar 27 is a mode J satellite.  Your uplink needs to 
be a low power 2-meter signal.  AO27 is at times a difficult bird to 
hear.  You will need 70-cm FM receive capability.  Many operators use a 
dual band HT to work this bird.

A gain antenna for 70-cm is usually required; a stock rubber ducky will not 
be adequate.  I have had limited success with a long, wispy dual band ‘cat 
whisker’ type gain antenna.  If you use a car body or another piece of 
metal as a reflector, you will increase your chances of working the 
bird.  In any event, whichever antenna you use will have to be rotated to 
best match the polarity of the bird.  Experience shows a vertical 
orientation at the beginning of the pass, to nearly horizontal mid pass 
works best.

AO27 is a polar orbiting satellite, meaning the orbit of the bird takes it 
nearly over both the South and North Poles.  Software controls the amateur 
radio payload, which toggle the satellite on during passes from north to 
south, and only during daylight passes.  The satellite turns on several 
minutes after entering daylight, and stays on for another several 
minutes.  Because of these limitations, the bird is only usable by 
operators in the Northern Hemisphere, and those close to the equator -- 
ONLY during daylight passes.

Operators should understand that this satellite is seldom vacant, and if 
you can’t hear it, DON’T transmit.  You will only cause QRM to other 
operators, and sully your reputation.  AO27 has a very sensitive receiver, 
and I have managed to hit it with 100 mw of power at times.

Since AO27 is a very busy satellite, especially on holidays and weekends, a 
portable operator will most likely have limited success, unless they use a 
multi-element gain antenna for the uplink and downlink.  I have also found 
use of a preamplifier beneficial for hearing the bird well, and knowing 
when to jump in for a contact.

Most QSOs are short, contest style exchanges, including grid square, first 
name, and city.  This sort of contact maximizes use of the bird for the 
scores of operators who might be trying.  Weekend passes, to the 
uninitiated, sound a bit chaotic.  There is a culture, which exists on the 
bird, and my best advice is to listen to a couple passes, and model your 
operation after the successful operators you hear.

AO27 is a full duplex bird, meaning that you can listen to the downlink as 
you transmit.  If your rig is capable of full duplex operation, fine, 
otherwise half-duplex operation works just fine on the FM birds if you 
program the frequencies in your HT correctly.

You should program your HT with 5 frequency pairs for working AO-27.  Start 
with the first pair, using a non-standard split, and tune to the next one 
as the pass progresses.

Downlnk -  Uplink
_________________
436.805 - 145.845
436.800 - 145.850
436.795 - 145.850  Mid Pass
436.790 - 145.850
436.785 - 145.855

The Doppler shift on the 70-cm downlink can be a little more than 10 
kHz.  The 2-meter Doppler is close to 3 kHz.

I seldom need to use the 5th pair, except on high passes, and only when the 
TEPR keeps the bird on so far south like it is operating presently!



WORKING SO35 - SUNSAT

SO35 typically operates in a mode opposite AO27 -- mode B as opposed to 
mode J.  Mode B is 70-cm up and 2-meters down.  While the 2-meter uplink 
Doppler correction on mode J is not terribly critical, you must compensate 
for Doppler on the 70-cm uplink while using this bird.  The Doppler 
correction on this bird is counter-intuitive, if you are used to working a 
mode J bird.  Doppler shift on the 70-cm uplink is roughly 3 times as great 
as the 2-meter Doppler shift.  Maximum Doppler shift on the 70-cm uplink 
can be a little over 9 kHz!  If you DON'T tune the uplink, you probably 
WON'T be one of the successful operators.

While the downlink on AO27 is hard to hear, SUNSAT has a very strong 
downlink signal, and is receivable with a standard rubber ducky antenna 
atop a handheld scanner or HT.  The bird also seems to have a very 
sensitive receiver, so low power HTs will work the bird if conditions allow.

Since this satellite has been usable only a few times, and is active only 
on weekend daylight passes; it is a very popular bird when active.  As with 
all FM receivers or repeaters, the satellite is captured by the strongest 
signal.  As a portable operator, you might have only limited success 
working this bird, although you should be quite successful receiving 
signals from the satellite.

As with AO27, short contest style contacts help facilitate more users 
during a pass.  Common sense and courtesy must prevail.  As with any 
amateur communication, use the minimum power necessary to complete the 
contact.



If your rig is capable of tuning small increments, use this table as a 
guide.  Tune the downlink until your discriminator meter, or S meter shows 
you are tuned to the correct downlink frequency.  Look across the table and 
make certain your transmit frequency is close to the associated 70-cm table 
entry.

Downlink  --  Uplink
--------------------
145.828      436.282
145.827      436.285
145.826      436.288
145.825      436.291  Satellite directly east or west of you
145.824      436.294
145.823      436.297
145.822      436.300



If you are using a scanner to listen, or an HT which only tunes in 5 kHz 
increments, use this table as a guide. Since the downlink frequency will be 
closest to 145.825 during most of the pass, break the pass into a little 
over 3 minute chunks, and increment your programmed pairs (you will need to 
program nonstandard splits) during the pass for best centering in the 
passband of your uplink signal.


Downlink  --  Uplink
--------------------
145.830      436.280
145.825      436.285
145.825      436.290  Satellite directly east or west of you
145.825      436.295
145.820      436.300


The first or last pair may not be required, depending on your latitude.

To determine the latest operating schedule and mode (if it changes) for 
SO35, check out the SUNSAT website:

http://sunsat.ee.sun.ac.za/ham.htm




WORKING UO-14

UO-14 is currently operating as an FM bent pipe "repeater" satellite. As 
such, it is a full duplex bird, meaning that you can listen to the downlink 
as you transmit. If your rig is capable of full duplex operation, fine, 
otherwise half-duplex operation works just fine on the FM birds if you 
program the frequencies in your HT correctly.

UO-14 is functionally similar to AO-27, but is available during all passes 
visible tot he operator.  The transmitter is a little more powerful than 
AO-27, so antenna gain and orientation do not seem to be as critical.

I can hear UO-14, using an HT, in the middle of my one story ranch 
home.  Working the bird, at the time of this writing is difficult at QRP 
levels.  Due to the popularity of the bird, and perhaps because it is new, 
this bird is very active.  Until the activity subsides, working this bird 
as a low power operator will surely test your abilities.

You should program your HT with 5 frequency pairs for working UO-14. Start 
with the first pair, using a non-standard split, and tune to the next one 
as the pass progresses.


Downlnk - Uplink
_________________
435.080 - 145.970 AOS
435.075 - 145.975
435.070 - 145.975 Mid Pass
435.065 - 145.975
435.060 - 145.980 LOS

As with the other FM birds, if the satellite is busy, limit both the 
quantity and duration of your QSOs.  All users should view the amateur 
satellite fleet as a shared resource, and strive to develop considerate 
operating practices.





OTHER INFORMATION

One of my favorite web sites to send an inquiring person for a visit is:

         http://sulu.lerc.nasa.gov/rleonard/index.html#section1

A great place for kids to learn about space science is:

         http://www.nasa.gov/kids.html

Another site which all teachers, scout leaders, or any other person wanting 
to bring the world of space science to others should bookmark is:

         http://education.nasa.gov/


A site for those wanting to know a little about the distinction between Low 
Earth Orbit, Medium Earth Orbit, and High Earth Orbit satellites should 
visit this slow loading, but comprehensive site:

         http://www.geocities.com/~saltillocib/sitepages/commentindexp.html


An excellent web site, maintained by Jerry, K5OE, is:

         http://hometown.aol.com/k5oe

Jerry has designed and documented some very nice antennas, capable of 
working the LEOs.  Most of his projects can be built for low cost, using 
materials from a home improvement store.




PROCEDURES FOR THE SUCCESSFUL OPERATOR

Here are some parting thoughts on how to help ensure you will be a 
successful operator on the easy sats.  As with all things in life, careful 
planning, thoughtful attention to your skills, and a friendly style will 
help assure you of many hours of satisfying satellite operation.

1) Operators who only put their call out are seldom picked out of the crowd 
and engaged in a QSO. Instead, pick a station and call them specifically. 
Try to time your transmission so you jump right in when the last QSO clears.

2) Rehearse what you're going to say. When the bird is yours, speak loudly, 
clearly, and to the point. Excess "umm, ahh, well, ah" transmissions will 
only cause other operators to ignore you, especially on a busy bird.

3) Don't call CQ. If there is at least one other operator out there, they 
will hear you. Reserve calling CQ for the linear birds where one must hunt 
up and down the transponder for a signal. If you are calling CQ, most 
operators assume you can't hear the bird.

4) Use email and posts to the BB as an effective means to increase your 
chances. Pick a regular, and send them an email. You might want to tell 
them you are going to be QRP portable on AO27, SO-35 or UO14 the second 
pass tomorrow, and ask then to listen for you. Many times such a technique 
will open the door, and other operators who have heard your call and grid 
will call you as well.

Usually, when an operator posts they are going to be working a special 
events stations, or a rare grid, or from a unique operating position, they 
generate traffic. Try announcing you will be working mass transit 
portable.  :-)

5) Use a gain antenna, properly oriented and pointed at the satellite. Move 
around and optimize your position. Many times unseen elements affect the 
antenna pattern, and moving a few feet makes all the difference.

6) Invest in a preamplifier. Many times it makes the difference between 
being able to work the bird or not. If you can't hear it, you can't work 
it! (see #3)

7) Be polite and thank the other operator for the QSO. Nice guys DO win, 
and will be given a second chance.

8) If another operator calls a station, and you hear them, wait a second 
before "grabbing" the bird. If you jump in too soon, you will acquire a bad 
reputation and other operators will avoid you.

I think many times the case is an operator does NOT hear the initial call, 
instead of a callous disregard for decorum, which stems from having a poor 
downlink. (see #6) There are several frustrated operators out there who fit 
this model, and believe me, they ARE ignored. There IS a culture on the 
easy sats, and a little time spent monitoring and learning this culture 
will be time well spent.

9) Don't whine. If you whine on the sigs or bulletin boards, or on the 
satellites, you might acquire a bad reputation and other operators will 
avoid you. If someone else tries to engage you in negativism here or on the 
birds, dismiss them. Do not enter into negative dialog, period.  Generally 
negativism comes from failure. Encourage them to improve their lot, and 
become a winner.

So, the well equipped operator, who is polite, persistent, speaks clearly, 
and gets to the point is the operator who will have most success as a 
portable satellite operator.


73, and think positively -  Mike

If you have any comments, additions, or modifications to this document, 
please contact me directly.  We will attempt to post the latest version of 
this document monthly.

This document is copyright © 1999 by Michael J. Gilchrist and may not be 
reprinted in part or whole without permission from the author.





                                        __\/__
     |                              .  / ^  _ \  .
     |                              |\| (o)(o) |/|
     ^    ---   * -----------------.OOOo--oo--oOOO.------------------- *
    |||   | |   * Mike Gilchrist - KF4FDJ ..... AMSAT Area Coordinator *
    |X|   | |   * P.O. Box 763 ................ AMSAT  member   #31884 *
    [X]~~~|k|   * Fort Myers, FL  33902 ....... ARRL  member  #1781549 *
   /   \  |f|   * http://www.gate.net/~seven77  telephone 941.772.7907 *
  |     | |4|   * kf4fdj@amsat.org ............................ EL96ap *
  |  P  | |f|   * I.S. Professional .............. Computer Consultant *
  |  3  |=|d|   * AO10, AO27, Fujis, RS13, RS15, MIR?, SO35, UO22, ATV *
  |  D  | |j|   * KITSAT,  kf4fdj-9 van tracker, SSTV, MS,  E&F Layers *
  |     | | |   *    Bringing Oscar demos to the Lee County Schools.   *
  |_____|=| |   * * * * * * * * * * * * * *  * * * * * * * * * * * * * *
   /*X*\  | |   *  Black holes were created when God divided by zero.  *
  ________|_|______________________________Oooo.________________________
                                   .oooO   (   )
                                   (   )    ) /
                                    \ (    (_/
                                     \_)

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org