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October 16, 2005

*How to be successful with the ISS Slow Scan TV (SSTV) Imaging system*

/By G. Miles Mann, WF1F MAREXMG  for the
ARISS-International Team/

There are currently two projects on board the
International Space Station that will support Slow
Scan TV (SSTV).  These projects are called SuitSat and SpaceCam.  The 
SuitSat project may be activated in December 2005 and SpaceCam in 2006 
(all dates are subject to change without notice).  The goal of this 
series of memos is to get the world ready to start decoding SSTV images 
from Space.  If you want to get Ready for SuitSat and SpaceCam Slow Scan 
TV, then now is the time to  start getting ready.

*/How to Slow Scan TV from Space, Part 1./*

* Slow Scan TV on the International Space Station:*
The ISS Slow Scan TV system will support two-way SSTV image 
transmission. SSTV is a form of sending still images via an Analog 
format by radio.  Amateur Radio operators have been using SSTV since the 
Today there are many software applications available that will allow you 
to connect your home computer to a radio and allow you  to decode images 
from space.

*The Basics:*
The Slow Scan TV system on the International Space Station that I will 
be focusing on is called
SpaceCam1.  The SuitSat Project may be activated
first, however the functionally is very similar. The
SpaceCam1 project is a PC based application that will be running on 
board the International Space Station.
The system will be connected to an Amateur Radio
transceiver called the Kenwood D700.  This radio will transmit on the 
Amateur radio 2-meter satellite band from the ISS (The exact uplink and 
down link
frequencies will be posted later).  The transmission
mode will be FM (aprox 4k deviation) and will be
sending images in the Slow Scan TV format called
Robot-36.  When SpaceCam becomes operation, it will be transmitting over 
400 images per day from the International Space Station.  The crew will 
load a directory full of still images taken earlier and then
tell SpaceCam to run "Slide Show".  SpaceCam will then keep sending the 
images from the directory over and over again.  This will allow people 
on earth several chances to decode all of the images from the directory 
on board the International Space Station.

The SpaceCam slide show will be configured for a
specific delay between images.  Lets assume the delay is set for 3 
minutes. The Space Station will pass within radio range of  your house 
several times a day for up to 10 minutes per pass.  During a typical 
10-minute window you will have the opportunity to receive 2-3 images per 

*SpaceCam & Kenwood D700 System:*
The Kenwood transceiver that has a built in Packet
modem. This system is located in the Service Module.
The Kenwood model D700 supports two Amateur radio bands: 2-meter FM (144 
- 146 MHz) and the
70-centimeter FM (435 - 438 MHz).  The built-in modem or TNC supports 
1200 and 9600 baud data rates.  The D700 is currently connected to one 
of the 4 Amateur Radio antennas mounted outside of the Service Module.
The typical power output of this system is 5, 10 or 25 watts.  The 
Kenwood D700 system was activated in December 2003.  The D700 will also 
be the primary radio for the SpaceCam SSTV project.  The ISS crew will 
connect the D700 to a laptop computer via a custom designed adapter 
module made by ARISS. The VOX-Box will match the audio signals from the 
laptop computer to the D700 radio.  The VOX-box will also signal the 
radio when it is time to transmit.

*What do I need at home?*
To work ISS from your home, you should have at least the following 
Amateur Radio equipment:
A 2-meter FM radio with an output rating of 25 to 50 watts.
An Omni-directional antenna or small beam (the higher the gain the better).
A short run of good quality coax (RG-213, 100 feet or less).
A PC running one of the common Slow Scan TV decoding applications.
(In this memo I will not go into the details of any
one specific SSTV applications at this time.)
And that is it for radio equipment. I use an
inexpensive Laptop computer with a 233 MHz CPU and Windows 2000.  The 
software I use is either CPIX by Silicon Pixels or and engineering 
version of SpaceCam1
(Sorry, SpaceCam1 is not for sale).
Slow Scan TV Decoding Software
Here are just two of the many Share-Ware SSTV
applications on the market.  There may be many more.

W95SSTV by Silicon Pixels


There are also many High quality pay software
applications that offer many more features, such as
multiple windows that allow your to simultaneously
receive an image while preparing your next image that you want to transmit.


You will need access to a computer or web to tell you when ISS is in 
range of your station. The timing of your contact is the most important 
part of a
successful contact with ISS. There are many tracking programs out in the 
market place today. The ARISS team does not endorse any specific 
tracking program. Some programs are share-ware (STSPLUS); others cost a 
few bucks. I recommend using the DOS InstantTrack, program by AMSAT. 
www.amsat.org <http://www.amsat.org>  This program is very easy to
use and works very well with older style computers
such as 80286 style PC's. The cost of most tracking
software applications is approximately $50-100.

*Doppler Shift:*
The ISS Space Station is traveling around the Earth at over 17,500-mph 
(28,000 Kph). This great speed will make radio signals appear to shift 
in frequency. This phenomenon is called Doppler Shift. Many of us have 
radios that are Channel locked. This means you cannot make any fine 
tuning adjustments to your receiver or transmitter's frequency. Most 
Mobile and HT radios cannot make any frequency changes less than 5 kHz 
channel steps (lets hope that radio manufacturers will add 1 or 2 kHz 
channels steps in the future). This Doppler shift will cause the ISS 
transmit frequency (145.800) to look as if it is 3.5 kHz higher in 
frequency when ISS is approaching your location.
Fortunately we will be using the FM mode, and this
mode does help compensate for part of the Doppler
frequency drift automatically.  If you are fortunate
enough to have a radio with the ability to make
smaller channels steps then you should take advantage of this feature.  
You will need to review the owner's manual for your radio to learn how 
to program "Odd-Splits" channel combinations and program the following 
consecutive frequencies into your radios' memories.

For 5 kHz channel step radios do not try to adjust for Doppler.  The 
exact frequency for Slow Scan TV has not been announced at this time.

( Region 2--North & South America, Region 3Asia,
Channel 1 145.800.0 RX 144.490.0 TX Voice
Channel 2 145.800.0 RX 145.990.0 TX Packet (Worldwide)
Channel 3 145.800.0 RX 145.200.0 TX Voice (Region
1Europe, Africa)

For VOICE (Region 2North & South America, Region
3Asia, Australia)
2.5 kHz channel step radios
Channel 1 145.802.5 RX 144.487.5 TX
Channel 2 145.800.0 RX 144.490.0 TX
Channel 3 145.797.5 RX 144.492.5 TX
For Packet 2.5 kHz channel step radios (Worldwide)
Channel 4 145.802.5 RX 145.987.5 TX
Channel 5 145.800.0 RX 145.990.0 TX
Channel 6 145.797.5 RX 145.992.5 TX

For VOICE (Region 1Europe, Africa) 2.5 kHz channel
step radios
Channel 7 145.802.5 RX 145.197.5 TX
Channel 8 145.800.0 RX 145.200.0 TX
Channel 9 145.797.5 RX 145.202.5 TX

Let's assume ISS is approaching your location (QTH) and the Slow Scan TV 
system is active. Use channel #4 at the beginning of the pass, then when 
ISS is over head, use channel #5 and when ISS passes your QTH use 
channel #6. For best results, use an updated tracking program, which 
displays the current Doppler shift.
This will assist you in determining when it is best to
change channels.

As you may have noticed, it is not recommended for you to adjust your 
uplink frequency on 5 kHz radios. You may have better results if you 
leave your receiver on 145.800 and your transmitter on 145.990.  The 
Doppler shift is only at the +3.5 kHz setting for a few seconds, then it 
will slowly begin to approach zero.
After 5 minutes or less, the Doppler shift will be 0
for a few seconds, and then it will begin to swing
towards -3.5 kHz.

W*hat is Slow Scan TV:*
On this web page you will find many links to  help you
learn more about Slow Scan TV


*Practice Practice Practice:*
If you want to be successful in sending and receiving Slow Scan TV from 
ISS you must be fully proficient inusing Slow Scan TV on Earth first, 
before you make any attempt to use the Slow Scan TV on ISS.

If you can not find any friend locally to test with on
2-meter, you can always try 20-meter (14.230 USB,
assuming you have license privileges and equipment).
During most of day and night you can easily hear
people sending SSTV images on the 20-meter band.  On HF the most common 
SSTV analog mode is called Scotty-1.  Most SSTV applications support 
several of the common SSTV modes. 

You can also experiment with SSTV by plugging two
computers together, PC to PC via the sound card audio cables. 

*Receiving Images from Space:*
The SuitSat project will only be sending an image.
The SpaceCam project later on, will allow both
Uploading and down loading of images from ISS.  The Schedules for 
SpaceCam will be posted early next year.
 For now you will just need to concentrate on
receiving SSTV images from space.

*Picking A Pass:*
Use your computer program to select a good pass with high elevation 
angles. When ISS first appears on the
horizon, the satellite will be 1500 miles (2400 km)
away. When ISS is directly over your house, it is only
240 miles (384 km) away.
Using your tracking program, pick a pass with a
maximum elevation of over 40 degrees. These are
typically the best passes because ISS will be closer
to your QTH. For low elevation angles, your radio
signal will have to travel along the ground, where it
will be affected by trees, buildings and hills. When
ISS is high above the trees, you will have a clear
line-of-site shot to the ISS antenna. A 1000-mile
contact on 2-meters is easy, that is if there is
nothing between you and the other station. A good pass is only 10 
minutes long.

*Receiving SuitSat:*
The SuitSat Transmitter is preprogrammed to send a series of Voice 
messages, Telemetry and a single SSTV image, every 8:46.  Then the whole 
process then repeats from the beginning.  This means that each orbit 
over your house you will have one or two chances to receive and decode 
the image from SuitSat.  You may also want to have your tape recording 
device handy to record the rest of the messages.  The exact location of 
the image is approximately 6:42 seconds from the start of the first message.

*Don't wait to try SSTV:*
As more information becomes available on the
activation dates of the project, the information will
be posted.  It is possible that SuitSat may be
activated in December 2005.  If this it true, they you only have a few 
weeks to get your home station ready to receive SSTV image from Space. 
So, don't wait until the last minute to get your home station SSTV ready.

/73 Miles WF1F MAREX-MG

Until we meet again

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