[amsat-bb] New ISS SSTV Video and "ISS SSTV Reception Hints" webpage

Thu Dec 17 20:35:04 UTC 2015

To help promote the tentative December 26th International Space
Station Slow Scan TV event (and another that is planned over the next
few months) I made a new video of an ISS SSTV reception I filmed last
April. I also made an extensive webpage with information, resources,
and hints on receiving ISS SSTV events, including the upcoming ones.

Video: My First Perfect ISS SSTV Image!
https://www.youtube.com/watch?v=7to9uX1sWC4

Webpage: ISS SSTV Reception Hints
https://spacecomms.wordpress.com/iss-sstv-reception-hints/

Below is a text formatted version of the webpage I made

= Table of Contents =
Next planned event
Recommended decoding software
Tracking the ISS
What to expect during a pass
Hints

= Next planned event =

Tentative plans are being made for the International Space Station to
transmit Slow Scan TV images the weekend of December 26th to celebrate
15 years of continuous amateur radio operations on the ISS. A second
weekend event is planned over the coming months.

With 25 watts of power coming from the radio on the ISS, the signal,
transmitted on 145.800 MHz, can be received with a setup as simple as
a handheld amateur radio or scanner, and a rubber duck antenna.
Decoding the images can be as simple as holding the radio next to the
microphone of an iOS or Android device.

Ideally though, you would use a high gain or directional antenna, and
an audio cable connected directly between the radio and decoding
device, whether it’s a smart phone or a computer. Whatever software
you use, make sure it’s set to SSTV mode PD120, as that’s what the ISS
will be using, and if you don’t set that, you might not decode any
images at all (see hint below).

= Recommended decoding software =

For iOS use “CQ SSTV”
https://itunes.apple.com/app/sstv/id387910013

For Android use “Robot36”
https://play.google.com/store/apps/details?id=xdsopl.robot36&hl=en

For Windows use “MMSSTV” (see AMSAT UK link below for setup)
http://hamsoft.ca/pages/mmsstv.php

For Mac OS X use “Multiscan 3B SSTV” (not verified)
http://www.qsl.net/kd6cji/

= Tracking the ISS =

Howto use heavens-above.com to track the ISS
https://spacecomms.wordpress.com/howto-use-heavens-above-com-to-track-the-iss/

== Other ISS tracking methods ==

== Websites: ==

ISS Fan Club
http://issfanclub.com/

ISSTracker (no predictions, just live tracking)
http://www.isstracker.com/

Android:

Heavens-Above
https://play.google.com/store/apps/details?id=com.heavens_above.viewer

ISS Dectector Satellite Tracker
https://play.google.com/store/apps/details?id=com.runar.issdetector

iOS:

Space Station (ISS) (not verified)
https://itunes.apple.com/us/app/space-station-iss/id301984767?mt=8

= What to expect during a pass =

SSTV mode PD120 will be used instead of PD180 which was used during
previous SSTV events this year. With PD180 it takes about 3 minutes to
send an image. With PD120 it takes about 2 minutes to send an image.
Since images transmitted with PD120 take less time to send than with
PD180, more images can be received during a single ISS pass.

An ISS pass that goes right overhead (90 degrees elevation), lasts
about 10 minutes. ISS SSTV transmit time and off time are usually
setup to provide the radio with a 50% duty cycle (only transmit half
the time so the radio doesn’t overheat). With image transmission
taking two minutes, off time will probably be two minutes as well.

Compared to previous SSTV events using PD180, this means it should be
relatively easy to receive at least two complete images in one pass,
with the possibility to receive up to three images if timing,
conditions, and setup are ideal.

When the ISS comes into view/has line of sight with you, this is known
as Acquisition of Signal, or AOS. The ideal situation for a high
elevation 10 minute pass would be if the first image started
transmitting exactly at your AOS, and you had a directional antenna so
you could receive the signal even while the ISS was very low in the
beginning and end of the pass.

In this case you would be able to receive three images like this:

minute, image TX/off
0-2, complete image 1
2-4, off
4-6, complete image 2
6-8, off
8-9, complete image 3

The more common situation will be that the first image transmission
will start either before or after AOS. In this case you will only have
the opportunity to receive two complete images, but this is still
twice the amount of images that were possible with PD180. The downside
is the image quality is not as high as with PD180.

Even though you’ll have the opportunity to receive two complete
images, don’t expect to. It may take practice and it will certainly
take the right setup and conditions, to get just one complete image.
With that said, here are some tips that may help you get more images
and/or better images.

= Hints =

== Check Twitter for #ISS #SSTV status and images ==

For several hours after the April and July 2015 SSTV events were
scheduled to start, only a “blank signal” was transmitted. There was
no audio so no images could be decoded. During these events Twitter
users all over the world posted what they heard using hashtags #ISS
#SSTV. As soon as people started hearing the SSTV audio, they reported
it on Twitter.

By searching for these hashtags you can stay up to date on the current
status of the transmissions, which sometimes go longer than scheduled.
Maybe more importantly, you can also see all the images people are
getting!

https://twitter.com/search?q=%23ISS%20%23SSTV

== Open the squelch ==

For weak signal work you always want to leave the squelch wide open to
avoid missing any signals. Even though the radio used for ISS SSTV
puts out 25 watts, which is a lot for an amateur radio satellite, the
signal is still relatively weak when it’s hundreds of miles away and
hundreds of miles high. Don’t miss any of the signal. Keep the squelch
open.

This will also make it easier to identify the signal when it first
comes in, or when the transmission first starts because the change
between the high volume of the noise/static and the relative low
volume of the transmitted signal will be more noticeable than if you
had the squelch closed.

== Record audio and decode later ==

During previous SSTV events some listeners didn’t configure their SSTV
apps/software for the right mode. Even though they received the
signal/audio from the ISS, since the software wasn’t configured
properly, they decoded no images.

A wise choice would be to just record the audio from the radio and
play it back later when you have time to experiment with different
settings. This also makes it easier to fix slanted images/correct for
bad sync, which are common issues.

If you decide to just record the audio and worry with decoding later,
record the audio at a high quality to preserve as much of the original
fidelity of the audio as possible, otherwise the quality of the image
will suffer.

== Try low elevation passes if you have a directional antenna ==

If you’re using a directional antenna like an Arrow II antenna or a
tape measure antenna, don’t limit yourself to high elevation/altitude
passes.

With the 25 watt ISS SSTV transmissions, you can receive the signal
from horizon to horizon. Even a pass with only a max elevation of five
degrees can produce good images.

= Other resources =

== AMSAT UK webpage for beginners ==

If you’re using MMSSTV, please see the advice on configuring it at the
following AMSAT UK webpage. Also check it out for more detailed
information on ISS SSTV.

http://amsat-uk.org/beginners/iss-sstv/

(Thanks to AMSAT UK for the above page, as I used it for a couple of
the decoding software links and inspiration for this page. I tried not
to duplicate much though, so please read it too.)

== AMSAT-UK announcement for tentative December 26th-27th event ==

http://amsat-uk.org/2015/12/17/iss-sstv-activity-planned-for-late-dec-2015/

== YouTube videos of past ISS SSTV receptions ==

Watch YouTube videos of people receiving images during previous events
to see how they did it. You can start with two of my videos!

My First ISS SSTV reception – April 2015
https://www.youtube.com/watch?v=s2Y3BKZ9vPo

My First Perfect ISS SSTV Image! – April 2015
https://www.youtube.com/watch?v=7to9uX1sWC4

= End =

Good Luck and 73!

John, KG4AKV, Raleigh North Carolina, United States