ISS SSTV Reception Hints

ISS SSTV Blog post Image - Sammy Jim and me
(Last updated 2018-07-08) (My latest ISS SSTV Video)

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

Next planned event

The ARISS SSTV blog is the most authoritative source on ISS SSTV event info as it is maintained by the ISS ham project coordinator, who works for NASA. One way to find out when events are happening is by signing up to receive email notifications whenever new posts are made on the blog. Instructions for doing that are here.

The SSTV events are done by the Russians and they don’t announce them far in advance, sometimes only a few days, at most a week out. Also, lower priority stuff like ham radio can get cancelled for higher priority stuff like science.

In addition to the ARISS SSTV Blog, you can find ISS SSTV news at the following sources:

https://amsat-uk.org/
https://twitter.com/RF2Space  <– Also run by ISS ham project coordinator
http://www.amsat.org/mailman/listinfo/amsat-bb

With 50 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 “SSTV Slow Scan TV” by Black Cat Systems
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

RX-SSTV is another Windows option. If you disable BPF (band pass filter I believe) on RX-SSTV it will decode them as sharp as MMSSTV. If the reception is noisy enable BPF and things will be smoothed out a bit. In that case the decode might look better than MMSSTV’s decodes. They are easy to compare if you record your passes and decode them later.

For Mac OS X use “Multiscan 3B SSTV”
http://www.qsl.net/kd6cji/

For Linux use “QSSTV”
http://users.telenet.be/on4qz/qsstv/index.html

Tracking the ISS

How to 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

A table of many different satellite tracking apps/programs/websites:

http://sats.wikidot.com/what-apps-can-i-use-to-track-satellites

What to expect during a pass

In 2017 they switched from using SSTV mode PD180 to PD120. 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. You’ll also have a better chance of receiving images with less noise, or more complete image transmissions, as you’re more likely to receive at least one image closer to the middle of the pass when the signal is strongest.

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.

Occasionally the off times are extended and it’s not clear why. One theory is that the Russians are lining up the transmissions to be conducive to reception in Moscow, as the extended off times often start over Western Europe.

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

SSTV Status reports can also be found on ISS Fan Club on the right side of the page. For details on all reports on that website go to https://www.issfanclub.com/sstv-reports

Lastly, if you go to the AMSAT satellite status page you can see “ISS-SSTV” reports at the very bottom of the table.  Yellow colored cells mean it was heard. Red means it wasn’t heard. Cells closer to the left are most recent. If you mouse over a cell you can see all the reports for that hour,  who it was by, and in what 15 minute block of the cell hour it was relevant to.

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.

Test Decoding Software

It’s really exciting to watch images decode live while receiving the SSTV transmission from the ISS. If you don’t want to record the pass and decode later, or you want to decode live and record, make sure to test your decoding software so you know it will work at the moment of truth. To do this you’ll need to play back an audio recording of an SSTV transmission created using the same mode as what the ISS will be using, which is PD180. I made one which is available on YouTube, SoundCloud and as an mp3 download via Dropbox:

https://youtu.be/fGBmUTESnC8

https://soundcloud.com/spacecomms/pd180-sstv-test-recording

https://www.dropbox.com/s/cgp5gtkzjdvm0m3/Space_Comms_PD180_SSTV_Test_Recording.mp3?dl=0

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

Official April 11th 2016 event announcement

Here is where I got the schedule and details of this event.

http://ariss-sstv.blogspot.com/2016/04/ariss-commemorative-event-april-11-14.html

https://twitter.com/RF2Space/status/718483066663104512

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

A video which shows how easy it is to receive the ISS with just an HT

https://www.youtube.com/watch?v=hsk85yutZlU

Official Sources of ISS SSTV information

http://ariss-sstv.blogspot.com/

End

Good Luck and 73!

John, KG4AKV, Raleigh North Carolina, United States

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