Re: Yes - Another ISS SSTV Project!
For those who are new to our SSTV events, occasionally throughout the year, ARISS coordinates with the ISS crew to set up our ham station on board the ISS to automatically downlink SSTV images over several days, allowing radio enthusiasts on Earth to receive them and post them online at the ARISS SSTV Gallery.
We will be starting such an event tomorrow and you can review details about it in a post I sent out on this time line a few days ago.
Below I've reposted a tutorial on an easy way you can get in on the action.
A Quick and easy way to receive the SSTV transmissions from the ISS
I know everyone gets really excited when they hear about an upcoming ARISS SSTV Event. These events currently run at 145.8 MHz using the PD-120 mode. So here is an easy and portable way that I use to receive and store the SSTV images. In my case, it involves using my Android Smartphone and a handheld 2 meter handy talkie or more commonly referred to as an HT. As long as you have a radio that will receive the 2 meter ham band in FM mode and at least a ¼ wave whip antenna or better, you should be able to receive pretty clear images during the downlinking depending on the maximum height of the pass and a moderately reasonable audio level coming from the ISS.
But first, if you don’t already have an app that predicts when the ISS will pass over your location, you can search for a free app online that does this. I use ISS Detector myself and found it gives me all the information I’m looking for plus a real time tracking map, but there are other tracking apps out there that should work just as well for what we are doing here. You can also visit the AMSAT website at www.amsat.org, go to Pass Predictions under the Satellite Info dropdown, configure your location and other parameters and print upcoming passes for the period of the event.
So now to acquire the SSTV images, I like to use a free app called Robot36 that I found using Google and installed on my Smartphone. Don’t let the name fool you. This software is capable of demodulating more SSTV modes than just Robot 36 and as I mentioned before, the mode we’ll be going for is PD 120. So once you have the software installed, launch it and it will automatically begin scanning. It will probably default to Auto Mode when you launch the app. If not, you can press on the three vertical dots in the top right hand corner of your screen to open the main menu. Here I press Select Mode and then press either Auto Mode or PD 120. You’ll see the screen just scanning noise before the signal is heard. If you want to be sure you phone mic is working before the pass, you can whistle a steady tone into the phone for a few seconds and you should see where the noise smoothed out on your screen, proving the mic heard your whistle and is in working order.
Once the pass begins, hold your phone close to your radio speaker and before too long, you should hear the SSTV signal start up and your screen should begin printing the top edge of the image. Once the image begins to print to the screen, I immediately press the X in the top screen tool bar, resetting the scan to the top of the screen. The printing continues down the screen until the entire image is displayed. For Apple users, see the note at the end for available software.
So now you’re set up to know when the next ISS pass will occur over your area and you have a way to capture and view the images. You’re almost done! All you need to do now is switch on your 2 meter rig. If it’s a multimode rig, but sure it’s switched to receive FM signals. Tune the rig to receive 145.8 MHz, raise the volume to a reasonable listening level, place it near your smartphone and YOU’RE DONE!
Once you receive an image you’re proud of, you can submit it online at the ARISS SSTV Gallery at https://www.spaceflightsoftware.com/ARISS_SSTV/ for all the world to see and to really make your day, you can receive a really nice SSTV ARISS Award just for posting your image. See details about this at https://ariss.pzk.org.pl/sstv/ .
Now for a few hints and details.
I suggest you start listening for the image at least 5 minutes prior to the posted start time. That way you’re pretty much guaranteed to not miss any of the action and the best passes only last around 10 minutes.
Whip antennas work pretty well, but a small 3 element handheld 2 meter beam works much better for getting a clear image with little if any noise lines. These beam antennas can be purchased or you can use the DIY method from directions available from online sources.
Using your tracking app, figure out where along the horizon to expect the ISS to start rising so you will know where to point your directional antenna if you’re using one and not miss any of the action.
Due to Doppler shift, you may find that the audio of the SSTV signal begins to take on noise that can erode the quality of the image as you are receiving it. If that begins to happen during a pass, you should slightly retune your radio to the correct signal frequency coming from the ISS. Try moving your frequency slightly up or down (no more than +/- 3 KHz from 145.8 MHz).You may find this attenuates the noise and improves your image reception.
To save and send your images from your Robot36 app, press the “share” symbol at the top of the screen and then choose See All to list all the choices for image transfer or storage. Also you can use the symbol at the top of the screen that resembles an old floppy disc. That’s another way to store an image.
For Apple users, I did a quick survey of fellow hams to see what SSTV viewer was their favorite for IPods, IPhones and IPads. Black Cat Systems for Ipod, IPhone and IPad was most mentioned as a source for apps.
Now it’s time to tune in and have some fun!