Listening to Amateur Radio Satellites FOX-1B (AO-91) and FOX-1D (AO-92) Using gPredict

Since the International Space Station's two meter packet radio system went down in July 2017, there really hadn't been a lot of fun activities to do with radio in space until I discovered FOX-1B, which was launched on 8 October 2015 and FOX-1D which was launched on 18 November 2017 and officially commissioned on 23 November 2017.

The great thing about these two birds is they can be heard with a very strong signal on very modest equipment. To listen, all you really need is an RTL-SDR dongle, scanner, two meter portable, or a two meter mobile. On the antenna end, all you need is a humble two meter 1/4 wave ground plane or even just a mag mount on a car roof.

Also, due to the "VHF Capture Effect" there is no need to adjust for frequency drift caused by "doppler shift" as the satellite approaches you and leaves you. These satellites travel so fast that the speed of light (radio waves) has to be taken into account when communicating with them. We only have to worry about this when we uplink to the satellite, so, since this is only an article on listening, I'm not going to go into any depth on doppler shift correction.



The next step is to figure out when to listen for our target satellite. I use Linux so in this article we'll cover gPredict. WXTrack is an excellent, free, tracking program for Windows. Pretty much everything you need to get WXTrack up and running can be found right there on the website.


To install gPredict on Debian Linux, open a terminal and type:

sudo apt-get install gpredict

Everything should download and install automatically. When asked if you want to install just type "yes". To open, search your program menu for "gpredict" and click on it or open a terminal and simply type "gpredict".

Now, you should see something similar to this:

 

The first thing we'll do is set up our station location and there are two ways to do this which are pretty easy and self explanatory but I'll walk you through them, anyway.

Click on Edit > Preferences

Then make sure "General" is chosen in the options on the left of the window and then click on the "Ground Stations" tab.

We have two options at this point. To add your location from a list of cities click on "Select" and find your nearest city from the options on the next window. Double click on your city and the location information should be loaded into the ground station information box. Now, all you have to do is add a name (no spaces) and a short description (optional). That's it for station location with this method. Now restart gPredict and you'll see your location on the map.

The second option is to manually enter your location information using GPS coordinates. Just enter the name of your location (or your callsign), short description (optional). Then, use your favorite GPS app to find your coordinates and enter them in the boxes. Be sure to use decimal coordinates and not degrees/minutes/seconds because gPredict will not recognize that format. At this point, your grid square locator should be automatically entered. Last enter your altitude and select your nearest weather station (optional). Now click "Okay" and "Okay" again and you will be back at the original screen. Restart the program and your station location should be marked on the map. If it's not in the right spot double check your coordinates and restart again.



Next we update our "Keplerian Elements (aka Keps)" file. Keplerian elements are the numbers the tracking software crunches to predict the orbital data for each satellite. These should be updated at least once a week.

To update the keps click on: Edit > Update TLE > From Network

The updater will run and if all goes well we'll have a fully updated set of Keps for all the satellites in the database. As I mentioned, it's a good idea to update your Kepler set every few days.



Now we remove satellites that we don't want to track from the list and add the ones we do.

To do this, click on this arrow (Circled in Red):

Then click "Configure" and the configure window will pop up. At the top select your station location from the list. Next, remove the satellites you don't want to track from the "Selected Satellites" list. Now, search for "FOX" in the search field and both 1B and 1D should be listed in the "Available Satellite" list. Double click on both and they will move to the "Selected Satellite" list. Click "Okay" and you will be tracking them on your map. To see the satellites ground track (the path it is taking over the Earth) right click on it and select "Ground Track".

With gPredict you can see the ground track of multiple satellites which can be handy from time to time, so, repeat that process if you want to view the ground track of other satellites as well.

If you want to view the orbital information of a particular satellite, click on the arrow in the top corner of the bottom right module which shows the orbital data and select the satellite you want to view (Shown Below).

In the bottom right corner of the map, you will see the AOS (Allocation of Signal) information of the satellite you are tracking. By default, it shows a T-countdown so I set a countdown timer with that information and when the alarm goes off, it's time to tune in and start listening.



Instead of listing the frequencies, I'm going to link to the AMSAT page for each satellite since it's possible the frequencies may change.

FOX-1B (AO-91)

FOX-1D (AO-92)

It is also a good idea to periodically check the AMSAT Satellite Status page to see what mode the satellites may be in at a given time or if they are active or not active

Do explore the AMSAT page and read as much as you can. You will learn quite a bit on their site. I know I did.

Alright, happy hunting ladies and gentleman and if anyone sees anything that needs corrected, please send me a message or comment below.