Greencube and You (meaning me)

One thing that long-time satellite ops will tell you is they worked birds that are long out of service, and they had some amazing capabilities. While we can’t bring them back we can try to take full advantage of the sats we have while we have them. Here in the northeastern USA we don’t have many nearby DXCCs. FO-29 and RS-44 are reliable LEOs that put some of Europe in a common footprint with my station, but the limitations are clear. I just don’t have access to many DXCCs from FN41. When I started my path toward working satellites in early 2022 I realized we didn’t have a Mid-Earth Orbit (MEO) or Geostationary (GEO) like QO-100 accessible to North America. So in early 2023, when I heard we might have a MEO bird available to hams, I was very interested.

The newest and highly popular kid on the block is Greencube, aka IO-117, a Mid-Earth Orbit (MEO) satellite with a 435MHz digipeater on board. This is good news because the footprint is huge, allowing access to grids you won’t get on RS-44 or FO-29, as well as Zones and DXCC Entities you won’t get any other way. I am still not in a great spot for those European DXCCs, but I have worked plenty of them now, along with stations in Africa, Japan and China, so it’s working well enough.

One good thing about IO-117 is you do not need a full-duplex radio to communicate with it. It’s a simplex digipeater much like the ARISS FM APRS digipeater. You do need some way to track uplink and downlink doppler independently and this is typically done in split mode. My Yaesu FT-991A is a very good choice for this application. It can put out 50W max on 435Mhz and split mode is no problem as it is a dual-VFO radio.

THE BIG DISCLAIMER: None of the other tutorial pages for this kind of thing worked for me as written. Mine will probably not work for you as written. You will need to know how to configure audio and CAT devices. Your base frequency for doppler correction might be different. Your CAT software might handle doppler correction differently… You should be familiar with the software packages you are using. Be ready to crack a manual. That sort of thing.

Here’s a blow by blow of how I got my Yaesu FT-991A to play nice with the software needed to access IO-117.

The Elements of my IO-117 Station:

  • Yaesu FT-991A
  • Windows Laptop
  • USB Cable w Ferrite Chokes
  • Ham Radio Deluxe software
  • UZ7HO Software Modem for Greencube
  • UZ7HO CAT.dll file in directory with Soundmodem
  • OZ9AAR Greencube Termimal
  • Eterlogic Virtual Serial Ports Emulator

The challenge for me is to get my computer to track the uplink and downlink doppler corrections over CAT, while also allowing UZ7HO Soundmodem to access the PTT over that same same CAT port. The VSPE software takes care of that.

What you will definitely need is a good IO-117 entry for your Doppler.sqf file, or a good base frequency for doppler correction. That will tell the software what kind of correction to make and what the rig is expecting. Check HF5L’s FT991 tutorial for more info, but this entry is a good starting point:


My base frequency is around 435.308.7Mhz. You want to adjust this base frequency until the IO-117 downlink signal is centered at 1500Hz in the Soundmodem waterfall. It doesn’t have to be exact, but it has to be close.

In order, my startup routine is:

  • 991A connected and Ports noted in Device Manager
  • 991A in Split Mode
  • Set up VSPE as Splitter
    • Yaesu Standard COM Port to an Unused Virtual COM Port Number
  • Open HRD
  • Connect to Virtual Port
  • Open HRD Satellite Module
  • Select IO-117 pass in HRD Satellite
  • Open Radio Control, Check Both RX and TX
  • Open Soundmodem
  • Open GC Terminal
  • Open GC Telemetry (be sure to check TCP Client box)

Here’s the VSPE setup. The VSPE Device you want is a Splitter:

My Yaesu Standard COM Port is COM6, and I am choosing COM20 as the Virtual Port. All your apps will now address COM20 with no sharing issues. TIP: Once your configuration works use the SAVE function and put the config file in with your other Greencube stuff. When you start a session just OPEN the saved config file, and Bob, as they say, is your uncle.

At this point the radio should be tracking Doppler shift in both VFOs. Remember that the RX Freq is Plus Doppler Correction and the TX is Freq Minus Doppler Correction. Once the satellite passes the point where the shift is Zero, the sign of the Doppler shift correction changes to negative so you will see RX decreasing and TX increasing. That’s normal.

The Soundmodem and Terminal setup can be a challenge if you aren’t familiar with these packages. I’m not doing a UZ7HO guide, but the communications part goes something like this:

  • Open UZ7HO for Greencube
  • Make sure you have the Audio Ports set correctly
  • Set CAT to Virtual COM port, Select rig, baud, RTS/DTS…
  • Once you have audio and have confirmed PTT operation…
  • Open Greencube Terminal

I don’t have a al-az rotator for my antenna so I manually point it at the sat. That’s not a big deal because you don’t have to be too fine, and the apparent motion of the satellite is not too fast. I make maybe seven or eight corrections over the course of 45-60 minutes. Yes, a typical pass lasts an hour or more. Welcome to MEO. It isn’t like frantically chasing CAS-10 across the sky!

I’ll go into the antenna side in a bit, but if you are pointing anywhere near the bird you should hear packets and see something on the Soundmodem waterfall. You want to see the GC downlink signal centered arond 1500hz and the decode “bar” in the waterfall set the same way. You can change your reference frequency in HRD Satellite and see the change in real time. I wouldn’t lean too hard on moving the deode bar or picking a different center frequency. These settings might get you some downlink decodes, but it will mess up your uplink frequency.

At this point you are ready make contacts. There is more on this below, but my advice is to be patient. There are many stations transmitting packets at the satellite. Just try to transmit between downlink transmissions and you will get digipeated eventually. There is a pattern and you will get the hang of it pretty quickly.

Helpful Links:

Greencube Observer – Put in your grid and see which stations are in your possible footprint

FG8OJ Greencube Setup – A comprehensive page about IO-117 from Bert FG8OJ, one of the early GC ops

UZ7HO Main Page – You will get a security warning, it’s not HTTPS, but you want and

OZ9AAR Greencube Terminal – The Cadillac of GC Terminals. Use this one. You won’t be sorry.

DK3WN Telemetry Software – A telemetry decoder application. Useful!

Antenna Chat:

I’m using a 70cm Wimo X-Quad on a heavy Gitzo photo tripod. It isn’t fancy, and it isn’t automated, but it works. I use the very fine iOS app THEODOLITE to set both azimuth and altitude. Until I have the mone-ays (sp. Monet) for an automated alt-az setup it is all armstrong rotation for me.

During the pass I use GoSatWatch on iOS (Sky Mode) to know where the bird is, and Theodolite for iOS for setting the azimuth and altitude of the antenna.


The X-Quad has parallel horizontal and vertical inputs, and they make a phasing harness for circular polarization. In my naivete I thought RHCP was going to be a set-and-forget decision. That has not been the case. In fact, I am often connecting straight to the horizontal input and that seems to have less fading and better performance. That kinda means I could have bought a yagi with better performance, but the X-Quad is a steal at under $200 and it fits in the back seat of my car. So I’m happy with it and would buy it again.

The X-Quad has a good published pattern but it isn’t so tight that I am chasing the sat around. I typically move the antenna aim-point in 10-degree increments, putting the antenna 5 degrees ahead of the bird, letting the sat cross the antenna’s capture area. In many cases you can widen that out to 15 or even 20 degrees with the antenna 10 degrees ahead.

Predicting IO-117 Passes:

Use your choice of satellite pass prediction application and get used to the times and types of passes you have at your location. For me it is the usual East, Overhead, and West passes, but the western passes appear to cross NW-NE, as opposed to a SW-NW pass like RS-44. This is a good thing as I can often work the last third of that pass down to about 10-degrees toward Europe and Asia. YMMV, but when you put in the time to examine pass orientation and satellite footprint you will make more and further contacts.

SATPC32 is still one of the best apps for analyzing passes in non-real-time. You can plug in a time/date and an interval and see what the footprint will cover during a pass. On Greencube it can be a little disorienting because the footprint is so huge, but it can help plan your operations if you are interested in contacts at the fringes of the coverage. And, trust me, you are.

Here’s a short discussion of IO-117 operating practices:

If you have worked, or more likely attempted to work, the ARISS APRS digipeater then you have an idea of what IO-117 is doing. It is listening, decoding incoming packetized messages, and then retransmitting them, all on the same frequency. Much like FM sats you are essentially fighting capture effect. The strongest stations have the best chance of being digipeated when there are many stations transmitting. You can’t work around that. You will notice a pattern of digipeats, telemetry packets, and gaps where the digipeater is listening. Find your own approach to getting heard.

A good example of where digipeater operating practices fail is when you show up as a new station, or another new station shows up, it becomes a frenzy of QSO requests. If you are the “DX” I suggest just relaxing and working one at a time. It will be difficult because stations will keep calling you even if you are in QSO. It will suck as you try to get digipeated while doing whatever else you need to do (like pointing an antenna or even tuning a VFO). It is frustrating and you probably work half the stations you could (that’s optimistic) because those same stations are clogging up the digipeater even though they have clearly been digipeated several times and everyone knows they are there. Take that knowledge with you when you see a new station. All those “me me me” calls are just making it harder for the DX to make the contacts they are hoping for.


Here’s a short rant regarding IO-117 operating practices:

IO-117 is a flying digipeater, and as such it has very limited bandwidth when it comes to messaging. If you see 20 stations on a pass, most of them are trying to get digipeated. Only one or two will get digipeated on each transmission because Greencube is only digipeating the transmissions it can decode. As well, there is no time synchronization so it is receiving a morass of signals. My rule is to transmit as little as possible, and only CQ when absolutely necessary. This approach reduces the QRM the digipeater has to deal with.

However… There are operators who will send a CQ message every 60 seconds, or even more often. This is simultaneously bizarre, counterproductive, and boorish. If you have worked a FM bird like the ARISS FM Voice Repeater you know this pattern. You hear two stations trying to complete a QSO and another op calls CQ. They can hear that station trying to get a grid confirmed (usually because someone doubled over that station), but they don’t care. A digipeater has the same limitations, and the same bad operating practices. Rise Above.

I have worked a lot of VHF contests and thrown my call around in many DX pileups. As hectic as those situations can be, most stations will back off to let the DX complete a QSO. Not so on Greencube. Everyone just keep calling and calling, unwilling or unable to realize the reason the DX isn’t working ANYONE is they keep “winning” on the uplink, and the DX keeps losing.

As for the ultra-frequent CQ calls it is obviously a way to avoid having to compete in a pileup if a new station appears. The hope is the new station will call the CQ they see before just calling a station they see in QSO. As above, they are taking up digipeater slots that the “DX” needs to get digipeated themselves. Four big-gun stations sending CQ every 60 seconds are monopolizing about a third of the available slots in any given minute. Probably more.

Here’s an actual screengrab from a IO-117 pass. If a weaker station was trying to get digipeated they will have given up at some point.

That’s an extreme example during a quiet pass over South America. But you will see this during crowded conditions.

Rant Mode Off, but I hope it helps at least frame the issue of a limited resource and how easily it can be wasted by bad operating practices. Enjoy, and Best 73. N1QDQ

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