Following on from my article about my QO-100 Satellite Ground Station Complete Build, this article goes into some detail on the Node-RED section of the build and how I put together my QO-100 Satellite Ground Station Dashboard web app.

The Node-RED project has grown organically as I used the QO-100 satellite over time. Initially this started out as a simple project to synchronise the transmit and receive VFO’s so that the SDR receiver always tracked the IC-705 transmitter.

Over time I added more and more functionality until the QO-100 Ground Station Dashboard became the beast it is today.

Looking at the dashboard web app it looks relatively simple in that it reflects a lot of the functionality that the two radio devices already have in their own rights however, bringing this together is actually more complicated than it first appears.

Starting at the beginning I use FLRig to connect to the IC-705. The connection can be via USB or LAN/Wifi, it makes no difference. Node-RED gains CAT control of the IC-705 via XMLRPC on port 12345 to FLRig.

To control the SDR receiver I use GQRX SDR software and connect to it using RIGCTL on GQRX port 7356 from Node-RED. These two methods of connectivity work well and enables full control of the two radios.

The complete flow above looks rather daunting initially however, breaking it down into its constituent parts makes it much easier to understand.

There are two sections to the flow, the GQRX control which is the more complex of the two flows and the comparatively simple IC-705 section of the flow. These two flows could be broken down further into smaller flows and spread across multiple projects using inter-flow links however, I found it much easier from a debug point of view to have the entire flow in one Node-RED project.

Breaking down the flow further the GQRX startup section (shown below) establishes communication with the GQRX SDR software via TCP/IP and gets the initial mode and filter settings from the SDR software. This information is then used to populate the dashboard web app.

The startup triggers fire just once at initial startup of Node-RED so it’s important that the SDR device is plugged into the PC at boot time.

All the startup triggers feed information into the RIGCTL section of the GQRX flow. This section of the flow (shown below) passes all the commands onto the GQRX SDR software to control the SDR receiver.

The TCP RIGCTL -> GQRX node is a standard TCP Request node that is configured to talk to the GQRX software on the defined IP Address and Port as configured in the GQRX setup. The output from this node then goes into the Filter RIGCTL Response node that processes the corresponding reply from GQRX for each message sent to it. Errors are trapped in the green Debug node and can be used for debugging.

The receive S Meter is also driven from the the output of the Filter RIGCTL Response node and passed onto the S Meter function for formatting before being passed through to the actual gauge on the dashboard.

Continuing down the left hand side of the flow we move into the section where all the GQRX controls are defined.

In this section we have the VFO step buttons that move the VFO up/down in steps of 10Hz to 10Khz. Each button press generates a value that is passed onto the Set DeltaFreq change node and then on to the Calc new VFO Freq function. From here the new VFO frequency is stored and passed onto the communications channel to send the new VFO frequency to the GQRX software.

The Mode and Filter nodes are simple drop down menus with predefined values that are used to change the mode and receive filter width of the SDR receiver.

Below are the HAM band selector buttons, each of these will use a similar process as detailed above to change the VFO frequency to a preset value on each of the HAM HF Bands.

The QO-100 button puts the transmit and receive VFO’s into synchro-mode so that the receive VFO follows the transmit VFO. It also sets the correct frequency in the 739Mhz band for the downlink from the LNB in GQRX SDR software and sets the IC-705 to the correct frequency in the 2m VHF HAM band to drive the 2.4Ghz up-converter.

The Split button allows the receive VFO to be moved away from the transmit VFO for split operation when in QO-100 mode. This allows for the receive VFO to be moved away so that you can RIT into slightly off frequency stations or to work split when working DXpedition stations.

The bottom two Memory buttons allow you to store the current receive frequency into a memory for later recall.

At the top right of this section of the flow there is a Display Band Plan Info function, this displays the band plan information for the QO-100 satellite in a small display field on the Dashboard as you tune across the transponder. Currently it only displays information for the satellite, at some point in the future I will add the necessary code to display band plan information for the HF bands too.

The final section of the GQRX flow (shown below) sets the initial button colours and starts the Powermate USB VFO knob flow. I’ve already written a detailed article on how this works here but, for completeness it is triggered a few seconds after startup (to allow the USB device to be found) and then starts the BASH script that is used to communicate with the USB device. The output of this is processed and passed back into the VFO control part of the flow so that the receive VFO can be manually altered when in split mode or in non-QO-100 mode.

The bottom flows in the image above set some flow variables that are used throughout the flow and then calculates and sets the RIT value on the dashboard display.

The final section of the flow is the IC-705 control flow. This is a relatively simple flow that is used to both send and receive data to/from the IC-705, process it and pass it on to the other parts of the flow as required.

The IC-705 flow is started via the timestamp trigger at the top left. This node is nothing more than a trigger that fires every 0.5 seconds so that the dashboard display is updated in near realtime. The flow is pretty self explanatory, in that it collects the current frequency, transmit power, SWR reading, PTT on/off status and S Meter reading each time it is triggered. This information is then processed and used to keep the dashboard display up to date and to provide VFO tracking information to the GQRX receive flow.

On the left are the buttons to change band on the IC-705 along with a button to tune to the VOLEMT on the 60m band. Once again there two memory buttons to save and recall the IC-705 VFO frequency.

The Startup PTT Colour trigger node sets the PTT button to green on startup. The PTT button changes to red during transmit and is controlled via the Toggle PTT function.

At the very bottom of the flow is the set transverter IF Freq function, this sets the IC-705 to a preselected frequency in the 2m HAM band when the dashboard is switched into QO-100 mode by pressing the QO-100 button.

On the right of the flow there is a standard file write node that writes the 2.4Ghz QO-100 uplink frequency each time it changes into a file that is used by my own logging software to add the uplink frequency into my log entries automatically. (Yes I wrote my own logging software!)

The RX Audio Mute Control filter node is used to reduce the receive volume during transmit when in QO-100 full duplex mode otherwise, the operator can get tongue tied hearing their own voice 250ms after they’ve spoken coming back from the satellite. This uses the pulse audio system found on the Linux platform. The audio is reduced to a level whereby it makes it much easier to talk but, you can still hear enough of your audio to ensure that you have a good, clean signal on the satellite.

As I said at the beginning of this article, this flow has grown organically over the last 12 months and has been a fun project to put together. I’ve had many people ask me how I have created the dashboard and whether they could do the same for their ground station. The simple answer is yes, you can use this flow with any kind of radio as long as it has the ability to be controlled via CAT/USB or TCP/IP using XMLRPC or RIGCTL.

To this end I include below an export of the complete flow that can be imported into your own Node-RED flow editor. You may need to make changes to it for it to work with your radio/SDR but, it shouldn’t take too much to complete. If like me you are using an IC-705 and any kind of SDR controlled by GQRX SDR software then it’s ready to go without any changes at all.

More soon …

I get quite a few emails from readers of my blog asking how my QO-100 satellite station is put together and so, I thought perhaps now is a good time to put together an article detailing the complete build.

My QO-100 satellite ground station is built around my little Icom IC-705 QRP transceiver, it’s a great little rig and is ideal for the purpose of driving a 2.4Ghz transverter/up-converter.

Of course all the software used for the project is Opensource and freely available on the internet.

The station comprises of the following building blocks:

• Icom IC-705 Transceiver
• DXPatrol 28/144/433Mhz to 2.4Ghz Up-Converter
• DXPatrol GPSDO Reference Oscillator
• DXPatrol 2.4Ghz 5/12w Amplifier
• Nolle Engineering 2.2 turn 2.4Ghz IceCone Helix Antenna
• 1.1m (110cm) Off-set Dish
• Bullseye 10Ghz LNB
• Bias-T to feed 12v to LNB
• NooElec SmartSDR Receiver
• PC Running Kubuntu Linux Operating System
• GQRX SDR Opensource Software
• Griffin Powermate USB VFO Knob
• QO-100 Ground Station Dashboard developed using Node-RED
• LMR400-UF/RG58 Coax Cable

To get a good clear view of the QO-100 satellite I have the dish mount 3.2m above the ground. This keeps it well clear of anyone walking past in the garden and beams the signal up at an angle of 26.2 degrees keeping well clear of neighbouring gardens.

The waterproof enclosure below the dish houses all the 2.4Ghz equipment so that the distance between the feed point and the amplifier are kept to a minimum.

The DXPatrol amplifier is spec’d to run at 28v/12w or 12v/5w, I found that running it at 28v produced too much output for the satellite and would cause the LEILA alarm on the satellite to trip constantly. Running the amp at 12v with a maximum of 5w output (average 2.5-3.5w) is more than enough for me to have a 5/9+10 signal on the transponder.

The large 1.1m dish gives me quite an advantage on receive enabling me to hear the very weak stations with ease compared to other stations.

The photo above shows the 2.4Ghz equipment mounted in the waterproof enclosure below the dish. This photo was taken during the initial build phase before I rewired it so, the amplifier is shown connected to the 28v feed. To rewire the amp to 12v was just a matter of removing the 28v converter and connecting the amp directly to the 12v feed instead. This reduced the output from a maximum of 12w down to a maximum of 5w giving a much better (considerate) level on the satellite.

It’s important to keep all interconnects as short as possible as at 2.4Ghz it is very easy to build up a lot of loss between devices.

For the connection from the IC-705 to the 2.4Ghz Up-Converter I used a 7m run of
LMR-400 coax cable. The IC-705 is set to put out just 300mW on 144Mhz up to the 2.4Ghz converter and so it’s important to use a good quality coax cable.

Once again the output from the 2.4Ghz amplifier uses 1.5m of LMR-400-UF coax cable to feed up to the 2.2 turn Icecone Helix Antenna mounted on the dish. This keeps loss to a minimum and is well worth the investment.

The receive path starts with a Bullseye LNB, this is a high gain LNB that is probably one of the best you could use for QO-100 operations. It’s fairly stable frequency wise but, does drift a little in the summer months with the high temperature changes but, overall it really is a very good LNB.

The 12v feed to the LNB is via the coax and is injected by the Bias-T device that is in the radio shack. This 12v feed powers the LNA and associated electronics in the LNB to provide a gain of 50-60dB.

From the Bias-T the coax comes down to the NooElec SmartSDR receiver. This is a really cheap SDR device (<£35 on Amazon) based on the RTL-SDR device but, it works incredibly well. I originally used a Funcube Dongle Pro+ for the receive side however, it really didn’t handle large signals very well and there was a lot of signal ghosting so, I swapped it out for the NooElec SDR and haven’t looked back since.

The NooElec SmartSDR is controlled via the excellent Opensource software GQRX SDR. I’ve been using GQRX SDR for some years now and it’s proven itself to be extremely stable and reliable with support for a good number of SDR devices.

To enhance the operation of the SDR device I have added a Griffin Powermate VFO knob to the build. This is an old USB device that I originally purchased to control my Flex3000 transceiver but, since I sold that many moons ago I decided to use it as a VFO knob in my QO-100 ground station. Details on how I got it working with the station are detailed in this blog article.

Having the need for full duplex operation on the satellite this complicates things when it comes to VFO tracking and general control of the two radios involved in the solution and so I set about creating a QO-100 Dashboard using the great Node-RED graphical programming environment to create a web app that simplifies the management of the entire setup.

The QO-100 Dashboard synchronises the transmit and receive VFO’s, enables split operation so that you can transmit and receive on different frequencies at the same time and a whole host of other things using very little code. Most of the functionality is created using standard Node-RED nodes. More info on Node-RED can be found on the Opensource.radio Wiki or from the menu’s above.

I’ll be publishing an article all about the QO-100 Dashboard in the very near future along with a downloadable flow file.

I’m extremely pleased with how well the ground station works and have had well in excess of 500 QSO’s on the QO-100 satellite over the last last year.

More soon …

Ever since my QO-100 ground station has been operational I’ve been using my NodeRed QO-100 Dashboard to control my IC-705 and GQRX SDR software to drive my NooElec SmartSDR receiver. This gives me a full duplex ground station with both transmit and receive VFO’s synchronised.

This solution has worked incredibly well from the outset and over time I’ve added extra functionality that I’ve found to be useful to enhance the overall setup.

The latest addition to the ground station solution is a Sennheiser Headset that I picked up for just £56 on Amazon (Much cheaper than the Heil equivalents at the HAM stores!) and have found it to be excellent. The audio quality from both the mic and the headphones is extremely good whilst being light and comfortable to wear for extended periods.

To incorporate this into the ground station the headset is connected to my Kubuntu PC and the audio chain to the IC-705 is sent wirelessly using the latest version of WFView. This works extremely well. The receive audio comes directly from the GQRX SDR software to the headphones so that I have a full duplex headset combination.

Audio routing is done via pulse audio on the Kubuntu PC and is very easy to setup.

Since I no longer have a mic connected to the IC-705 directly I found that I needed a way to operate the PTT wirelessly and this is where the latest addition to my NodeRed QO-100 Dashboard comes in.

Adding a little functionality to the NodeRed flow I was able to create a button that toggles the IC-705 PTT state on and off giving me the ability to easily switch between receive and transmit using a simple XMLRPC node without the need for a physical PTT button.

The PTT state and PTT button colour change is handled by the Toggle PTT function node shown in the above flow. The code to do this is relatively simple as shown below.

The entire QO-100 Dashboard flow has grown somewhat from it’s initial conception but, it provides all the functionality that I require to operate a full duplex station on the QO-100 satellite.

This simple but, effective PTT solution works great and leaves me hands free whilst talking on the satellite or the HF bands when using the IC-705. This also means that when using my IC-705 it only requires the coax to be connected, everything else is done via Wifi keeping things nice and tidy in the radio shack.

The image above shows the QO-100 ground station in receive cycle with the RX/TX VFO’s in split mode as the DX station was slightly off frequency to me. The PTT button goes red when in TX mode just like the split button shown above for visual reference.

As you can probably tell, I’m a huge fan of NodeRed and have put together quite a few projects using it, including my HF Bands Live Monitoring web page.

More soon …

I’ve been making a few improvements to my QO-100 Node Red Dashboard whilst waiting for the 2.4Ghz hardware to arrive. I’ve added the ability to split the RX and TX VFOs so that I can tune away from the TX frequency for working split stations or for tuning to slightly off frequency stations. I also added a series of tuning buttons to the top of the GQRX side of the dashboard to enable easy tuning using the trackball connected to my Kubuntu PC. This worked well but, I really missed having a real VFO knob like a conventional radio.

As I had a Griffin Powewrmate USB VFO from a previous SDR radio I added it to the flow as well so that I had a physical VFO knob for the SDR receiver. Details on how I got it working using evtest and a simple BASH script are in the Griffin Powermate article.

The Node Red flow is looking a little busier with the addition of split mode and the Griffin Powermate USB VFO which has really enhanced the useability of the solution. It’s very impressive what can be achieved with Node Red with a little imagination. You really don’t need to be a heavy weight programmer to make things work.

I also put together some code to calculate the S Meter reading from the dBFS data the GQRX SDR software generates. It’s not 100% accurate but, it’s close enough to be useful.

On the IC-705 side of the Dashboard I also now display the 2.4Ghz uplink frequency so that it’s available for logging.

So with the QO-100 Dashboard ready to go live I have now started putting together the 2.4Ghz transmit path of the ground station. I have the 2.4Ghz transverter and matching 12w amplifier from DXPatrol, the IceCone Helix 2.4Ghz antenna from Nolle Engineering, some LMR-400-UF and connectors from Barenco and an appropriate water proof enclosure from Screwfix to fit all the kit into however, I’m now being held up by one simple little SMA male to SMA male connector that I need to connect the transverter and amp together.

The SMA connector has been ordered but, is taking a month of Sundays to arrive! Hopefully it’ll arrive soon and I’ll finally get on the QO-100 satellite and start enjoying the fun.

More soon …