LNB – M0AWS Amateur Radio

12 June 202422 June 2024

Deep Dive – Node-RED QO-100 Satellite Ground Station Dashboard

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.

M0AWS QO-100 ground Station Control Dashboard built using Node-RED. — M0AWS QO-100 Ground Station Control Dashboard built using Node-RED.

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.

M0AWS Node-RED QO-100 Ground Station Dashboard - 12/06/24 — M0AWS Node-RED QO-100 Ground Station Dashboard Flow as of 12/06/24

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.

M0AWS - Node-RED QO-100 Ground Station Dashboard - GQRX Startup — M0AWS Node-RED QO-100 Ground Station Dashboard – GQRX Startup Flow

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.

M0AWS - QO-100 Ground Station Dashboard - GQRX RIGCTL flow — M0AWS Node-RED QO-100 Ground Station Dashboard – GQRX RIGCTL Flow

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.

M0AWS - QO-100 Ground Station Dashboard - GQRX Controls — M0AWS Node-RED QO-100 Ground Station Dashboard – GQRX Controls Flow

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.

M0AWS - QO-100 Ground Station Dashboard - Powermate VFO section — M0AWS Node-RED QO-100 Ground Station Dashboard – Powermate VFO Flow

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.

M0AWS - QO-100 Ground Station Dashboard - IC-705 control flow — M0AWS Node-RED QO-100 Ground Station Dashboard – IC-705 Control Flow

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.

M0AWS-QO-100 Ground Station Dashboard 12 June 2024 Download

More soon …

5 June 20245 June 2024

QO-100 Satellite Ground Station Complete Build

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.

M0AWS QO-100 Ground Station Build Visual (Click to Enlarge)

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

M0AWS QO-100 1.1m off-set Dish and IceCone Helix antenna ground station — M0AWS QO-100 1.1m (110cm) off-set Dish with IceCone Helix antenna and Bullseye LNB.

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.

2.4Ghz ground station enclosure ready for testing

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.

Bullseye 10Khz High Stability Unversal Single LNB for 10.489-12.750Ghz

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.

Bias-T to inject 12v feed into the coax for the Bullseye LNB

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 …

29 June 202330 June 2023

Just one little rain drop is all it takes!

We’ve not had rain for over 6 weeks here in Eyke, Suffolk. The ground is incredibly dry and dusty. The farmers have been pulling vast quantities of water from their bore holes for weeks to keep the crops alive and we’ve been putting extra water out for the birds and animals that visit our garden daily.

Then one night we had about 30mins of light rain, not much at all and it was consumed by the dry earth is seconds. By morning you’d never of known it had rained however, strangely the next day when I fired up my QO-100 ground station I noticed that my signal into the satellite was way down from it’s normal S9+10dB level. Checking drive into the up-converter and SWR at the IC-705 everything looked fine. I then decided to check the SWR from the 2.4Ghz amplifier output only to find that it was off the scale.

I checked inside the enclosure for water ingress but, all was bone dry as normal. I disconnected the coax cable from the output of the amplifier and the IceCone Helix uplink antenna, tested with a multimeter and found everything was fine, no short and perfect continuity.

After scratching my head for a few minutes I decided to take both the N Type and SMA connectors apart to look for water ingress. Since the inside of the enclosure was dry I wasn’t expecting to find anything.

The N connector at the Helix antenna end on the dish LNB mount was perfectly dry, no water ingress at all. The layers of self amalgamating tape I’d put over the connector had done its job perfectly. Shame I had cut the tape off to remove the plug!

Upon removing the SMA connector at the amplifier end of the coax I noticed a tiny drop of water in the bottom of the housing where the pin goes through the white plastic insulator, not a good sign.

Sure enough upon further inspection I found that the white plastic disc that is situated above the pin on the centre conductor was wet and the coax braid felt damp. I knew immediately this wasn’t good.

At first I didn’t understand how there could possibly be water in the SMA connector when the rest of the enclosure was dry. Where the coax goes into the top of the enclosure there is a water tight junction that tightly grips the coax cable and seals it, supposedly stopping water ingress.

Since there was water in the SMA connector I feared that perhaps the water had gone further and entered into the amplifier so, I decided to remove the amp from the enclosure and remove the top cover to check.

After some close inspection I found the amp to be perfectly dry and free from water ingress, a relief for sure.

Before putting it all back together I decided solder on a pair of wires to the SWR and FWD-PWR pins on the amplifier and run them down into the radio room. This would then allow me to check the SWR and power output without having to get up to the enclosure with a multimeter.

Once this was done I then set about cutting 5cm of LMR-400-UF off at the SMA connector end so that I had a fully dry piece of coax cable to refit the SMA connector to. Having to do this outside and up a ladder wasn’t the easiest but, with a little perseverance and cooperation from the breeze I managed to get the pin soldered back onto the end of the coax and the connector back together.

I reconnected the amp to the 28v feed so that I could check the SWR and power output at full rating instead of the lower 12v setting that I had been using. Checking the voltage on the SWR pin I found that it fluctuated between 0.2v and 0.44v. This wasn’t what I was expecting as the PDF manual for the amplifier states that with a 1:1 SWR you should see 1.5v on the SWR pin.

DXPatrol 2.4Ghz Amplifier Manual Page for SWR/FWD-PWR voltages

After checking all the connections and retesting and getting the same voltage reading I emailed Antonio at DXPatrol detailing my findings and asking if he could advise on the voltages I was seeing. Sure enough in no time at all he came back to me saying that the manual was incorrect and that I should see between 0.2 and 0.5v on the SWR pin for a good SWR match. Being happy that the readings I was getting were fine I emailed back thanking him for his swift reply and then moved on to check the power output safely in the knowledge that the SWR reading was within tolerances.

Checking the FWD-PWR pin I found that on SSB the voltage was fluctuating between 2v and 3v, this equates to 6w and 9w output, about right for SSB. Switching to CW mode I found the full 4v was present on the FWD-PWR pin confirming I had the full 12w output from the amp. Of course this set off “Leila” on the satellite immediately as I was a huge signal on the bird with such high power output and was a reminder to reconnect the amp to the 12v supply instead to ensure I didn’t exceed 5w output and thus keeping to a considerate level on the transponder input.

After further investigation I came to the conclusion that the water ingress could only of come from the cable inlet on the top of the enclosure, it had then run down the coax cable into the SMA connector. Somewhat annoying as the inlet is supposed to be a water tight fixing. Once I had everything back in the enclosure and securely fitted, I covered the cable inlet and coax in self amalgamating tape in the hope that this would stop any further water ingress. I also re-taped the N connector at the antenna end as well to ensure it was also protected from water ingress in the future.

I’m hoping this will be the end of my water ingress issues and that I have a dry 2.4ghz future ahead of me.

More soon …

8 June 20238 June 2023

Replacement for the Funcube Dongle Pro+

For some time now I’ve been using my Funcube Dongle Pro+ (FCD) as my QO-100 downlink receiver. It’s worked fairly well and has given me the ability to listen to stations on the satellite over the last few months.

During this time I have noticed a couple of things about the FCD that has lead me to the final decision to change to a new SDR device.

The first of these ‘things’ is the fact that the FCD gets seriously overloaded when there are multiple large SSB signals within the receive pass band. The only way to manage this is to constantly keep changing the software based AGC, mix and LNA settings to reduce the levels of the incoming signals so that the overloading stops. This is great except when you tune to a quiet part of the satellite transponder you have to turn all the settings back up again to be able to hear the weaker signals. After a while this becomes tiresome.

The fact that there isn’t a hardware AGC in the FCD is a major drawback when being used for satellite reception especially when it’s on the end of a very high gain LNB and dish antenna.

The second of these ‘things’ is the fact that I can’t see the whole transponder bandwidth at one time with the FCD as it has a very small receive bandwidth capability. This means that I am constantly tuning up and down the transponder to see if there are any stations further up or down in frequency.

Talking to more experienced satellite operators in the Matrix Amateur Radio Satellites room they recommended replacing the FCD with a NooElec NESDR SMArt v5 that has hardware AGC and is capable of receiving and displaying a much wider bandwidth.

Looking on Amazon the NooElec NESDR SMArt v5 is only £33 so I decided to place an order for one and give it try.

In typical Amazon style the SDR receiver arrived the next day and I wasted no time getting it plugged in and connected to the QO-100 ground station.

The NESDR SMArt v5 is based on the well known RTL-SDR that came onto the market some time back but, has a number of improvements in it that take it to the next level.

The first thing that I was happy with was the fact that the GQRX SDR software I use recognised it immediately on startup, no configuration or drivers were required it just worked, straight out of the box. Since I use Kubuntu Linux on my radio room PC I did wonder if I would need to get into installing extra libraries etc but, thankfully none of that was required.

Looking at the signals from the QO-100 satellite initially they appeared to be nowhere near as strong as they were on with the FCD. Looking at the settings in GQRX I noticed that the hardware AGC was off and the LNA setting was back to it’s default very low level.

I switched on the AGC and then increased the LNA setting to 38.4dB and found that the signals were now plenty strong enough on the display but, not overloading the receiver.

I then went on to adjust the display so that I could see the whole satellite transponder bandwidth on the screen. This is great as it enables me to see the low, middle and high beacons that mark out the narrow band section of the transponder and at a glance see all the stations using the satellite. This was a massive improvement in itself and one that I am very pleased with.

Using the NooElec NESDR SMArt v5 SDR it very soon became clear that it copes with multiple large signals in the pass band so much better than the FCD did. There’s no more overloading of the receiver, no more ghost signals appearing on the waterfall due to the front end not being able to cope and no more having to constantly keep playing with the settings to get things under control. The hardware AGC built into the SDR device does a great job at keeping it all under control whilst receiving a much wider bandwidth than the FCD ever could.

The satellite beacons are now received at S9+15dB without the receiver being overloaded, the first time I have seen this since starting out on my QO-100 venture.

The other thing that became obvious very quickly is that frequency stability is much better than it was with the FCD, it doesn’t drift up and down the transponder now and stays tuned exactly where I put it. It’s also on frequency whereas, the FCD was always 1.7Khz off frequency.

The NooElec NESDR SMArt v5 is very well put together, it has an aluminium case that acts as a heatsink (it does get warm!) and overall the build quality is much better than the plastic cased FCD. When I think that I paid close to £100 for the FCD and the NooElec NESDR SMArt v5 only cost £33, I am amazed at the build quality.

Overall I’m extremely pleased with the purchase of the new SDR, it slotted in perfectly as a replacement for the FCD, works great with GQRX, my QO-100 Node Red Dashboard and performs considerably better than the FCD. Overall money well spent!

You can find the NooElec NESDR SMArt v5 spec sheet here.

More soon …

7 June 202324 July 2023

UPDATE: QO-100 Node Red Dashboard

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.

M0AWS QO-100 Node Red Dashboard as of 07/06/23

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.

M0AWS Waterproof enclosure from Screwfix

M0AWS Laying out the 2.4Ghz TX kit in the enclosure — M0AWS Waterproof enclosure from Screwfix

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 …

1 May 202324 May 2023

QO-100 Satellite Ground Station Build

Over the long bank holiday weekend I started putting together my QO-100 ground station. To start with I’ve concentrated solely on the receive path. I’ll start the transmit path once I have the receive path operational at a satisfactory level.

A few weeks ago I purchased a 1.1m off-set dish antenna and a Bullseye LNB. These have been sat in my garage waiting for the weather to improve so that I could start the build in the dry.

Fortunately we’ve had a mini-summer for the last 2 days and so I started work on getting the dish mount built. Using some timber from the local saw mill I made a braced 3m tall post which I screwed to the side of the cabin to provide a stable fixing platform. I used a couple of threaded bars to bolt through the walls of the cabin to ensure a solid fixing.

Next I mount the metal dish bracket to the top of the wooden post taking the total height up to around 3.2m above ground. This gives plenty of head clearance down below.

Next I assembled the dish and and attached it to the metal dish bracket at the top of the wooden post.

QO-100 1.1m dish mounted on the 3.2m AGL fixing

Attaching and cabling the Bullseye LNB was an easy job. I used some high quality coax cable that I purchase from the Satellite Superstore when I purchase the dish. I also had to set the LNB skew to -17.8 degrees. The marking on the LNB are tiny and go up in fives and so it’s pretty much impossible to get exactly -17.8 degrees so I turned it to 15 and then a tiny bit. It was as close I could get it!

Next I needed the information on where to point the dish. Fortunately there is a great web app on the BATC website where you can move a pin on a map to your location and all the information you need to align the dish is automagically calculated for you.

Armed with this info I set about aligning the dish. Getting it as close as possible I lightly locked off the dish and continued getting the coax in to the radio room so that I could connect it to my Funcube Dongle Pro+ (FCD) SDR receiver. Since the LNB needs a 12v DC feed I had to put inline a “Bias Tee” unit. This unit allows you to inject 12v onto the coax going up to the LNB but, stops it from coming back into the receiver. I used a Bias Tee that I purchased from Amazon with the Bullseye LNB.

Connecting the coax to my Funcube Dongle Pro+ I was really pleased to see that I was receiving signals from the satellite perfectly well. I decided to take my laptop up onto the roof of the cabin and see if I could improve the reception further. To my amazement with very tiny changes in elevation and azimuth I was able to improve the QO-100 beacon signal by a further 10dB.

Being pleased with the dish alignment I started to tighten it so that it couldn’t move in the wind. Unfortunately this caused the dish to move a tiny amount which reduced the signal strength. I loosened the bolts off again and realigned the dish once more. This time when I tightened the clamps I did it a bit at a time on each bolt working my way round them so that the dish didn’t move. Doing it this way I still lost 1dB off the QO-100 beacon signal due to tiny amounts of movement but, decided I could live with the 1dB reduction.

QO-100 dish successfully mounted & aligned with HF antennas in the background

Below is a very short video clip showing a German station talking on the QO-100 satellite. As you can see the signal is nice and strong and extremely clear. I did find that the output from the LNB was actually too much for the FCD SDR and so I reduced the LNA setting in GQRX to 0dB. This reduced the background noise level considerably as the receiver was no longer being overloaded and made the signals much more prevalent above the noise floor.

Short video clip showing signal clarity from the QO-100 Satellite

I’m really pleased at the performance of the receive path and have now ordered the 2.4Ghz hardware from DXPatrol and Nolle Engineering so that I can build the transmit path.

I have also made some improvements to my QO-100 Node Red Dashboard so that I can work split on the satellite using my IC-705 and FCD SDR.

QO-100 Node Red Dashboard with ‘Split’ capability

Once the 2.4Ghz hardware arrives I’ll update the blog with progress.

More soon …

27 February 202327 February 2023

QO-100 Station – Initial parts purchase

After much reading and viewing of youtube videos I have finally settled on the parts that I want to use to build my QO-100 Satellite ground station.

Initially I’m only going to build the receive path of the QO-100 station. From the articles and blogs I’ve read online all the experienced Amateur Radio satellite Op’s recommend getting the receive side sorted first and then moving onto the transmit path.

I need to stress here that I have no experience of radio above 433Mhz (70cm), a band that I have only used a handful of times. 99% of my Amateur Radio life has been spent below 30Mhz and so this is going to be a very new experience for me.

So, what am I going to purchase for the receive path?

I’ve settled on a 1.1m off-set dish from the Satellite Super Store that should give me plenty of gain if I manage to get it pointed successfully at the bird.

I’ll pair a Bullseye 10Ghz TCXO LNB with the dish to give me a high stability receive path that shouldn’t wander too much up and down the band with temperature changes throughout the seasons.

The Bullseye LNB gets extremely good reviews from the HAM Satellite community, although it is a little on the expensive side compared to many others available. Since I only want to do this once I’ve gone with the more expensive option in the hope that it gives me the stability I’m looking for.

Since we’ve never had satellite TV here at home I’ve only just learnt that LNBs require a voltage feed since reading about other peoples QO-100 station builds. Most LNBs can be used for either horizontal or vertical polarisation and are switched by feeding with either 12v or 18v respectively. The LNBs also use this same voltage feed to do the frequency down conversation and some amplification of the received signal.

At the moment I’m only looking to get onto the narrowband part of the QO-100 satellite service and so I will need to feed the LNB with around 12v to ensure vertical polarisation is achieved. The easiest way to do this is to inject the 12v feed up the coax cable to the LNB.

To achieve this I will need to purchase a little circuit called a Bias Te e. This relatively simple circuit consists of a capacitor and inductor combination that stops the 12v from going back into the receiver whilst at the same time stopping the RF from going back into the power supply.

Bias Tee units are relatively cheap to buy online and I have decided to get one from Amazon that has been recommended in a number of blogs posts I have read during my research.

With these parts ordered I now need to source the materials to mount the dish up above head height in the garden with a clear view of the sky in the direction of the satellite.

Getting the dish up high enough to be above head height will be important for when I get the 2.4Ghz uplink path in place. At these frequencies it’s important to ensure that no one is able to walk across the front of the dish whilst I’m transmitting. I’m hoping to get the dish up about 3m in the air in such a fashion that it is rigid enough to stop the dish moving around in the wind. I must admit I’ve not done any wind load calculations for the 1.1m dish so I’ll have to see how it goes over time. Fortunately where I want to put the dish is fairly well sheltered from the north wind that often howls through here so, hopefully it won’t be an issue.

More soon …

16 January 202317 January 2023

Funcube Dongle Pro+ / GQRX / Kubuntu

Many years ago I purchased a Funcube Dongle Pro+ (FCD) SDR. Since it’s arrival it has just been stored in my “Get round too it” drawer.

It’s been many years but, today is the day it comes out into the light and finally gets powered up.

I’m hoping to be able to use the FCD as the receiver in my QO-100 satellite ground station setup.

The output from the 10Ghz dish mounted LNB is around 739Mhz, well within the FCD receiver range of 150khz to 2Ghz. This will save me from having to transvert from 739Mhz to 430Mhz (70cm band) on the receive path.

This will also give me full duplex operation as I will use my Icom IC-705 on the 2m band (144-146Mhz) to drive the 2.4Ghz transverter for the satellite uplink whilst listening to my own signal via the 10Ghz downlink fed into the FCD.

Before I can even start to build the QO-100 satellite ground station I need to get to grips with the FCD, get the software installed, configured, resolve audio routing via virtual audio cables and get it decoding FT8/JS8/WSPR etc.

Talking to G0DUB in the General Amateur Radio Chat room on Matrix he recommended trying the GQRX software to drive the FCD. GQRX is open source which fits perfectly as I want to control the FCD from my Kubuntu PC.

Checking the Ubuntu repo’s I found that GQRX v2.12 is available for installation.

sudo apt install gqrx-sdr

Once installed I fired up GQRX and set about configuring it. Initially it appeared to have automatically detected and configured the FCD however, when I started the FCD the software ran for 5 seconds and then just hung.

Diving into the configuration settings I found that the FCD actually appears twice in the list of available devices and all I had to do was select the other one in the list and start the software again and all was well.

I connected my 20m Band EFHW Vertical antenna and trawled up and down the band. The receiver performed well even with fairly strong signals so, I spent some time listening to a few of the stations coming in from the USA.

Next I wanted to sort out the configuration for digital modes. I already have a couple of virtual audio cables in the form of loopback audio devices configured on my Kubuntu PC as this is how I connect the audio between WFView for the IC-705 and WSJT-X/JS8CALL.

Sadly, GQRX doesn’t recognise the loopback audio devices that already exist and so I had to do a little further research to get to the bottom of the issue.

Digging deeper I discovered that GQRX requires loopback audio devices created using Pulse Audio and not the kind I had already created at the O/S level. A quick read of the pactl man page and some further searching online I found all the info I needed to create the correct kind of loopback audio devices.

Two commands are required to create the pulse audio server audio loopback devices:

pactl load-module module-null-sink sink_name=gq2jt sink_properties=device.description="gq2jt"

pactl load-module module-loopback latency_msec=1

Once I’d created the loopback audio devices I was able to select the gq2jt devices in both GQRX and WSJT-X/JS8CALL so that the audio was routed correctly.

GQRX SDR and WSJT-X working with the Funcube Dongle Pro+

The overall solution works well and doesn’t put much load on the CPU of my Kubuntu PC, leaving plenty of horse power for me to do other things at the same time.

So I now have the Funcube Dongle Pro+ working perfectly on my Kubuntu PC, all I need now is a 1.2m dish, a 10Ghz LNB and some high quality coax cable.

UPDATE: I decided to leave the FCD connected to the 20m Band EFHW Vertical overnight and monitor FT8 on the 40m band. The EFHW antenna isn’t anywhere near resonant on the 40m band and so I thought it would be interesting to see how well the FCD performed on a completely non-resonant antenna.

To my surprise it did exceptionally well, stations from all over the world were heard with ease, the FCD really is an excellent little SDR receiver.

Map showing stations heard on 40m Band FT8 over night 16/17 Jan 2023

If you’re looking for a relatively cheap but, effective receiver for FT8/WSPR monitoring then I can highly recommend the FCD. If paired with a RaspberryPi then it would be a really cheap to purchase/operate solution for any HAM operator or short wave listener (SWL).

More soon …