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 …

I’ve been active on QO-100 for a few days now and I have to admit that I’m really pleased with the way the ground station is performing. I’m getting a good strong, quality signal into the satellite along with excellent audio reports from my Icom IC-705 and the standard fist mic.

I’m very pleased with the performance of the NooElec v5 SDR receiver that I’m now using in place of the Funcube Dongle Pro+ SDR receiver. Being able to see the entire bandwidth of the satellite transponder on the waterfall in the GQRX SDR software is a huge plus too.

As can be seen on the map of contacts above, I’ve worked some interesting stations on some of the small islands in the Atlantic and Indian Oceans. The signals from these stations are incredibly strong on the satellite and an easy armchair copy.

DX of note are ZD7GWM on St. Helena Island in the South Atlantic Ocean, PP2RON and PY2WDX in Brazil, 8Q7QC on Naifaru Island in the Maldives, VU2DPN in Chennai India, 5H3SE/P in Tanzania Africa and 3B8BBI/P in Mauritius.

There are many EU stations on the satellite too and quite a few regular nets of German and French stations. I’ve not plucked up the courage to call into the nets yet, perhaps in the future.

There are a lot of very experienced satellite operators on QO-100 with a wealth of information to share. I’ve learnt a lot just from chatting with people with some conversations lasting well over 30mins, a rarity on the HAM bands today.

We also had our first Matrix QO-100 Net this week, an enjoyable hour of chat about all things radio and more. We have a growing community of Amateur Radio enthusiasts from around the world on the Matrix Chat Network with a broad spectrum of interests. If you fancy joining a dynamic community of radio enthusiasts then just click the link to download a chat client and join group.

More soon …

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 …

I’ve been gradually building my QO-100 ground station over the last few months and have had the receive path working for some time now. One of the things I really miss with the Funcube Dongle Pro+ (FCD) SDR is a real VFO knob for changing frequency.

My QO-100 Node Red dashboard is configured so that I can have the FCD track the uplink frequency from the IC-705 but, sometimes I use the FCD without the IC-705 in the shack and so a physical VFO would be handy.

Many years ago when I lived in France (F5VKM) I had a Flexradio Flex-3000 SDR, a great radio in it’s time and one that gave me many hours of enjoyment. One addition I bought for that station was a Griffin Technology Powermate VFO knob. It worked extremely well with the PowerSDR software for the Flex-3000 and I used it for many years.

Many years later I’m back in the UK and much of my equipment is packed away in the attic, including the Griffin Technology Powermate VFO.

I decided to dig it out and see if I could get it working with GQRX SDR software. Sadly I couldn’t get it working with GQRX however, I did find a way of getting it working with Node Red and thus could add it to my QO-100 Node Red Dashboard and then control GQRX with it via a simple Node Red flow.

Plugging the Powermate VFO into my Kubuntu PC it wasn’t immediately recognised by the Linux O/S. After a little searching I found the driver on Github. I added the PPA to my aptitude sources and installed the driver using apt.

https://launchpad.net/~stefansundin/+archive/ubuntu/powermate

Once installed the default config for the Powermate device is to control the default audio device volume. To make the device available for use as a VFO knob you need to change the configuration so that the default setting is disabled. To do this is relatively easy, just edit the config file using your favourite command line editor (Vi/Vim in my case) and add the following entry.

vi /etc/powermate.toml

# Entry to control HDMI volume with Powermate
#sink_name = "alsa_output.pci-0000_01_00.1.hdmi-stereo"

# Set powermate not to work with volume control
sink_name = ""

As shown above, comment out the default “sink_name” entry (Yours may be different depending on audio device in your PC) and add in the Powermate “sink_name” entry that effectively assigns it to nothing.

Once this is done, save the file and exit your editor and then reboot the PC.

Next you’ll need to install a small program called evtest.

sudo apt install evtest

To check the evtest program has installed correctly, plugin your Powermate VFO to any available USB port and run the following command in a terminal.

evtest /dev/input/powermate

Turning the Powermate knob you should see output on the screen showing the input from the device. You should also see BTN events for each press of the Powermate device.

Input driver version is 1.0.1
Input device ID: bus 0x3 vendor 0x77d product 0x410 version 0x400
Input device name: "Griffin PowerMate"
Supported events:
  Event type 0 (EV_SYN)
  Event type 1 (EV_KEY)
    Event code 256 (BTN_0)
  Event type 2 (EV_REL)
    Event code 7 (REL_DIAL)
  Event type 4 (EV_MSC)
    Event code 1 (MSC_PULSELED)
Properties:
Testing ... (interrupt to exit)
Event: time 1685816662.086666, type 2 (EV_REL), code 7 (REL_DIAL), value -1
Event: time 1685816662.086666, -------------- SYN_REPORT ------------
Event: time 1685816662.318638, type 2 (EV_REL), code 7 (REL_DIAL), value -1
Event: time 1685816662.318638, -------------- SYN_REPORT ------------
Event: time 1685816662.574615, type 2 (EV_REL), code 7 (REL_DIAL), value -1
Event: time 1685816662.574615, -------------- SYN_REPORT ------------
Event: time 1685816663.670461, type 2 (EV_REL), code 7 (REL_DIAL), value 1
Event: time 1685816663.670461, -------------- SYN_REPORT ------------
Event: time 1685816664.030421, type 2 (EV_REL), code 7 (REL_DIAL), value 1
Event: time 1685816664.030421, -------------- SYN_REPORT ------------
Event: time 1685816664.334389, type 2 (EV_REL), code 7 (REL_DIAL), value 1
Event: time 1685816664.334389, -------------- SYN_REPORT ------------
Event: time 1685816665.334255, type 1 (EV_KEY), code 256 (BTN_0), value 1
Event: time 1685816665.334255, -------------- SYN_REPORT ------------
Event: time 1685816665.558230, type 1 (EV_KEY), code 256 (BTN_0), value 0
Event: time 1685816665.558230, -------------- SYN_REPORT ------------
Event: time 1685816666.030161, type 1 (EV_KEY), code 256 (BTN_0), value 1
Event: time 1685816666.030161, -------------- SYN_REPORT ------------
Event: time 1685816666.182151, type 1 (EV_KEY), code 256 (BTN_0), value 0
Event: time 1685816666.182151, -------------- SYN_REPORT ------------

At this point you’re ready to stop evtest (CTRL-C) and then create the following little BASH shell script that Node Red will run to collect the O/P from the Powermate USB device.

#!/bin/bash

###############################################
# Griffin Technology Powermate control script #
# for Node Red.                               #
#                                             #
# 04/06/23 - M0AWS - v0.1                     #
#                                             #
###############################################

VAL="1"
echo "STEP-1Hz"

/usr/bin/evtest /dev/input/powermate | while read LINE 
do
   case $LINE in

      *"(REL_DIAL), value 1") echo "$VAL"
           ;;

      *"(REL_DIAL), value -1") echo "-$VAL"
           ;;

      *"(BTN_0), value 1") case $VAL in

                              "1") VAL="10"
                                   echo "STEP-10Hz"
                                      ;;

                             "10") VAL="100"
                                   echo "STEP-100Hz"
                                      ;;

                             "100") VAL="1000"
                                    echo "STEP-1Khz"
                                       ;;

                             "1000") VAL="10000"
                                     echo "STEP-10Khz"
                                         ;;

                             "10000") VAL="1"
                                       echo "STEP-1Hz"
                                          ;;
                              esac
                                 ;;
        esac
done

Once the BASH script is copied and pasted into a file called powermate.sh you need to make it executable by using the following command.

chmod 700 ./powermate.sh

If you now run the shell script in a terminal you’ll see a similar output to that shown below from the device when used.

./powermate.sh 
STEP-1Hz
-1
-1
-1
1
1
1
STEP-10Hz
10
10
10
-10
-10
-10
STEP-100Hz
100
-100
-100
STEP-1Khz
1000
STEP-10Khz
STEP-1Hz
1
1
STEP-10Hz

As you can see above the shell script outputs a positive or negative number for VFO tuning and changes the VFO step size each time the Powermate is depressed.

Getting this output from the BASH shell script into Node Red is really simple to achieve using just 3 or 4 nodes.

In the Node Red development UI create the following nodes.

The first node in the flow is a simple inject node, here I called it trigger. This sends a timestamp into the next node in the flow at startup to set the flow running.

The Griffin Powermate node is a simple exec node that runs the script we created above.

Configure the node as shown above and connect it to the inject node that’s used as a trigger. Note: Change “user” in the Command field shown above to that of your username on your Linux PC)

Once done create the third node in the flow, a simple switch node and configure as shown below.

The switch node has two outputs, the top one is a text output that is fed into a text field to show the current step size of the Powermate device and the lower output is the numeric output that must be fed into your VFO control flow so that the VFO value is incremented/decremented by the amount output by the Powermate device.

I’ve found the Griffin Technology Powermate USB device works extremely well with Node Red and GQRX that I use for controlling the FCD SDR radio and it’s now part of my QO-100 ground station build.

As shown above you can see the Powermate Step size at the bottom of the dashboard, this text changes each time the Powermate device is depressed and will set a step size of 1Hz, 10Hz, 100Hz, 1Khz, 10Khz in a round-robin fashion.

The next stage of the build is the 2.4Ghz transmit path. I now have all the necessary hardware and so this part of the build can finally commence.

More soon …