Category: Satellite

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QO-100 Satellite Node Red Dashboard

Whilst I’ve been waiting for the weather to improve so that I can get my QO-100 dish antenna up I’ve been working on my QO-100 Node Red dashboard.

The idea of the dash board is to bring together the operating of the receiver and transmitter into one control centre so that the two separate devices are able to communicate and behave as if they were actually one device, like a transceiver rather than being individual components.

Ideally I would like to have the transmitter and receiver talking to each other such that when the VFO on the transmitter is incremented/decremented the receiver VFO also moves by the same amount.

By doing this the receiver VFO should always be in the right place on the 10Ghz band to hear my 2.4Ghz uplink signal and of course, any station coming back to my CQ calls.

So far I’ve only been working on the receive part of the Node Red flow, it’s certainly been a lot of fun getting it put together.

I control my Funcube Dongle Pro+ (FCD) using GQRX SDR on my Kubuntu PC. This software is working extremely well with the FCD and I’m happy with the level of functionality it offers.

GQRX SDR has the ability built in to control the SDR via remote TCP connection using RIGCTL protocol. Currently there isn’t a RIGCTL node available for Node Red so I have written a number of Javascript function nodes that provide the appropriate functionality in conjunction with a standard Node Red TCP node. This is working extremely well on the local LAN in the radio room and is proving to be very stable and responsive.

M0AWS QO-100 Node Red Flow – Receive Section

The flow for the receive section of the dashboard looks fairly complicated but, in reality it’s really not too difficult to get to grips with. The receive flow provides the facility to switch bands, switch modes, change receiver filter band width, display a realtime signal strength meter, receive +/- clarifier in 10/100/1000Hz increments and put the receiver into QO-100 mode where the SDR VFO is tuned to 739.550Mhz whilst the dashboard VFO shows the QO-100 downlink frequency in the 10Ghz band. This is all working very well and I’m happy with the initial result.

M0AWS QO-100 Receive Dashboard in QO-100 mode

I now need to start work on the transmit side of the QO-100 dashboard and get communications between my IC-705 transceiver and the FCD SDR working via Node Red. This could be a little more challenging as it will involve communicating with the IC-705 via WFView over wifi.

More soon …

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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.

1.1m Off-Set Dish for QO-100

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.

Bullseye 10Ghz TCXO LNB

To achieve this I will need to purchase a little circuit called a Bias Tee. 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.

Broco Bias Tee

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 …

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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.

Funcube Dongle Pro+ USB SDR

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 …