The Hermes-Lite is a low-cost direct down/up conversion software defined amateur radio HF transceiver based on a broadband modem chip and the Hermes SDR project. It is entirely open source and open hardware, including the tools used for design and fabrication files.
The SDR is controlled over your LAN, and plugs into your router. This can provide both local and remote operation. You can read more online about the project on the Hermes website.
The board comes fully installed, although you do need to follow the instructions on thermal dissipation for the PA. The radio will deliver 5w and is suitable for all modes and works particularly well on digital modes.
The microphone can be plugged into your PC, and then defined as the soundcard on the radio. In this audio clip, you can hear Gerald G4AXP (40w), and M0TAZ (5w) both using Hermes Lite SDR to have a chat on 5 MHz. In this case, I was using a cheap USB headset as I find headphones often help with noisy HF bands.
M0TAZ 5w and G4AXP 40w both using Hermes Lite SDR radios
The example RX filter setup in Spark SDR shown here.
The radio needs to be controlled by software locally installed on your PC, and you have a wide choice. I started with SparkSDR, as this program has a number of really neat features. The ability to have 4+ receivers running decoding digital modes on the fly. You will find SparkSDR have a online forum for questions and support.
Here we will look at the setting to use Spark SDR with WSJT-X, setting up the sound card option, and radio mode set to DIGIU and hamlib.
In WSJT-x you need to set the rig to Hamlib NET rigctl and Network Server to your local IP address of the PC using port 51111
Here we see WSJTx configured with SparkSDR and Hermes receiver decoding FT8
Its possible to do FT8 and other digital modes directly in SparkSDR, you dont even need to VAC but its good to have control as we can use this with other programs.
SparkSDR can be integrated with FLdigi using Hamlib
I have been running the Hermes Lite now for a few days. 140 QSO most FT8 or FT4 between 3 to 5w. This reception report is amazing, not worked but nice to know you have potential. ZL4AS
I know I am late to the party as ever, but I wanted to try and increase my knowledge of the Raspberry Pi and Linux so decided to try my had at 1090 MHz ADBS reception.
I wrote up some initial thoughts in a previous blog, this was my attempt to improve the reception and remote mount the Pi close to the antenna.
The problem with traditional deployment is the antenna and SDR receiver (FlightAware) are mounted some distance apart. High quality coax is needed, and even then the losses at 1090 MHz are high. I calculated 10 m of RG213 would equate to at least 3 dB loss, my antenna would need 25 m or coax to mount it in a convenient location. Factor in connectors and I was looking at a 9 dB loss, close on 90% or my received signal lost in attenuation.
The Pi has WiFi, and previous tests had shown me the range and reception was very good, so the idea of mounting the Pi in a waterproof box close to the antenna was conceived. Its not new, im not the first but this is my process and lessons I learned.
The rule of thumb in a box, is think of a size then double it, its not the pi that causes the issues, that is small.
85 mm x 56 mm in new money.
Its the routing of power, USB, SDR and the coax socket that need some consideration. Cooling may also be an issue, a sealed box could get very warm in the summer without some fan and ventilation.
Next was some waterproof sealant, I was going to be drilling holes in the box, and some waterproofing would be required. A tube of Silicon bathroom sealant seemed suitable. I would use this to seal around the power and coax cable entry points. I was going to be drilling all my holes on the bottom of the box, but everything needs to be sealed
The next issue was around the USB ports, I wanted the flexibility to mount the Flight Aware USB receive in a location of my choice and not be limited to the position of the USB ports.
The short extension cable offered the ability to mount the USB receiver flush to the case, with a hole drilled for the SMA to poke out.
Only suitable for short runs of power cable.
Powering the Pineeded some thought, was I going to connect 5v directly onto the board (this would have been easier) of could I look for some way to wire directly into the USB C connector. In the end this connector cause me a few concerns, it worked exactly as described, but in a tight box it takes up and incredible amount of space. If I could have got a right angled version, this would have made for a much neater installation. They are also quite expensive, but needs must.
For longer power cable runs voltage drop will become significant, and so I used a DC to DC converter from PIMORONI. They have one detailed on their website as Wide Input voltage SHIM, and you can power it with 3 to 16v
The last piece of the puzzle for me was a coax cable, I wanted N type on one end to connect to the antenna, and SMA on the other for the Flight Aware receiver.
If you wondered why I selected the blue Flight Aware receiver, in the tests I completed the band pass filtering and amplification out performed a standard RTL dongle by 10 to 20% range.
You will need a good 1090 MHz antenna, having something with some gain mounted as high as possible will make all the difference. I opted for a commercial made option, but if you have the equipment you could consider making a co-linear.
So having gathered all the items together, it was now just a case of positioning them in the box, the flight aware receiver has a long SMA shaft, so the hole can simply be drilled through the box and SMA pushed out. Once the SMA plug with coax is connected you can use a liberal application of silicon sealer to prevent water ingress.
I added a fan into the box, and made sure the Pi had a large heat sink fitted to the processor. The fan isn’t running right now, but this in itself provides a challenge. Not much point adding a fan if it doesn’t extract or force air into the box. I decided to drill 4 x 6 mm holes, and then as it turned out badly align these with the fan. I fitted some foam to the inside of the box, and then bolted the fan down, sandwiching the foam to the inside of the box.
This again was mounted on the bottom of the box, as with every hole, to hopefully prevent water ingress. The other issue is likely to be insect infestation, they like nothing more than a warm dry home high up on a pole!
You may want to consider the application of some grease on the pole, its amazing how earwigs can find these warm homes.
Power was the final thing to do, I did try and power it direct from home, but the voltage drop was just too much. I decided to use a DC to DC converter, this allowed me to feed with anything from 3 to 16v.
PoE was considered, but i couldn’t really see the advantage over WiFi and separate power cable.
Under voltage messages would indicate I still have some issues to resolve, but its working.
The box on a pole, cable ties used as a temporary fix
New to amateur radio, or a seasoned operator some people have never experienced the fun of operating out portable. The thrill of operating in a low noise environment.
If you going to take out your VHF/UHF handy, make sure you have a good antenna fitted. The stock antenna or the fake cheapo antenna on eBay is exactly that mostly useless. VHF operators sometimes take a vertical antenna with some gain to take advantage of an elevated location.
If your hill walking with unlicensed operators, then consider some PMR 446 radios as they provide good range and the ability to keep in touch with your fellow walkers.
Speaker wire makes excellent antenna wire, lightweight and strong, and I would suggest you make a few dipoles and maybe wind them onto a former so they are easy to deploy.
If you are taking the equipment in the car, then you may want to consider getting a telescopic mast. These can be deployed behind the car with a suitable mount.
Para style cord is great for putting up guy ropes. You will also need some tent pegs to secure items in the ground. Flimsy tent pegs often bend, why not try these more robust pegs.
The 50 MHz trophy cup is a great opportunity to work some stations, with lots of activity from both the UK and EU. Due to the current situation with Covid 19 this years event wasnt going to be on the same scale as previous events.
It was decided the event needed to me small scale, and to comply with the RSGB rules it needed to be a fixed station as no portable operating was allowed. Unfortunately that meant we could only put in a check log this year, as our operating site is away from home.
We operated from our contest site at Kelvedon Hatch, using a 6e 50 MHz beam. The beam was located on the 12m scam mast, and the radio was the Icom 7610. 400w RF power was delivered by the Expert 1.3KFA.
The contest was somewhat different to usual, no portable and hence many contest stations stayed away. Conditions on Saturday was flat, with just a few SPe openings towards the end of the day. Sunday was much more interesting, with the band packed full of stations all over the EU.
We worked 161 stations in 21 DXCC, best DX was UY1HY @ 2288 KM
I have been using Flightradar24 for a while and found it very helpful in identifying local air traffic and listening to aircraft approaching and departing London City, Stansted and Heathrow.
I had for some time a Kinetics SBS-1 this was around 10 years old now, and I was looking at a more modern receiver that could link to the internet. I read that you could upload your data to Flightradar and in return, they would provide you with a business account. You can read how Flight Radar 24 collects and displays data on its website.
The best option for me was to look towards a FlightAware USB stick and to run the unit 24×7 from a Raspberry Pi. The Pie Hut even provide an SD card with Flightware already installed.
You can read more about the FlightAware USB on the RTL SDR website. The comparisons I completed with the Kinetics SBS1 and the FlightAware showed the aware was 10 to 20% better at distant reception. This could be a combination of its filtering and amplification. You can read more about the advantages and choices on the RTL website.
I opted to download the software and follow the instructions on the FlighRadar24 site. This take you through the options of downloading the Pi24 Image for your SD card, and then how to write that image to your SD card.
For me that all worked, up until the last stage, I setup my WiFi in the “wpa_supplicant.conf” file on the SD card and then just expect everything to work. It wasn’t quite like that, and for me I need to SSH into my PI to configure the software. Not being a regular Pi user, I needed some instructions.
The most comprehensive I could find was located here. These steps took a while to follow, but my system was never going to work without following the steps outlined. I could see from my wireless router the local IP address and port number, and worked out I could ssh by bring up a terminal window and typing
Or what ever IP address you PI is located. Once that was completed I needed to log into my FlightRadar24 and data started to upload the account was upgraded to business. You will need a reasonable antenna, I have described that process in this article. Coax length and antenna choice and positioning is a major issue with 1090 MHz and the associated losses.
The Flight Aware receiver is both cheap and high performance
The stock antenna with the RTL dongle is too long and will require cutting down. 68 mm is the required length, and you can use some snips to reduce its size. This will improve reception, but an external antenna will provide the best results.
The receiver connects to your PC via USB and requires Software to enable easy allocation of memory channels. You can search online, software ranges from free beta to expensive commercial software.
Beta Software from Wayne Taylor is available online I don’t know how long this will stay beta before going full release, so an archived copy can be found here.
DL8MRE Marcus has written some software on his site. This costs around £40, but works well and allows you to edit and search VFO with ease. The format of the native AOR memory files (CSV) is a mystery, no one seems to understand the syntax. I may have a go at decoding them sometime.