MLA-30, any good for anything?

Back in August I read about MLA-30 a (very) cheap active loop antenna that was said to be at least a good one, if not even as good as the more expensive “original” loops.

I wanted to test how well it might perform here at my city home in the middle of huge QRM and no place for long wire antennas. I got one from eBay with only 37€ (including p&p) so it was cheap enough to test without spending some 300+ € just to find out that it won’t work well where I’m planning to use it.

The kit was like “Plug & Play”, all you need to get started with springy like loop, all the cables and the power supply unit. What you need to provide yourself is some kind of support for the loop as it is very wobbly and will not stay upright by itself.

MegaLoop MLA-30

It took much longer to arrive than I expected. I ordered the MLA-30 from The Netherlands thinking that it will be quick delivery inside EU (to Finland), but instead of like one week I waited three weeks – well, I have all the time 🙂

All the parts needed for the antenna arrived in good shape

For the temporary support I used camera tripod, some velcro and wooden stick to get the loop up and turnable. After some tests I found out that I need to position the loop so that it is facing east-west (when looking directly through the loop). By doing this I was able to minimize the huge QRM I have in my city home.

The tests:

It took several days before the ‘radio weather’ was good enough for me to test the loop.

For the benchmark I used my remote site, SRPDuo with Windom wire antenna (40m). The loop was powered by a USB powerbank – perhaps not the best idea due to the way USB powerbanks works – they usually have a Buck&Boost voltage converter that uses some 100-300khz switching frequency. This is not the best way to power sensitive radio device that is meant to be used for listening in the same frequency band, but this was test so i used it anyway.

I used AirSpy Mini as a SDR radio with NooElec HamItUp up-converter as the AirSpy Mini cannot tune under 24Mhz. HamItUp “moves” the lower bands (0-30Mhz) up to 125Mhz so that the radio can hear them (125Mhz = 0 … 155Mhz = 30Mhz).
Software used for testing was Airspy’s own SDR# and the excellent SDR Console.

The loop was indeed very easy to put into action, right away I was able to receive all the “basic stations”. I have no real testing equipment nor enough experience with loop antennas, so I am not the best one to judge but if I can receive some (from my point of view) exotic stations from my city balcony then the loop really works!

The final test was done using some not-so-official stations that usually have very low power, self made equipments and lots of DIY spirit behind them.

For my surprise I was indeed able to receive those stations, sometimes with as good signal as the benchmark system at my remote site.

Benchmark system: SDRUno – RSPDuo – City Windom (40m)
MLA-30 test: SDR Console 3 – AirSpy Mini – HamItUp – MLA-30

31m, 41m, 49m and 75m band’s – comparison:

For reference I took screen captures of some HF bands where it is easy to see how well the MLA-30 loop performs, remember that it is tested against 40 meter long wire antenna and very good quality SDR receiver.

First four pictures are from MLA-30 (with black background) and rest are from City Windom (greyish background).

Final words:

From my experience this kind of cheap loop indeed can be used well with SDR’s. I find it very interesting piece of an antenna especially if you need very light, very small antenna that is very easy to operate and even take with you to your holiday trip!

From APT to LRPT

On July 5 2019 the Russian Meteor M N2-2 weather satellite was successfully launched into orbit. Unlike NOAA satellites Meteor uses LRPT to transmit pictures down.

Main difference between APT and LRPT is that APT is fully analog while LRPT uses digital data transfer. APT is very easy to receive and I have been using my system for years to receive NOAA pictures.

I wanted to learn about how to receive Meteor LRPT pictures so deep dive to internet was needed. I soon realized, that the LRPT is not easy thing! It took few days to get everything to work.

What I actually did:

I’ve read before about how these LRPT pictures can be decoded but found it way too complex process. When the excellent SDR site published an update to some older article of “METEOR M DEMODULATOR SDR# PLUGIN AND LRPT-DECODER UPDATED” I got curious – maybe there are now tools that are easier to use than before, perhaps even WxToImg APT like reception automation!

The RTL-SDR article follows instructions from Happysat site with great results, my turn to try!

The first try! White bars/lines in the picture are due to loss of the signal.

What surprised me the most was the amount of details in the received picture. I have been so used to receive APT pictures that have 4x4km grid resolution and smuggy kind of appearance that these Meteor LRPT images with crisp resolution and loaded with details looked so good.

System, software and documentation used:

Radio: AirSpy Mini
Antenna: Cross dipole tuned to 137Mhz
LNA: No LNA was used, hence the LOS and gaps in the data

Software radio: SDR#
Demodulator: Meteor Demodulator Plugin v2.3
LRPT Decoder: M2 LRPT Decoder V55
Image processing: SmoothMeteor and LRPT Image Processor

Documentation: Setup Meteor M-N2/N2-2 with LRPT-Decoder

“Some minor adjustments…”

Well, not that minor after all. I decided to do a full re-installation to my antennas, locate them to a different place and also add some new ones too.

The original concept was that I had a small antenna mast on the roof, about 7 meter high.

Now the new idea was to remove everything that has anything to do with my DX hobby, fix some TV antennas and create a new antenna array some 25 meters away from the house.

I have no luxury to install a full 25 meter or so antenna mast, so another solution had to be implemented here – The answer was to use a standard flag pole as the mast and create some kind of cradle to the top of it so that I can install all my whip, dipole and wire antennas to that, get all the cables to the house and have an extra grounding too. Also two new antennas needed to be installed to this mast.

The flag pole has been installed with so called “earth screw”, a 1,6m long sturdy pole screwed into ground. The flag pole is then fixed to it. With this combination I was able to create a very light but sturdy 10m high antenna”mast”. The flag pole is so light that I was able to lift it up alone, only 23kg – of course all antennas and peripherals attached to it the total weight was around 50kg and some help was required to lift the mast up.

Grounding of the mast is done by connecting the antenna cradle (metal one) to the earth screw with 16mm copper wire and to the existing grounding too so that the antenna cradle, earth screw, two older grounding points and all radios are now fully isolated from the power line earth and connected to this same ground.

Details about all the installation steps, new antennas, grounding and so on are published later to this blog.

So, was it worth it?

One word – YES – I have just started to test all things, but so far I have seen a huge boost in reception performance, noice levels went down at least 20dbm and also the interference that was caused by the LTE modem is now fully gone.

The All New remote RIG – Part 1.2 – “Testing with APT reception”

One of the first thing ever I did with a computer and a radio was to try to receive APT weather satellite telemetry and data. As I’m creating brand new system I wanted to test how my new shiny system can handle APT reception without any modification to the antenna or LNA but only the software and used radio (SDR).

I’m happy with the early results, still so much to do but already the results are very nice and promising!

Date: 31. Mar 2019
Radio: AirSpy HF+
Radio Software: SDR#
Antenna: DIY Turnstile
Software: WxToImg (Windows version)

The All New remote RIG – Part 1.1 “Testing the HF shield”

One problem in my system is that I need to power it using cheap switched-mode power adapters. They are – well, cheap, universal, small, easy to get – and a huge source of wideband HF interference.

The best solution would be to replace all these power supplies with real transformers and linear regulators, but for my project they are way too heavy and big. I need to have 8 different power sources from 5V to 24V and one of the power adaptors needs to be able to communicate with the system itself to automatically choose the power level (USB-C powered SoC computer).

So, there must be some way to – if not totally get rid off – but at least to get the noise level down.

I decided to test if a cheap metal mesh would be enough. I got 60cm x 200cm roll with 0,9mm mesh size with 15 euros.

After few hours (and very painful finger mutilation – oh those spikes!) I had a test “box” that I could use to test if this kind of shield is enough to isolate most of the HF interference these switched-mode power adapter causes.

I covered a table with the metal mesh, then used empty wine bottle as an support for small loop-antenna. The antenna was connected via DownConverter to AirSpy Mini so that I can see what happens down there in HF (VLF) range.

From the power adapters I have I selected the most noisy one for this test. A halogen lamp was used for the load and the power adapter was placed so that is was directly under the loop-antenna – approx. 30cm from the antenna.

The software I used for measuring was SpectrumSpy, really simple yet powerful small software that comes with SDR# that can be used to monitor large block of spectrum at once. It only draws the waterfall, so no sound is extracted from the radio.

Test results – were AWESOME!

Yes yes, I know that this is the basic Faraday’s cage -sort of, but still I was very surprised about how well it was able to ‘clean the band’.

Here is 10MHz wide band starting from 0Hz ending at 10MHz. Note that because of the DownConverter the scale in the picture is +125MHz higher than the actual tuned frequency, so 125MHz = 0Hz and 135MHz = 10MHz.

Time to hide the power supply just by placing the cage cover over it. Note that there is no grounding whatsoever in this system, just a metal mesh on wooden table. Look at that iPad screen – Wow! Just covering the power supply, no grounding of the mesh and huge difference!

This was so promising that I wanted to take the test one step further and create a very AdHoc grounding for the metal mesh to see if it helps at all … and it did.

This is the SpectrumSpy view of 0Hz – 10MHz with me ‘grounding’ the mesh with my both hands – is this perhaps called “The nerding of the mesh?” 🙂

This was indeed something I did not expected to see. Just 30cm above the veeeeery noisy power supply and the whole band is almost clear.

Here is the same in one picture, the mesh cover removed and then put back with grounding (me).

Yes, oh yes – I think I found a solution to get rid of most of the HF interference caused by these yet wonderful but also very noisy power supplies.

Time to create a full cage with all power supplies … more painful finger prickling 🙂

The All New remote RIG – Part 1 “The POC”

I had a plan to create all new remote Rig already during 2018, but due to some problems to get parts to it (the main computer) this has now been moved to be “The Project – 2019”.

The Idea:

* Fully remote controlled – power supplies included
* Windows 10 based main computer
* RaspberryPi based controll computers
* Video monitored, all led-lights, displays, others
* Enough computing power for realtime AirSpy R2, 10MHz bandwith
* Fully internal networking solution for standalone use
* Enough USB slots for:

– Four USB3 connected radios
– Six USB2 connected radios
– External keyboard and mouse
– External USB3 SSD for full system clone
– Spare USB3 & USB2 slots for later use

* At least 20/20mbit internet connection

After several iterations, tests and re-planning I finally had a system for real-life PoC (Proof of Concept) that I could use for testing all the aspects of my idea.
There are still some parts missing from the Rig, like display and another USB-hub, but with the current configuration it was possible to test the raw computing power and usage of the system to find out if there are huge problems, or not!

Here is the system under testing and some details about the components used and for what are they for:

1: 10/100mbit standard ethernet switch
2: 3G/4G/Broadband router with WiFi base station
3: USB3 HUB with external power supply (3xUSB3 & 4xUSB2)
4: External USB3 240GB SSD for full system clone/backup
5: RaspberryPi 3 for Remote access, Webcams & Power control
6: RaspberryPi Zero W, Remote keyboard and Remote access backup
7: Webcams for remote video feed
8: Lattepanda Alpha 864 Intel based SoC computer


Internet connection is deliverd via either 3G/4G mobile broadband or via other broadband connection (ethernet). The router has fully configured SOHO router system with firewalls, access control and other basic services.

The USB HUB is capable of hosting three USB3 devices and four USB2 devices. There is also USB2 & USB-C power output (no data) available in case there is a need to power some equipments, like fan’s, lights or so. In this PoC there is only one HUB connected, but in the final configuration there will be two of them.

The external SSD drive is mainly for full clone of the Lattepanda Alpha Windows 10 system as when this system is finally installed to the remote location there is no easy physical access to the system, so if something bad happens one must be able to remotely restore the system – by having a full clone of the system it is possible to boot from that clone and fix the main SDD with fresh copy of the system.

The RaspberryPi 3 handles the most important part of the remote access. Via it all connections will be opened so that one can remote access and control all the local computers safely via Internet using SSH. The RaspberryPi 3 also handles the power supplies of the USB HUB’s and Lattepanda Alpha with the Relay Card installed to it.

The RaspberryPi Zero W handles the remote keyboard functions for Lattepanda Alpha. For full remote control one must be able to enter commands via keyboard even if the system is fully halted – or access to Lattepanda BIOS is needed. With the RaspberryPi Zero W it is possible to mimic external keyboard connected to the Lattepanda Alpha and because it is a linux computer one can SSH into it and remotely give commands as “a remote keyboard”. Very crusial for this project as one must have access to the Lattepanda Alpha what ever happens.

Four webcams are for “remote eyes” to the system.
Using VLC one can see the system remotely to check the status of the system/led’s and also to see the screen of the main computer enough to handle possible system problems when there is no remote access available to the main computer via RealVNC, Anydesk or Microsoft Remote Desktop (RDP) – even if the connection to the Windows 10 is lost because a BSOD, Windows crashed, system down for other reason or whole computer halted while booting.

And the main computer, a Lattepanda Alpha 864. A very powerfull SoC (System on Chip) computer capable of handling the load of a new MacBook Pro. It has a Windows 10 OS installed as that is the most supported OS with SDR softwares and devices currently available.

Specs for LPA864 are:

UHF Satcom pirates, what are these!?

Summer 2018 I read about UHF-Satcom pirates.

RTL-SDR.COM explains: “The UHF-Satcom band is anywhere between 243 – 270 MHz and contains fairly strong signals from many several US satellites that can be received with a simple antenna. Some of the satellites are simple repeaters without security, and pirates from Mexico and South America often hijack the satellite for their own personal use.”

I wanted to see if reception of these is possible with my current system, and it was, surprisingly easy!

The original article:

System used in my shack:

AirspyHF+ (The radio)
Cross-Dipole antenna mainly used for 137MHz WxSat reception
SDR# (receiver software)

Oldies from archive: DDH reception via SpyServer link!

After SpyServer was published my hobby took a huge leap as now I was able to stream the IQ data directly from the remote antenna to my local shack using just kbits of internet bandwidth instead several megabits and full Windows RemoteDesktop session. Spyserver also gave me a change to create a separate stream to all my antennas (radios) at the same time, so I was able to receive both telemetry and AM at the same time. This video was about my first tests with the SpyServer.

SpyServer is an excellent software created by the guys behind the also excellent SDR software SDR# –

Receiver (HW): RTL-SDR dongle (Direct sample mod), PA0RDT mini whip, LNA4HFL
Link: Remote SDR location, IQ-stream with Spyserver via Internet
Receiver (SW): SDR#
Decoder (SW): MultiPSK

Oldies from archives: SYNOP reception!

It seems that I have recorded some videos about my early test with the system back in 2015. This time it was about SYNOP, those funny sounding HF transmissions that sounds like a morse code after some Quattro-Espresso’s.

Receiver (HW): RTL-SDR dongle, HamItUp converter, LongWire antenna, LNA4HFL LNA
Receiver (SW): SDR#
Decoder (SW): MultiPSK

Thunder in Radio!

Have you ever wondered about how thunder looks like in receiver – it is something like this.

This was recorded Friday, 13.Jul 2018 5:30pm in Finland, grid KP01tn. Radio was tuned to VLF frequency of 72,3Khz (AM). The delay between the radio interference (lines across the whole screen, left side of the video) and the lightning locator (right side of the video) is about 2 seconds.