One hour in the 20 m ham radio band with LimeSDR and SpyVerter, zoomed out of a one hour’s recording of 30 MHz width. Antenna: quadloop of 20 m circumference.
LimeSDR is a Crowdsupply project – delivering an SDR which covers 100 kHz to 3.8 GHz with bandwdiths of up to 2 x 30 MHz. I was interested almost exclusively in the range 100 kHz to 30 MHz. The board arrived on March 17th, and I already have done some tests with it. From these very first results & a recommendation:
- Installing is easy (W10), if you follow the instructions.
- Without modification, LimeSDR is simply useless on HF. It’s deaf near to a dummy load.
- The producer recommends a “modification” by just removing one SMD. Then some life came into this range. But it was hard to sort the ghost stations from the real ones.
- Even a low-pass filter from Heros didn’t helped that much.
- Just before selling the board on ebay, I connected the antenna first with Spyverter – a state-of-the-art up-converter with an IIP3 of +35 dBm, transferring the band of 0 – 30 MHz to 120 – 150 MHz. This is a range, where LimeSDR sees some light.
So, if you are disappointed by the near-non HF performance of naked LimeSDR: an able up-converter will change the game. Recording and sonagrams had been made with SDR-Radio.com V3.
30 MHz live with LimeSDR and SpyVerter shows that it generally works. Same antenna as above.
“Ghost signals” make it sometimes difficult to distinguish them from real signals. This sonagram has been made with SpyVerter. Broadcast stations are easy to find out (in their majority). But it gets difficult to sort the ghost stations from the few real ones in the left part.
A strong combination: State-of-the-Art SDR transceiver Zeus ZS-1 and digimode software FLDIGI. With a step-by-step instruction, the combination of both with audio in/out, keying and freqeuncy transfer is easy.
With software-defined radio or SDRs, also ham radio has made a considerable leap forward. SDR transceivers are around for many years but failed to have a major impact until now. Among these transceivers, Russian and German-made Zeus ZS-1 is an outstanding example, covering each amateur radio band from 160 m to 10 m with up to 15 watt output. It received enthusiastic reviews around the world, e.g. by RadCOM of RSGB and QST of ARRL with excellent ratings.
Recently, I again bought on ZS-1 to re-vitalize my amateur radio activity with also again a focus on QRP and digital modes. For this purpose, ZS-1 with its outstanding clean signal under transmit and Receiver plus tidy interface is almost ideal. BUt Ehen I needed a fool-proof instruction to set up the combination of ZS-1 and a multimode software like FLDIGI, I didn’t found what I need: a step-by-step approach.
This was the reason for writing such an instruction by myself. I concentrate on the combination of ZS-1 and FLDIGI which in a PDF is laid out in detail and with instructive screenshots. In an appendix, I go also through some other digimode software like FreeDV and EasyPal. To my own disappointment, I couldn’t get work WSJT/WSPR. So your help is very appreciated!
You can download the 20-paged PDF with its 24 screenshots right here.
HFDL is a net for data communications between airplanes and ground. The results can be shown on Google Earth. This screenshot shows a part of 29.000+ entries, received and processed on August 15th, 2016.
Communications between air and ground is mostly done on VHF, UHF and SHF. But if an aircraft is out of reach of a ground station station due to the limited “radio horizon” of these bands, it has to maintain communications by either satellite or HF. This HFDL net is in fact the most massive professional user of HF right now. Within 24 hours, I get more than 40.000 live messages with a modest equipment.
With his software Display Launcher, Mike Simpson from Australia provides a most valuable tool to analyze up to nine channels in parallel. His software also draws positions and routes onto Google Earth. Mike has spent much energy on coping with many inconsistencies of transmitted data before it all really goes smoothly.
This free software is the vital part of a monitoring project to receive, demodulate and analyze live up to nine HFDL channels in parallel. Other ingredients you need is a software-defined radio (SDR), nine virtual audio cables (in fact, a piece of software) and a decoder software. Don’t forget an antenna and a PC …
This setup comprises a semi-professional monitoring station which will allow you to receive and track many of the nearly 3.000 airplanes using HFDL. This also covers the military, business jets, helicopters and some other delicate users. It maybe used as an important complement to Flightradar24’s web service, whenever their VHF/UHF/SHF-based net is out of range of the aircraft. This is particularly true over vast water masses like oceans and sparsely populated land masses. Furthermore, Flightradar24 erases some sensible flights from the raw material before publication on their website. This is clearly no “censorship”, but some thoughtfulness in regard to those countries where reception and publication of HFDL data is more tolerated than explicitly encouraged by the government.
In a 9-page PDF, I published a step-by-step recipe on how to set up such an HF monitoring station for up to nine parallel HFDL channel. You can download it here.
This screenshot shows the automatically visualized result of a 15 hours’ session receiving the DGPS band, March 11th/12th, 2017. You clearly see the propagation effect during night (marked yellow).
For years, Chris Smolinski of Black Cat Systems offers a fine selection of Mac software, among them many pieces for hams and shortwave listeners.
He now presented an unique software dubbed Amalgamated DGPS which decodes, analyzes and visualizes all DGPS stations on long wave at once. This is done from an I/Q wav file of e.g. Perseus SDR. DGPS stand for “Differential Global Positioning System” and is a system of long wave transmitters in the range of 283,5 to 324,5 kHz transmitting FSK data in 100 and 200 Baud to correct for GPS signals. Look here for a short introduction to this topic.
[Einen deutschsprachigen Test der aktualisierten Software habe ich in der April- Ausgabe 2017 der Fachzeitschrift FUNKAMATEUR veröffentlicht.]
These transmitters are of regional coverage, like non-directional beacons, or NDB, in the same band. This makes them interesting for DXing and propagation studies as well.
All you have to do is to let the software analyze your I/Q files of a receiving sessions. Yes, it is automatically “chaining” your files. You then get a detailed list of decoded stations with some additional data. You also can visualize these data, as I did in the screenshot at the top. This is based on a 15 hours’ session resulting in 56 wav files of 675 MB each.
The software runs on both, Mac/iOS and Windows. On both systems it works fine, covering .0 and .5 kHz channels as well as both baud rates.
Here you see the complete list of stations and the number of their receptions. “Amalgamated DGPS” has decoded 516.918 logs in roughly 15 hours!
The software’s unique feature is 3D raytracing, showing an anatomy of propagation (see text).
HF propagation software seems to be full of mysteries. But its all about modeling physics. There are several models around, the most prominent surely is VOACAP, followed by ASAPS. VOACAP comes in very many different tastes like e.g. PropMan 2000 or ACE. It often has been coined to be the “Gold Standard” among hams and professionals as well. VOACAP gives reliable results on a statistical base for a month, whereas ASAPS returns propagation based on the current conditions of a day. It also gives propagation for an aircraft en route during its flight and takes at least a bit care of multi-path propagation which may degrade digital modes. Both work offline as online, and they are fast.
[Einen ausführlichen deutschsprachigen Test mit vielen Screenshots und Beispielen habe ich in der Januar- Ausgabe 2017 der Fachzeitschrift FUNKAMATEUR veröffentlicht.]
PropLab is giving you a much smarter view on what is really happening on a specific day and time at a specific path or area. It relies on the International Reference Ionosphere (IRI 2007) and uses the ray tracing technique. In short, PropLab is automatically fetching all relevant space weather data (not just sunspots) from scientific sources of the internet to model the ionosphere with its different “layers”.
You then give in your path, antenna etc. in a well-supported way. After having started “ray tracing”, PropLab lets refract rays at exactly this ionosphere with its high granularity and some real-world effect like tilts of layers which will result in e.g. propagation off the great circle. It will also beautifully show effects like focusing and gray line propagation, including Pedersen’s long ranging ray with time resolution up to one second – rather than one hour as that of VOACAP.
As I was asked for a look onto my monitoring workbench, I decided to write it down. It’s not to show “the real stone”, but an invitation for discussing efficient workflows which State-of-the-Art technology has to offer.
This PDF of 13 pages contains 25 hopefully instructive illustrations to comprehend my approach to monitoring; or, in this case: Utility DXing. Part of this PDF is also a 2:50 video, showing how to stroll between aero channels and to decode ALE. This video is also placed on top of this page.
The paper explains in detail the advantages of leafing through recorded HF files using the technology of the “living sonogram”. It also discusses some efficient strategies of voice and data reception, eventually touching even documentation.
To make use of the video content, download it on your hard disk, save it and open it by the most recent version of your PDF reader. It works on a PC as well as on a Mac. You can download it here.
The world is full of software-defined radio (SDR), but HackRF One has a rather unique position – thanks to its vast maximum bandwidth of 20 MHz. With an up-converter, this combination covers more than 70 percent of the whole HF range from 3 to 30 MHz. Even better: with proper software you can record and play this enormous band!
However, this stunning bandwidth is achieved by a moderate resolution of 8 bit, resulting in a dynamic range of just nearly 50 dB. Or the half of SDRs like Elad’s FDM-S2.
Anyway. I wanted to know in practice what you can actually do with such a set at a budget price plus mostly free software. The results surprised even me: Properly used, this combination convinced as a quite decent performer on HF! The world map above shows some of the stations received with the set (see insert bottom left) to test its performance.
I laid down my experiences and recommendations for best reception in a paper of 17 multi-media pages full of examples – including 55 screenshots, 21 audio clips and one video. The PDF shows how to optimize reception of broadcast, utility and amateur radio stations. It covers many examples on how to analyze recordings, to decode data transmission with free software plus live decoding of 14 channels in parallel. It also gives some examples of combining HF reception with the internet, e.g. regarding the reception of signals from airplanes (ARINC, HFDL) and vessels (GMDSS).
My experiences really left me enthusiastic about this set.
You may share this enthusiasm and download the PDF of 43 MB here. Save it on your hard disk or USB stick, and open it with a most recent Adobe Reader. Otherwise, the multimedia content will not work.
[Einen deutschsprachigen Test habe ich als Titelgeschichte in der April- Ausgabe 2017 der Fachzeitschrift Radio-Kurier – weltweit hören veröffentlicht.]