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.
In recent posts, I already wrote about my experiences with Simon Brown’s software SDR Console V3.0. It matches most SDRs, delivers now up to 24 virtual receivers and is capable to run multi instances, i.e. you may run several SDRs on one PC in parallel.
That’s exactly what I did when I connected three SDRs FDM-S2 to a PC, running 35 different ARINC-635 channels in parallel resulting in 68.000 decoded messages. It worked brillantly.
And there is much more, e.g. recording and playing 24 audio channels from broadcasters throughout 20 MHz (the whole FM band!) with hardware RFHack One.
This paper provides a hands-on and step-by-step guide for some vital monitoring tasks like:
- using up to three receivers on one antenna and one PC
- working with multi instances of GUIs
- working with multi instances of software decoders like PC-HFDL and MultiPSK
- carefully planning a monitoring session
- analyzing the decoded results and apply some basic statistics on 68.000+ messages
- record and play 24 channels incl. RDS data within a bandwidth of 20 MHz on the FM broadcast band plus on HF with RFHack One (see screenshot on top of this page, “Matrix” mode)
- … and much more
The original software for Elad receivers provides a very useful feature, resembling the old radio scale: it inserts some station data from a list on their proper place in the spectrum – see screenshots above (utility) and below (broadcast).
You may invoke several lists like EiBi and your own memories. These list just must comply to the data standard, Elad had set. You may also set up your own list. If you sepcify a transmission time other than 0000-2400, only the stations active at this time will pop up.
With Bernd Friedewald’s (DK9FI) International Listening Guide there is such as matching list available providing 31.000+ entries of brodcast as well as of utility stations. Bernd is a long-time professional in the field of broadcast monitoring and international consulting in this field. You may also edit this list.
(Disclaimer: I have no commercial relationship with ILG, and bought the data like everyone.)
24 virtual channels in sizeable windows of 24 kHz width each – also zoomable.
In a sneak preview of his SDR software “SDR Console”, Simon Brown again presented all SDR enthusiasts with again another major achievement: up to 24 independent virtual receivers!
Called “Matrix”, and beautifully layouted, each virtual receiver can be placed within the bandwidth of an SDR, i.e. about 5 MHz using an FDM-S2 by ELAD. Each virtual receiver may carry it’s whole individual settings of e.g. mode, bandwidth and AGC.
I also tried out three instances of this software in parallel with three FDM-S2 to cover 15 MHz with 72 indvidual virtual receivers. Their output may be fed to recorders and/or decoders via virtual audio card.
See this introductory paper for a first view. It shows in praxi how to use this stunning feature to tune into 24 broadcasters in parallel, record and play their transmissions. More to come, e.g. examples with of monitoring with decoders.
ELAD’s FDM-S2 provides the output of three different channels within a given HF bandwidth of up to nearly 5 MHz. Hence, you may decode these channels in parallel. ARINC’s reporting system of ground and airborne stations is an excellent candidate to show this feature.
This paper is a step-by-step introduction in how to set up the receiver, the virtual audio cables (VAC), decoder, documenting software and Google Earth to show the results on the globe.
You may then easily configure hard&soft for other applications, e.g. the monitoring of GMDSS channels with communications from ship and shore.
SDRs give us the chance to receive, record, play and analyze wide frequency ranges. The width is a trade-off of resolution (in bit) and transfer rates via the SDR’s interface and/or writing to hard disk.
Recently, I connected the ELAD’s FDM-S2 to one PC to achieve a combined bandwidth of 18,3 MHz, of which nearly 15 MHz are alias-free / at 16 bit resolution. All went smoothly. Read more