Tag: digital

Decoding 433 MHz Signals with RTL SDR

One of the members at the radio club Merlin suggested trying out this sensor decoding program for the RTL SDR receiver.

The software RTL 433 is a generic sensor decoder, and it will decode and display a variety of environmental data. Despite its name the frequency can be defined in the setup, and sensors can be found on 315, 433, 868 and 915 MHz depending on your location.

In the UK 433.92 is the most popular, and so this is a good place to start. Firstly you will need to install and have run the RTL SDR, you can do this by plugging it into the USB port on your computer and waiting. Windows will helpfull install the incorrect drivers, and this can be resolved by running Zadig. Follow the instructions here. The Quickstart guide is also online.

If your running Pi, Linux or Mac then you will need to look up the instructions on the link given for installation instructions.

Once the RTL dongle is installed, then the addition of a good 433 MHz antenna will allow the reception of some interesting signals, even if you just have the default magnetic antenna the chances are you will pick up some local traffic.

The RTL has lots of diverse supported software, you can find a list available at RTL-SDR.com

Merlin also pointed out that while the program will run from the windows explorer it is best to create a .bat file in notepad.

Mine looks something like this

mode 800
rtl_433_64bit_static.exe -f 433.4M -s 1024k

Sorcerer Decoding Software

Whilst looking for digital decoders I read a review on the software package Sorcerer. The software can be used with any HF receiver and allow you to decode a multitude of digital modes. You will find the standard FAX, CW, PSK and olivia decoders, but also the Nato standard Stanag.

Whilst testing the software I centered the receiver on 127.5 Khz and decoded the European EFR data signal. The European EFR system is described on their website, and uses 3 x 100 KW transmitters at Mainflingen 129.1 Khz, Burg 139 Khz and Lakihegy 135.6 Khz. Your dial frequency may vary a little depending on the location of the signals in your passband.

The EFR signal sounds like this.

You can download the free software. To decode EFR, run the program and select “Add Decoder” select EFR.

A setup guide is provided by the UXDF group.

Once received the decoded signal and  Sorcerer software should look like this.

EFR_time_signal

The development of Demand Side Management (DSM) and the history of Radio Ripple control and load management is also explained here.

The decoded text shows the time, date and hex address, and the message is transmitted every 10 seconds. The system is described in some detail in this PDF file.

The system can be used to remote control street lights and power load management.

The decoding software Sorcerer would seem to have been developed by Avonlea Services, although the web provides no trace of this company today.

I cant find any trace of the described website in the help file and therefore cant credit anyone with the software. I have hosted the software for free download on my site, although if you are the author please get in touch.

The software is capable of decoding many modes including

DPRK 600 bd FSK* EFR Telemeter
Facsimile (FAX) 60-90-120-240 LPM
Facsimile (FAX) B&W – Gray Scale
France-Inter Time Signal
Globe Wireless Dataplex Marker
Globe Wireless FSK & PSK
G-Tor ARQ G-Tor FEC
Greek 145bd 1265 Hz FSK*
Grintek DT-309
Harris RF-3560 PSTN TIU
Hart PRIME
Hellschreiber – Basic Hellschreiber – FELD
Hellschreiber – FM Hellschreiber- MT
Hellschreiber- Duplo Hellschreiber – PSK
HF Datalink (HFDL) ARINC 635
IRA-ARQ (ASCII-ARQ)
Israeli Tadiran Burst Message System*
Italian FSK Burst 600 bps*
Italian FSK 300/600 bd*
Italian FSK 1200 bd*
IRA-ARQ (includes Zip archive recovery)
MD-513B 16PSK MT63
MD-674 Asynchronous FSK
MD-1061 16PSK MD-1239 16PSK
MD-1268 16PSK MFSK8 & 16
Mil-Std 188-110A App A 16DPSK
Mil-Std 188-110A serial
Mil-Std 188-110A serial HRS variant
Mil-Std 55529A NB Asynchronous FSK
Mil-Std 55529A WB Asynchronous FSK
MSF Rugby Time Signal
Nokia M85200 M90*
OLIVIA (all submodes)

 

Dave M0TAZ

The Birth of a New Digital Mode SIM31

Read the article on how the mode invented by Nizar Ben Rejeb was developed, and the advantages it has over traditional PSK31.

The article is available to read online.

You can download a free copy of the program, and read more online at ON4NB website.

A handy guide to installation can be read here.

Ive been using it for a few days now, but its too early to test its robustness. Many digital modes come and go over the years, but its always interested to test and understand the advantages and disadvantages.  It certainly looks very much like PSK31, but the program helps identify that by a CW ident SIM and in PSK31 you will decode NEW SIM31 on your screen.

It also has an interesting “beacon mode” that can fully automate QSO. Imagine the joy of leaving that on overnight, and in the morning finding out you have worked 10 new DXCC while you have been tucked up in tog heaven dreaming of that 30 meter tower and 5E stepper IR …

Dave M0TAZ

sim31