Testing CMA-77-100 antenna with SYM-RFT-77 DCF77 receiver module

Michail Papadimitriou is in the process of developing a Nixie clock which will synchronize with the DCF77 time signal. These standard time signals are transmitted on 77.5 kHz from Germany, and Michail intends to use a DCF77 Time Receiver Module, like SYM-RFT-77 to demodulate the signal. Basically, this module receives the time standard signal and […]

RTL-SDR APCO Project 25 (P25) receiver

Balint Seeber has done it again! In this video he shows how to take the RTL-SDR dongle and use it in conjunction with the open source OP25 project to successfully demodulate APCO Project 25 (P25) digital radio voice communications. P25 is a term used to refer to a modulation system used by many public safety […]

Matchstiq SDR transceiver

Drone writes to inform us of a new SDR: Here is an interesting new handheld SDR transceiver called Matchstiq from Epiq solutions. 300MHz to 3.8GHz. I sure would like to know how they’re implementing the configurable suboctave RF filters. There is on-board CPU, DSP, and Xilinx Spartan FPGA. Noise figure at 8dB is nothing to […]

MIT online course: Principles of Digital Communications I

As part of their ongoing OpenCourseWare program, MIT is offering the free online course “Principles of Digital Communication I.” Course description: The course serves as an introduction to the theory and practice behind many of today’s communications systems. Topics covered include: digital communications at the block diagram level, data compression, Lempel-Ziv algorithm, scalar and vector […]

SDR Sunday – monitor web SDRs and decode digital data

Want to try out software defined radio (SDR) before you buy or build a rig? Or do you just want to see what all the ham radio chatters about? Then check out the online SDRs available for your listening pleasure at WebSDR. This unique website lists dozens of online radios which you can click on […]

Arduino TNC

Amateur radio operators use various digital data modes for radio communications. One such mode is known as packet radio, which transmits data in groups or “packets” of bytes. As described by the ARRL, “packet radio allows improved throughput and error control. The basic protocol for packet radio is AX.25. Transmission speeds typically range from 300 […]

ARISSat-1/KEDR test transmissions planned from ISS July 30-31

We know, we’ve been down this road before with the ARISSat-1, but this time they say it’ll work. Test transmissions from ARISSat-1/KEDR are scheduled to begin four days prior to deployment at 19:15 UTC on July 30 and then continue until 1430 UTC on July 31. The satellite will be connected to an external antenna […]

Video: DSP/SDR basics

Here’s Jeri Ellsworth’s latest video, explaining the basics of DSP and SDR for beginners, and how to build a digital direct conversion receiver (SDR) using sampling detectors and FPGA DSP processing. (If you want to skip the silly cat portion of the video, start at 1:25.) The links referred to in the video are below: […]

Si4707 weather band radio receiver ICs

NashblackCat writes to inform us of a chip that reads weather radio data: Silicon Laboratories makes an IC Weather Band (WB) radio called the Si4707. This IC is capable of using the specific area message encoding (SAME) and also supports the detection of the 1050Hz alert tone that is used by the National Weather Service. […]

UPDATE: ARISSat-1 deployment delayed until July

UPDATE: According to information posted on the arissat.org website on February 13, 2011, the deployment of the ARISSAT-1 has been delayed until July, 2011. Project developers had originally announced that ARISSat-1 (f/k/a Suitsat-2), would be launched and transmitting by February 16, 2011! However, due to unforeseen problems, the actual deployment into space has been delayed […]


Supervisory Control and Data Acquisition Systems (SCADA) present a means of networking industrial infrastructure monitoring and control systems. From a central reading location a SCADA system can track a number of remote sites equipped with Remote Terminal Units (RTUs) or Programmable Logic Controllers (PLCs). The RTUs can measure an array of conditions and a wider […]

APRS homebrew digital radio interface

Automatic Packet Reporting System (APRS) is a digital data communications system often used by amateur radio operators in the 2-Meter FM band. You may hear such data transmissions on 144.390 MHz FM and other frequencies. DK7IN has published an interesting project which promises to let you transmit APRS data when connected to a licensed amateur […]

Running your own GSM stack on a phone

Harald Welte and Steve Markgraf presented at 27C3 CCC in Berlin, Germany, on the OsmocomBB project, a Free Software implementation of the GSM protocol stack running on a mobile phone. This provides the security researcher a tool equivalent to an Ethernet card in the TCP/IP protocol world: a simple transceiver that will send arbitrary protocol […]

Mystery QR code found in radio digital data

When receiving digital radio data with a program such as FLDIGI you may occasionally see unusual patterns on the software’s “waterfall” display. Scott Harden found what looked like a QR barcode encoded in digital amateur radio data on the 40 Meter Band and proceeded on a quest to decipher the code. Via Hack a Day