Software Defined Radio

Introduction Modulation by frequency shift (FSK, Frequency Shift Keying) is a digital modulation technique where binary information is transmitted by varying the frequency of a carrier between two or more discrete values. In its simplest form, 2-FSK, a bit 0 is represented with a specific frequency (f0) and a bit 1 with another (f1). This technique is widely used in low-speed wireless communications, such as remote controls, telemetry systems, RFID, and IoT devices. ...

Introduction The Flipper Zero is a multifunction device for hacking, security testing and radio frequency protocol exploration. One of its most highlighted features is the ability to transmit and receive SubGHz signals, using the Texas Instruments CC1101 chip, a programmable low-power RF transmitter. SubGHz refers to the range of radio frequencies below 1 GHz (typically between 300 MHz and 928 MHz, depending on the region). These frequencies are used by devices such as remote garage door controls or wireless sensors (temperature, movement, alarms). ...

Introduction️ GSM (Global System for Mobile Communications) (2G) is a communication standard developed for the transmission of voice and data in mobile networks. Originally created in Europe in the 80s by the European Telecommunications Standards Institute (ETSI), it became the most popular mobile phone system worldwide, used by most mobile network operators around the world. The GSM technology allows users from different operators to communicate with each other and use services like SMS (text messages) or calls. With the arrival of 4G and 5G, the use of GSM networks has decreased and some operators are gradually removing support for these networks.️ ...

Introduction️ KeeLoq is a security protocol based on a symmetric key cryptographic algorithm that is mainly used in remote control systems, such as garage door remotes and remote access systems for cars. It was developed by Microchip Technology and is widely used due to its low cost and relatively simple implementation.️ KeeLoq implements a “rolling code” system to prevent replay attacks. This means that every time the remote control button is pressed, a unique code is generated that never repeats. The receiver (such as a garage door opener) recognizes this code and validates it against an expected sequence, ignoring any duplicate codes.️ ...