Signal Replay Research Articles

Hu-Fu: Replay-Resilient RFID Authentication

We provide the first solution to an important question, “how a physical-layer authentication method can defend against signal replay attacks”. It was believed that if an attacker can replay the exact same reply signal of a legitimate authentication object (such as an RFID tag), any physical-layer authentication method will fail. This paper presents Hu-Fu, the first physical layer RFID authentication protocol that is resilient to the major attacks including tag counterfeiting, signal replay, signal compensation, and brute-force feature reply. Hu-Fu is built on two fundamental ideas, namely inductive coupling of two tags and signal randomization. Hu-Fu does not require any hardware or protocol modification on COTS passive tags and can be implemented with COTS devices. We implement a prototype of Hu-Fu and demonstrate that it is accurate and robust to device diversity and environmental changes, including locations, distance, and temperature. Hu-Fu provides a new direction of battery-free/low-power device authentication that enables numerous IoT applications.

Application of Cache Control Circuit in Radar Signal Replay System

This article studies the design ideas of the peripheral circuits related to radar signal playback. Mainly cache module and clock circuit. These peripheral circuits provide control logic and operating clock for the radar signal playback module. This design mainly focuses on DMA transmission, radar data extraction, and playback.

Research on Overall Design of Pulse Radar Signal Replay System

In order to better meet the needs of monitoring and control tasks, this paper studies the overall design of the pulse radar IF signal playback system. It mainly introduces the hardware and software platform of the system from the overall perspective. This article provides the basis for the post-mortem analysis of test tasks and daily training.

Two laboratory methods for the calibration of GPS speed meters

The set-ups of two calibration systems are presented to investigate calibration methods of GPS speed meters. The GPS speed meter calibrated is a special type of high accuracy speed meter for vehicles which uses Doppler demodulation of GPS signals to calculate the measured speed of a moving target. Three experiments are performed: including simulated calibration, field-test signal replay calibration, and in-field test comparison with an optical speed meter. The experiments are conducted at specific speeds in the range of 40–180 km h−1 with the same GPS speed meter as the device under calibration. The evaluation of measurement results validates both methods for calibrating GPS speed meters. The relative deviations between the measurement results of the GPS-based high accuracy speed meter and those of the optical speed meter are analyzed, and the equivalent uncertainty of the comparison is evaluated. The comparison results justify the utilization of GPS speed meters as reference equipment if no fewer than seven satellites are available. This study contributes to the widespread use of GPS-based high accuracy speed meters as legal reference equipment in traffic speed metrology.

自動語音聴力検査装置(CASA)の開発

A new computer-aided speech audiometer (CASA) was developed. The system which employs a 5-choice speech discrimination that method, operates on a personal computer (NEC-9801) with auxiliary hardware which included D/A converter for speech signal replay, touch screen for input of patient's choice among the alternative syllables on the CRT, and an electronic attenuator and amplifier. Advantages of this system: 1) touch screen simplifies patients' response for both slow and quick patients; 2) testers' scoring time and error in scoring task are reduced; 3) a data bank were automatically built for future reference.