Topic
High frequency
About: High frequency is a research topic. Over the lifetime, 754 publications have been published within this topic receiving 4940 citations.
Papers published on a yearly basis
1 / 2
Papers
TL;DR: This paper shows that pinhole diversity is available in a rich scattering environment caused by modulating backscatter with multiple RF tag antennas - no diversity combining at the reader, channel knowledge, or signaling scheme change is required.
Abstract: Backscatter radio systems, including high frequency radio frequency identification (RFID), operate in the dyadic backscatter channel - a two-way pinhole channel that has deeper small-scale fades than that of a conventional one-way channel. This paper shows that pinhole diversity is available in a rich scattering environment caused by modulating backscatter with multiple RF tag antennas - no diversity combining at the reader, channel knowledge, or signaling scheme change is required. Pinhole diversity, along with increased RF tag scattering aperture, can cause up to a 10 dB reduction in the power required to maintain a constant bit-error-rate for an RF tag with two antennas. Through examples, it is shown that this gain results in increased backscatter radio system communication reliability and up to a 78% increase in RF tag operating range.
301 citations
TL;DR: The AN/GSC-10 (KATHRYN) is a new modem equipment for digital data transmission on HF radio circuits that provides a wide range of signal redundancy and data rate to allow optimum performance over the correspondingly widerange of propagation conditions characteristic of HF radio.
Abstract: The AN/GSC-10 (KATHRYN) is a new modem equipment for digital data transmission on HF radio circuits. Its unique modulation technique provides a wide range of signal redundancy and data rate to allow optimum performance over the correspondingly wide range of propagation conditions characteristic of HF radio. Efficient detection is achieved at all levels of redundancy by utilizing a fully coherent correlation detection technique. The detector is a continually self-adjusting matched filter to the timevarying ionospheric transfer function. The fine grain propagation data derived for detection allow continuous observation of parameters such as multipath delay and coherence time. As a variable data rate modem with channel measurement capabilities, it can serve in future fully adaptive communication nets.
132 citations
Patent•
15 Jul 1985
TL;DR: In this article, a high frequency (HF) frequency-management system for automatically selecting optimum HF frequency is presented, where a frequency management means controlling the operation of a regular HF radio communications transmitter and receiver at each station.
Abstract: A high frequency (HF) frequency-management system for automatically selecting optimum HF frequency. A frequency management means controls the operation of a regular HF radio communications transmitter and receiver at each station. The frequency-management means transmits sounding signals synchronously and repeatedly over a finite group of HF frequencies, from a first radio communications station to a second radio communications station. Link quality evaluation (LQE) is carried out at the second station. Sounding signals are transmitted synchronously and repeatedly back to the first station. Optimum HF frequencies are selected based on the sounding signals and LQE. An HF communications path is automatically established between stations. The system performs the scanning of the HF frequencies, the detection and measurement of signals, noise and interferences on each frequency and the timing synchronization as required for the frequency management operation.
105 citations
Patent•
20 Apr 1939TL;DR: In this article, the generation and utilization of ultra high frequency currents is discussed.This invention relates, generally, to the generation of ultra-high frequency currents and the invention has reference, more particularly, to novel high frequency radio apparatus including electronic oscillators or converters of the general type disclosed in copending application.
Abstract: This invention relates, generally, to the generation and utilization of ultra high frequency currents and the invention has reference, more particularly, to novel high frequency radio apparatus including electronic oscillators or converters of the general type disclosed in copending application...
95 citations
13 Feb 2006
TL;DR: Experimental measurements of the frequency and time domain responses in order to investigate the transmission characteristics of the human body as a conductor of low power high frequency radio signals (up to 3GHz).
Abstract: Body area networks (BAN) will become increasingly important in the future personal communication systems. We believe that intra-body communications (IBC) based on near field electromagnetic waves is a suitable solution for BAN. This paper presents experimental measurements of the frequency and time domain responses in order to investigate the transmission characteristics of the human body as a conductor of low power high frequency radio signals (up to 3GHz). In the measurements, several distances between transmitter and receiver (up to a long distance from the head to the foot) and six test people (to study the possible variation results due to physiological body effects) have been considered. Besides analyzing the intra-body channel response, we also aim to define a suitable frequency range for IBC. Finally, this paper also presents an initial evaluation study of several digital modulation schemes in order to investigate the optimal technique for IBC.
89 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 13 |
| 2024 | 19 |
| 2023 | 17 |
| 2022 | 32 |
| 2021 | 17 |
| 2020 | 28 |