A photonics-based radar jamming signal generator is proposed in this paper. By adjusting a polarization controller, interrupted-sampling repeater jamming (ISRJ), comb spectrum modulation jamming ...(CSMJ), ISRJ and CSMJ composite jamming can be respectively generated after photoelectric conversion. We have experimentally verified the generation of ISRJ signals with duty cycles of 50% and 25%, the generation of CSMJ signals with comb spectrum frequency intervals of 5 MHz and 10 MHz, and the generation of their composite jamming signals in the Ku band. Additionally, the ISRJ and CSMJ composite jamming effect of radar signals in the Ka band has been tested. After matched filtering processing, multiple false targets are produced and the total number of jamming targets can be up to 25, demonstrating significant jamming effects. The proposed structure can generate multi-format jamming signals without using digital radio frequency memory, which is suitable for producing high-frequency and large-bandwidth jamming signals. It can be applied in electronic countermeasure systems.
•The scheme can generate multi-format jamming signals for LFM signal, namely interrupted-sampling repeater jamming (ISRJ), comb spectrum modulation jamming (CSMJ), ISRJ and CSMJ composite jamming.•The scheme does not use digital radio frequency memory, which is easy to generate high frequency and large bandwidth jamming signals. The experimental results show that the LFM signal with 1-GHz bandwidth in Ku band and the LFM signal with 1.2-GHz bandwidth in Ka band have good jamming effects.•After matched filtering processing, multiple false targets are generated and the total number of jamming targets can be up to 25, demonstrating significant jamming effects. The scheme has good application value in electronic countermeasure system.
Increasing incidents of cyber attacks and evolution of quantum computing poses challenges to secure existing information and communication technologies infrastructure. In recent years, quantum key ...distribution (QKD) is being extensively researched, and is widely accepted as a promising technology to realize secure networks. Optical fiber networks carry a huge amount of information, and are widely deployed around the world in the backbone terrestrial, submarine, metro, and access networks. Thus, instead of using separate dark fibers for quantum communication, integration of QKD with the existing classical optical networks has been proposed as a cost-efficient solution, however, this integration introduces new research challenges. In this paper, we do a comprehensive survey of the state-of-the-art QKD secured optical networks, which is going to shape communication networks in the coming decades. We elucidate the methods and protocols used in QKD secured optical networks, and describe the process of key establishment. Various methods proposed in the literature to address the networking challenges in QKD secured optical networks, specifically, routing, wavelength and time-slot allocation (RWTA), resiliency, trusted repeater node (TRN) placement, QKD for multicast service, and quantum key recycling are described and compared in detail. This survey begins with the introduction to QKD and its advantages over conventional encryption methods. Thereafter, an overview of QKD is given including quantum bits, basic QKD system, QKD schemes and protocol families along with the detailed description of QKD process based on the Bennett and Brassard-84 (BB84) protocol as it is the most widely used QKD protocol in the literature. QKD system are also prone to some specific types of attacks, hence, we describe the types of quantum hacking attacks on the QKD system along with the methods used to prevent them. Subsequently, the process of point-to-point mechanism of QKD over an optical fiber link is described in detail using the BB84 protocol. Different architectures of QKD secured optical networks are described next. Finally, major findings from this comprehensive survey are summarized with highlighting open issues and challenges in QKD secured optical networks.
Abstract
This paper investigates the sortal classifier system in Zauzou, a Tibeto-Burman language spoken in Southwest
China. Three etymological subclasses – repeater, non-repeater, and ...quasi-repeaters – are identified in two morphosyntactic
contexts: the bare classifier phrase
n+clf
and the full noun phrase
n+mod+clf
, serving as an
“individualizer” that transforms unindividualized nominal concepts into referential individuals. The three types of classifiers
classify nouns on the basis of different semantic parameters that differ in terms of semantic contrastiveness. Animacy, shape,
size, rigidity and quanta are non-contrastive semantic parameters commonly found among non-repeaters. Repeaters and
quasi-repeaters categorize nouns primarily on the basis of semantically contrastive taxonomy, meronomy, or arrangement. With
respect to the function of quantification, repeaters, quasi-repeaters, and non-repeaters are identical in
n+mod+clf
but
diverge in
n+clf
. They do not uniformly render the singular interpretation with all kinds of referents in
n+clf
. Non-repeaters are more grammaticalized classifiers than (quasi-)repeaters. The Zauzou data provide evidence
for the development from repeaters to non-repeaters, on a par with the commonly recognized grammaticalization path from nouns to
classifiers, which is conditioned by two types of “parameter shift”. This study offers a descriptive model that effectively
captures the relationship between semantic-functional properties of sortal classifiers and their historical development in
“repeater” languages.
•The cross ambiguity function of ISRJ is derived to demonstrate jamming distribution characteristics visually.•An ISRJ recognition and suppression method based on phase-coded signal processing is ...proposed.•The proposed method does not need to estimate ISRJ parameters, and it is applicable for suppressing direct forwarding ISRJ, repeated forwarding ISRJ, and frequency shifting ISRJ.
In modern electronic warfare, interrupted sampling repeater jamming (ISRJ) seriously affects radar target detection performance. It has the advantages of flexible modulation and fast response. The existing approaches mostly require accurate ISRJ parameter estimation and only apply to a specific type of ISRJ. We propose an ISRJ recognition and suppression method based on phase-coded signal processing. By analyzing the cross ambiguity function (CAF) of ISRJ, we find that ISRJ can form multiple peaks, and these peaks are uniformly distributed on the Doppler cut of the CAF. Using this characteristic, we propose an ISRJ recognition method based on Doppler compensation processing. On this basis, a Doppler filtering processing method is proposed to suppress the ISRJ. Both simulated and measured results corroborate the effectiveness of the ISRJ suppression with the developed methods.
•The distribution of entangled state to far distances is of enough importance in quantum technologies and quantum information processing.•Doing this task with trapped atomic ions using quantum ...repeater protocol is the purpose of this paper.•Entanglement swapping techniques in optomechanical cavities and Bell state measurement have been used to do the task.•Therefore using trapped atomic ions in optomechanical cavities is the novelty of this work.•The effects of detuning and amplitude of pump laser on the entanglement and success probability are considered.
Distribution of the entangled state of trapped atomic ions to long distance using quantum repeater protocol is considered. Indeed, the long distance is divided into short parts, and then using entanglement generation and entanglement swapping techniques in optomechanical cavities, the entanglement is distributed. To do the task, we perform interaction between trapped atomic ions in optomechanical cavities, operate proper measurements on trapped ions and also make Bell state measurement as a well-known way to swap the entanglement. Accordingly, the entanglement is distributed between target ions with satisfactory values of success probability and entanglement degree. The effects of detuning and amplitude of pump laser on the entanglement and success probability are evaluated. The fluctuations of entanglement and success probability are decreased by increasing of detuning. Via increasing the amplitude of pump laser, the maxima of entanglement are repeated more times and success probability undergoes the collapse-revival phenomenon.
This paper presents novel burst-mode automatic gain controlled semiconductor optical amplifiers (AGC-SOAs) that are utilized as one upstream channel of a repeater in long-reach time- and ...wavelength-division multiplexed passive optical networks (WDM/TDM-PONs). Two SOAs are cascaded in the AGC-SOAs to achieve high gain. Two-stage gain switching with a fast feed forward (FF) control circuit is applied to the first SOA and the second SOA equalizes output burst frame powers regardless of input powers; the combination plays a key role in expanding the system operating range of long-reach systems. The first SOA with the simple gain control scheme can be also utilized as a preamplifier, which is useful to realize high-splitting-ratio systems without facing any electric supply issues. Unlike conventional burst frame power equalizers which change the gain of a single SOA through an FF control circuit and so do not provide a wide enough input dynamic range for PON applications, our gain control scheme successfully overcomes this issue. It improves the accuracy of output power equalization by reducing the input power range to the second SOA. We develop a prototype that implements this scheme and experimentally confirm that it can expand the system operating range of both long-reach and high-splitting-ratio systems. Although we have only one prototype at this time, experiments and discussions that consider the presence of neighbouring WDM channels support the possibility of WDM operations.
ABSTRAKIndonesia merupakan negara rawan bencana alam yang dampaknya dapat melumpuhkan akses tekomunikasi publik. Hal ini menjadi penghambat ketika proses koordinasi evakuasi korban bencana. ...Diperlukan alternatif untuk berkomunikasi, seperti radio genggam atau Handy Transceiver (HT). Namun HT memiliki kekurangan pada jangkauanya yang terbilang kecil sekitar 2 – 5 Km tanpa penghalang. Untuk mengatasi kekurangan tersebut, Pada penelitian ini dilakukan perancangan dan realisasi cross band repeater (XBR) HAM radio berbasis Software Defined Radio (SDR) dan Raspberry-Pi. XBR HAM radio merupakan Radio Pancar Ulang dengan menerapkan 2 frekuensi yang berbeda pada sisi uplink dan downlink. Hasil pengujian pada area penduduk dengan intensitas padat menunjukkan bahwa XBR HAM radio yang telah dibuat dapat menjangkau area sejauh 8,8 Km dengan pancaran maksimal sebesar 10 watt serta penguatan pada SDR sebesar 49.6 dB pada ketinggian 15 meter.Kata kunci: Cross band repeater, HAM Radio, Raspberry-Pi, SDR ABSTRACTIndonesia is prone to natural disasters whose impact can paralyzing access to public telecommunication. It becomes an obstacle in the process of consolidating disaster victims. An alternative is needed to communicate, such as a handheld radio or Handy Transceiver (HT). However, HT has a disadvantage in its relatively small range of around 2-5 Km without obstructions. This study designed and realized a cross-band repeater (XBR) HAM radio based on Software Defined Radio (SDR) and Raspberry Pi to resolve the issue. XBR HAM Radio is a Retransmission Radio that applies two different frequencies on the uplink and downlink sides. Test results in residential areas with dense intensity show that the XBR HAM radio that has been made can reach an area of 8.8 km with a maximum beam of 10 watts and a gain of 49.6 dB at an SDR at the height of 15 meters from the gorundKeywords: Cross band repeater, HAM Radio, Raspberry-Pi, SDR
In this study, we implemented a high-performance multichannel repeater, both for FM and T-Digital Multimedia Broadcasting (DMB) signals using a Field Programmable Gate Array (FPGA). In a system for ...providing services using wireless communication, a radio-shaded area is inevitably generated due to various obstacles. Thus, an electronic device that receives weak or low-level signals and retransmits them at a higher level is crucial. In addition, parallel implementation of digital filters and gain controllers is necessary for a multichannel repeater. When power level is too low or too high, the repeater is required to compensate the power level and ensure a stable signal. However, analog- and software-based repeaters are expensive and they are difficult to install. They also cannot effectively process multichannel in parallel. The proposed system exploits various digital signal-processing algorithms, which include modulation, demodulation, Cascaded Integrator Comb (CIC) filters, Finite Impulse Response (FIR) filters, Interpolated Second Ordered Polynomials (ISOP) filters, and Automatic Gain Controllers (AGCs). The newly proposed AGC is more efficient than others in terms of computation amount and throughput. The designed digital circuit was implemented by using Verilog HDL, and tested using a Xilinx Kintex 7 device. As a result, the proposed repeater can simultaneously handle 40 FM channels and 6 DMB channels in parallel. Output power level is also always maintained by the AGC.
Summary
In this paper, an anti‐jamming approach is proposed for the downlink of satellite communication systems when encountering a hostile repeater‐jamming. Based on blind source separation, this ...approach can eliminate repeater‐jamming by separating the mixtures of the communication signals and the repeater‐jamming. Meanwhile, oversampling method is employed to transform the underdetermined mixing of signals into a determined mixing for facilitating the separation. In the simulations, the symbol error ratio (SER) of the separated communication signals can approximate the theory SER, and the anti‐repeater‐jamming capacity can arrive to nearly 28 dB.
In this paper, an anti‐jamming approach is proposed for the downlink of satellite communication systems when encountering a hostile repeater‐jamming. Based on blind source separation, this approach can eliminate repeater‐jamming by separating the mixtures of the communication signals and the repeater‐jamming. In the simulations, the symbol error ratio (SER) of the separated communication signals can approximate the theory SER, and the anti‐repeater‐jamming capacity can arrive to nearly 28 dB.
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