VHF Communication Research Articles

輻輳海域における国際VHFを用いた船舶間コミュニケーションの特徴について

It has become much easier to identify vessels nearby since AIS is required to be equipped vessel. The number of communication times using VHF has been increased. However, there are no rules which are applied how to use of VHF in Japan, though VHF is quite a useful tool that can be used for collision avoidance. VHF is an effective aid to safe navigation, but sometimes it leads to a worse situation between vessels because of misunderstanding, even where the language of communication is not a problem. The views of the propriety on using VHF in collision avoidance are divided. However, a bridge-to-bridge communication by VHF is used quite often under the present navigation circumstance.The purpose of our study was to propose an effective use of VHF in collision avoidance. We researched VHF communication and AIS data between vessels in Tokyo Bay, which is one of the dense area of the traffic in the world. As a result of this study, we grasped the feature of bridge-to-bridge communication using VHF in marine density area.

ECDIS Modernization for Enhancing Addressed VHF Communication

Standard ECDIS configuration doesn’t foresee interaction with Digital Selective Calling (DSC) device. The authors propose a reasonable way to eliminate the drawbacks of existing VHF radiotelephony using DSC and obtain new advantages in communication and navigation in the frame of existing conventional installations. The proposed innovation is based on ECDIS software updating and the interconnection to DSC equipment. ECDIS modernization would get rid a navigator of the routine procedures and handling with abstract data replacing them by understandable actions on ECDIS display. The proposed integration gives new abilities for smart addressed VHF/DSC communication by estimating the current navigational situation around the ship that is especially important in congested ports, waterways and poor visibility regarding human factor. The proposed modernization retains in operation all standard DSC and ECDIS functions and provides full compatibility with commonly used non-integrated equipment. Financial expenses to its implementation for ship-owner are minimal due to only software updating and standard cabling.

VHF 대역 통신 신호에서 TDOA/FDOA 정보 추출을 위한 순차 추정 알고리즘

VHF 대역 통신 신호에서 TDOA/FDOA 정보 추출을 위한 순차 추정 알고리즘

Dynamic Bandwidth Allocation Strategy for Marine VHF Communications

Dynamic Bandwidth Allocation Strategy for Marine VHF Communications

광대역 VHF 기저대역 모뎀의 효율적인 송·수신 기법

As an FMT (Filtered Multi-Tone) transmission method of Wideband VHF communication system specified by the ETS (European Telecommunications Standards) EN 300 392-2, this paper introduces three existing realization methods, i.e., the direct filtering method using different band SRRC (Square-Root Raised Cosine) filters for each subcarrier, the PPN-DFT method using the IDFT-PPN (Poly-Phase Network) and PPN-DFT at the transmitter and receiver, respectively, and the Extended DFT method. Then, it proposes the extended IDFT-SDFT (Sliding Discrete Fourier Transform) that computes the DFT values only for interested subcarriers every sample time, and shows that it has an advantage of blind symbol timing (using no training symbol) individually for each user signal (independently of other users` signals) in the multi-user environment where the subcarriers are assigned in contiguous or interleaved blocks to each user and each user signal possibly experiences different channels.

VHF communication channel characterisations over complex wooded propagation paths with applications to ground wireless sensor networks

Results of measurement trials to estimate path loss and signal fading levels in very-high frequency band are presented for a node-to-node ad-hoc sensor network communication link with very low elevated antennas. Different typical landscapes were tested; from flat open areas to uneven woodland areas. Practical recommendations regarding utilisation of VHF band are formulated.

Maritime VHF communications with polarization diversity over a Rician channel

SUMMARYIn this paper, we propose a polarization diversity scheme to enhance maritime VHF communications. Multiple antenna systems require an antenna separation of 5–10 wavelengths to keep the correlation coefficient below 0.7 to permit the realization of space diversity. However, this may be difficult to implement in a maritime VHF system, because the maritime VHF is working in the frequency range from 156 to 174 MHz, with wavelength of approximately 2 m. On the other hand, the polarization device technique allows two co‐located antennas by using a micro‐strip technique. For this reason, the polarization technique is a practical method of attaining diversity. However, the theoretical model of polarization is very difficult and complex. Therefore, we express the cross correlation of each polarization antenna and the cross polarization discrimination of multiple polarization antennas with a simple model. Simulations show that the polarization diversity of a maritime VHF system shows better BER performance than that of the conventional reception diversity on the basis of vertical antenna with the antenna separation of 10 wavelengths. Copyright © 2012 John Wiley & Sons, Ltd.

ASO-TDMA: ad-hoc self-organizing TDMA protocol for shipborne ad-hoc networks

A shipborne ad-hoc network (SANET), a maritime counterpart of the terrestrial vehicle ad-hoc network, can provide ships with diverse multimedia services by substituting digital maritime VHF communications for expensive satellite communications. This article proposes ad-hoc self-organizing TDMA (ASO-TDMA), a medium access control (MAC) protocol targeting SANETs. Frames in ASO-TDMA are divided into several sub-frames, and based on the proposed rules for assigning time slots, ships can only reserve time slots for data transfers through their available sub-frames. Accordingly, ASO-TDMA provides better performance in terms of reducing receiver collisions from hidden terminal problems compared to self-organizing TDMA (SO-TDMA) and carrier-sensing TDMA (CS-TDMA), two existing MAC protocols for maritime VHF communications. In addition, the article compares the performance of the three MAC protocols in terms of delays and collision rates (CRs). The results suggest that, given the same delay, ASO-TDMA can reduce the CR by as much as 30% in comparison with SO-TDMA and CS-TDMA. Similarly, given the same CR, ASO-TDMA can reduce delays by as much as 26% in comparison with SO-TDMA and CS-TDMA.

Transmitting intended and suggested routes in ship operations: cognitive off-loading by placing knowledge in the world

Transmission of intended and suggested routes to and from electronic chart systems has been identified as a user need. The idea was discussed during a focus group meeting and two field studies in fringe fields like search and rescue (SAR) and ice breaking. A prototype test was then conducted during a SAR drill. The features were very well received by all the participants in the drill. A system simulation with two ships and a VTS station was also conducted in a full mission bridge simulator. Preliminary results are very promising. Behavior with vessels in conflicting situations suggested that the intended routes could facilitate understanding when negotiating with or without VHF communication. No major concerns were expressed by the professional crew members that participated.

The Design of the Multi-Purpose Virtual Voltmeter Based on LabVIEW 8.2

The DTR100 multimode VHF transceiver produced by Italian OTE company is a state-of the-art communication unit. The air traffic control authorities in many areas currently used DTR100 to protect the VHF communication. The results of measured parameters must be a true reflection of the actual working condition of equipment. According to this thought, this paper first analyses the shortcoming of the standard CMS50 radio comprehensive measurement instrument, then introduces two virtues of OTE test box, and the implementation procedure on audio signal 600Ω impedance matching. Moreover, this paper is to improve to technical staff the routine operations and the maintenance, to play the best performance of the equipment, in order to ensure the rapid development of the civil aviation industry in China.

First results of mapping sporadic E with a passive observing network

Sporadic E (Es) can have dramatic effects on communications in the HF and low VHF range, producing over‐the‐horizon propagation for signals normally restricted to line‐of‐sight, and sometimes blocking F region propagation of signals in the lower HF range. Measuring the E region winds believed to produce Es is difficult, and no practical means of predicting Es occurrence currently exists other than statistical models. We describe a low‐cost observing network based on software‐controlled receivers that continuously watches for Es in near‐real time using oblique HF propagation from existing transmitters. Results from an 11‐day pilot campaign in July 2008 demonstrated that even a limited number of receivers in the network can readily determine the presence and extent of Es patches. These observations indicate that Es often develops quickly over regions of several hundred kilometers rather than gradually drifting across an area. These widespread Es “blooms” have been observed near winter solstice and occasionally at other times of the year; their lifetime depends on the season but can be several hours during the summer. The current network allows the extent of Es in portions of North America to be evaluated: the geographical distribution of Es and bounds on the density of the layer are inferred from its effects on the ionospheric maximum usable frequency (MUF). This study demonstrates quantitatively that Es mapping can provide information about Es layer geographical growth and decay. The observed sudden widespread Es blooms are space weather events that can have significant impact on HF/lower VHF communications and propagation model predictions.

A Study for the Determination Method with Precise Parameter Based on the DTR100 Transceiver

The DTR100 multimode VHF transceiver produced by Italian OTE company is a state-of the-art communication unit. The air traffic control authorities in many areas currently used DTR100 to protect the VHF communication. The results of measured parameters must be a true reflection of the actual working condition of equipment. According to this thought, this paper first analyses the shortcoming of the standard CMS50 radio comprehensive measurement instrument, then introduces two virtues of OTE test box, and the implementation procedure on audio signal 600Ω impedance matching. Moreover, this paper is to improve to technical staff the routine operations and the maintenance, to play the best performance of the equipment, in order to ensure the rapid development of the civil aviation industry in China.

Satellite‐based vessel Automatic Identification System: A feasibility and performance analysis

AbstractThe Automatic Identification System (AIS) is a VHF communication system that provides identification/location information to vessels and shore stations by exchanging data such as position, identification, course, speed, etc. Recently, the interest in detecting and tracking ships at distances from coastlines larger than what can be accomplished by normal terrestrial VHF communications has grown, driven by requirements of long‐range applications such as better handling of hazardous cargo, improved security and countering illegal operations. This paper presents an extension of AIS to a long‐range positioning reporting through a constellation of LEO satellites. It outlines technical challenges like the high rate of message collisions from ships in the field of view of a satellite. Technical solutions are proposed at system and sub‐system level to address these challenges. A computer‐based system simulator is used to assess the system performance and carry out a high‐level system sizing. Results show that a relatively small constellation of LEO satellites can guarantee good ship position detection probability as well as a reporting time interval of a few hours. System performance aspects to be addressed in future work are the possible impact of terrestrial mobile communications interference as well as variations of the estimated traffic data. Copyright © 2009 John Wiley & Sons, Ltd.

PDA를 활용한 홍수예보시스템의 효율적 관리방안에 대한 연구

관측소의 기록저장 장치는 수위계와 우량계로부터 5분 간격으로 측정된 데이터를 저장한다. 그리고 관측소의 RTU(Remote Terminal Unit)는 VHF와 위성통신을 이용하여 10분 간격으로 홍수통제소의 TM(Telemetering)으로 측정된 데이터를 전송한다. 이때 전송되는 데이터는 레코더에 저장된 전체 데이터가 아니라 10분 간격으로 측정된 데이터이다. 홍수 통제소에서는 수신된 데이터를 홍수예보를 위해 분석한다. 또한 중요한 점은 관측소의 유지보수이다. 본 논문에서는 홍수예보를 위한 효과적인 유지보수 시스템을 제안한다. 그것은 PDA의 CDMA와 Blutooth 기술을 사용하였다. 제안된 시스템은 휴대용이며 관측소에 저장된 데이터를 RTU없이 쉽게 홍수통제소로 전송할 수 있다. 또한 홍수통제소로 부터 전송 받아서 다른 지역의 관측소 데이터를 원격으로 볼 수 있다. 따라서 제안하는 시스템은 인력과 시간의 낭비를 줄여서 관측소의 유지 보수 업무를 효율적으로 할 수 있다. The recorder at observatory can save the measured data from water gauge and rain gauge at an interval of five minutes. And then, the RTU (Remote Terminal Unit) in observatory sends the measured data in the recorder to the TM (Telemetering) in FCO (Flood Control Office) at an interval of ten minutes using VHF or satellite communication. But the transmitted data is not the stored data at the recorder, it is just data that is measured at an interval of ten minutes. In the FCO, the transmitted data is analyzed in order to forecast the flood. And also one of the most important things is the maintenance of an observatory. In this paper, an effective management system for the flood forecast is proposed. It uses the CDMA and the Blutooth technology on PDA. The proposed system is very portable, and also easily able to send the data stored at the recorder in observatory to TM in FCO without RTU. And it allows us to view remotely the data of other observatories by downloading from the FCO. Hence the system can do efficiently the maintenance of observatory without wasting manpower and time.

Operational concept for multi-carrier broadband VHF communications

Operational air traffic management needs have led to the concept of the broadband VHF (B-VHF) aeronautical communications system. This explains the functional principles, architecture, and internal mechanisms of the B-YHF system, showing how it can be used to provide the existing aeronautical voice and data link communications services and a multitude of new data link services expected for the next decade or two.

7.4.3 Integrated Communications Architecture for Homeland Security

AbstractThe fateful event of September 11 in the US and subsequent terrorist attacks in many countries had changed the world. We now live in a world of troubled peace, a far more dangerous world for many of us. A well‐networked security force will have comprehensive situation awareness to respond to unconventional threats like terrorism, low intensity conflict and even SARS. Conventional military communications has proven to be ineffective especially in urban environment where high‐rise buildings hinder the electromagnetic wave propagation of VHF and UHF communications. In Singapore, a well‐defined and integrated network centric based communications infrastructure is being put in place to link military and homeland security forces into an integrated force.

Multipath effects on the efficiency of interference compensation in VHF adaptive antenna systems

We consider the characteristics of signals in a multipath VHF communication channel which affect the efficiency of spatio-temporal processing of those signals. We present the results of experimental measurements of the efficiency of interference compensation with frequency-shift modulation under controlled conditions. Using the obtained data on various characteristics of the interference propagation channel, we analyze the factors decreasing the degree of compensation for such interference. We show that the multipath nature of the radio channel is the main factor leading to frequency and spatial selective fadings and uncorrelated distortions in the shape of the signal received by separated antennas.

On the Design of a Hybrid-Chebyshev Collinear Folded Dipole Antenna Array

ABSTRACT The arrangement of a Mast-mounted folded dipole antenna array with corner reflectors is considered. The method of moments (MoM) in a wire grid model is used and a suitable optimization procedure is applied Due to the constraints for high power gain and low SLL the array is designed as a simple broadside Chebyshev one. The presence of 120° corner reflectors change the pattern and makes the array to be a Hybrid-Chebyshev one with approximately the same SLL. The distance of the array from the corner of the reflector is critical for the HPBW. Two different types of antennas with 60° and 120° HPBW in the horizontal plane for possible mobile applications are studied.The whole design work is given in a general form, useful for VHF and UHF communication applications. To ensure the accuracy, two different wire grids for each model are used. In the examples several interesting cases will be analytically presented.

Relative impact of meteor scatter and other long‐distance high‐latitude propagation modes on VHF communication systems

We have analyzed the duty cycle, due to ionospheric propagation, of very high frequency sounding signals for both polar cap and auroral paths. We find that at 35 and 45 MHz the propagation is often sustained by sporadic E layers and other nonmeteoric modes rather than by meteor scatter. At the higher frequencies of 65 and 85 MHz we find that the path is generally dominated by meteor scatter modes. These results have important ramifications for frequency reuse and security in meteor burst communications systems and for the development of extended frequency range HF systems (above 30 MHz) with a capability to operate on any available propagation mode. The diurnal, seasonal, and geomagnetic variations of the nonmeteoric duty cycle have been examined. A polar cap path model is presented for the nonmeteoric duty cycle as a function of geomagnetic activity.

The Control Terminal of the GPS Mobile Surveillance System

Being a “revolutionary” satellite navigation system, the GPS can provides real-time and successive high accurate information of location, speed of three dimensions and time. Once the GPS receiver is equipped on the moving object, and the mobile communication chain (such as VHF, SSB or satellite communication) has existed, the GPS Mobile Surveillance System can be established. The targets’ information can be gathered by the control center successively and shown audio-visually on the display units of the control terminal which allows the center controlers easily monitor the real-time motion of the moving objects. This paper focuses on the technical realization of the control terminal of the system.