Showing papers in "IEEE Transactions on Vehicular Technology in 1969"
TL;DR: A system was devised that makes it possible to automate the signal strength measurements, called the signal amplitude sampler and totalization unit (SASTU), and a series of curves are developed which specify the anticipated error for a four-station grid.
Abstract: A method of vehicle location is discussed in which the attenuation of the signal from a mobile transmitter is measured. A test system and procedure for obtaining data is described. A series of curves are developed which specify the anticipated error for a four-station grid. The signal strength measurements could be very tedious and time consuming, but a system was devised that makes it possible to automate the procedure. This system, called the signal amplitude sampler and totalization unit (SASTU), is fully described.
77 citations
TL;DR: In this article, the authors investigated the relationship between the flow capacity of an automated highway and the small-signal longitudinal response of a vehicle, and concluded that a linear mathematical representation of the longitudinal dynamics was valid, and thus it could be used for predictive purposes.
Abstract: Virtually all proposed vehicle control systems for highway automation must include a steady-state car-following mode. This mode was intensively investigated for various situations where headway and relative velocity inputs were used. In addition, a fundamental relationship between the flow capacity of an automated highway and the small-signal longitudinal response of a vehicle was investigated. The predictions obtained from mathematical models of various car-following modes were compared to those from full-scale tests. It was concluded that a linear mathematical representation of the longitudinal dynamics was valid, and thus it could be used for predictive purposes. Furthermore, it was verified that flow capacity on an automated highway is sharply limited by certain vehicle characteristics if headway feedback is used for vehicle control.
53 citations
TL;DR: In a small-cell mobile telephone system, each channel may be used simultaneously in cells spaced sufficiently apart to limit cochannel interference.
Abstract: In a small-cell mobile telephone system, each channel may be used simultaneously in cells spaced sufficiently apart to limit cochannel interference. The extent of the interference depends upon the distance between cochannel cells, the number of land stations per cell, and the receiver capture ratio. The quantitative relationships among these parameters are derived for various cell configurations.
29 citations
TL;DR: In this article, a leaky coaxial cable having a new type of slot as a radiating element combining longitudinal slots with circumferential slots is described, and the desired radiation power or coupling loss can be easily designed by varying the dimensions of the slots and by selecting an appropriate pitch length.
Abstract: In railway radio systems and vehicular communications, a very important problem is that of maintaining stable communications at all locations, especially in tunnels and in spaces between buildings. A leaky coaxial cable having a new type of slot as a radiating element combining longitudinal slots with circumferential slots is described, and the desired radiation power or coupling loss can be easily designed by varying the dimensions of the slots and by selecting an appropriate pitch length. The results of the experimental studies at a frequency of 450 MHz are expected to give a satisfactory solution to this problem.
22 citations
TL;DR: When FM is employed, the phase of the demodulated composite is a nonlinear function of the parameters of the multipath structure of the channel, and this functional relationship is derived.
Abstract: Position location techniques based on propagation delay have been proposed previously. A narrow-band version of this technique involves the transmission of RF carrier, modulated by a single audio frequency. At a receiver, the audio phase is a measure of distance provided the propagation delay is less than one quarter cycle. The transmission medium introduces multipath distortion and the received signal consists of a set of signals, each an attenuated and delayed replica of the transmitted signal, having traversed a different path. When FM is employed, the phase of the demodulated composite is a nonlinear function of the parameters of the multipath structure of the channel. In this paper, this functional relationship is derived.
22 citations
TL;DR: In this article, the effects of tropical forests (jungle) on the performance of VHF radios have been explored, and the results of the measurements have been applied to a determination of vehicular radio sets.
Abstract: Some of the effects of tropical forests (jungle) on the performance of VHF radios have been explored. To better understand average propagation effects, the dielectric constant and the conductivity of selected forests have been measured. The effect of forests on the gain and pattern of simple VHF antennas has been explored, as well as signal loss along a trail. Scattering of VHF radio waves by nearby trees has been found to be a significant factor affecting received signal strength at any given point down a forest trail. Comparisons between propagation inside and outside a forest have been made. The results of the measurements have been applied to a determination of the performance of vehicular radio sets. A new concept of effective range of VHF radios operated in a forest is presented; its performance criterion is word intelligibility.
14 citations
TL;DR: It is both economically as well as technically feasible to introduce automatic brake and acceleration control a few years from today for automobile driving on freeways, with complete automatic highways evolving over the years and finally coming to fruition, possibly in the 1990's.
Abstract: Highway automation systems must be evolutionary and begin with present vehicles and highways. Development of a simple vehicle tracker as an optional extra on new vehicles to control braking and accelerating on presently controlled-access highways is a necessary first step. Once this device is prevalent, contains built-in self-test, and has engendered public confidence, then automatic steering can easily be added with minimal highway department assistance. This then would lead to a partially automatic highway, approximately ten years after introduction of the vehicle tracker. Finally, when the interim partially automatic system is proven, new highways could be of the completely automatic variety by inclusion of synchronous guidance; the previous vehicle tracker and partial automatic system would then become the first level backup system. Building of completely automatic highways might be anticipated about ten years after introduction of the partially automatic version. It is both economically as well as technically feasible to introduce automatic brake and acceleration control a few years from today for automobile driving on freeways, with complete automatic highways evolving over the years and finally coming to fruition, possibly in the 1990's.
7 citations
TL;DR: A transmitter multiplexer has been developed which can be used for multiplexing more than twelve 100-W transmitters in the 450-MHz band with a channel spacing of 150 kHz and the principal features are H 101 mode cavity resonators which are ultrastable with respect to the variation of environment conditions such as temperature and humidity.
Abstract: At a base station of a UHF mobile radio telephone system in a large city, many transmitters are used. In such a case it is not practical to use an individual antenna for each transmitter from the viewpoint of system economy and interference. Common use of one antenna for many radio-frequency channels is suitable and transmitter multiplexing devices should be used for this purpose. A transmitter multiplexer has been developed which can be used for multiplexing more than twelve 100-W transmitters in the 450-MHz band with a channel spacing of 150 kHz. The multiplexer consists of circulators, cavity resonators, and junction boxes. The principal features of this multiplexer are H 101 mode cavity resonators which are ultrastable with respect to the variation of environment conditions such as temperature and humidity. The resonators are temperature compensated to maintain the variation of resonant frequency within 5 kHz at the ambient temperature variation of 40°C. The voltage standing-wave ratio (VSWR) of the multiplexer, looking from the transmitter side, is less than 2.0 and the insertion loss is less than 3 dB at the operating frequency. Design objectives, over-all performance, and characteristics of cavity resonators and circulators are also presented.
6 citations
TL;DR: The patrol car emitter-call box sensor technique could be used on passenger buses and taxicabs to summon police assistance and would be particularly feasible for cities, such as Washington, D. C., that have an extensive police call box system.
Abstract: High accuracy is not required for car locator systems used in police operations. Relatively inaccurate patrol car locator devices can greatly improve police operations by significantly reducing response time, by permitting dynamic redeployment of forces, and by providing for better administrative control of forces. The patrol car emitter-call box sensor technique could also be used on passenger buses and taxicabs to summon police assistance. The technique involves equipping patrol cars, buses, or taxicabs with a short-range coded radio frequency (RF) emitter devices and equipping call boxes or other public electrical facilities with a device for sensing the emitter signal of the passing vehicles. Presence and identity of the vehicles can be detected and automatically telemetered over existing telephone or electrical lines to a computer-controlled display board in the dispatching center. Vehicle identification encoding is accomplished by modulating the emitter-transmitter with a selected combination of tones that differs for each vehicle. The system would use a transmitter-receiver combination similar to that used by automatic garage door openers. Vehicle identification encoding would be accomplished by using techniques similar to those of the touch-tone dialing system of the telephone company. By taking advantage of existing call box systems, the implementation of this system would be particularly feasible for cities, such as Washington, D. C., that have an extensive police call box system. How such a system could be installed in Washington, D. C. is described in detail. Features of the system are the following: 1) relatively low installation cost; 2) minimum spectrum space requirements; 3) accuracy of ±¼ mile achievable with existing call box locations in Washington, D. C.; 4) it is possible to selectively increase accuracy by area; 5) spectrum requirements remain constant with increased accuracy or increased geographical area of coverage; 6) simple inexpensive and proven equipment requirements.
5 citations
TL;DR: In this paper, a side-by-side rendezvous technique is proposed to improve the collection and transfer of passengers in a rail-guided intercity transportation system, where a nonstop express train provides service between cities, while frequent-stop local trains are used to provide coverage of metropolitan areas.
Abstract: START (system of transportation applying rendezvous technology) is a side-by-side rendezvous technique designed to improve the collection and transfer of passengers in a rail-guided intercity transportation system. In operation, a nonstop express train provides service between cities, while frequent-stop local trains are used to provide coverage of metropolitan areas. The local trains link up with the express trains through a side-by-side rendezvous on parallel rendezvous tracks, and transfer of passengers and cargo takes place while both trains are in motion. The START concept offers the advantage that passengers and cargo can be transferred at many points along an intercity express route without severely affecting the average speed of the intercity system.
3 citations
TL;DR: The Southern California Rapid Transit District (SCRTD) two-way radio system now in service provides voice communication and a silent alarm feature for safety purposes and the same equipment also provides automatic transmitter identification.
Abstract: The Southern California Rapid Transit District (SCRTD) two-way radio system now in service provides voice communication and a silent alarm feature for safety purposes. The same equipment also provides automatic transmitter identification. These features have been accomplished using an added logic assembly installed in the driver's area of the bus not far from the handset hanger. The equipment sends four digits of vehicle identification, six digits of assignment information, and one digit of message type marking, generated with integrated circuit logic and transmitted with keyed audio tone. The assignment information is determined by a code card plugged in by the driver at the start of an assignment. At the base station, the information transmitted from each bus is first presented on a visual display in front of the dispatcher, recorded on a digital printer with a time code, and then analyzed for alarm and acknowledgment significance. In the event of an alarm, the location of the bus is known from the complete identification of route and run number. This information is used by dispatchers to provide rapid police assistance in emergencies.
TL;DR: A digital radio dispatch system for control of mobile forces offers improvements over some of the shortcomings of existing voice systems while still retaining voice communication for emergency and special mobile-originated messages.
Abstract: A digital radio dispatch system for control of mobile forces offers improvements over some of the shortcomings of existing voice systems. The four functions involved in dispatching--- signaling, message, acknowledgment, and status---are described. Both the remote station and control center operations are described with emphasis placed on message format and timing. Polling controls the mobile tracsmissions for automatic acknowledgment status and other common messages. Such a system can assume the bulk of dispatch communications with the speed and security of digital communication while still retaining voice communication for emergency and special mobile-originated messages.
TL;DR: A new maritime mobile radio telephone system adopted by Nippon Telegraph and Telephone Public Corporation (NTT) and the satellite repeater arrangement, adopted to reduce service-dead areas, is described.
Abstract: A new maritime mobile radio telephone system adopted by Nippon Telegraph and Telephone Public Corporation (NTT), is described. An outline of the technical features of the entire system and the satellite repeater arrangement, adopted to reduce service-dead areas, is given.
TL;DR: By utilizing the dual criteria for acceptable performance as one of low message-loss probability and small time delays, data requirements for uniform vehicular traffic have been obtained and an extension to nonuniform Vehicular traffic is suggested.
Abstract: For the effective and efficient utilization of mobile vehicles, a vehicle locator and tracking system is necessary. Possible users of the system include the police, municipal bus systems, taxicabs, utilities, and others. One often suggested approach employs a network of distributed sensors, which sense and identify vehicles in the immediate vicinity. The sensors which receive transmissions from the vehicles then pass the vehicle identity, together with the sensor identity, to a central facility via a relay link. For the relay link, message-loss probability and time-delay statistics have been evaluated as a function of message traffic offered. By utilizing the dual criteria for acceptable performance as one of low message-loss probability and small time delays, data requirements for uniform vehicular traffic have been obtained. An extension to nonuniform vehicular traffic is suggested. Engineering estimates of data rate requirements for different system configurations can be made by using the figures presented.
TL;DR: In this paper, a study of a high channel density 450-MHz communication system employing 6 groups of 10 channels each in a 300-kHz band was made for air-ground telephone service by single sideband.
Abstract: Directed toward FCC Docket 16073 on air-ground telephone service by single sideband, a study has been made of a high channel density 450-MHz communication system employing 6 groups of 10 channels each in a 300-kHz band. To accomplish necessary tolerance to out-of-band transmitter radiation, all mobile stations need automatic power output control. Other important system features, such as privacy and first come, first serve from queue when all busy, result from the use of a common data channel. With the accomplishment of the necessary equipment and logical techniques, a communication system of much greater frequency utilization appears technically and economically feasible.
TL;DR: In this paper, the use of walkie-talkie radios to supplement fixed wire interior communications systems on ships is discussed, and many other problems were found to exist when alternate interim solutions to a man-on-the-move communication (MOMCOM) problem were tried on the U.S. Mars (AFS-1).
Abstract: The use of walkie-talkie radios to supplement fixed wire interior communications systems on ships is discussed. Electrical and acoustical noise interference problems were studied on replenishment ships, and the use of FM at VHF together with noiseproofed acoustic transducers was found necessary for many operations and/or for men in certain locations. RF signal penetration tests showed VHF to be superior to HF for reliable communications between certain interior spaces and the weather decks. In some cases antennas with coaxial lead-ins had to be provided to maintain adequate communications. These and many other problems were found to exist when alternate interim solutions to a man-on-the-move communication (MOMCOM) problem were tried on the U.S.S. Mars (AFS-1). In addition to finding a workable interim system, many problems and some answers were uncovered that will lead to a better integrated MOMCOM system for future ships.
TL;DR: In this article, human factors considerations in the design of command and control systems are viewed from the aspect of three common classes of human system participants: the sensors, the filters, and the decision makers.
Abstract: Several human factors considerations in the design of command and control systems are viewed from the aspect of three common classes of human system participants: the sensors, the filters, and the decision makers. An attempt is made to demonstrate the effects of particular perceptual variables upon the performance of each of these classes of participants. Several suggestions are made, based on recent research findings, concerning techniques the system designer may incorporate to enhance the role performance of each of these participants. A plea is made for early analysis to define system goals and alternatives and to study in detail the interrelationships of critical elements, including the human components, before the design of the system is completed.
TL;DR: The mathematics of intermodulation (IM) generation are surveyed in this article, and it is shown that for land mobile receivers, worst case IM is a third-order effect occurring in the first mixer.
Abstract: The mathematics of intermodulation (IM) generation are surveyed, and it is shown that for land mobile receivers, worst case IM is a third-order effect occurring in the first mixer. The importance of relating the IM specification to the receiver sensitivity is pointed out. RF gain reduction or elimination, selectivity at both RF and IF, and the new square law mixing devices are all mentioned as techniques used for receiver IM reduction. The new diodes and field effect transistors are examined in greater detail. Their advantages of low noise and high burnout resistance are contrasted with the problems of conversion gain and high required local oscillator power levels.
TL;DR: Forward error-correction equipment based on cyclic coding, which is applicable for selective calling and direct-printing systems in the maritime mobile service, is described.
Abstract: Forward error-correction equipment based on cyclic coding, which is applicable for selective calling and direct-printing systems in the maritime mobile service, is described. Some field test results are presented.
TL;DR: For a Doppler-signal ratio of less than 10 percent the dynamic signal-to-noise ratio is essentially equal to the static one, indicating why certain simple multipath analyses in use today have been successful.
Abstract: A signal-to-interference ratio for the transmission of scanned images and digital data in the dynamic multipath environment was derived in an earlier paper The dynamic case depends upon a Doppler environment-signal parameter ratio, while the static result is independent of the signal structure The dynamic case is asymptotic to, but always worse than, the static one For a Doppler-signal ratio of less than 10 percent the dynamic signal-to-noise ratio is essentially equal to the static one Most real systems today fall in this region This indicates why certain simple multipath analyses in use today have been successful The method of designing a signal to fall below the 10-percent value is indicated Signal-to-noise ratio curves are provided for system design purposes These results permit system analysis and tradeoff studies to be based on earth reflection coefficient distributions and aircraft or satellite operation envelopes
TL;DR: In this article, the disadvantages of the present multiple frequency monitoring methods are reviewed and the design considerations of a new unique technique which overcomes these limitations are presented, which utilizes sampling or time-sharing to always assure reception of the system's primary channel.
Abstract: A requirement for multiple frequency reception is placed on many mobile radio systems. The disadvantages of the present multiple frequency monitoring methods are reviewed and the design considerations of a new unique technique which overcomes these limitations are presented. Basically, this method utilizes sampling or time-sharing to always assure reception of the system's primary channel.