By Topic

Communications Systems, IRE Transactions on

Issue 1 • Date March 1956

Filter Results

Displaying Results 1 - 20 of 20
  • [Front cover and table of contents]

    Publication Year: 1956 , Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (113 KB)  
    Freely Available from IEEE
  • Keynote address - Symposium on Communications by Scatter Techniques

    Publication Year: 1956 , Page(s): 3 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    The newly developed scatter technique appears to make possible extremely reliable communication circuits over distances of 100 to 1000 mi. These distances had previously been considered too short for good ionospheric propagation and too long for VHF or UHF transmissions. Thus, the facts brought forth in the investigation of scatter propagation have led to a modification of the theories and concepts held by many engineers and scientists. Accordingly, the author believes it is most appropriate that a symposium be devoted to a discussion of this new development, which has opened up many interesting possibilities, and which will undoubtedly have a great impact upon future communication circuits between fixed points. The papers to be presented at this symposilu will discuss both ionospheric and tropospheric scatter. It appears from the knowledge now available that ionospheric scatter will be useful in the band of frequencies ID approximately 25 Mc to 60 Mc and over distcnces. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Some practical aspects of auroral propagation

    Publication Year: 1956 , Page(s): 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    Assoclated with visible auroral activity there is some kind of reflection or scattering mechanism that can result in radio communication in the VHF band over distances up to 1000 km with low power transmitters and probably up to 2000 km with high power transmitters. The transmission-loss experienced over such a circuit is somewhat less than is involved in regular VHF scatter-communication but is much greater than for sporadic E openings at VHF. For auroral propagation the direction of arrival is deviated from the great circle plane towards the direction of auroral activity, whereas for regular VHF scatter-transmission, and for sporadic E transmission, propagation is approximately geodesic on most occasions. For auroral propagation the bandwidth available for communication is almost always severeley limited, frequently to the extent that amplitude-modulated (AM) radio-telephony is impossib1e. Moreover the ratio of the fading rate to the carrier frequency is rather more than a power of ten greater than is customary for ionospheric transmiseion under quiet ionospheric conditions. Auroral propagation occurs most frequently at night and is hardly ever experienced between sunrise and noon. It occurs most frequently at the equinoxes and more often in years of high sunspot activity. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Progress of tropospheric propagation research related to communications beyond the horizon

    Publication Year: 1956 , Page(s): 6 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1099 KB)  

    It is proposed to give a simple elementary review of tropospheric mechanisms believed to be capable of propagating short radio waves well beyond the earth's horizon together with some selected experimental data indicatine the potential communication capacity of these tropospheric propagation mechanisms. In view of the wide general interest in the useful applications of the propagation of short radio waves, well beyond the horizon to communications systems, it is hoped that the rather simplified method of presentation will serve to introduce those communications engineers, not intimately associated with past radio propagation research, to the subjects to be discussed. The simplified presentation of theoretical models and discussion of selected experimental results discussed in this paper was intended to give communications engineers a general physical picture of tropospheric scattering. The results of experimental measurements have shown that reliable communications with useful bandwidths can be obtained at UHF and SHF over paths 150 to 300 miles in length utilizing radio waves scattered by the troposphere provided that several kilowatts of power and highly directional antenna system are utilized. The angular measurements of pulse signals scattered by the troposphere indicate that the mechanism of scattering is highly directive and that nmltipath delays are less serious than were originally anticipated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • VHF propagation by ionospheric scattering - a survey of experimental results

    Publication Year: 1956 , Page(s): 17 - 27
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (978 KB)  

    A brief survey is given of results from an experimental program extending over the last five years to investigate the nature and characteristics of high-loss regular VHF propagation by means of scattering and other mechanisms in the lower ionosphere. Short-term characteristics as well as diurnal, seasonal and geographical variation of the observed signals are described. The results of pulse-determination of height of scattering, spaced-antenna and polarization experiments, and observations of realized gain of directive antenna systems are given. The dependence of the strength of the signals on path length, scattering angle and frequency is described. Considerations for communication applications are summarized. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Practical consideration for forward scatter applications

    Publication Year: 1956 , Page(s): 28 - 31
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (542 KB)  

    It is now possible to provide communications with high reliability factors in geographical areas which are resistant to the more conventional high-frequency radio. For the past two years, the US Air Force has been operating an ionospheric scatter system (FPIS) between Loring AFB, Maine, USA, and Thule AFB, Greenland. Relay stations in this system are located at Goose Bay, Labrador, Canada and Sondrestrom, Greenland. The US Air Force tropospheric scatter system (FPTS) has been in operation since May, 1955, along the Labrador coast in support of a chain of radar stations. Practical considerations in the application of either of these scatter systems include but are not limited to such factors as cost, reliability, channel capacity, geography, topography, path length, interference, manpower requirements (both as to skill and number) and logistics support. Although tropospheric and ionospheric scatter systems are linked in the similarity of nomenclature, the characteristics and practical considerations are quite different. Accordingly the FPIS and FPTS systems are discussed separately. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Some Meteorological Effects on Scattered Radio Waves

    Publication Year: 1956 , Page(s): 32 - 38
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (605 KB)  

    The long term variations of received scattered fields due to atmospheric effects are estimated for frequencies of 100 to 50,000 Mc and over propagation paths of 100 to 1000 miles. The long term variations are presented in two parts: (1) empirically derived variations excluding absorption and (2) theoretically derived variations due to gaseous atmospheric absorption. The absorption effects are obtained by following a scattered radio wave through an actual atmosphere. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Point-to-Point Radio Relaying via the Scatter Mode of Tropospheric Propogation

    Publication Year: 1956 , Page(s): 39 - 49
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (912 KB)  

    Formulas are given for determining the transmitter power required to provide a specified grade of service in point-to-point radio relaying of the following types of signals: television, frequency modulation high fidelity music, frequency modulation voice, frequency shift telegraph, and a just measurable signal. Allowance is made for the antenna gains, the carrier frequency, the systems bandwidth, distance, the antenna heights above the ground and the effects of the terrain and the atmosphere along the transmission path. The formula for the transmission loss allows separately for the effects of the actual distance, the angular distance and the antenna heights, and this separation of the influence of these variables provides the basis for the development of rules for the efficient siting of the terminals of a tropospheric forward scatter relay circuit. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A simplified diversity communication system for beyond-the-horizon links

    Publication Year: 1956 , Page(s): 50 - 55
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (335 KB)  

    For nearly a year the US Federal TelecomMunication Laboratories have had in operation a 900 mc beyond-the-horizon two-way link between the Nutley, New Jersey laboratories and Southampton, Long Island. Early results using PTM have already been reported. Briefly, an annual median path-loss some 20db greater than that predicted by Bullington was found, but the bandwidth was adequate for pulse modulation. Since then, frequency modulation, frequency division multiplex and diversity reception have been emnloyed. This report covers the present system, with special emphasis on equipment economies achieved and an analysis of diversity combining methods. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High-Gain Antennas for VHF Scatter Propagation

    Publication Year: 1956 , Page(s): 56 - 63
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (793 KB)  

    Rhombic antennas were the first type employed in the study of propagation via ionospheric scatter. By the use of electrically long leg-lengths gains of the order of 20 decibels were obtained. Experimental measurements using model techniques indicated that assumptions usual in the design of rhombic antennas remained valid even for leg-lengths of 25 to 40 wavelengths. In order to obtain a more compact antenna, while retaining the gain, experimental investigation was carried out on corner-reflector and Yagi-types of antennas. By the use of 60 degree corner-reflector and a collinear array, a corner reflector antenna having gain of 19.9 db. was constructed. By exercising care in adjusting the lengths of parasitic elements, a Yagi antenna, 4.2 wavelength, having a gain of 14.2 decibels, was designed. An array of four such Yagis, having a horizontal spacing of 1.8 wavelengths and a vertical separation of 1.6 wavelengths was measured to have a gain of 19.0 decibels. Full scale corner-reflector antennas and Yagi antennas have been erected and have proved to be operationally satisfactory. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Transmitting Tubes for Scatter Communications

    Publication Year: 1956 , Page(s): 64 - 68
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB)  

    Continuous wave klystron amplifiers have undergone considerable development in recent years, and a marked advance in the state of the art has resulted. The characteristics of these amplifiers that make them especially attractive for scatter communication will be reviewed. The design philosophy of some modern amplifiers will be reviewed, including the following tubes: 1) 10 kw output at 2000 mc, 50 db gain, 2) 2 kw output at 6000 mc, 50 db gain. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Power amplifier klystron for U.H.F. transmission

    Publication Year: 1956 , Page(s): 69 - 76
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1059 KB)  

    A review of design considerations and expected performance of external cavity klystrons is given. Information on availability of these power amplifier klystron tubes is presented along with comments on systems engineering considerations in klystron applications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • VHF Transhorizon Communication System Design

    Publication Year: 1956 , Page(s): 77 - 86
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1417 KB)  

    The basic properties of a signal received over a typical VHF transhorizon circuit are presented. The necessary parameters and features of a system designed to utilize efficiently this signal are then considered. These include modulation, diversity reception, teletype transmission, frequency control, equipment reliability, and duplex operation. In conclusion curves are presented showing system voice and data channel capacity and quality as a function of circuit length, reliability required, and frequency. It is concluded that available VHF equipment may be employed to provide reliable voice transmission and extremely reliable multichannel teletype transmission for circuits in the 300 to 1200 mile range. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • System Parameters Using Tropospheric Scatter Propagation

    Publication Year: 1956 , Page(s): 87 - 96
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (986 KB)  

    Accumulated data from published sources and from unpublished research on tropospheric forward scatter propagation are reviewed and condensed for practical applicatian to FM communication systems. Antennas suitable for use on scatter paths are reviewed and the limitations on usable gains are discussed. General design methods for FM systems are presented and reduced to a design chart that includes the relationship of all parameters in a frequency-division multiplexed FM telephone system. Then follow computed values of transmitter power as functions of distance, frequency and antenna size for a number of systems of practical interest using tropospheric forward scatter. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A simple picture of tropospheric radio scattering

    Publication Year: 1956 , Page(s): 97 - 101
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (372 KB)  

    The purpose of this paper is to describe the scatteriing of radio waves by a turbulent troposphere in a simple way. The description provides a useful picture for the radio engineer who mustst apply the scatter mechanism to a system. It does not replace a more rigorous treatment or oversimplify to the extent that any important ideas are omitted. It is hoped that this prosentation will facilitate the application of the material on scattering presented in this issue, in the Proceedings of the IRE for October 1955, and elsewhere. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Long distance VHF-UHF tropospheric field strengths and certain of their implications for radio communications (abstract)

    Publication Year: 1956 , Page(s): 102 - 103
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (135 KB)  

    Sufficient knowledge of normal VHF-UHF tropospheric field strengths has been obtained for distances far beyond the radio horizon to enable sensible planning of communication circuits having ranges of some 200-250 statute miles. It is desirable, of course, to exploit this propagation mode to the greatest possible distance and this requires a detailed knowledge of the path loss to distances beyond 200 mi. Data available from long path length measurements made by the Central Radio Propagation Laboratory of the National Bureau of Standards, Bell Telephone Laboratories, the Lincoln Laboratory of the Massachusetts Institute of Technology (MIT), and the Propagation Laboratory of the US Air Force Cambridge Research Center have been subjected to analysis and comparison. As a result, it appears that a good estimate of temperate latitude transmission loss can now be made within the' 100-500 Mcps region to distances of 400 mi, and usable estimates to 600 mi. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Results of propagation test at 505 Mc and 4090 Mc on beyond horizon paths

    Publication Year: 1956 , Page(s): 104 - 111
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    This paper summarizes the results of some radio propagation tests that were conducted for a full year in Newfoundland starting in late 1953. A more detailed paper on these results was declassified in time to be included in the October 1955 issue of the Proceedings of the IRE. The Newfoundland tests were sponsored by the US Air Force to obtain information for engineering beyond horizon radio relay systems. The field work and most of the data analysis was done by the Bell Telephone Company of Canada. From these results and other data it is possible to generalize on the median gain that can be realized beyond the horizon. Theoretically, the variations in antenna gain should be separated from the fading in the transmission path. However, the practical importance of such separation depends largely on whether the realized antenna gain is consistently low when the signal level is low. A correlation of this type was looked for at the time of these tests but no significant correlation was found. Additional tests are needed on antennas that are significantly larger than 100 wavelengths in diameter. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Some ionosphere scatter techniques

    Publication Year: 1956 , Page(s): 112 - 117
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (630 KB)  

    This paper discusses three possible applications of ionospheric scatter which are useful to the high frequency communicator. The first of these involves the use of backscatter to determine the zone of communication for a certain frequency when utilizing normal innosphere modes of propagation. Normal modes are those in which the layer is sufficiently ionized to allow a direct ray to be propagated from the transmitting station to the receiving station via the ionosphere. The second also involves the use of backscatter but in a sense that the intelligence is actually carried from the transmitter to the receiver by way of the backscattered rays from a distant point not necessarily on the great circle path between the stations. Such a technique can often be applied when the frequency to be used is above the maximum usable frequency for the path. The third technique makes use of actual scattering within the layer so that a small amount of energy may be returned to many possible receiving pointseven though most of it is lost into space. Each of these three applications of scatter will be considered separately. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Signal Fluctuations in Long-Range Overwater Propagation

    Publication Year: 1956 , Page(s): 118 - 122
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (463 KB)  

    Measurements of overwater propagation in the Pacific on 3 and 9 cm between airborne transmitters and fixed receivers are reported. Within the horizon, the direct and surface-reflected rays formed the usual interference patterns. Beyond the horizon, the 3-cm signal always behaved in general accord with normal-mode theory, the attenuation rate averaging 0.5 plus or minus 0.2 db per (nautical) mile. In roughly the first 30 miles past the horizon, the 9-cm signal had a heightgain and an exponential decay rate (0.9 to 1.9 db per mile), both reasonably dependent on measured duct strength. On 9 cm only, all greater ranges comprised a "turbulent region," where a new, lower attenuation rate prevailed, averaging 0.17 plus or minus 0.05 db per mile, and where there was no average height-gain, turbulent-region signals were approximately Rayleigh-distributed and the autocorrelation of their fluctuation vanished in at most 1.5 seconds. The turbulent-region signal undoubtedly was due to scattering by some highaltitude atmospheric mechanism. The surf in the foreground of the receiving tower, effectively forming an extension of the antennas, produced a periodicity in the records and other behavior suggesting the importance of foreground in diversity measurements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • [Back cover]

    Publication Year: 1956 , Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (10 KB)  
    Freely Available from IEEE

Aims & Scope

This Transactions ceased publication in 1962. The current retitled publication is  IEEE Transactions on Communications.

Full Aims & Scope