IEEE Transactions on Communications Systems

The peculiar requirements of a military communications satellite system as distinguished from a commercial one are examined. The effects on the system of requiring the system to operate with transportable ground stations, to be jam resistant, and to degrade gracefully are discussed. The choice of orbit inclination and altitude along with the number of satellites is shown to be a function of booste... View full abstract»

The ferrite limiter is a device which has the property of independently limiting two or more RF carriers if they are spaced by several megacycles from each other. This property may have utility in communication satellites as a multiple access tool or for minimizing the effects of jamming signals. The introductory section describes the device, its limiting action, and mode of operation in a commerc... View full abstract»

Intermodulation distortion measurements were made on traveling-wave tube amplifiers to determine the suitability of this tube type for use in single-sideband (SSB) frequency division multiplex transmitters. It was found that coupled cavity tubes exhibit better intermodulation distortion properties (by a factor of 5 or 6 db) than helix tubes. By employing a direct narrow-band feedback loop around a... View full abstract»

When two or more frequency modulated signals are transmitted simultaneously through a nonlinear device, intelligible crosstalk from one signal to another is a potential problem. Such a situation arises in connection with the multicarrier use of satellite transponders. In this paper, intelligible crosstalk arising from transmission vs frequency deviations followed by amplitude-to-phase (AM-PM) conv... View full abstract»

It appears not to have been widely recognized that intermodulation distortion of a SSB-AM signal will be generated by AM-PM conversion effects present in amplifiers (such as traveling wave tubes), as well as by output-input nonlinearity. When the SSB-AM signal is carrying multichannel telephony this can be an important source of distortion. In the present paper, a formula is developed relating int... View full abstract»

A method is presented for the solution of network programming problems through the iterative execution of the same algorithm for each station of the network. At a given station, the algorithm requires data only from adjacent stations of the network. The theory of the method is developed through the use of electrical models of network programming problems. The techniques should be useful for the co... View full abstract»

In this paper the properties of the total loss function of exclusive alternate route communication networks, the realizability of the networks, and the existence region of optimal allocation of channels are investigated. A practical procedure for solving this optimization problem is suggested. This principle is followed by illustrative examples showing the practical procedures and the advantage of... View full abstract»

A mathematical model which utilizes queuing theory is devised for estimating the storage requirements of a message switching computer. Since the storage needed for a message is proportional to the message length, the familiar derivation of a queue distribution in terms of the number of messages is not applicable. Instead the composite queue, resulting from a number of sending lines, is developed i... View full abstract»

In this paper, the synchronizing of a coherent receiver with a transmitter is investigated. It is assumed that the receiver knows the exact nature of the arriving signal, except its carrier frequency and arrival time. These, however, are known to be within some bounds. The receiver must then search through this frequency and arrival time space and find the signal in the shortest average time. The ... View full abstract»

In digital communication systems using binary phase modulation and differentially coherent detectors, it seems reasonable to suspect that errors tend to occur in pairs. The intuitive arguments are plausible, since these receivers obtain their reference from past bits. To put these arguments on a firmer ground, an analysis of this phenomenon was undertaken. It is shown that when the cause of errors... View full abstract»

Phase reversal keying (PRK) with coherent detection is becoming increasingly popular for use in binary data communication systems. Coherent detection of double sideband-suppressed carrier signals requires precautions to avoid inadvertent reinsertion of the local carrier 180° out of phase with the suppressed carrier, as this would convert every demodulated 1 to a 0 and vice versa. Some of ... View full abstract»

Error data from about 350 hours of 1200-baud data transmission tests are used to evaluate cyclic error detection codes. For polynomials of low degree (<7), the ratio of undetected erroneous messages to total erroneous messages is inversely proportional to the period of the coding polynomial. In a commercial synchronous operation, the typical optimum block length (>4,000 digits) is su... View full abstract»

A new method of coding complex signals based on 3-unit (+1,0,-1) quantization of their slopes, similar to the equalslope approximation used in network synthesis, and the resultant modulation schemes have been investigated. Using some compression and equalization, the optimum SNR for sinusoidal signals is found to be 25-34 db for the PRF of 20-60 kc. When feedback is used from a local receiver to t... View full abstract»

By the use of the proper combination of angle modulation and amplitude modulation, it is possible to generate a wave which may be detected without distortion on a conventional FM detector, but which has all its energy concentrated on one side of the carrier. A (SSB-FM) transmitter has been constructed by implementing each part of the mathematical equation for this wave. The signal generated by thi... View full abstract»

Advances in technology are causing many technical disciplines to merge. This is also true of optics and electronics which today often meet in the same system. The present paper is meant to serve as an introduction to analyzing classical optical components in communications and data processing systems and also as a practical aid in applying these techniques by collecting the most important data req... View full abstract»

Being quite narrow, the bandwidth of low-frequency transmitting antennas is often insufficient for modern communication requirements. Some physical reconstruction of the existing antenna, or damping of the output circuit may be used for broadbanding. In this paper, a method of synthesis for broadbanding coupling networks is shown, together with curves relating the Chebyshev and Butterworth types o... View full abstract»

The author describes how to derive the average cross-correlation as ⩾ [-1/(n-1)] (average signal energy), where the averaging is over the ensemble of signals. In the important special case in which all signals have the same energy E and all the cross-correlations are made equal to R, this result reduces to the constraint R ⩾ -[E/(n-1)]. View full abstract»