The experiments described in this paper were carried out to determine the probability of simultaneous reception of meteor-burst signals at different geographic locations (interception) so that the possibility of interference and frequency sharing as well as the suitability of this type propagation to broadcasting may be assessed. Interception tests were conducted at five different sites using transmissions on a 1000-km circuit between Terminal A, near The Hague, The Netherlands, and Terminal B, near Toulon, France. The five monitoring stations were located at Harrogate (Station C) in England, Station D near Paris, Station E near Frieburg in Germany, Station F near Rome, Italy, and Station G, some 35 km from Terminal A. It was found that at Station G the same signal bursts were received as at Terminal A and interception was practically total. At the other four stations, interception was mainly due to the simultaneous occurrence of two meteor trails reflecting waves in different directions. The amount of information intercepted was on the average between 3 and 16 percent, but could occasionally be 100 percent due to sporadic-E reflections. However, the experiments used a frequency of 36 MHz; by operating at 70 MHz or higher interception due to abnormal ionospheric propagation conditions could be virtually eliminated. It is estimated that interference to meteor-burst link from beyond the horizon would be very inefficient since the power ratio at 40 MHz is about 25 to 1 in favor of the link. At higher frequencies the advantage for the link would be much greater. The results of the interception tests show that meteor-burst systems can be used for broadcasting provided that three separate antenna systems are employed to cover ranges up to 2000 km and to repeat the message continuously from one to several minutes to achieve a high probability of reception. Frequency sharing between several meteor-burst links operating in the same area also appears to be feasible with frequencies high enough to eliminate ionospheric scatter and sporadic-E layer reflections.

Three different ground terminal transmit power control concepts for a Satcom system are examined. The effectiveness of constant satellite power (CSP) sharing among the carriers and adaptive satellite power (ASP) sharing is compared with constant ground terminal transmit power (CTP). It is shown that ASP offers substantial advantages over CSP in combating environmental degradations and that both can increase link availability with respect to the constant power (CTP) case. The effectiveness of the ASP control technique is shown to depend on the interconnectivity of the network if multidestinational carriers are used. The measurements required for system control, as well as their accuracies, are described.

The use of chaff for establishing communications of limited duration between nonadjacent troposcatter stations is investigated. The optimum location for the release of chaff is determined theoretically considering the path geometry, the antenna elevation and directivity, and the weather and atmospheric effects. Amplitude, polarization, and fading characteristics of the signal energy scattered by chaff are calculated and the type and weight of chaff required to provide a given signal-to-noise ratio (S/N) is estimated. Experiments which were conducted to check the validity of the theoretical calculation are then described. Finally, a practical scheme for overpassing troposcatter stations and for communications between mobile users which are not in line of sight is considered.

The salient features of a militaryX-band satellite system, which has been planned at SHAPE Technical Centre (STC) to form part of an automatically switched network, is outlined. Satellite post-launch test and system operational requirements such as in-orbit testing, orbit determination and prediction, frequency planning, and system control are discussed. Technical facilities and techniques which have been and are being used at STC to meet these requirements for the North Atlantic Treaty Organization (NATO) Satellite System are described. These include three ground terminals and laboratory, as well as computer models of the entire satellite communications system.