This paper presents and discusses the results of technical tests on land mobile communications conducted in June and July 1989 in Europe using a EUTELSAT satellite. The land mobile communication system under test was that already operated by QUALCOMM in the U.S.A. under the registered name OmniTRACS.The field trial was organized in conjunction with the Signatories who expressed to EUTELSAT an interest in a full-scale technical investigation of the system. The aim of the field trial was to evaluate the technical characteristics of the system and test its performance in different operating conditions.The results establish the relationship between transmission performance (i.e. essentially the required number of transmission attempts in order to get a message through the communication channel), and the environment of the land mobile, the satellite transponder's mode of operations and the interference conditions.
This paper presents some results obtained in laboratory measurements of interference caused by FM television signals to encoded SCPC/QPSK carriers. Certain parameters, such as the TV energy dispersal excursion, the frequency spacing between wanted and interfering carriers, the SCPC bit rate, etc., were varied during the measurements in order to study their influence on the amount of interference suffered by the SCPC channel.
Computer simulations were also carried out in order to analyse and interpret measurement results obtained in some cases.
Conclusions are drawn on the use of a possible interference criterion when rate 1/2 convolutional encoding and soft decision Viterbi decoding is used in the SCPC system as well as on the expected improvement with frequency offset.
This paper contains the results of a measurement campaign to determine the protection ratio requirements for PAL FM TV satellite transmissions in a form suitable for direct application in satellite planning exercises.The following cases were considered in the study:(a) the mutual interference between two co-frequency PAL TV signals frequency modulated using a deviation sensitivity of either 16 MHzN or 25 MHzN (b) the interference effects created by two independent co-frequency PAL TV carriers interfering with the same victim PAL TV carrier, with all signals frequency modulated using a deviation sensitivity of 25 MHzN. Protection ratios were assessed with a wide variety of different conditions assumed for the wanted and interfering signals, such as the target picture quality and the operating carrier to noise ratio.The analysis of the results indicates that the required protection ratio is dependent upon some of the study parameters such as the picture content of the wanted signal. Protection ratio guidelines are derived on the basis of this analysis for co-frequency interference into PAL FM TV signals. The results also confirm that, for planning purposes, multiple interfering signals can be treated by addition on a power basis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.