This paper provides a description of the INTELSAT TDMA/DSI system. A discussion is given of the overall system configuration including the satellite connectivities, burst and frame format, method of acquisition and synchronization, and the use of the TDMA system monitor. Details are provided on the reference station equipment and traffic terminal interfaces including the use of DSI, DNI, and plesiochronous interworking. Finally, the overall system coordination methods are discussed, including the burst time plan generation, verification, and rearrangement techniques.

This is in reply to the comments made by Messrs. X. T. Vuong and H. J. Moody on "A general theory for intelligible crosstalk between frequency-division multiplexed angle-modulated carriers." We do want to express our gratitude for the editorial comments which were made by Messrs. Vuong and Moody which could be of help to the reader. The comments of substance however we feel are in many cases misleading and in certain cases incorrect. An item by item assessment of each of the fifteen (15) points which were raised follows below.

A new method for calculating intelligible crosstalk between frequency-division multiplexed (FDM) angle-modulated carriers has been developed and is directly applicable to multicarrier operation in communications satellite systems. The analysis is general in scope and accounts for both the nonlinear amplitude and phase characteristics of the amplifying device by the use of a complex Bessel function expansion. Group delay and amplitude variation preceding the input of the nonlinear device are modeled using a Fourier series expansion. FDM baseband loading is also considered in the analysis. A comparison of theoretical results with measurement shows good agreement.

An investigation of interference between angle-modulated systems carrying multichannel telephony, which is directly applicable to existing satellite and terrestrial radio-relay systems, has been undertaken. This study includes a general solution for arbitrary narrow-band interference into an angle-modulated system with arbitrary modulation. The algorithm has been implemented on a digital computer to provide calculations of interference between two FDM/FM systems. The analysis is valid for all modulation indices, and may be applied to any PM, FM, or preemphasized FM baseband. A comparison of calculated results and experimental measurements shows good agreement. An extensive investigation, covering a wide range of modulation indices and basebands, has been conducted for the particular case of preemphasized FDM/FM signals. Wherever possible, a generalized presentation of interference results is given. Interleaving criteria are also presented for certain cases of interference involving two identical signals.