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For advanced digital space transponders, the Digital Phased-Locked Loops (DPLLs) can be designed using the available analog loops. DPLLs considered in this paper are derived from the Analog Phase-Locked Loop (APLL) using S-domain mapping techniques.
This article investigates and identifies the baseline design and implementation of the digital baseband architecture for advanced deep space transponders. Trade studies on the selection of the number of bits for the analog-to-digital converter (ADC) and optimum sampling schemes are presented. In addition, the proposed optimum sampling scheme is analyzed in detail. Descriptions of possible implementations for the digital baseband (or digital front end) and digital phase-locked loop (DPLL) for carrier tracking are also described.
Packaging technique for producing rendezvous radar and transponder noting structural design, reliability, cooling, outgassing, humidity, etc
S band turnaround ranging transponder
Test program on feasibility of digital phase measuring subsystem of pulse-coherent retrodirective transponder
Range coverage diagrams for CSM rendezvous radar transponder antenna raised 4 in. and tilted forward 15 deg
Advanced S-band transponder study program
Range and range rate transponder capability for ground system tracking relay of Nimbus-E
Apollo 14 command service and lunar module orbital velocity data from radio navigation S-band transponder experiment for lunar gravitation effects
ATS 1 and 3 satellite VHF transponders for ships and aircraft location, communication and remote sensing, discussing performance test results
The use of artificial satellites for time synchronization of geographically distant clocks is hindered by problems due to satellite motion or equipment delay measurements. The ATS-3 satellite with its two C-band transponder channels helps solve these problems through techniques for synchronization to accuracies of tenths of microseconds. Portable cesium clocks were used to verify the accuracy of the described system.
A loop transponder for regenerating the code of a mu type ranging system is disclosed. It includes a phase locked loop, a code generator, and a loop detector. The function of the phase locked loop is to provide phase lock between a received component wk of the range signal and a replica rafter wk of the received component, provided by the code generator. The code generator also provides a replica of the next component rafter w(w+1). The loop detector responds to wk rafler wk and rafter w(k+1) to determine when the next component w(k+1) is received and controls the code generator to supply w(k+1) to the phase locked loop and to generate a replica rafter w(k+2) of the next component.
A series of experiments utilizing a multimode transponder mounted in an aircraft working either through a spacecraft or directly with a ground station is studied. The purpose of the experiments is to determine the best modulation and encoding techniques for combating RFI and multipath propagation and to determine the characteristics of VHF and UHF RFI in discreet bands. The experiments would also determine the feasibility and accuracy of range and range rate measurements with the various modulation and encoding techniques.
Plans and implementation concepts were developed for utilizing a multimode transponder mounted in an aircraft working either through a spacecraft or directly with a ground station. The purpose would be to determine the best modulation and encoding techniques for combating RFI and multipath propagation and to determine the characteristics of VHF and UHF RFI in discreet bands. The experiments would also determine the feasibility and accuracy of range and range rate measurements with the various modulation and encoding techniques.
Procedures for the performance of two tests (electrical and airlink) for the transponder are outlined. The C-band test console used in performing the above tests is described (circuit diagrams and block diagrams), and equipment specifications are given. Calibration of the test equipment is also discussed.
Test procedures necessary for the calibration and performance verification of the noncoherent C-band transponders after spacecraft hardware integration, but prior to spacecraft/launch vehicle integration are presented.
An experiment to evaluate the possibility of disseminating a time code via the SIRIO-1 satellite, by using the onboard VHF repeater is described. The precision in the synchronization of remote clocks was expected to be of the order of 0.1 to 1 ms. The RF carrier was in the VHF band, so that low cost receivers could be used and then a broader class of users could be served. An already existing repeater, even if not designed specifically for communications could be utilized; the operation of this repeater was not intended to affect any other function of the spacecraft (both the SHF repeater and the VHF telemetry link were active during the time code dissemination via the VHF transponder).