Performance analysis and validation of precision multisatellite RF measurement scheme for microsatellite formations

Abstract

Almost all existing studies on inter-satellite radio-frequency (RF) measurement have focused on two-satellite formations. Although some frequency division multiple access and code division multiple access multisatellite RF measurement schemes have been proposed, their poor scalability does not satisfy the inter-satellite measurement requirements of multisatellite formations, especially large-scale formations. Two-way ranging (TWR), which is based on a time division mechanism, is an effective solution that has been used for inter-satellite links in the global positioning system and Beidou navigation constellations. However, the high measurement accuracy achieved with TWR in these navigation constellations is heavily reliant on high-performance atomic clocks and the assistance of navigation ephemeris, which are not available on microsatellite platforms. This work focuses on a scalable multisatellite measurement scheme that adopts a distributed broadcast-based time division multiple access mechanism as the media access control layer and uses an asymmetric double-side TWR method as the physical layer. The measurement performance of the proposed scheme is evaluated through in-depth theoretical modeling, simulation verification, and experimental validation, along with a comprehensive comparison with the conventional TWR method. The experimental results show that centimeter-level measurement accuracy can be achieved with the proposed scheme when only a common miniaturized frequency source is used. This accuracy level is two orders of magnitude better than that of the TWR method, and thus satisfies the application requirements of general large-scale microsatellite formations.

Precision Joint RF Measurement of Inter-Satellite Range and Time Difference and Scalable Clock Synchronization for Multi-Microsatellite Formations

“…In a similar way to the analysis in [20], the following derivation will show how the satellite motion error arises when ADS-TWR is used for the time difference measurement. The relationship among the inter-satellite range, the times of flight, and the component of the satellite's absolute speed in the direction of the line connecting satellite A to B can be deduced as follows:…”

“…The researchers [15,20] described a TDMA and ADS-TWR-based method for distributed multi-satellite measurement. Because the ADS-TWR method was originally proposed for ranging applications, they only analyzed and simulated the inter-satellite ranging performance.…”

“…Based on the ADS-TWR time measurement, the distance, R, between the two nodes can be obtained as follows [20]:…”

“…Moreover, the ionosphere delay and hardware delay need to be corrected. The influence of each error source on ranging and the corresponding compensation measures can be found in [20]. For the time difference measurement, the influence of each error source and the compensation measures are similar to ranging.…”

“…Therefore, we focus mainly on receiver thermal noise and transmitter code-phase jitter noise. We used a delay-locked loop (DLL) for code tracking, and the standard deviation σ DLL of the receiver thermal noise error can be expressed as [20]:…”