Telemetry Recovery and Uplink Commanding of a Spacecraft Prior to Three-Axis Attitude Stabilization

2014 7th Advanced Satellite Multimedia Systems Conference and the 13th Signal Processing for Space Communications Workshop (ASM

et al. 2014

Aiming at increasing the satellite link performance, advanced modulation techniques have been thoroughly studied. On the other hand, reliable transmission techniques with a low computational overhead are pursued for many applications in critical scenarios such as: control operation of a satellite while it is placed into its orbit, the disposal of a satellite at the end of its life or the deep-space missions. In these specific mission critical scenarios, fast and correct data reception is even more important than high channel capacity. An unknown and fast variable channel state condition, with large Doppler shifts and low available power require incoherent and light computationally modulation techniques. This paper introduces a whole digital implementation of a receiver, based on the Double Differential PSK (DD-PSK) modulation, that is perfectly compliant with these requirements.

Section: A Scenariomentioning

confidence: 96%

Robust modem design for satellite communications in emergency scenarios

2014 7th Advanced Satellite Multimedia Systems Conference and the 13th Signal Processing for Space Communications Workshop (ASM

et al. 2014

“…Figure 1A reports the SNR values at the receiver as a function of time during a visibility window; its minimum values are reached at the beginning and at the end of each window, ie, when the satellite is close to the horizon. On the other hand, Figure 1B shows the SNR versus time in case of uncontrolled attitude of the spacecraft; the signal strength presents large variations because of satellite motion …”

Section: Scenariomentioning

confidence: 99%

“…The early operations after separation from upper launcher stages, as well as the end of life disposal manoeuvres, are critical satellite mission phases that require a robust and reliable communication system . In these scenarios, the spacecraft may have reduced functionalities and uncontrolled attitude, and consequently, the communication link could be weak and unstable, eg, signal's amplitude may be subjected to deep fading according to satellite tumbling rate . In this context, the communication becomes bursty and the link reliability harms the bit‐rate performance.…”

Section: Introductionmentioning

confidence: 99%

Frequency recovery techniques for TM/TC satellite modem in critical scenarios

Ronga³

et al. 2017

Satell Commun Network

Reliability and effectiveness are essential features of satellite transceivers for telemetry and telecommand applications. Modem performance has a strong impact on the success of a satellite mission, in particular, during critical scenarios as the early operation phase, the disposal of a satellite at the end of its life, or the deep-space missions. In these specific mission critical scenarios, fast and correct data reception is even more important than high channel capacity. An unknown and fast variable channel condition, which can be caused by uncertain spacecraft attitude and large Doppler shift with respect to the data rate, requires efficient and innovative receiver architecture. This paper introduces a complete digital implementation of a transceiver for TM/TC application in low Earth orbit mission that is perfectly compliant with aforementioned requirements. Particular attention is dedicated to the definition and selection of the most appropriate frequency recovery technique; 2 open-loop techniques that are derived from ML optimal estimator are presented and compared. Additionally, the performance of the proposed receiver is extensively studied and compared with an incoherent technique that is based on the double differential PSK modulation and is known to be suitable for sat-com in critical scenarios. KEYWORDScritical scenarios, frequency recovery, satellite modems, telemetry and telecommand applications INTRODUCTIONThe success of a space mission strongly depends on the quality and performance of satellite subsystems. The Telemetry and Telecommand (TM/TC) is an essential module for a spacecraft along with the electrical power system, on-board data handling and attitude and determination control system.The availability of the communication link with the satellite from the early mission phase allows the ground operator to monitor satellite status and to perform recovery actions if something goes wrong; an on-board computer failure may be recovered by rebooting the associated power line through a direct telecommand to the electrical power system.The early operations after separation from upper launcher stages, as well as the end of life disposal manoeuvres, are critical satellite mission phases that require a robust and reliable communication system. 1,2 In these scenarios, the spacecraft may have reduced functionalities and uncontrolled attitude, and consequently, the communication link could be weak and unstable, eg, signal's amplitude may be subjected to deep fading according to satellite tumbling rate. 3 In this context, the communication becomes bursty and the link reliability harms the bit-rate performance.Moreover, new challenges are receiving the interest of the space communication community. Nowadays, an innovative and popular way to access space is by means of new low-cost satellite solutions such as micro or nano-satellites. 4,5 These systems have typically less stringent performance requirements when compared with traditional space systems but, on the other hand, limited energetic and computationa...

“…The minimum E b /N 0 14 dB is in the downlink curve at the beginning and end of each visibility window, when the satellite is closer to the horizon. Nevertheless, in a scenario with damaged attitude control system, the channel results becomes extremely unstable and the signal strength would follow the antenna radiation pattern dropping out completely when the antenna rotates away from ground station [6]. Figure 3 reports the values of the previously considered curves as given by the link budget curves in a possible critical scenario.…”

Section: Link-budgetmentioning

confidence: 99%

“…The reliability and robustness are key features for a satellite communication system, particularly during critical satellite mission phases, like the early operations after separation from upper launcher stages or the end of life manoeuvres [3,4]. In these scenarios, the spacecraft may have reduced functionalities and uncontrolled attitude and consequently, the communication link could be weak, unstable and with a rapid variability e.g., signal's amplitude could drop down or go up according to satellite tumbling rate [5,6]. In this context, the communication becomes bursty and the link reliability harms the bit rate performance.…”

Section: Introductionmentioning

confidence: 99%

Effective Doppler Mitigation in Critical Satellite Communications

Wireless and Satellite Systems

Ronga

et al. 2017

Abstract. The modems for telemetry and telecommand applications are a key component in each satellite system: they shall guarantee reliable and effective performance during every mission phases including also critical scenarios such as the control operation of the satellite while it is placed into its orbit, the disposal of a satellite at the end of its life or the deep-space missions. In these scenarios, the link could be unstable and with a rapid variability and the communication become bursty and be characterized by poor performance. This paper introduces an alldigital implementation of a receiver, which is based on the Differential PSK (D-PSK) modulation and an enhanced version of the Digital Delay and Multiplier frequency estimator and compensator for mitigating the Doppler effect, and that results to be perfectly compliant with the aforementioned requirements. The performance of the proposed receiver is extensively studied and compared with an incoherent technique which is based on the Double Differential PSK (DD-PSK) modulation and is known to be suitable for sat-com in critical scenarios.