Performance of advanced telecommand frame synchronizer under pulsed jamming conditions

Abstract

Abstract-This paper studies frame synchronization for use with the advanced communication link transmission unit format that was recently proposed for updating the telecommand synchronization and channel coding standard for space applications. With a view to improving the robustness against jamming, future satellite telecommand systems are planning to adopt directsequence spread spectrum modulation and advanced channel coding. Compared to the frame synchronization algorithm specified in the current Consultative Committee for Space Data Systems (CCSDS) recommendation, we consider a longer start sequence and relax the condition for declaring synchronization. We investigate the performance of this algorithm in the presence of jamming, and show that the frame synchronizer can be designed such that the overall system's robustness against pulsed jamming is limited by the robustness of the code rather than the synchronizer.

Towards improved satellite telecommand link availability

“…In total possible positions need to be researched. This synchronization problem shows many parallels to the frame synchronization problem investigated in Noels and Moeneclaey . In the second case, symbol transitions occur in the middle of a chip.…”

“…In this respect, the development of an on‐board spreading code synchronizer capable of fast acquiring very long spreading codes at low signal‐to‐noise ratio and large jammer‐over‐signal power ratio has been an important first step . A more recent study has considered the impact of jamming on the performance of a candidate frame synchronization algorithm for TC applications. The corresponding results confirm the potential of the novel CLTU structure (with multiple LDPC code blocks and a novel 64‐bit start sequence) as an effective protection measure against jamming.…”

“…This requires re‐acquisition of the symbol timing and causes the loss of one or more CLTUs. For the long spreading code repetition periods envisaged for future TC applications (between 2 20 and 2 26 chips), pulsed jamming with a well‐chosen duty cycle is usually considered as the most realistic and most harmful type of jamming for all post‐despreading processing . For this reason, we focus our analysis on wideband pulsed jamming.…”

Frame synchronization for pulsed jammed satellite telecommand links

“…() The usual space TC packet transmission scenario, where a known start sequence (SS) is prefixed to each block of coded data, is considered only in Driessen; however, the corresponding analysis is limited to continuous jamming and so does not include the important case of pulsed jamming. More recently, the performance of a simple frame synchronization procedure based on sequential hypothesis testing and hard symbol‐decisions has been studied under pulsed jamming conditions in Noels and Moeneclaey . The considered frame synchronizer was designed with the objective to minimize the modifications to the legacy SS search algorithm described in the CCSDS standard() for missions using a (63,56) modified BCH code with a hard‐limiting detector followed by a triple‐error‐detection or a single‐error‐correction decoder.…”

“…Several practical ML‐based frame synchronization algorithms are considered in Section . As opposed to the sequential frame synchronizer from Noels and Moeneclaey, all considered algorithms are characterized by a full search over the complete a priori uncertainty region of the starting position of the SS. Among these are two decision‐directed correlation‐based algorithms, which do not require jammer state information (JSI).…”