The present paper provides a focus on the ROSE-L instrument internal calibration (iCAL) design. The ROSE-L SAR Instrument has been conceived to realize a full Digital Beam Forming (DBF) architecture, requiring an innovative iCAL approach.

The paper provides a summary on the context and on the updated status of the ROSE-L mission, which carries an L-Band SAR instrument and represents one of the six ESA Copernicus Sentinel Expansion missions. The overview will include the description of the SAR imaging modes and performance, as expected at the current mission phase (start of phase C), and of the synergic illumination design with Sentinel-1.

The present paper provides an overview of the ROSE-L instrument architecture and functionality, with emphasis on internal calibration, mode design, and overall SAR performance. In particular, all the SAR modes have been described and relevant (simulated) performance has been presented.Moreover, a sequential internal calibration concept is also proposed and discussed.

This paper provides an overview of the Copernicus L-band SAR mission referred to as ROSE-L (Radar Observing System for Europe at L-band).In particular, the paper provides an overview of the ROSE-L spacecraft and focuses on the ROSE-L SAR instrument architecture, performance and critical technology developments.The current status of the instrument activities (project is in Phase C) will be presented, highlighting the main achievements and challenges.

Hydroterra has been considered as one of three candidates for ESA's Earth Explorer 10 mission, and consists of a geosynchronous Synthetic Aperture Radar to measure key processes of the diurnal water cycle. These measurements would improve the prediction of intense rainfall, flooding and landslides. This concept has been the subject of Phase 0 studies, in which the mission requirements were consolidated and initial system design possibilities were investigated. This paper summarizes some of the elements of the mission concept contributing to the requirement consolidation process, namely the orbit design aspects, with focus on potential sub-sidereal interferometric capabilities, and the optimization performed in the bandwidth/integration time trade-space to define the operational scenarios and coverage zones, which are key inputs for the mission design.

After decades of success for the classical single-channel SAR operating in various frequency bands, the next generation spaceborne SAR takes shape through the use of multiple (simultaneous) channels for information generation. Multiple azimuth phase centres offer enhanced capabilities and significant performance improvements with respect to single channel SARs. For instance the classical conflict between swath width and resolution can be overcome, allowing wide-swath systems providing high resolution to become reality. Improvements in imaging capability by factors of 5 to 10 are realistic. In addition multiple channels can be exploited as well for single pass interferometric applications which open new classes of environmental and surveillance applications of SAR systems. The paper gives an overview of ongoing developments funded by the European Space Agency (ESA) in the field of next generation multi-channel spaceborne missions. National programs are not presented.

A new class of piecewise linear polyphase codes of perfect square length, named PAT codes, is introduced. PAT codes derive from an innovative design procedure and present excellent performance in terms of both merit factor and peak to side-peak ratio with respect to previously proposed sequences such as Frank, P1, P2, and Px codes. In particular, for odd lengths, the merit factor of PAT codes is larger than that of all other polyphase sequences under analysis, and the peak to side-peak ratio is as large as that of the best of these sequences (namely the Frank and P1 codes). For even lengths, the merit factor and the peak to side-peak ratio performance of PAT codes coincide with those of Px and P2 codes, which are the best polyphase sequences under analysis. PAT code synthesis is based on a rigorous analytical method in the code spectral domain and leads to a simple recursive formula for the generation of sequences of arbitrary length.

Wavemill is a microwave instrument designed to retrieve ocean surface currents in two dimensions. After initial internal investigations and the successful results of a feasibility study, the European Space Agency (ESA) is pursuing a programme of steps aimed towards the development of a Wavemill-based mission. This includes a proof-of-concept campaign, scientific assessment of the product validity, end-to-end simulator development, mission (Phase 0) study and hardware risk retirement for the antenna and on-board processing sub-systems. This paper briefly covers all these activities and establishes a notional timeline for their completion. The end goal of a Wavemill mission is dependent not only on a successful conclusion to these activities but also on the interest and enthusiasm of the oceanographic community as well as the validity and applicability of the products such a mission could provide.