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AN INTERNAL CALIBRATION SYSTEM MODEL FOR THE ESTIMATION OF SAR INSTRUMENT ERRORS

Kroll, Jan Paul und Younis, Marwan und Krieger, Gerhard (2019) AN INTERNAL CALIBRATION SYSTEM MODEL FOR THE ESTIMATION OF SAR INSTRUMENT ERRORS. In: CEOS SAR WORKSHOP. CEOS SAR Workshop on Calibration and Validation (CEOS SAR CalVal), 2019-11-18 - 2019-11-22, Frascati, Italy.

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Kurzfassung

Two key requirements for a modern spaceborne Synthetic Aperture Radar (SAR) are a high azimuth resolution and a wide swath. This can be achieved by using SAR instruments with multiple digital channels. The Multiple Azimuth Channels (MACs) technique ensures a high azimuth resolution, while in elevation SCan-On-REceive (SCORE) is employed to improve the Signal-to-Noise Ratio (SNR) and suppress range ambiguities. The influences of the channels on the amplitudes and phases in a multi-channel system are crucial. Differences between the channels lead to a reduced performance due to the degraded antenna pattern. The SNR as well as the resolution are deteriorated. To account for that the system has to be calibrated by correcting the channel differences. The azimuth calibration can be done on ground, but for SCORE it has to be done on-board and in real time. In this paper we focus on the internal calibration. A signal is fed in at transmit receive module (TRM) level and is evaluated in the digital unit. Error sources on Radio Frequency (RF) level are: mutual coupling between the antenna elements, bleed through between the signal paths, temperature drifts, changes to the transfer functions over time and temperature and the analog-to-digital converters synchronization. The internal calibration concept suggested here allows for a simultaneous calibration while performing the transmit or receive operation. The instrument RF and digital chain is divided into several layers. For the calibration, a single tone calibration signal is sequentially coupled to the echo signal path. It is possible to vary the frequency of the calibration signal. The evaluation is done by using the original calibration signal and the output of the respective layer to get an estimation of the error. We created a mathematical model and a simulation tool to estimate the errors in such a calibration system and aid in the system design. The calibration signal sequences can be changed to determine the TRMs in which a calibration signal is fed in or alter the frequency of the signal. By varying the frequency we can account for frequency dependencies. We show results with calibration signals outside and inside the SAR echo signal spectrum as well as with a varying frequency over time. We then analyze the effect of different methods to estimate the current drift and make a prediction for the future. Further, the simulation tool allows for an analysis of the estimation errors. A proposal to refine the estimation and reduce the estimation error is included.

elib-URL des Eintrags:https://elib.dlr.de/129542/
Dokumentart:Konferenzbeitrag (Vortrag)
Titel:AN INTERNAL CALIBRATION SYSTEM MODEL FOR THE ESTIMATION OF SAR INSTRUMENT ERRORS
Autoren:
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID-iDORCID Put Code
Kroll, Jan PaulJan.Kroll (at) dlr.dehttps://orcid.org/0000-0003-3131-2480NICHT SPEZIFIZIERT
Younis, Marwanmarwan.younis (at) dlr.dehttps://orcid.org/0000-0002-8563-7371NICHT SPEZIFIZIERT
Krieger, GerhardGerhard.Krieger (at) dlr.dehttps://orcid.org/0000-0002-4548-0285NICHT SPEZIFIZIERT
Datum:2019
Erschienen in:CEOS SAR WORKSHOP
Referierte Publikation:Ja
Open Access:Nein
Gold Open Access:Nein
In SCOPUS:Nein
In ISI Web of Science:Ja
Status:veröffentlicht
Stichwörter:calibration, multi-channel calibration, internal SAR calibration, SAR internal errors, instrument calibration simulator
Veranstaltungstitel:CEOS SAR Workshop on Calibration and Validation (CEOS SAR CalVal)
Veranstaltungsort:Frascati, Italy
Veranstaltungsart:internationale Konferenz
Veranstaltungsbeginn:18 November 2019
Veranstaltungsende:22 November 2019
Veranstalter :ESA
HGF - Forschungsbereich:Luftfahrt, Raumfahrt und Verkehr
HGF - Programm:Raumfahrt
HGF - Programmthema:Erdbeobachtung
DLR - Schwerpunkt:Raumfahrt
DLR - Forschungsgebiet:R EO - Erdbeobachtung
DLR - Teilgebiet (Projekt, Vorhaben):R - Entwicklung eines Mini-SAR
Standort: Oberpfaffenhofen
Institute & Einrichtungen:Institut für Hochfrequenztechnik und Radarsysteme > Radarkonzepte
Hinterlegt von: Kroll, Jan Paul
Hinterlegt am:14 Okt 2019 09:24
Letzte Änderung:24 Apr 2024 20:32

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  • AN INTERNAL CALIBRATION SYSTEM MODEL FOR THE ESTIMATION OF SAR INSTRUMENT ERRORS. (deposited 14 Okt 2019 09:24) [Gegenwärtig angezeigt]

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