{"title":"Receiver Technology","authors":"J. Duyn","doi":"10.1002/9781119564621.ch5","DOIUrl":"https://doi.org/10.1002/9781119564621.ch5","url":null,"abstract":"Since the introduction of the NMR phased array (Roemer et al., 1990), and the application of accelerated parallel MRI (Pruessmann et al., 1999, Sodickson and Manning, 1997), it has become increasingly clear that the use of a large number of RF coils for signal reception offers substantial increases in SNR and acceleration rates. The optimal number of coils is dependent on application and field strength and might exceed 100 for whole body applications at high field. Because these coil signals have to be received, amplified and digitized independently, the result is an increased complexity of the MRI receiver. At the same time, with the advent of digital radio in the early 1990’s, receiver technology has developed rapidly as well, with increased performance, and reductions in size and cost made possible by improvements in semiconductor technology. Currently, MRI scanners are becoming available with 32 independent channels based on digital receiver technology, and this high number is likely to grow substantially in the near future. In the following we will review some of the issues involved in designing a digital receiver for use with MRI.","PeriodicalId":309755,"journal":{"name":"Design Technology of Synthetic Aperture Radar","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130190933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Antenna System","authors":"올리버 폴 레이스텐","doi":"10.1002/9781119564621.ch3","DOIUrl":"https://doi.org/10.1002/9781119564621.ch3","url":null,"abstract":"An antenna system for operation at frequencies in excess of 200MHz, comprises an antenna, a transmission line and a receiver stage, the transmission line electrically connecting the antenna to an input of the receiver stage, and the antenna having: an antenna core of a solid insulative material having a relative dielectric constant greater than 5, the material of the core occupying the major part of the volume defined by the core outer surface, and a three-dimensional antenna element structure disposed on or adjacent the outer surface of the core; wherein the antenna is fed by the transmission line at a proximal end of the dielectric core; the receiver stage comprises an amplifier and an electromagnetic radiation screen, the amplifier being positioned within the screen; and the transmission line includes a current choke arranged to provide a substantially balanced condition at a feed connection of the antenna.","PeriodicalId":309755,"journal":{"name":"Design Technology of Synthetic Aperture Radar","volume":"554 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133254889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Image Information Processing System","authors":"Young-Ku Kang","doi":"10.1002/9781119564621.ch7","DOIUrl":"https://doi.org/10.1002/9781119564621.ch7","url":null,"abstract":"Summary This paper proposed that an advanced algorithm for selecting a seam line automatically which used to be selected by human operator for mosaicking images. The presented algorithm is based on the identification induced by the correlation and the direction of tie points. Tie points were selected from two geometrically distored spatial ortho-images. And the identification of selected tie points were represented by FOM. Additionally, four factors were taken into account for weights of the directed graph. These five factors were adjusted finely to work equally on selecting seam line. Then, the Dijkstra algorithm was executed repeatedly after each line adjustment. Using the seam line selected by this method, two spatial orthoimages were merged, and the effect of the identification of tie points was analyzed.","PeriodicalId":309755,"journal":{"name":"Design Technology of Synthetic Aperture Radar","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122786237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Radar System Design","authors":"Jiaguo Lu","doi":"10.1002/9781119564621.ch2","DOIUrl":"https://doi.org/10.1002/9781119564621.ch2","url":null,"abstract":"A spaceborne synthetic aperture radar (SAR) system is employed to illustrate the principal parameters of a SAR system. Mission parameters and system performance parameters are included. The former consists of coverage, revisit period, view scope, and lifetime. The latter comprises frequency, polarization, power, antenna gain, noise factor, loss, and imaging quality‐related parameters. The SAR system can be designed by properly optimizing the parameters to meet the requirements of the mission. SAR can be operated in different modes so as to provide radar images with a variety of resolutions, swath widths, or polarization in different applications. The operation modes of SAR include strip‐map mode, scanning mode, spotlight mode, sliding spotlight mode, mosaic mode, and terrain observation by progressive scans mode. According to the characteristics of the detected target and its background, the moving target working mode is generally divided into the ground moving target mode, the marine moving target mode, and the airborne moving target mode.","PeriodicalId":309755,"journal":{"name":"Design Technology of Synthetic Aperture Radar","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126051570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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