Citation
Abstract
CommunicationsSwtemsResearchSection 1. Introduction carrier does not nccesswily line uil tvilh the ccnttr frcqucnty of the maser when there are Doppler offsets. Because of these Figure I illustrates the various stages of a Dlock IV receiver. effects there will be phase shifts on the recons!rmlcd carrier. Vnriom bondposs filtering occurs in the chain of IF stages in and the CXOCt31110tln[ wilt be Doppler Stld fll~s~r-L-!)firilC!~risli~ the rcccivcr before the signal is demodulated. cilher with a dependent. It is true. however, tll:lt tl;csc ph:lse shifts will ph:lse I(wk loop. when residun! carrier signals are rcceivid, or occur on the residwrl c:lrrier loop’s rcwmslruclcd c:lrricr. :1s I),i; h a COSIM loop, when suppressed carrier signals are well ;1son that of the Coslss loop. received, In either me, there will be asymmetric bmrdpfiss Iiltcring on the received signal spectrum. The Lxmfpass filters follt~lvirlg Ilw ~lrst nliscr.mnplifier will always hove their center t’reqmwcies line Np with the proper IF frequencies. when carrier tracking is achieved so tlmt the VCO is in frequency Itwk with the received carrier. Nevertheless. filtering on the siSn:ll Spcctrunt is still not cxaclly symmetrical with respect to rhc cclltcr frcqucrwy, due to limitations in bmdpms tlltcr i!tsigns. The cltwlimsnt asymmetric tlltering etTect, however. ~t\IIIM fr~ml IIIC nmwr amplilicr, wllictl precedes lhe Iirsl nlixcr-:lnlplificr in the receiver IF clurin. Since the mmcr :Inlptillcr is in frml[ (~f Ilte Iirst rltiser.attl~~litler.
Details
- Volume
- 42-51
- Published
- June 15, 1979
- Pages
- 105–112
- File Size
- 285.9 KB