This Month in QEX -- September 1992 Digital signal processing is the "hot ticket" today in amateur radio--and other communications technologies. A fascinating look into DSP filtering techniques is presented in, "Using The LMS Algorithm for QRM And QRN Reduction," by Steve Reyer, WA9VNJ and Dave Hershberger, W9GR. This article is a companion piece to an article published this month in ARRL's flagship publication, QST. We hope to do more such companion pieces in the future, allowing authors the opportunity to expand on the technical niceties of their projects in QEX when QST page space limitations don't permit detailed coverage there. Long-time amateur satellite operators may remember the 4$X3$X5 mode-J filter used with OSCAR 8. The advent of later mode-J birds, such as AMSAT's microsats, has reawakened interest in this design. This month, ARRL Technical Advisor and AMSAT stalwart Dick Jansson, WD4FAB, describes a new kit implementation of the filter in, "The 4$X3$X5 Filter--Revisited." AM lives, and synchronous detection promises to help it live a fuller, richer life as ARRL Laboratory Engineer Mike Gruber, WA1SVF, reports in, "Synchronous Detection of AM Signals." Mike presents a complete theoretical discussion as well as practical circuits. This month in QEX -- October 1992 Continuing our coverage of the DSP25 plug-in DSP board introduced in January, 1992 QEX, John Albert, WA9FVP, and Will Torgrim, N9PEA, give us "Developing Software for DSP." This article looks at some of the design considerations that go into making a flexible, practical, DSP-based packet system. In "Lightning--Your Home and Ham Gear," Stu Gurske, K9EYY, shows us one route to protecting ourselves from the dreaded effects of lightning strikes. It can be done! Ken Wickwire, KB1JY, wraps up his four-part series, "The Status and Future of High Frequency Digital Communication," with a look at where we go from here. Zack Lau's "RF" column looks at some portable microwave station design considerations, and Geoff Krauss chimes in with some devices suitable for portable--and other--"VHF+" uses. This month's "Gateway" includes a brief report on KITSAT, the most recent addition to the amateur space program. That it is a valuable addition is demonstrated by the KITSAT image reproduced on this month's cover! This Month in QEX -- November 1992 John Champa, K8OCL, shares with us some of his expertise in the developing world of digital video systems. It's a technology that amateurs can exploit! Making the computer do the work is one of the obvious trends in amateur development. James Vandiver, WB4LHG, follows this trend with his "Multi-Mode Computer/Radio Interface." Although implemented on an obsolete computer, the techniques he describes are applicable to any platform. In this month's "Components" column, Mark Forbes rounds up some handy hardware, software and "bookware" for your consideration. "Gateway" this month reports on the results of a recent meeting between the ARRL Digital Committee and operators of the HF automatic-forwarding STA network. This Month in QEX -- December 1992 Power supplies, especially those using the ubiquitous 723 regulator chip, have been published ad infinitum, but Dennis Connole shows us in "Twin-Bridge Power Supply" that there is still fresh ground to be plowed on the subject. In "An Audio Peak Filter with Noise Reduction Effect for CW Reception," Yoshiharu Mita, JH1XEO, exploits the common-mode rejection of an op amp to differentiate noise from a signal using bandpass filters. Gregory Glass, N2MOH, wants us to experiment with video image processing, and in "The Video Experimenter" he shows us how easy it is to set up a video lab and describes some simple experiments to get us started. This month, Zack Lau's "RF" column describes a 10-GHz preamp Zack designed and shows us some of the trials and tribulations of building and measuring 10-GHz equipment. Harold Price kicks off his "Digital Communications" column by looking at how HF packet evolved to its present state and how it could be improved using existing techniques.