Xref: utzoo comp.sys.next:829 sci.electronics:4342 Path: utzoo!attcan!uunet!husc6!bu-cs!mirror!frog!cpoint!die From: die@cpoint.UUCP (David I. Emery) Newsgroups: comp.sys.next,sci.electronics Subject: Re: Mouse cord nuisance from lap (was Re: Monitors: What Next?) Keywords: induction, magnetic coupling, corrdless mouse Message-ID: <1381@cpoint.UUCP> Date: 20 Nov 88 05:33:00 GMT References: <15572@agate.BERKELEY.EDU> <16891@shemp.CS.UCLA.EDU> <31811@bbn.COM> <1405@neoucom.UUCP> <1227@microsoft.UUCP> Reply-To: die@cpoint.UUCP (David I. Emery) Organization: Clearpoint Research Corp., Hopkinton Mass. Lines: 37 In article <1227@microsoft.UUCP> michaelw@microsoft.UUCP (Michael Winser) writes: >In article <1405@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: >>I'd like to see a microwave or infrared operated mouse that used >>doppler shift or some form of interferometry for sensing motion >>over an arbitrary surface. I suppose this could be done with an > >I do think getting rid of the rodent's tail would be very nice, it's >always getting tangled up with my keyboard and monitors etc. A boring bit of hardware suggestion. IR is subject to shadowing by the users hand and rf links in VHF or UHF or low microwave are expensive (because of the need to handle strong nearby signals) and there are only limited channels available anyway. How about plain old induction with the mouse transmitting somewhere in the vlf or lf range on a narrow band fsk'd carrier (say 180 khz +- 500 hz) to a simple loop antenna in the mousepad (and nearby for those who want to use the mouse on any surface). A more complex but interference resistant modulation might be some form of direct sequence spread spectrum similar to what has been tried experimentally to send data on carrier current over power lines. Unfortunately this implies a battery powered mouse unless the pickup antenna loop could also serve to create a lf ac magnetic field strong enough to power the mouse. One advantage of this is that, at least with a mousepad mouse, the coupling would be uniformly strong near the mousepad and weak to the mousepad on the system at the next desk. RF linked systems and especially optical systems might have real problems with multiple mice in an office area or terminal room due to mutual interference. -- David I. Emery Clearpoint Research Corp. 99 South Street, Hopkinton Ma. 01748 1-508-435-2000 {decvax, cybvax0, mirror}!frog!cpoint!die