Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request From: James Blocker Newsgroups: comp.dcom.telecom Subject: Re: Boston Gas "Specially-equipped Gas Meter" Message-ID: <8437@accuvax.nwu.edu> Date: 30 May 90 22:37:21 GMT Sender: news@accuvax.nwu.edu Organization: TELECOM Digest Lines: 53 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 10, Issue 398, Message 2 of 13 In message <8329@accuvax.nwu.edu> (Volume 10, Issue 390, Message 6 of 7), henry@garp.mit.edu (Henry Mensch) writes: [form letter from gas company describing new remotely read meters deleted] >Now, aside from not including very many details of this new system >(does it continuously broadcast use? If not, then how does it know to >broadcast? how is the signal encoded? ...), one wonders what gives >boston gas company the idea that I want them to install a radio >transmitter in my home. This sounds very much like a system that I saw a presentation on sometime in the mid-70's. I don't remember a lot of the details, but this should answer at least some of your questions. This particular remote meter reading system had two antennas, a varactor (frequency) tripler, and some circuitry to fetch the current meter reading (be it cu. ft. of gas, gallons of water, kwh, or whatever). The system worked by having a van drive down an alley or street transmitting a continuous carrier on a given frequency (say 450 MHz). This RF energy was received through the first antenna (your receiving antenna) and tripled up to your transmitting frequency (say 1350 MHz) by the varactor tripler. The associated meter reading circuitry sensed the presence of RF (I believe it was even powered by the received RF energy) and modulated the transmitter with your meter information by keying the output of the tripler on and off at a certain bit rate. A serial number and checksum was also included as part of this transmission to guard against false readings. The van then would have a receiver operating at three times its transmitting frequency, demodulate your transmission and feed that into a computer (possibly through a serial port) for storage of the meter reading. What I thought was so slick about this system was that it was mostly passive from the customer's (your) standpoint. No external power was required, since it was powered off of received RF and it did not transmit unless a carrier of the proper frequency and adequate strength was in the vicinity. Unfortunately, I am very hazy on the details as far as the actual frequencies involved and the data format. After your new "remote reading" meter is installed, I'd be interested in hearing what it actually looks like and if it is close to the system I have described. Jim Blocker (KF5IW) Currently working at, but not representing, Rockwell International ..!texbell!texsun!digi!fozzy!phoenix!blocker