From: utzoo!decvax!harpo!npois!ucbvax!telecom Newsgroups: fa.telecom Title: TELECOM Digest V2 #62 Article-I.D.: ucbvax.7218 Posted: Mon May 17 13:58:34 1982 Received: Tue May 18 01:58:50 1982 >From JSOL@USC-ECLB Mon May 17 13:50:54 1982 TELECOM AM Digest Tuesday, 18 May 1982 Volume 2 : Issue 62 Today's Topics: ACTS and ABC - Automated Coin Collection Bell 212 Frequency Selection Satellite Propagation ---------------------------------------------------------------------- Date: 4 May 1982 1651-PDT From: Ian H. Merritt Subject: ACTS and ABC - Automated Coin Collection I receved the following documment from a friend who was then a TSPS operator, one year ago -- just before LA cut over to the ACTS/SSAS system. In light of some recent discussion over automated coin telephone service, and automatic calling card service as well, I am submitting it to the list. [This article is 19,000 characters long, and thus is too long to mail out via the digest. It has therefore been made available for FTP distribution. Thanks go to Ian Merritt, Richard Lamson, Don Woods, Jim Mcgrath, Roger Duffey, and Will Martin for providing space on their machines. If you find yourself unable to FTP the file, you should send mail to TELECOM-REQUEST@USC-ECLB and I will mail you a copy. [USC-ISIB] PS:ACTS.DOC [MIT-MULTICS] >udd>sm>rsl>telecom>acts.text [PARC-MAXC] [maxc]Telecom.ACTS [iris]Telecom>ACTS [note that the "." vs ">" is correct as shown for the two file names.] [SU-AI] ACTS.TXT[T,JPM] [OFFICE-8] ACTS.TELECOM [MIT-AI] DUFFEY;TELCOM ACTS [Note: you can TYPE or FTP the file from SU-AI without an account or password.] For the benefit of those people who read this on USENET as fa.telecom, I will follow this digest with a copy of the ACTS text in full.] ------------------------------ Date: 15 May 1982 12:25-EDT From: Peter J. Castagna Subject: Bell 212 To: lauren at UCLA-SECURITY The frequencies selected in the 212 were selected merely because they were very simple to generate from a standard (3.684Mhz) crystal and were multiples (easy to switch by selecting one or another output of a divide-down-by-two counter array). Vadic's frequencies were selected for INTELLIGENT reasons. ------------------------------ Date: 15 May 82 22:48:31-EDT (Sat) From: J C Pistritto Subject: Satellite propagation It is quite possible, even likely, that a satellite in say a 2 to 3 hundred mile orbit could be hit FULL QUIETING (50db SINAD), by a handheld walkie talkie, much less a 20watt mobile unit. When travelling in the midwest recently, I was able to consistently hit repeaters at 100 miles with only 5 watts of power, and was informed I had a full quieting signal on several of them. With 45 watts, I was able to hit almost everything I could reach at all, full quieting. The only major obstacles I encountered were, the curvature of the earth, cities, and other stations on the same channel. None of these are a problem in space. The home TV type receivers produce a signal with over 45db S/N, (to obtain a clear picture), and typically those have roughly 30db antennas, and are receiving 5 watt or so satellite transmitters, (power is EXPENSIVE up there). That's on a signal at a much higher wavelength too, where circuitry is almost 'magic', (particularly the front end preamp). At lower frequencies, (70 cm would be my personal choice, ~ 440 Mhz), and a lower noise requirement, (30db would do fine, 20db in a pinch), it is ENTIRELY possible that the problem could be overcome with a good ground plane antenna properly oriented. Even *older* satellites contain receivers better than anything a ham is likely to own, also, as the cost of orbiting a satellite, (particularly a geo-synch one), vastly overshadows the cost of the reciever. Sounds definitely plausible to me. -Joe Pistritto- N3CKF ------------------------------ End of TELECOM Digest ********************** -------