Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!asuvax!hrc!godzilla!dalyb
From: dalyb@godzilla.UUCP (Brian Daly)
Newsgroups: sci.electronics
Subject: Re: Questions about cordless phones
Summary: Answers....
Message-ID: <4efd9537.1423f@godzilla.UUCP>
Date: 3 Jan 91 21:10:13 GMT
References: <52@bootsie.UUCP>
Organization: gte
Lines: 43

In article <52@bootsie.UUCP>, olson@bootsie.UUCP (Eric Olson) writes:
> I've got a few simple questions about cordless phones:
> 
> 1.  About 5 years ago, they started selling "new freqency" phones.
>     What was new, compared to the old phones?

      The base units of the older sets used 1.69MHz, 1.71 MHz, 1.73 MHz,
      1.75 MHz and 1.77 MHz. The newer sets use 46.61, 46.63, 46.67, 46.71,
      46.73, 46.77, 46.83, 46.87, 46.93, and 46.97 MHz. These new
      frequencies are classified as channels 1 thru 10. 
    
      The handsets of the older units use 49.83, 49.845, 49.86, 49.875,
      and 48.89 MHz. The newer sets use 49.67, 49.77, 49.83, 49.845, 49.86,
      49.875, 49.89, 49.93, 49.97, and 49.99 MHz.

 > 2.  What frequencies are used by modern ("new frequency") phones?
>     AM or FM?  Sidebands?  Are they all exactly the same frequency,
>     or do some have different or multiple frequencies?

      See above... Cordless phones all use frequency modulation (FM).
      Legal cordless phones in the US may operate on the assigned
      frequencies listed above. Every phone may not be on exactly
      the same frequence (since there are 10 channels available). 
> 
> 3.  My roommate has an AT&T cordless phone with 3 "channels".  I
>     guessed that they were upper SB, lower SB, and main band.  He
>     claimed they were separate frequencies.  What's the scoop?

      No, cordless phones use FM, so the "upper sideband", "lower
      sideband" scheme is not applicable. 3 channels means 3 frequencies,
      as your roommate claimed.
> 
> 4.  (Not really a question)  I know there are security codes sent
>     between base & handset, my questions don't pertain to those.
> 



-- 
Brian K. Daly WB7OML @ AG Communication Systems, Phoenix, Arizona
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Phone: (602) 582-7644    FAX: (602) 582-7111
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