olson@bootsie.UUCP (Eric Olson) (12/30/90)
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?
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?
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?
4. (Not really a question) I know there are security codes sent
between base & handset, my questions don't pertain to those.
Thanks for any info you might have!
Cheers! Happy New Year!
-Eric
--
Eric K. Olson, Editor, Prepare() NOTE: olson@bootsie.uucp will not work!
Lexington Software Design Internet: olson@endor.harvard.edu
72A Lowell St., Lexington, MA 02173 Usenet: harvard!endor!olson
(617) 863-9624 Bitnet: OLSON@HARVARDdt@yenta.alb.nm.us (David B. Thomas) (12/30/90)
olson@bootsie.UUCP (Eric Olson) writes: >1. About 5 years ago, they started selling "new freqency" phones. > What was new, compared to the old phones? I believe the old cordless phones used to use approximately 27 Mhz and 1700 Khz for duplex operation. All the newer ones use ~46 Mhz for the base unit and ~49 Mhz for the handset. >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? There are ten channel pairs (base, handset). I'm sure someone will post the exact frequencies. I don't have them online just now. The FM (narrow) mode is used. >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? You owe your roomie a beer :-) FM is always used, and the three channels are actually separate frequencies. little david -- This is my .sig. n?e .sgurd no gis. ym si sihT
tad@ssc.UUCP (Tad Cook) (12/31/90)
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 old phones used several frequencies around 1.7 MHz for the base unit to transmit to the handset. They used channels around 49 MHz to go from the handset to the base. The 1.7 Mhz band was phased out, and now the base units operate at 46 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? The MODE (which has nothing to do with FREQUENCY) is FM. There are ten channels, and here they are: Base Handset 46.61 MHz 49.67 MHz 46.63 MHz 49.845 MHz 46.67 MHz 49.86 MHz 46.71 MHz 49.77 MHz 46.73 MHz 49.875 MHz 46.77 MHz 49.83 MHz 46.83 MHz 49.89 MHz 46.87 MHz 49.93 MHz 46.93 MHz 49.99 MHz 46.97 MHz 49.97 MHz If you listen with a VHF scanner radio, the best listening is on the base unit side, as this side transmits BOTH sides of the call. Several handset freqs, including 49.83, 49.845, 49.86, and I think 49.89 MHz are shared with kids walkie talkies, real CHEAP radio controlled toys, and those wireless "nursery monitors" used in baby's room. In fact, if you drive around any residential area with a scanner, there is a continuous carrier on 49.83 and 49.86 MHz from all the nursery monitors. > > 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? Yes, it uses three of the channel pairs on the list above. There are no tricks with upper and lower SSB. The FCC recently ruled that the manufacturers do not have to stick to the assigned channels anymore, as long as they are within the band, so things should get a LOT more chaotic soon. > > 4. (Not really a question) I know there are security codes sent > between base & handset, my questions don't pertain to those. The security code prevents folks from using another cordless phone to make calls on your base unit. It does nothing for voice privacy. Cordless phones are NOT private. It is legal to listen to them, and quite easy. > > Thanks for any info you might have! You're welcome! Tad Cook Seattle, WA Packet: KT7H @ N7HFZ.WA.USA.NA Phone: 206/527-4089 MCI Mail: 3288544 Telex: 6503288544 MCI UW USENET:...uw-beaver!sumax!amc-gw!ssc!tad or, tad@ssc.UUCP
dalyb@godzilla.UUCP (Brian Daly) (01/04/91)
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 UUCP: {...!ames!ncar!noao!asuvax | uunet!zardoz!hrc | att}!gtephx!dalyb Phone: (602) 582-7644 FAX: (602) 582-7111 ~