💾 Archived View for gemini.spam.works › mirrors › textfiles › hamradio › MODIFICATIONS › cordinfo.ha… captured on 2022-07-17 at 02:14:05.
⬅️ Previous capture (2022-06-12)
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On Cordless Phone Reception --------------------------- Cordless phones all employ at LEAST two universal frequencies - one for the base unit to communicate to the handset with various data (46.6 - 47 MHz), which performs all functions. This, the 46 MHz frequency, carries incoming signals from the phone line (dial tone, the CALLER's voice, and the user of the cordless phone's voice as well since it is directed back TO the handset as a voice is in a standard telephone). The handset operates in conjunction with the base unit and uses the 49.6 - 50 MHz to transmit back to the base, and only transmits the user's voice and the numbers that the user dials. It is possible in the monitoring of these frequencies that you may be too far away to hear a user's base unit, yet the handset may come in clear, or vice-versa. Then again if you can hear the base unit fine, the user's handset frequency may be occupied by a nearby baby or room monitor and get clobbered altogether. So now you know that a cordless phone utilizes at least two frequencies. That is all that even the SIMPLEST phone needs to operate. But, get this: since there are TEN POSSIBLE CHANNELS, that is, TWENTY FREQUENCIES in all, you'd get lost if there weren't something halfway universal about this whole operation. Apparently, so would the manufacturers. There is, fortunately, a coordination of frequencies between base and handset, and they are categorized by channel: Channel Base Handset ------- ---- ------- 1 46.610 49.670 2 46.630 49.845 3 46.670 49.860 4 46.710 49.770 5 46.730 49.875 6 46.770 48.830 7 46.830 49.890 8 46.870 49.930 9 46.930 49.990 10 46.970 49.970 So, some lazy phone manufacturer wasn't just standing around tossing coins one day deciding, "This Channel 10 phone's handset is going to be on one frequency, and this channel 10's handset is going to be on something ELSE". At first, I thought that any handset frequency could be used with any base channel the manufacturer wanted. Something else, too. Don't be surprised if you hear a cordless conversation on one base channel, and on the next conversation you hear the same person talking on ANOTHER channel. Some phones are switchable between frequency pairs. It did catch ME by surprise when I first heard this, not being 100% familiar with all types of cordless phones. My first reaction was, "that woman must be loaded and have a cordless in every room. That's about 5 frequencies I've heard her talking on..." when in reality, she may only have one or two. Radio Shack advertises at least one type of phone that allows a caller to push a button on the phone - even during a conversation - to change channel for clearest possible reception. It also boasts that it has a fully automatic 640,000-combination security code making it virtually impossible for another cordless phone to access the line. This probably has no effect on a scanner buff's ability to HEAR the conversation. One other cordless phone, specifically made by Radio Shack, has a cordless cradle where it would normally plug into the wall, then the handset is corded to the cradle which includes the keypad. It operates on three size "C" batteries and boasts that it can be used on coffee tables, or areas where wires would probably be in the way. So, it's obvious that there are now a multitude of cordless phones "out there" that are available to consumers, and the more different types and appealing styles there are, the more you'll probably be hearing. Personally I smile at the AT&T Cordless "talking in a tin can" TV commercial when it comes on, and say, "yeah, sell more of those so I can listen to you..." I too have a cordless phone, but I don't use it as often anymore. I wonder if the new instructions enclosed with cordlesses have a statement, "privacy on this phone is not guaranteed.." People are listening!