A cordless phone question

The early ones used different frequencies. Then when the multiple channel units came out (in the early 1990's) they added some sort of digital encoding to the signal (such as a low level digital subcarrier) to identify one base station from another.

Some of the earlier phones had switches inside to set this, later ones were just hard coded in a ROM somewhere or with soldered jumpers on the boards.

The digital ones just include it in the digital data stream.

Generally they are designed NOT to allow to change them so that you buy a new one when the old one dies.

The new generation of cordless phones, DECT (there are similar but not compatible DCT phones) are IMHO best. DECT phones are wifi friendly they operate in a different band (1.8gHz) and listen to make sure a frequency is NOT in use by someone else before they transmit.

They also have the ability to connect multiple handsets to the same base station and some have the ability to roam handests between multiple base stations.

Geoff.

--
Geoffrey S. Mendelson,  N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(

It's almost certainly handled in the digital realm rather than a single change in the base frequency. The handset and base are paired together by something like both sharing the same seed value for a pseudo-random number generator. The PRN is used as the basis of digital spectrum spreading of the RF signal, frequency hopping or direct sequence, so that only units that share the same sequence can inter-operate.

Some base units and handsets can be "registered" together so that the base can operate with more than one handset. Since that capability isn't mentioned in the 1475's manual, I'd guess that the pairing is done once, at the factory.

*If* the pairing key in the handset is stored in an identifiable chip, say, a serial EEPROM, then it might be possible to get at the key and change it.

--
Rich Webb     Norfolk, VA

(...)

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I don't know, but I RTFM and this seems likely:

See page 36 of:

Place your new-to-you base unit into a carton and tape securely closed. Do not touch it for about a week.

Unplug the power from your existing base unit. Count to five slowly.

Take the battery out of the new-to-you handset, count to five slowly and then put it back in.

Place your new-to-you handset onto your base unit and plug the base unit power back in.

This will cause the unit to reinitialize (and probably pair your new-to-you handset to your base unit).

Test your old handset to see that it still works.

If this doesn't work try:

or call 1 800 222?3111.

--Winston

I got a couple of Unidens that interchange just fine. They do it digitally so once you stick one in the other base, the remaaining base and handset will not work until plugged in once. When the charge light comes on it flickers a bit after about a half a second, that is the handshake I would assume.

Years ago a buddy of mine bought a couple of Vtechs that did the same thing, but he had them connected to different phone lines. That has it's own set of advantages but mine are still hooked to the same line. I just switch them when a battery starts dying.

However when one dies there is a loud audio noise until one of the handsets goes on the base that was in use. Then being reinitialized of course it hangs up, so you have to take another phone off hook to make the transistion.

They wil also work simultaneously, they sidestep each others' channel.

They are getting old now, the battery life is not what it once was but I like the phones themselves. There is also a problem if I use a certain wireless camera because it's also only 2.4 Ghz.

J

Thanks for your comments. Thanks to everyone I have several ideas now that I did not have before.