Text 11506, 73 rader
Skriven 2005-08-07 18:52:30 av Björn Forsström (2:203/614.61)
     Kommentar till en text av Michiel van der Vlist (2:280/5555)
Ärende: Cell phone cost
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 >> I can set two of mine to communicate without any base station and probably
 >> all four and use them as walkie-talkies

 MvdV> I wasn't aware of DECT phones that can do that.

Now you are.

 MvdV> So if you tale them along to the beach, where there is no base station
 MvdV> around, they can still talk to each other?

Just like walkie-talkies.

 >> or as baby-sitters but then I can't use them to make a phone call.

 MvdV> It will not even signal there is an incoming call?

No. That might wake up the child you know....

 >> I have Siemens cordless phones, don't know if this is available on other
 >> brands.

 MvdV> Not on mine anyway. But I have a cheap thing, it ony supports one
 MvdV> handset and dies not even support GAP. The number that links it it the
 MvdV> base station is hard coded into it.

Well, Siemens is the Rolls Royce in cordless phones.


 MvdV> Yes, I know of a trick to double the theoretical range of 35 km. It sort
 MvdV> of makes the time slots in the base station "miss a round" so that
 MvdV> timing advance 0-255 now corresponds to a distance of 35-70 km. Creating
 MvdV> in fact a second cell that is ring or kidney shaped and starts at a
 MvdV> distance of 35 km from the base station. They use it here in coastal
 MvdV> areas as a service to the boating people. But I was not aware that
 MvdV> subscribing is required or even possible. The base station either
 MvdV> supports it or it doesn't.

You must have a subscription for it so the system knows that it should be used.

 MvdV> The extended range however can only be exploited over open sea with a
 MvdV> base station in a favourable location and with high gain antennas at the
 MvdV> base station. Otherwise the signal will be too weak due to RF
 MvdV> propagation conditions.

Is this really true? Even if the base station have high-gain antennas the phone
doesn't and then it doesn't help how many watts you put out at the base when
it can't hear the phone.

 >> What is PMR?

 MvdV> Personal Mobile Radio. There is a set of frequencies in the 450 MHz band
 MvdV> set aside for personal communications. A second generation CB so to say.
 MvdV> You can buy the walkie talkies for PMR at most radio shops.

Perhaps not here in Scandinavia where we still use 450 for NMT (Nordic Mobile
Telephone) which have superior coverage then GSM. 20 W mobile stations with
a 3 dB coalinear gain-antenna.


 >> You can't talk via bluetooth but play.

 MvdV> You can talk to a bluetooth headset or car kit. So making two handsets
 MvdV> talk to each other must also be possible. I do not know of any phone
 MvdV> that has it implemented it though...

Well, I have a bluetooth headset to my Ericsson z1010 3G but that is
diconnected
when I put the phone in the car-handsfree. Even if it would work the range for
bluetooth isn't more then about 10 m so I might as well go to the other person.

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 * Origin: . (2:203/614.61)