PAXboy
Yes. A mobile phone will search for a transmitter on all the frequencies that it is capable of and do so at maximum power. It will do this at an interval set by the manufacturer. This might be one minute or two, or even three but it will do so for as long as it is switched on.
Wrong. Cell phones do NOT always TX. There is an idle mode, which is when you are not making a call and this does not require the phone to TX. It searches for base stations by listening and measuring the received signal. It only transmits (and not always at full power) when it is first turned on to register itself on the network or when it moves from one LAC (local area code) area to another. This is a problem as you will be sure to pass between several of these while flying causing a transmission to be made for about 6 or 8 seconds each time. There is also a Location update, which is set on a timer specified by the network which can be several hours, this is what you are referring to in your post, which sends the same information every update (again it only last for 6 to 8 seconds). This is the “dit diddle lit dit” type sounds you hear over your radio or TV from time to time when your mobile is close to it.
In due course, combination units may have separate power switches for PDA type functions and phone but at present, as far as I know, they do not.
Wrong again. Increasing numbers of phones and wireless PDAs have aircraft modes, which disable the transmission side of the phone, but still leaves you able to use its other facilities. I own a Siemens S45 with just such an option. Nokia 9000 series communicators have the same option.
For all that a class 4 cell phone (which is what most modern phones are) have a power output of only 0.2 to 2 watts (haven’t checked this and my memory is not perfect but it is not far out). This is a very small amount of RF energy. That being said there have been cases mentioned earlier, where even this has proven enough to cause problems. The rule stipulating no phones on during the whole flight is a reasonable safety net to prevent accidents. Besides, as was mentioned earlier someone can still call in and it will then carry out a lot of signaling and if accepted then into dedicated mode, which is when it starts transmitting all the time.
For those interested most calls made in a jet would fail anyway, as GSM (or CDMA for the Americans and some Asians) is not designed to work above 300KPH for many many technical reasons. Not least of which it does not have time to hand over the call between cells fast enough.
I think the 4-month custodial sentence is a little OTT but it will send a clear message to people in future.
If I'm sounding 'preachy', it is due to 23 years in telecommunications and involvement with mobile radio for 19 of them!
I am not trying to knock you here but GSM and mobile radio is as different as chalk and cheese. I’m not questioning your ability but in this case you prove the point of a little knowledge is a dangerous thing, problems then arise when people quote you as being gospel when clearly it is not. I am a GSM Optimisation and planning engineer working for one of the mobile operators in the UK, as well as having worked for several of the vendors such as Ericsson and Nokia, and do really know what I am talking about.
On a slightly different note why are you not allowed to use CD players on flights?