Inflight SMS

[Guest Fred Bear]

In-flight mobile phone use to be permitted

 

By 7News Airline passengers will soon be allowed to use their mobile phone while their plane is in the air. The Federal Government has announced a year-long trial that will see passengers able to send and receive text messages and emails on some domestic Qantas routes.

 

But they will not be allowed to make phone calls.

 

Pilots will also have the power to block phone reception if there are any problems.

 

The Australian Communications and Media Authority will closely monitor the trial.

 

 

[Ultralights]

if my knowedge of the mobile phone system and sms workings is correct, then how can you send and recieve SMS messages when no hon calls are allowed?

 

from what i understand is, the sms message is transmitted from your phone to the mobile phone tower server computer thingo, then the data fro the sms message is attached to the data stream on another phone conversation from the tower the recipient of the message phone is registered on

 

 

[Guest Fred Bear]

Apparently there will be cells above the PAX heads in the a/c.

 

 

[hihosland]

Apparently there will be cells above the PAX heads in the a/c.

As there would need to be because as I understand it in the GSM protocol if you are more than a pre determined distance from a tower then the call will fail and at cruising altitude you would be exceeding that distance.

 

Presumably the data collected by the pseudo tower in the aircraft will be then downlinked to the network using a special protocol dedicated to this aerial usage

 

Davidh

 

not really knowing just guessing

 

 

[Guest Andys@coffs]

Yep, I think we need a bit more info, everyone here is talking GSM, of course to provide 100% of customers with the capability described will require:-

 

1) A GSM Cell that operates independant of the carrier (ie needs to carry all service provider calls)

 

2) CDMA (for at least the next 6 months or so) benefit being that at least only telstra are CDMA (other carriers resell, but the service is fully telstra provided as I understand it)

 

3) 3G, problem here is that not only are there different service providers but I think there are different h/w and freq allocations.

 

4) Telstra NextG wich is sort of part of 3) above and the natural evolution of the CDMA solution

 

Now if SMS is Ok and I presume (GSM) that GPRS is also Ok because I heard discussions of people being able to email. If so will the widebandwidth data accesses also be OK (384kbps or greater) which would also allow internet surfing onboard. (will do wonders to make 3 hours dissappear in a heart beat.

 

Now the real issue I have with that is that in all mobile systems past the old 018/019 analogue systems voice is encoded and sent as a data stream. If data streams are Ok, SMS and GPRS, then why not allow voice?

 

Also when they say that the pilot can turn it off, I presume that they mean they will cut the downlink service, not the cell service. If they cut the cell then everyones mobile will immediately start searching for a new basestation, presumably at a progressively higher and higher transmit power levels. If the pilot turned it off due to percieved interference that would just make the problem worse.

 

My experience with a Telstra NextG Service is that coverage is fantastic for us in our small chariots. If you have an Aviation headphone (preferably ANR) that can link by cable to your phone so that the headset becomes the handsfree solution then the service is fantastic. In traveling from Adelaide to Narromine and then to Maitland I was rarely out of coverage. Similarly in flying from Tully FNQ to Adelaide again I was rarely out of coverage. In both cases you would hardly call the ground I covered well populated. 10 out of 10 for telstra in my books!

 

Andy

 

 

[Case]

I think it will be a fairly basic set up. Your phone will need to be GSM. 3G (or Next G) phones will use normal GSM as they do on the ground if 3G coverage is lost. They will probably run a 'leaky coax' antenna above the passenger seats connected to a base station in the aircraft similar to terrestrial bases. Direct connection to a terrestrial base is not possible as the Doppler effect makes it impossible to maintain GSM connections when travelling faster than about 250Km per hour. The aircraft will have a satellite link for it's external communications. GSM phones have separate voice and signalling channels, SMS uses only the sig channel so I suspect they will only provide a signalling channel on the base station. Not sure how email is achieved.

 

 

[Guest Fred Bear]

I had diagrams somewhere of just how far signals can be achieved from a mobile phone tower to an a/c. Definately by those in ultralights at a thousand foot and a little higher but definately not at 35,000ft.In simple terms, the signals are made to travel out, not up. There is no use for them up there.

 

 

[Ben Longden]

The astonishing thing in this is that according to ABC news, CASA is quoted as saying that digital phones do NOT interfere with (RPT) electronic navigation systems.

 

Ive written a number of times to CASA and Qantas to outline the basis for the phone ban, and so far have never received a reply, other than a recept of the letter.

 

On the downside, I would hate to be sitting on a flight from Melb to Perf next to a "merchant banker" talking loudly on the phone.. the last refuge would be gone! ;)

 

Ben

 

 

[Guest Fred Bear]

From a Qantas pilot:

 

We operated the first trial flight yesterday, QFA0429 to Melbourne. There is a card on board the size of a safety card instructing passengers on the use of the Picocell system as well as the requirements for it's use, such as the phone being in silent mode. 15 SMS messages were successfully sent and 3 received. The aircraft is essentially it's own nation, with international SMS rates charged to the user.

[Jex207]

Picolcell Technical Info

 

Some info for the more technically minded:

 

Once activated, the Picocell avionics provide the following level of functionality:

 

- Full duplex voice and text message support for GSM phones capable of operating within the 1800 MHz/1900 MHz GSM frequency bands

 

- GPRS data (email, internet) and related services

 

- SMS text

 

- Supplementary services (call forwarding, caller ID, call waiting, voicemail, etc)

 

- Pre-paid services

 

- RF management of all phone technologies (GSM is supported from a service

 

perspective at the phone - minimum power level. Other mobile technologies

 

[CDMA, 3G etc] are supported from an RF management perspective to mitigate against possible interference events.)

 

The Picocell system is made up of three key elements:

 

Mobile Sub-System (MSS): The MSS, which can be considered the core of the Picocell system, emulates a ground cellular network base transceiver station (BTS) within the aircraft cabin. It provides a wireless connection to passengers’ mobile devices, at a minimum level of RF power in the GSM 1800 MHz frequency band. The MSS includes both RF hardware and software components, which provide call management and service level control.

 

Radio Interference Avoidance Sub-System (RIAS): By means of low level screening emissions in specific mobile phone frequency bands and formats, the RIAS provides effective RF isolation of the aircraft cabin from any ground mobile base station or handset. The intention of this function, which is provided by two Cell Phone RF Management Units (CRFMUs) under the control of software, is to prevent interference between the aircraft and the overflown ground mobile phone networks.

 

Antenna System: A dual “leaky line†antenna is used to transmit and receive GSM communications within the cabin and is also used to broadcast the RIAS signals. The aircraft is also equipped with a Satellite Communications system (SATCOM) to enable the information to be sent and received from the Ground Station Service Provider.

 

cheers

 

Jeremy