Haha, I need all the viagra I can get! Thanks a lot for the tip off! A bit of head scratching and I realised that 1password had filled my address into the title field without me noticing! Nice catch!
What I originally mused was how this change would affect Three UK customers who roam onto Orange currently when no 3 signal exists.
Why is it stated that it is more complicated and expensive to fit filters to communal systems (CATV)? The filter goes between the antenna and input to any communal system (which normally consists of an amplifier driving a splitter where the amplifier gain should match the loss of the subsequent splitters). The level coming from the antenna in a CATV system will be similar to a home antenna so places no different needs of the filter whatsoever. If anything it will be cheaper as only one filter would be needed for each entire CATV system.
Filtering is another question too, the top DVBT channel 60 ends at 790MHz and 4G will start within 1MHz or so above that. Filtering a signal as close as 10MHz let alone 1MHz next at a high frequency (it's the ratio of wanted/unwanted frequencies that is relevant) requires filters with a very high 'Q factor' (http://en.wikipedia.org/wiki/Q_factor) and multiple poles (stages) of filtering. In practise it means a relatively large physical size and silver plated cavity resonators, so it will be very expensive to implement . It will also have an increasing loss as the cutoff frequency is approached so will reduce signals in CH60 (and maybe lower).
Well I have recently moved from O2 to 3 with my iPhone and am very pleased so far, 3G almost everywhere. Haven't needed customer service as all very smooth.
With all these accolades I can see 3 growing their subscriber base, this could be a problem as they around half the spectrum of the other networks.
IIRC 3 can get some spectrum released by the merger of T Mobile and Orange (correct me if I'm wrong). If this is the case I hope it happens before the network starts to sag from lack of channels...
I have always been curious about how, by giving someone your 'bank details' (presumably account number and sort code), someone can take your money. I always thought this would only help them deposit money... Maybe I am missing something, can anyone enlighten me?
Indeed it is called attenuation, and this happens when RF (radio frequency) signals pass through anything, even air has a small lossy effect relative to a vacuum. The body, as has been described by others, is mostly salty water, and therefore very lossy.
It's worth adding something about the 'detuning' effect I mentioned above; when your body detunes the antenna it affects it in two ways, firstly it changes the resonant frequency of the antenna which can drastically reduce radiation efficiency and secondly it affects the 'return loss' (sometimes known as 'VSWR' or 'voltage standing wave ratio). This is the (impedance) match between the transmitter circuitry and the antenna, and a poor match (high VSWR or low return loss) actually causes the RF power to bounce off the antenna back towards the transmitter, this 'bounced' power will either be absorbed by the circuitry and/or bounce back to the antenna, only to bounce back and forth (like an echo between two flat surfaces), eventually dying out, but, importantly, never actually radiating from the antenna.
To be fair to Apple, both of the effects I have mentioned (loss/attenuation and detuning) will be noticed in all mobile devices where the antenna is not in free space (closer than several wavelengths from the body or other lossy item). It's just that Apple have not made their lives easy by designing their antenna such that actual contact will cause the worst possible detuning by the body. Other manufacturers place their antennas behind an insulator (the case) and the detuning will be less, though still present when the hand is over or near it. The loss/attenuation effect will be similar to other phones.
I have tried to not make this too technical, but if I don't use the correct technical terms it seems I get pulled up. For my sins RF has been my job for over 30 years, so apologies if I have been too geeky!
I'll try to keep this really simple, it's been said before but here we go again concisely:
Antenna efficiency can be compromised either by detuning or loss. Loss occurs when a 'lossy' object (such as a hand) comes between the transmitting antenna and the receiving antenna. This lossy object could be anywhere between these two, doesn't matter.
An antenna works most efficiently when it 'resonates' on the frequency that it is designed to work on, with a voltage peak normally at the extremities of the antenna. Proximity of your body to the antenna, it doesn't have to touch but the closer the more marked the effect, prevents this resonance and voltage peak. This is known as 'detuning' and has the effect of reducing radiation from the antenna by a very large degree.
All mobiles have to compromise aesthetics with technical function and in all cases the proximity of the body will cause a combination of detuning and loss, but, I fear, in the case of the latest iPhone the design allows the user to completely detune the antenna AND provide a lossy path to the receiving site, thus it is the worst of both worlds. A fundamental mistake which shows a total disregard of physics that CANNOT be corrected with software, so a bit of a fail I am afraid...
Funnily enough that is exactly what I was thinking when Jobs was talking about using the casing as an antenna.
As I happens (and rather boringly!) I know quite a lot about antenna theory and design. Antennas rely on 'voltage gradients' in their radiating elements and touching any part of an antenna causes those voltages to be reduced and/or dissipated. This can severely impair the radiation efficiency of the antenna.
This is why antennas need to be in (or as close as possible) to free space, and are either sticking out the tops of the phone (not so much these days) or behind an insulating cover.
I had rather assumed that Apple were using hyperbole in their statements about the case actually being the aerial and that it in some way supplemented internal antennas, but if that is not the case (pun intended) then they have made a fundamental error.
Sounds fascinating, but 'microwave' covers a pretty broad chunk of electromagnetic spectrum. Would be interested to know over what band of frequencies this device works efficiently.
I have recently discussed this issue with my ISP who cap at 30GB, I am on a rural exchange and therefor on BT equipment. BT push me back into contention automatically if I do more than a couple of gigs a day.
My point is that, in this day and age, even 30 gigs let alone 10 is ridiculous. You can burn through several gigs a day just watching a couple of HD programmes on iPlayer. I have had to watch in SD and limit my iPlayer usage just to get back in limit. Why should I have to hold back? It is completely at odds with progress on the internet with more bandwidth hungry content whilst the ISPs cut back. 10 gigs a month is PATHETIC.
Unless, like me you've been using an iPhone on 02 for a long time now. I reckon 90% of my data download is GPRS, even in London 3G is hit an miss. On that basis 1GB would go a loooooong way!
When buying a pay as you go SIM in France recently I had to give ID and evidence of an address. I was told that it is law that all mobile phones have a verified name and address associated with them.
This would make it easier for operators to return unused credit!
What's the issue with HD streaming over wifi? Isn't the throughput on 802.11g about 20Mbps, surely enough for a decent HD stream, or am I being a berk?!
Fantastic article from Bill as usual, puts the whole history of mobile data in perspective very clearly and understandably without skimping on the technical info. Great read.
This is surely in contravention of the terms of the merchant account to accept cards, and complaints from people who have been shafted like this could result in the withdrawal of Apple's credit card service.
I know when I signed up to accept cards for my business there were very stiff warnings and penalties for this sort of practice.
Register
30 posts • joined Thursday 29th May 2008 14:46 GMT
Re: p****@hotmail.com
Haha, I need all the viagra I can get! Thanks a lot for the tip off! A bit of head scratching and I realised that 1password had filled my address into the title field without me noticing! Nice catch!
What I originally mused was how this change would affect Three UK customers who roam onto Orange currently when no 3 signal exists.
This post has been deleted by its author
A perfect example of 'Merkins difficulty with irony. Why use a rubber mallet when you can use a sledgehammer...
A picture is worth... £25m
Interesting that community TV is getting so much money thrown at it.
Guess how much money community radio got?
Answers on a postcard to The mates of Mr Hunt, Dept. for Culture TV and sport...
Stuffed here
Not able to connect IMAP or web mail since about 7am this morning.
Communal antennas
Why is it stated that it is more complicated and expensive to fit filters to communal systems (CATV)? The filter goes between the antenna and input to any communal system (which normally consists of an amplifier driving a splitter where the amplifier gain should match the loss of the subsequent splitters). The level coming from the antenna in a CATV system will be similar to a home antenna so places no different needs of the filter whatsoever. If anything it will be cheaper as only one filter would be needed for each entire CATV system.
Filtering is another question too, the top DVBT channel 60 ends at 790MHz and 4G will start within 1MHz or so above that. Filtering a signal as close as 10MHz let alone 1MHz next at a high frequency (it's the ratio of wanted/unwanted frequencies that is relevant) requires filters with a very high 'Q factor' (http://en.wikipedia.org/wiki/Q_factor) and multiple poles (stages) of filtering. In practise it means a relatively large physical size and silver plated cavity resonators, so it will be very expensive to implement . It will also have an increasing loss as the cutoff frequency is approached so will reduce signals in CH60 (and maybe lower).
My experience
Well I have recently moved from O2 to 3 with my iPhone and am very pleased so far, 3G almost everywhere. Haven't needed customer service as all very smooth.
With all these accolades I can see 3 growing their subscriber base, this could be a problem as they around half the spectrum of the other networks.
IIRC 3 can get some spectrum released by the merger of T Mobile and Orange (correct me if I'm wrong). If this is the case I hope it happens before the network starts to sag from lack of channels...
New country alert
Interesting that 75uS pre-emphasis is used in 'USB and Japan'!
I know that the US has had a pummelling of late, perhaps it has been downgraded!
Curious
I have always been curious about how, by giving someone your 'bank details' (presumably account number and sort code), someone can take your money. I always thought this would only help them deposit money... Maybe I am missing something, can anyone enlighten me?
Attenuation and mismatch
Indeed it is called attenuation, and this happens when RF (radio frequency) signals pass through anything, even air has a small lossy effect relative to a vacuum. The body, as has been described by others, is mostly salty water, and therefore very lossy.
It's worth adding something about the 'detuning' effect I mentioned above; when your body detunes the antenna it affects it in two ways, firstly it changes the resonant frequency of the antenna which can drastically reduce radiation efficiency and secondly it affects the 'return loss' (sometimes known as 'VSWR' or 'voltage standing wave ratio). This is the (impedance) match between the transmitter circuitry and the antenna, and a poor match (high VSWR or low return loss) actually causes the RF power to bounce off the antenna back towards the transmitter, this 'bounced' power will either be absorbed by the circuitry and/or bounce back to the antenna, only to bounce back and forth (like an echo between two flat surfaces), eventually dying out, but, importantly, never actually radiating from the antenna.
To be fair to Apple, both of the effects I have mentioned (loss/attenuation and detuning) will be noticed in all mobile devices where the antenna is not in free space (closer than several wavelengths from the body or other lossy item). It's just that Apple have not made their lives easy by designing their antenna such that actual contact will cause the worst possible detuning by the body. Other manufacturers place their antennas behind an insulator (the case) and the detuning will be less, though still present when the hand is over or near it. The loss/attenuation effect will be similar to other phones.
I have tried to not make this too technical, but if I don't use the correct technical terms it seems I get pulled up. For my sins RF has been my job for over 30 years, so apologies if I have been too geeky!
You can't escape physics
I'll try to keep this really simple, it's been said before but here we go again concisely:
Antenna efficiency can be compromised either by detuning or loss. Loss occurs when a 'lossy' object (such as a hand) comes between the transmitting antenna and the receiving antenna. This lossy object could be anywhere between these two, doesn't matter.
An antenna works most efficiently when it 'resonates' on the frequency that it is designed to work on, with a voltage peak normally at the extremities of the antenna. Proximity of your body to the antenna, it doesn't have to touch but the closer the more marked the effect, prevents this resonance and voltage peak. This is known as 'detuning' and has the effect of reducing radiation from the antenna by a very large degree.
All mobiles have to compromise aesthetics with technical function and in all cases the proximity of the body will cause a combination of detuning and loss, but, I fear, in the case of the latest iPhone the design allows the user to completely detune the antenna AND provide a lossy path to the receiving site, thus it is the worst of both worlds. A fundamental mistake which shows a total disregard of physics that CANNOT be corrected with software, so a bit of a fail I am afraid...
FUDge
Jobs - "I want this antenna problem fixed right now or you're fired. Issue a software update"
Scotty - "I cannae change the laws of physics wi' software cap'n"
Jobs: - "well issue a software update anyway and make something up"
Scotty - "aye"
Not much better if you get local SIM
As someone who spends a few weeks a year in France I have always been looking for the best option to get online.
I have an SFR SIM which gets me online for EUR9 per day. This is still very expensive indeed and not much less than the T Mobile deal.
Looking at non-roaming data charges in much of Europe I think we are blessed with very low prices in the UK for data.
I was worried this might happen
Funnily enough that is exactly what I was thinking when Jobs was talking about using the casing as an antenna.
As I happens (and rather boringly!) I know quite a lot about antenna theory and design. Antennas rely on 'voltage gradients' in their radiating elements and touching any part of an antenna causes those voltages to be reduced and/or dissipated. This can severely impair the radiation efficiency of the antenna.
This is why antennas need to be in (or as close as possible) to free space, and are either sticking out the tops of the phone (not so much these days) or behind an insulating cover.
I had rather assumed that Apple were using hyperbole in their statements about the case actually being the aerial and that it in some way supplemented internal antennas, but if that is not the case (pun intended) then they have made a fundamental error.
Bandwidth?
Sounds fascinating, but 'microwave' covers a pretty broad chunk of electromagnetic spectrum. Would be interested to know over what band of frequencies this device works efficiently.
In this day and age?!
I have recently discussed this issue with my ISP who cap at 30GB, I am on a rural exchange and therefor on BT equipment. BT push me back into contention automatically if I do more than a couple of gigs a day.
My point is that, in this day and age, even 30 gigs let alone 10 is ridiculous. You can burn through several gigs a day just watching a couple of HD programmes on iPlayer. I have had to watch in SD and limit my iPlayer usage just to get back in limit. Why should I have to hold back? It is completely at odds with progress on the internet with more bandwidth hungry content whilst the ISPs cut back. 10 gigs a month is PATHETIC.
02 deal looks good on paper...
Unless, like me you've been using an iPhone on 02 for a long time now. I reckon 90% of my data download is GPRS, even in London 3G is hit an miss. On that basis 1GB would go a loooooong way!
I want this...
... functionality In my TomTom iPhone app. It's got a data connection on tap so why no live services!
It's not lost in France
When buying a pay as you go SIM in France recently I had to give ID and evidence of an address. I was told that it is law that all mobile phones have a verified name and address associated with them.
This would make it easier for operators to return unused credit!
HD Streaming
What's the issue with HD streaming over wifi? Isn't the throughput on 802.11g about 20Mbps, surely enough for a decent HD stream, or am I being a berk?!
Problems again for me too
It's down again for me too. This happens almost every week since they 'upgraded' their systems :(
Superb article
Fantastic article from Bill as usual, puts the whole history of mobile data in perspective very clearly and understandably without skimping on the technical info. Great read.
Ssssssssssssh
If the passband of the new codec is 8kHz to 12kHz people will have to speak using only the letter 'S' in order to be heard!
Forget capitols, grab a merkin...
Merkin -> http://dictionary.reference.com/browse/merkin
Are we turning into merkins?
I didn't realise we had a capitol in the UK!
What do points make?
I wonder if these powers will extend to putting points on licences for totting up in the UK for crimes committed abroad? I hope not!
It could be worse...
They could live in sCUNThorpe.
Cheeky monkeys!
This is surely in contravention of the terms of the merchant account to accept cards, and complaints from people who have been shafted like this could result in the withdrawal of Apple's credit card service.
I know when I signed up to accept cards for my business there were very stiff warnings and penalties for this sort of practice.
Hey
Should've got a mac.
You gotta be jokin' man
Why is it every time I hear:
"... was provoked by BA mislaying one of Campbell's two checked bags, and then informing her she'd have to leave the flight as a result."
In connection with this story I have a sneaking suspicion there is a vital missing detail or two!