or you need to install a "count down to yellow" counter, to warn drivers of when the light will be red/yellow.
And if you can't afford the countdown hardware, just turn the yellow light on during last two or three seconds of green. Two lights will be on at the same time. The approaching drivers will know that they have just a couple seconds of green left, and will make their decision rationally.
The "two lights on at the same time" system is used in Europe (red+yellow, at least) so there should be no technical problem, just a software change.
I don't know the technical feasibility, but ramping it up so it can disable a car without running the risk of killing the occupants, and now we're talking.
An EMI/EMP attack against an older carburetor engine or a diesel engine is most likely hopeless. Those engines have no computers, and an attack against whatever little they have will be not effective. Most likely majority of vehicles in 3rd world are like that. A diesel engine will keep running even after an EMP produced by a nuclear blast.
If I am tasked with solving this, I'd build a physical barrier that must be moved by guards to allow the vehicle to proceed. Nobody is stupid enough to drive through a concrete block (or an armored vehicle,) and even if they try they won't get through. This way you don't need to do anything to stop incoming vehicles - they either are stopped by their drivers, or they blow up at a designated location.
Actually, it failed because they were firing a heat ray at a bunch of desert-dwellers
It probably also matters that those attackers aren't forming an obvious, convenient marching band and march toward the protected installation making sure they are all exposed to those rays.
Far more likely the attackers are approaching unseen, then using mortars from behind the hills, or shooting rifles while under cover. Earth is conductive and absorbs / reflects microwaves. At those frequencies there isn't much difference between this "heat ray" and visible light. So as long as the attacker stays hidden he is not risking pain. And even if he does, big deal - he is risking death.
Add to that the fact that the heat ray's effective range is about 500 meters, which is about the minimum engagement distance in Afghanistan. It gets closer if troops on foot get into an ambush, but that's hardly relevant here. Stationary installations, as I read, are shot at from larger distances, and this heat ray is not suitable to cover a single sniper even if it could reach that far. The sniper is probably gone before the sound of the shot reaches the target.
At least with water cannons people can see it coming so they know the gloves have come off and its time to run.
And most importantly people can see where the water is coming from, and run away. But microwaves are invisible, and it might be hard for some people to tell the difference between "insanely painful" and "intolerably painful" - since that's the only way to figure out in which direction to NOT run.
Besides, it is well known that microwaves affect eyes before the skin even feels anything. So what are the effects of this weapon on eyesight?
In fact, "fox hunting" is a popular activity among amateur radio operators.
Not in the mountains:-) You need to listen on repeater's input, and the terrain most likely doesn't give you the line of sight. On top of that, the criminal doesn't know the frequency, and doesn't know timing of transmissions (those are given to fox hunters.)
Basically geolocation with a single, not moving station is not possible; you only get a bearing to the strongest direction of arrival. To triangulate without moving you need to have many stations (more than three, probably.) To triangulate with a single site you have to move yourself - and you have to move fast because you need to change your position so much that the LOB changes, and you have to move faster than your transmitter moves. Ideally you spiral around the transmitter. This requires a vehicle, most likely a flying vehicle (that solves the LOS problem also.) Such a setup is completely out of a common trail stalker's league. Perhaps a rescue team would be sufficiently equipped and trained to do DF, since they often use helicopters. The professional equipment with Watson-Watt antennas will cost you just under $100K, ham level equipment with Doppler antennas will be much cheaper, but it will distort the audio with the switching tone.
If we set the reference risk of a hiker meeting a criminal at 100%, 99.(9)% of it will come from the criminal just lying in wait near the trail. No radio needed, and he instantly knows who is coming, how many people, are they armed or not, etc. - facts that can't be determined from a brief radio communication. Criminals are usually not very smart, and their methods are amazingly simple; that's why they so often work.
No citation needed because what the GP claims (HF DF done by criminals) is impossible and unbelievable. HF DF requires huge installations ("elephant cages") and this technology is not available to many nations, let alone vagrants. VHF DF is theoretically doable with a man-portable equipment, but in practical terms it isn't. Besides, any DF in mountains will result in tons of multipath, so you need to be in an airplane if you want to perform DF with any hope for accuracy.
It is true that there may be danger present when you are out there. There may be danger from weather, from [lack of] luck, from poisonous plants, from dangerous animals... and from people. People would be the last on your list, unless you hike in Central Park of NYC. Criminals are not entirely stupid, they don't wait for people in the middle of nowhere; and hikers aren't likely to have their diamond rings and thick wallets with them. Some hikers may be armed. The most dangerous place for a hiker is probably the sidewalk in front of his home.
If I'm correctly deciphering the thread, you here talk about the original poster (bartle.) If so, then his own words are quite clear:
I'm only interested in acquiring a radio and license if it is a lot more effective and reliable
So he has no license at the moment. If so, I agree that prodding him toward ham radio just so he has a better cell phone would be a distraction, if not worse. I, for one, can't recommend ham radio to him over the satellite beacon, because if he breaks a leg he won't be able to throw an HF antenna into a tree. Satellite beacons are better suited for emergency use.
There was also a separate discussion between Suzuran and N2UX, but it's on a different level. I don't think you are talking about that - at least because N2UX clearly has a license:-)
However, many seem to get the license anyway by understanding how to memorize answers to question pools.
QRO to them, as long as they retain that knowledge. And they will remember what is important. Most of the Technician level questions are regulatory, and most of that is not applicable to everyday operations. For example, it's great that a ham knows how to take his HT to Canada, but there will be no major calamity if before going on vacation he has to check the book about that. It's not something that you need to remember while talking on a repeater during your morning commute.
As the ham progresses to General and Extra, the questions become more and more technically complex, requiring candidates to do calculations. Again, not everyone is born with detailed knowledge of the Smith chart. If, say, someone is more inclined toward DX work, as opposed to hand-building his antennas, that works too. Modern antenna tuners are amazingly simple to use (press a button and it's done.) So if the guy buys an FT-950, for example, the internal tuner will match the output connector to whatever the shack end of the cable looks like. Not optimal, sure, but it's usable.
when he dead-keyed his mic on SSB he wasn't reading any power output
Was he, by any chance, a CB'er in his previous life? I had a brief encounter with AM many years ago. Never liked it. My first rig was CW only, though SSB was theoretically supported too.
As I understand, you need the radio for a purely utilitarian purpose - to talk to specific people. You are not a ham yourself (not yet, at least) and likely the people you want to talk to are not hams either (otherwise you'd ask them, not Slashdot.) This means none of you can legally (or effectively) use ham radio. This can be corrected; ham license exams are not complicated, I took three on the same day, from no license to extra, but I have radio background and I'm not new to ham radio (I was first licensed around 1980, I think.) A man from the street will have lots of problems with higher level exams unless he understands things like the theory of linear circuits, complex impedance, and such.
You certainly can go ahead and get a ham radio license for yourself, if that is interesting to you in any way (there is more than one way to enjoy ham radio.) But you probably can't tell your friends, parents, or whoever is on the other end, to go and get a license - that's probably beyond most people's abilities, just like it is for me to learn classical dance:-) People are all different.
However if you only want communication then getting a ham radio and license doesn't make much sense. If I want to fly from SF to Paris I don't want to study for a pilot license; I buy a ticket, and a professional pilot will do all the flying for me. It is cheaper, simpler, safer, and lets me do things that I want to do - not what I have to do.
Technically, ham radio in emergency is the absolute best way to make a contact with another ham. Even satellites are not as reliable. Ham radio depends primarily on equipment that you (and the other guy) have. No need for expensive satellites that may or may not be in the sky or otherwise operational. There are many ham bands, and you can always find a band that works at the time of need. HF bands will work for short range communication pretty much at any time (using the ground wave.) In mountains NVIS makes sense. V/UHF is not likely to work there because distances are large, terrain - rough, and repeaters would be scarce. To be well prepared for an emergency you need to have an HF rig, and if you can do CW (at any speed) it's even better.
An experienced ham would probably take a small transceiver with him into mountains; either HF or HF+VHF. He wouldn't need much of an antenna - any long wire would do fine at his elevation. In good conditions he'd be able to communicate with the whole USA with mere 5W; in bad conditions he'd be able to contact a local ham to report an emergency (and he'd have his GPS coordinates.)
A new ham most likely won't be able to fully utilize the spectrum that he has access to (depends on his license.) He'd bring a UHF HT with him, and he wouldn't be able to hear anything. Also repeaters are tricky sometimes, they require PL tones and you need to know them in advance to elicit a response from a silent repeater. So you must come prepared.
In your situation it would be safer for you if you rely upon commercial methods of communication. They are better supported and they require hardly any experience. If you need the radio only to report an emergency then you can get a beacon for that. If you want to talk to your friends from the top of a mountain then you need a satellite phone (and lots of money to pay for it.)
The thing is, the larger surface area of the external metal antenna does mean the iPhone gets really much better reception - both voice and data.
Not exactly. Diameter of the element affects the bandwidth of the antenna (the range of frequencies where you can tolerate the SWR of the antenna.) The "surface area" is important only in dishes.
The iPhone 4 may or may not be more sensitive than other phones, but improvements in sensitivity usually come from many parts of the device, not just the antenna.
For all the whining about this look for competitors to start introducing external antenna soon.
That is very unlikely because there is no electrical benefit of having an external antenna. The case is transparent to radio waves. An ideal design places the antenna inside the case, but at some distance from other conductive surfaces (primarily the PCB.) Apple already conceded defeat and reverted to the "internal" antenna by using a plastic bumper; essentially Apple sells a kit, and the final assembly is done by the customer:-) That's certainly a first in the cell phone business!
You say that as if there's an inherent reason why ebooks can't be handled in a similar fashion.
ebooks can be copied by the customers at zero cost and without loss of quality, unless DRM puts some limits to that. Copying of a paper book is possible, but it costs more than the physical book, considering equipment, software and time.
how many hand positions you use when making calls? one.
At least two, since I have two hands. Besides, what is the chance that out of 100,000,000 cell phone users all of them use exactly the same position? And if some positions are never tried by anyone, nobody would care if holding the phone there affects the signal.
This is exactly now the iPhone 4 problem was discovered - by lefties that held the phone in a natural, very common way.
Why did you think it's too late to return it? I don't think I'm missing anything?
I should have been more explicit. Apple may hope to sufficiently muddy the waters and keep the users happy enough until the return period expires. People who live in large cities may not experience the low signal strength until, once in a blue moon, they go to a park - and then the death grip strikes. But by then it's too late to do anything, and in any case most of their phone use is in the city, so...
Myself, I live outside of the city, and the AT&T signal here is nearly zero. If I don't have the repeater turned on, the phone will ring but the voice connection can't be maintained. The repeater (Wi-Ex) helps with that. An iPhone would be completely useless to me; probably it won't even ring here. Besides, I only use flip phones (they are smaller) so none of current smartphones are of interest to me.
The antennas disappeared into the phone to gain style points, not to improve overall reception. Perhaps an RF engineer could comment?
Primarily you need a manufacturing engineer to comment on this. External antennas are large, expensive to make, and they tend to break, and you must depend on the customer to extend them (if they are extendable.) But from the RF point of view, a well designed and well matched internal antenna is not any worse than an external one. The technology of antennas has also improved, CST came up with specialized simulators and models, new LNAs are now available to increase sensitivity, and so on.
one theory says that since iPhone4 makes antenna design, especially the gap, so prominent, it is far easier for people to correlate signal quality with hand position.
People (and animals) are amazingly good in sensing their hand position. If a phone tends to fail with a hand in some specific position it would be unavoidably noticed, given that billions of calls are placed daily. Also the gap between iPhone antennas is not something people would even notice, unless it marks the trouble spot.
The reason that other phones work and the iPhone 4 doesn't is, IMO, because the signal drop in other phones is very small - small enough to stay under the radar, just as intended. There was no such complaint about earlier iPhones either - simply because they behaved reasonably enough.
on other phones, even if the same problem exists, it is very difficult for people to discover, because the antenna is internal.
It's damn easy to discover if your call is dropped when you grip the phone exactly *there*. If this is not discovered on other phones it's only because the calls aren't dropped, and then there is no problem.
drop of signal is so common, you just won't think too much about it.
If the loss of the signal is small then I don't care. If the loss is so large that a perfectly good call gets disconnected then it's clearly a problem.
Bullshit. I am putting my hand on that spot and NOTHING HAPPENS.
Apple hopes that most of the iPhone 4 sucke^W users live and work in areas with great AT&T coverage. Sure, if you sit under the tower you will see no problem. Keep the phone. Then drive someplace with poorer coverage (easy to find on the AT&T network - I have an AT&T phone myself) and get zero bars. The phone is not returnable any more, so you are stuck. Unless, of course, you want to buy a redesigned iPhone 4.1, for full price, when Apple sells the entire manufacturing run of iPhone 4.0.
The OP not only someone to diagnose the problem but fix it right away just because he brought it in.
I'm unsure what makes you think the OP wanted an immediate repair. Here is what he said:
2. you need to make an appointment to speak to us,the next appointment is in 2 hours
The appointment was "to speak to us" (talk to the tech who, presumably, would look at the thing.) I can't imagine anyone insisting on an immediate repair, both due to parts that may need to be ordered, and due to time that it takes to do the work. No reasonable person would insist on repairs "while you wait".
Apple doesn't offer "leave it and we'll get to it later" service
Apparently so, and I say this is a stupid way to run a customer-facing business. What are Apple's good business reasons to not offer this service? IMO, as they sell more and more phones and iPods and stuff they will be eventually forced to do just that. It just wastes tech's time to talk to the customer. The customer probably knows nothing, and the tech can see what's wrong just by looking (or powering up) the computer. And if that's not enough, there is always a phone to call. In a sane world a clerk (dime a dozen) just takes whatever you bring in, prints the receipt, and you are free to go. Distancing the tech from the customer also gives you flexibility - if some store has a mountain of broken items you can send additional techs there, or offer them overtime pay, or ship some of those devices to a repair center. A "genius" standing in front of you and talking to you - it's so 70's...
The real question is - how many mechanics & doctors are there to service those 250 million people, versus mac "geniuses" to service those 9 million people?
That's not the real question. There are many other factors involved, like how often people get sick vs. how frequently Macs need service.
It's much better to ask "How long do you need to stand in line just for someone to have a look at your problem?" If that waiting time is unreasonably long, the computer maker's service - or your country's healthcare - is broken. If Apple needs to schedule an appointment for an estimate, instead of asking you to wait for 10 minutes in the worst case, they simply don't have enough workers.
It is not OK to optimize the workload of techs by manipulating customers. Apple, for example, could allow you to leave your computer with the clerk at any time. Then you are free to go, and the computer goes into the pile from which techs take them and look at them. Once they have an estimate they would call you, and if you don't like the price you can come at your convenience and take the computer back. If something has to wait, it better be inanimate objects. Customers are willing to wait a few days (or even weeks) for the repair to be done - as long as they don't have to be involved themselves. That's how many service industries work, from screen doors to watches and cars. Apple just doesn't feel the need to care about its customers - they are locked in with nowhere else to go.
So if you drove up to your local mechanic's shop and all the mechanics were backed up for hours, you'd expect to be serviced right away?
I don't know what mechanic you are working with, but the dealership that services my car is *always* ready to take the car in, and if you want to get on with your life they offer a shuttle to neighboring places, or a rental car (free sometimes.) They will call you if they have any questions; otherwise the only call you get is "your car is ready."
It is indeed more polite to call ahead and ask for a good time to come. But for many jobs (like an oil change / tire rotation) they don't even give appointments - you are welcome at any time. For other, more complex jobs (like all tires replaced and wheels aligned) you can drop the car off whenever you want. There are plenty of clerks to check incoming cars in, and their job takes a fixed amount of time per car. If mechanics are busy, the car (not you!) will wait in line.
I seriously doubt they would have rigged the demo, it would be way too easy for users of those phones to show how it doesn't happen on those phones at the same place as an iphone 4.
Yes, I can see now how a random citizen calls a nation-wide press conference and demonstrates that his personal phone works just fine. That would be Earth-shattering news. Besides, Apple won't disclose its testing conditions, or says that all testing was done on Apple's private property. Good luck getting into there.
The big problem with the iphone 4 is they showed exactly where you could destroy the signal. Every other phone obfuscates this.
It's not enough to obfuscate. There are billions of cell phone users out there. If their phones would have such an obvious defect, no obfuscation would be enough. And that's exactly how iPhone 4 defect was found - it's not like there was a sticker with words "Don't touch here."
The fact is that nearly all cell phones perform reasonably well even if gripped around the antenna. iPhone 4 is special because it has external antennas, and they are more susceptible to influence of the hand.
Nobody seems to care as much as the media would have you believe.
That may be true, but it tells plenty about the people who bought the iPhone 4. Perhaps they don't insist that their fashion accessory does anything useful?
Because, speaking as an electrical engineer (but not an antenna designer) I don't think anything other than pure DISTANCE (which the rubber bumper neatly provides) will actually help all that much.
Indeed, the vacuum (or at least air) is the best cure. A dielectric may actually make things worse. First, a dielectric with high permittivity will make the capacitance higher, so though your hand is now farther away it may affect the antenna more. Second, the dielectric will have losses in it, so an antenna shrouded in a dielectric may be not as good as one in free space. There are dielectrics suitable for encapsulation of antennas, but they are not of the kind that you spray onto stainless steel. If you get that far you probably want to redesign your whole phone enclosure - it will be cheaper, and will work better.
even to an outsider it's obvious they came up with this antenna design to *improve* reception.
I do RF design, and occasionally I design simple antennas. There is no way I'd recommend to build an antenna that would be randomly touched by people. Here is why.
Your typical 1/4 wavelength radiator is able to convert impedance approximately from zero to infinity. This means that you have high current at one end and high voltage on the other end. The current is OK. However the voltage can burn people! I had a few burns from low power output stages simply because the output impedance was set to be high. It's not like a 120V AC shock, it's like a small arc. If such an antenna is exposed, you can burn yourself by touching *some* areas of it. Antennas of higher power transmitters can be very dangerous, both field-wise and voltage-wise.
Another problem is that if you touch the antenna you introduce a fairly large capacitance (hundreds of pF) into a system that lives and dies on a few pF. Remember the impedance translation - if you touch the antenna in one place it will have a different effect than touching it in another place. If the antenna is designed to work in open space it will not perform the same when parts of it are loaded with random capacitors.
It is true that all cell phones are in some degree sensitive to placement of hands. Those are small devices, with small antennas, and as a rule of thumb a small antenna is bad news. But designers try to put some distance between the radiator and the hand; the plastic case often does enough separation so the effects are minor. Notably, we never heard (until now) about a cell phone that loses signal when held in a usual way. Sure, phone manufacturers put disclaimers into manuals, but the facts on the ground are simple - you buy a garden variety phone, hold it however you want, and it works well enough. In this case, however, there is no separation between the antenna and the hand; and not only the main antenna gets loaded, it is also bridged with another antenna that may or may not be transmitting at the same time!
I'm sure Apple engineers had their reasons to do what they did. The iPhone 4 is a great product, it's just the users who spoil its beauty by insisting that it must work not worse than every other cell phone on the market.
The iPhone 4 attenuates a maximum of 24 dBms according to Anandtech. The same test showed the Nexus one Attenuating 17 dBms.
Attenuation is measured in dB. Power may be measured in dBm.
Besides, 7 dB difference is 10^0.7 = 5. This means that Nexus One, gripped to death, still receives 5 times more power from the tower than the iPhone in a similar grip.
However, I don't tend to buy music these days either and I used to buy a lot.
There are several causes of that effect. Some, like me, just don't like RIAA's music - never liked and will never like, probably (considering that I wasn't born in that last 'A' anyway.) There are very few exceptions.
Secondly, as people get older they tend to get locked into the music of their formative years. New music doesn't look that much appealing to you. And as a side effect of that, you probably already have the music that you like. You might want, from time to time, buy other recordings from that period and of that style that you like, but the most active market - the one of today - may not interest you.
While they've reduced piracy they've also done untold damage to their revenue stream.
If most of their customers are young people then they have nothing to worry about - "There's a sucker born every minute."
Slashdot Mirror
or you need to install a "count down to yellow" counter, to warn drivers of when the light will be red/yellow.
And if you can't afford the countdown hardware, just turn the yellow light on during last two or three seconds of green. Two lights will be on at the same time. The approaching drivers will know that they have just a couple seconds of green left, and will make their decision rationally.
The "two lights on at the same time" system is used in Europe (red+yellow, at least) so there should be no technical problem, just a software change.
I don't know the technical feasibility, but ramping it up so it can disable a car without running the risk of killing the occupants, and now we're talking.
An EMI/EMP attack against an older carburetor engine or a diesel engine is most likely hopeless. Those engines have no computers, and an attack against whatever little they have will be not effective. Most likely majority of vehicles in 3rd world are like that. A diesel engine will keep running even after an EMP produced by a nuclear blast.
If I am tasked with solving this, I'd build a physical barrier that must be moved by guards to allow the vehicle to proceed. Nobody is stupid enough to drive through a concrete block (or an armored vehicle,) and even if they try they won't get through. This way you don't need to do anything to stop incoming vehicles - they either are stopped by their drivers, or they blow up at a designated location.
Actually, it failed because they were firing a heat ray at a bunch of desert-dwellers
It probably also matters that those attackers aren't forming an obvious, convenient marching band and march toward the protected installation making sure they are all exposed to those rays.
Far more likely the attackers are approaching unseen, then using mortars from behind the hills, or shooting rifles while under cover. Earth is conductive and absorbs / reflects microwaves. At those frequencies there isn't much difference between this "heat ray" and visible light. So as long as the attacker stays hidden he is not risking pain. And even if he does, big deal - he is risking death.
Add to that the fact that the heat ray's effective range is about 500 meters, which is about the minimum engagement distance in Afghanistan. It gets closer if troops on foot get into an ambush, but that's hardly relevant here. Stationary installations, as I read, are shot at from larger distances, and this heat ray is not suitable to cover a single sniper even if it could reach that far. The sniper is probably gone before the sound of the shot reaches the target.
At least with water cannons people can see it coming so they know the gloves have come off and its time to run.
And most importantly people can see where the water is coming from, and run away. But microwaves are invisible, and it might be hard for some people to tell the difference between "insanely painful" and "intolerably painful" - since that's the only way to figure out in which direction to NOT run.
Besides, it is well known that microwaves affect eyes before the skin even feels anything. So what are the effects of this weapon on eyesight?
In fact, "fox hunting" is a popular activity among amateur radio operators.
Not in the mountains :-) You need to listen on repeater's input, and the terrain most likely doesn't give you the line of sight. On top of that, the criminal doesn't know the frequency, and doesn't know timing of transmissions (those are given to fox hunters.)
Basically geolocation with a single, not moving station is not possible; you only get a bearing to the strongest direction of arrival. To triangulate without moving you need to have many stations (more than three, probably.) To triangulate with a single site you have to move yourself - and you have to move fast because you need to change your position so much that the LOB changes, and you have to move faster than your transmitter moves. Ideally you spiral around the transmitter. This requires a vehicle, most likely a flying vehicle (that solves the LOS problem also.) Such a setup is completely out of a common trail stalker's league. Perhaps a rescue team would be sufficiently equipped and trained to do DF, since they often use helicopters. The professional equipment with Watson-Watt antennas will cost you just under $100K, ham level equipment with Doppler antennas will be much cheaper, but it will distort the audio with the switching tone.
If we set the reference risk of a hiker meeting a criminal at 100%, 99.(9)% of it will come from the criminal just lying in wait near the trail. No radio needed, and he instantly knows who is coming, how many people, are they armed or not, etc. - facts that can't be determined from a brief radio communication. Criminals are usually not very smart, and their methods are amazingly simple; that's why they so often work.
[citation needed]
No citation needed because what the GP claims (HF DF done by criminals) is impossible and unbelievable. HF DF requires huge installations ("elephant cages") and this technology is not available to many nations, let alone vagrants. VHF DF is theoretically doable with a man-portable equipment, but in practical terms it isn't. Besides, any DF in mountains will result in tons of multipath, so you need to be in an airplane if you want to perform DF with any hope for accuracy.
It is true that there may be danger present when you are out there. There may be danger from weather, from [lack of] luck, from poisonous plants, from dangerous animals ... and from people. People would be the last on your list, unless you hike in Central Park of NYC. Criminals are not entirely stupid, they don't wait for people in the middle of nowhere; and hikers aren't likely to have their diamond rings and thick wallets with them. Some hikers may be armed. The most dangerous place for a hiker is probably the sidewalk in front of his home.
How do you know he didn't [?]
If I'm correctly deciphering the thread, you here talk about the original poster (bartle.) If so, then his own words are quite clear:
So he has no license at the moment. If so, I agree that prodding him toward ham radio just so he has a better cell phone would be a distraction, if not worse. I, for one, can't recommend ham radio to him over the satellite beacon, because if he breaks a leg he won't be able to throw an HF antenna into a tree. Satellite beacons are better suited for emergency use.
There was also a separate discussion between Suzuran and N2UX, but it's on a different level. I don't think you are talking about that - at least because N2UX clearly has a license :-)
However, many seem to get the license anyway by understanding how to memorize answers to question pools.
QRO to them, as long as they retain that knowledge. And they will remember what is important. Most of the Technician level questions are regulatory, and most of that is not applicable to everyday operations. For example, it's great that a ham knows how to take his HT to Canada, but there will be no major calamity if before going on vacation he has to check the book about that. It's not something that you need to remember while talking on a repeater during your morning commute.
As the ham progresses to General and Extra, the questions become more and more technically complex, requiring candidates to do calculations. Again, not everyone is born with detailed knowledge of the Smith chart. If, say, someone is more inclined toward DX work, as opposed to hand-building his antennas, that works too. Modern antenna tuners are amazingly simple to use (press a button and it's done.) So if the guy buys an FT-950, for example, the internal tuner will match the output connector to whatever the shack end of the cable looks like. Not optimal, sure, but it's usable.
when he dead-keyed his mic on SSB he wasn't reading any power output
Was he, by any chance, a CB'er in his previous life? I had a brief encounter with AM many years ago. Never liked it. My first rig was CW only, though SSB was theoretically supported too.
As I understand, you need the radio for a purely utilitarian purpose - to talk to specific people. You are not a ham yourself (not yet, at least) and likely the people you want to talk to are not hams either (otherwise you'd ask them, not Slashdot.) This means none of you can legally (or effectively) use ham radio. This can be corrected; ham license exams are not complicated, I took three on the same day, from no license to extra, but I have radio background and I'm not new to ham radio (I was first licensed around 1980, I think.) A man from the street will have lots of problems with higher level exams unless he understands things like the theory of linear circuits, complex impedance, and such.
You certainly can go ahead and get a ham radio license for yourself, if that is interesting to you in any way (there is more than one way to enjoy ham radio.) But you probably can't tell your friends, parents, or whoever is on the other end, to go and get a license - that's probably beyond most people's abilities, just like it is for me to learn classical dance :-) People are all different.
However if you only want communication then getting a ham radio and license doesn't make much sense. If I want to fly from SF to Paris I don't want to study for a pilot license; I buy a ticket, and a professional pilot will do all the flying for me. It is cheaper, simpler, safer, and lets me do things that I want to do - not what I have to do.
Technically, ham radio in emergency is the absolute best way to make a contact with another ham. Even satellites are not as reliable. Ham radio depends primarily on equipment that you (and the other guy) have. No need for expensive satellites that may or may not be in the sky or otherwise operational. There are many ham bands, and you can always find a band that works at the time of need. HF bands will work for short range communication pretty much at any time (using the ground wave.) In mountains NVIS makes sense. V/UHF is not likely to work there because distances are large, terrain - rough, and repeaters would be scarce. To be well prepared for an emergency you need to have an HF rig, and if you can do CW (at any speed) it's even better.
An experienced ham would probably take a small transceiver with him into mountains; either HF or HF+VHF. He wouldn't need much of an antenna - any long wire would do fine at his elevation. In good conditions he'd be able to communicate with the whole USA with mere 5W; in bad conditions he'd be able to contact a local ham to report an emergency (and he'd have his GPS coordinates.)
A new ham most likely won't be able to fully utilize the spectrum that he has access to (depends on his license.) He'd bring a UHF HT with him, and he wouldn't be able to hear anything. Also repeaters are tricky sometimes, they require PL tones and you need to know them in advance to elicit a response from a silent repeater. So you must come prepared.
In your situation it would be safer for you if you rely upon commercial methods of communication. They are better supported and they require hardly any experience. If you need the radio only to report an emergency then you can get a beacon for that. If you want to talk to your friends from the top of a mountain then you need a satellite phone (and lots of money to pay for it.)
The thing is, the larger surface area of the external metal antenna does mean the iPhone gets really much better reception - both voice and data.
Not exactly. Diameter of the element affects the bandwidth of the antenna (the range of frequencies where you can tolerate the SWR of the antenna.) The "surface area" is important only in dishes.
The iPhone 4 may or may not be more sensitive than other phones, but improvements in sensitivity usually come from many parts of the device, not just the antenna.
For all the whining about this look for competitors to start introducing external antenna soon.
That is very unlikely because there is no electrical benefit of having an external antenna. The case is transparent to radio waves. An ideal design places the antenna inside the case, but at some distance from other conductive surfaces (primarily the PCB.) Apple already conceded defeat and reverted to the "internal" antenna by using a plastic bumper; essentially Apple sells a kit, and the final assembly is done by the customer :-) That's certainly a first in the cell phone business!
You say that as if there's an inherent reason why ebooks can't be handled in a similar fashion.
ebooks can be copied by the customers at zero cost and without loss of quality, unless DRM puts some limits to that. Copying of a paper book is possible, but it costs more than the physical book, considering equipment, software and time.
how many hand positions you use when making calls? one.
At least two, since I have two hands. Besides, what is the chance that out of 100,000,000 cell phone users all of them use exactly the same position? And if some positions are never tried by anyone, nobody would care if holding the phone there affects the signal.
This is exactly now the iPhone 4 problem was discovered - by lefties that held the phone in a natural, very common way.
Why did you think it's too late to return it? I don't think I'm missing anything?
I should have been more explicit. Apple may hope to sufficiently muddy the waters and keep the users happy enough until the return period expires. People who live in large cities may not experience the low signal strength until, once in a blue moon, they go to a park - and then the death grip strikes. But by then it's too late to do anything, and in any case most of their phone use is in the city, so...
Myself, I live outside of the city, and the AT&T signal here is nearly zero. If I don't have the repeater turned on, the phone will ring but the voice connection can't be maintained. The repeater (Wi-Ex) helps with that. An iPhone would be completely useless to me; probably it won't even ring here. Besides, I only use flip phones (they are smaller) so none of current smartphones are of interest to me.
The antennas disappeared into the phone to gain style points, not to improve overall reception. Perhaps an RF engineer could comment?
Primarily you need a manufacturing engineer to comment on this. External antennas are large, expensive to make, and they tend to break, and you must depend on the customer to extend them (if they are extendable.) But from the RF point of view, a well designed and well matched internal antenna is not any worse than an external one. The technology of antennas has also improved, CST came up with specialized simulators and models, new LNAs are now available to increase sensitivity, and so on.
one theory says that since iPhone4 makes antenna design, especially the gap, so prominent, it is far easier for people to correlate signal quality with hand position.
People (and animals) are amazingly good in sensing their hand position. If a phone tends to fail with a hand in some specific position it would be unavoidably noticed, given that billions of calls are placed daily. Also the gap between iPhone antennas is not something people would even notice, unless it marks the trouble spot.
The reason that other phones work and the iPhone 4 doesn't is, IMO, because the signal drop in other phones is very small - small enough to stay under the radar, just as intended. There was no such complaint about earlier iPhones either - simply because they behaved reasonably enough.
on other phones, even if the same problem exists, it is very difficult for people to discover, because the antenna is internal.
It's damn easy to discover if your call is dropped when you grip the phone exactly *there*. If this is not discovered on other phones it's only because the calls aren't dropped, and then there is no problem.
drop of signal is so common, you just won't think too much about it.
If the loss of the signal is small then I don't care. If the loss is so large that a perfectly good call gets disconnected then it's clearly a problem.
Bullshit. I am putting my hand on that spot and NOTHING HAPPENS.
Apple hopes that most of the iPhone 4 sucke^W users live and work in areas with great AT&T coverage. Sure, if you sit under the tower you will see no problem. Keep the phone. Then drive someplace with poorer coverage (easy to find on the AT&T network - I have an AT&T phone myself) and get zero bars. The phone is not returnable any more, so you are stuck. Unless, of course, you want to buy a redesigned iPhone 4.1, for full price, when Apple sells the entire manufacturing run of iPhone 4.0.
The OP not only someone to diagnose the problem but fix it right away just because he brought it in.
I'm unsure what makes you think the OP wanted an immediate repair. Here is what he said:
The appointment was "to speak to us" (talk to the tech who, presumably, would look at the thing.) I can't imagine anyone insisting on an immediate repair, both due to parts that may need to be ordered, and due to time that it takes to do the work. No reasonable person would insist on repairs "while you wait".
Apple doesn't offer "leave it and we'll get to it later" service
Apparently so, and I say this is a stupid way to run a customer-facing business. What are Apple's good business reasons to not offer this service? IMO, as they sell more and more phones and iPods and stuff they will be eventually forced to do just that. It just wastes tech's time to talk to the customer. The customer probably knows nothing, and the tech can see what's wrong just by looking (or powering up) the computer. And if that's not enough, there is always a phone to call. In a sane world a clerk (dime a dozen) just takes whatever you bring in, prints the receipt, and you are free to go. Distancing the tech from the customer also gives you flexibility - if some store has a mountain of broken items you can send additional techs there, or offer them overtime pay, or ship some of those devices to a repair center. A "genius" standing in front of you and talking to you - it's so 70's ...
The real question is - how many mechanics & doctors are there to service those 250 million people, versus mac "geniuses" to service those 9 million people?
That's not the real question. There are many other factors involved, like how often people get sick vs. how frequently Macs need service.
It's much better to ask "How long do you need to stand in line just for someone to have a look at your problem?" If that waiting time is unreasonably long, the computer maker's service - or your country's healthcare - is broken. If Apple needs to schedule an appointment for an estimate, instead of asking you to wait for 10 minutes in the worst case, they simply don't have enough workers.
It is not OK to optimize the workload of techs by manipulating customers. Apple, for example, could allow you to leave your computer with the clerk at any time. Then you are free to go, and the computer goes into the pile from which techs take them and look at them. Once they have an estimate they would call you, and if you don't like the price you can come at your convenience and take the computer back. If something has to wait, it better be inanimate objects. Customers are willing to wait a few days (or even weeks) for the repair to be done - as long as they don't have to be involved themselves. That's how many service industries work, from screen doors to watches and cars. Apple just doesn't feel the need to care about its customers - they are locked in with nowhere else to go.
So if you drove up to your local mechanic's shop and all the mechanics were backed up for hours, you'd expect to be serviced right away?
I don't know what mechanic you are working with, but the dealership that services my car is *always* ready to take the car in, and if you want to get on with your life they offer a shuttle to neighboring places, or a rental car (free sometimes.) They will call you if they have any questions; otherwise the only call you get is "your car is ready."
It is indeed more polite to call ahead and ask for a good time to come. But for many jobs (like an oil change / tire rotation) they don't even give appointments - you are welcome at any time. For other, more complex jobs (like all tires replaced and wheels aligned) you can drop the car off whenever you want. There are plenty of clerks to check incoming cars in, and their job takes a fixed amount of time per car. If mechanics are busy, the car (not you!) will wait in line.
I seriously doubt they would have rigged the demo, it would be way too easy for users of those phones to show how it doesn't happen on those phones at the same place as an iphone 4.
Yes, I can see now how a random citizen calls a nation-wide press conference and demonstrates that his personal phone works just fine. That would be Earth-shattering news. Besides, Apple won't disclose its testing conditions, or says that all testing was done on Apple's private property. Good luck getting into there.
The big problem with the iphone 4 is they showed exactly where you could destroy the signal. Every other phone obfuscates this.
It's not enough to obfuscate. There are billions of cell phone users out there. If their phones would have such an obvious defect, no obfuscation would be enough. And that's exactly how iPhone 4 defect was found - it's not like there was a sticker with words "Don't touch here."
The fact is that nearly all cell phones perform reasonably well even if gripped around the antenna. iPhone 4 is special because it has external antennas, and they are more susceptible to influence of the hand.
Nobody seems to care as much as the media would have you believe.
That may be true, but it tells plenty about the people who bought the iPhone 4. Perhaps they don't insist that their fashion accessory does anything useful?
Because, speaking as an electrical engineer (but not an antenna designer) I don't think anything other than pure DISTANCE (which the rubber bumper neatly provides) will actually help all that much.
Indeed, the vacuum (or at least air) is the best cure. A dielectric may actually make things worse. First, a dielectric with high permittivity will make the capacitance higher, so though your hand is now farther away it may affect the antenna more. Second, the dielectric will have losses in it, so an antenna shrouded in a dielectric may be not as good as one in free space. There are dielectrics suitable for encapsulation of antennas, but they are not of the kind that you spray onto stainless steel. If you get that far you probably want to redesign your whole phone enclosure - it will be cheaper, and will work better.
even to an outsider it's obvious they came up with this antenna design to *improve* reception.
I do RF design, and occasionally I design simple antennas. There is no way I'd recommend to build an antenna that would be randomly touched by people. Here is why.
Your typical 1/4 wavelength radiator is able to convert impedance approximately from zero to infinity. This means that you have high current at one end and high voltage on the other end. The current is OK. However the voltage can burn people! I had a few burns from low power output stages simply because the output impedance was set to be high. It's not like a 120V AC shock, it's like a small arc. If such an antenna is exposed, you can burn yourself by touching *some* areas of it. Antennas of higher power transmitters can be very dangerous, both field-wise and voltage-wise.
Another problem is that if you touch the antenna you introduce a fairly large capacitance (hundreds of pF) into a system that lives and dies on a few pF. Remember the impedance translation - if you touch the antenna in one place it will have a different effect than touching it in another place. If the antenna is designed to work in open space it will not perform the same when parts of it are loaded with random capacitors.
It is true that all cell phones are in some degree sensitive to placement of hands. Those are small devices, with small antennas, and as a rule of thumb a small antenna is bad news. But designers try to put some distance between the radiator and the hand; the plastic case often does enough separation so the effects are minor. Notably, we never heard (until now) about a cell phone that loses signal when held in a usual way. Sure, phone manufacturers put disclaimers into manuals, but the facts on the ground are simple - you buy a garden variety phone, hold it however you want, and it works well enough. In this case, however, there is no separation between the antenna and the hand; and not only the main antenna gets loaded, it is also bridged with another antenna that may or may not be transmitting at the same time!
I'm sure Apple engineers had their reasons to do what they did. The iPhone 4 is a great product, it's just the users who spoil its beauty by insisting that it must work not worse than every other cell phone on the market.
The iPhone 4 attenuates a maximum of 24 dBms according to Anandtech. The same test showed the Nexus one Attenuating 17 dBms.
Attenuation is measured in dB. Power may be measured in dBm.
Besides, 7 dB difference is 10^0.7 = 5. This means that Nexus One, gripped to death, still receives 5 times more power from the tower than the iPhone in a similar grip.
However, I don't tend to buy music these days either and I used to buy a lot.
There are several causes of that effect. Some, like me, just don't like RIAA's music - never liked and will never like, probably (considering that I wasn't born in that last 'A' anyway.) There are very few exceptions.
Secondly, as people get older they tend to get locked into the music of their formative years. New music doesn't look that much appealing to you. And as a side effect of that, you probably already have the music that you like. You might want, from time to time, buy other recordings from that period and of that style that you like, but the most active market - the one of today - may not interest you.
While they've reduced piracy they've also done untold damage to their revenue stream.
If most of their customers are young people then they have nothing to worry about - "There's a sucker born every minute."
I'm just waiting for the "Android: Hold it any way you want!" ad campaign.
The wait is over.