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But they said it's a "barometric vent"; not a barometer. Could it just be a hole to make sure the internal and external pressure are the same?

I remember when the waterproof Yaesu VX-7 radio came out (hand-held amateur radio transceiver), and it had a problem with being too sealed.. The problem with anything that is waterproof and has a speaker and/or a microphone is that the pressure on the inside can be very different from the pressure on the outside. If you change altitude, you will find that the pressure difference inside can press on the speaker diaphragm and/or microphone diaphragm. This limits the diaphragm travel, and will result in distorted audio. When this happened on the VX-7, the users discovered that they could crack open the battery case to "burp" the unit, restoring normal audio (at least until they changed elevation again). The eventual solution from the manufacturer turned out to be (from what I understand) to actually put a hole in the case and cover it with Gore-Tex. Water still stays out, but enough air can get through to equalize the pressure.

Since the iPhone has both speakers and microphones, something like this is needed if you really want to make it waterproof. Since the interior then has the same pressure as the outside, that makes it easy to drop a barometric sensor anywhere there is space on the board.

bingo. the same is true of acoustic suspension speakers; they can't be absolutely airtight, they need some sort of tiny leak.

But they said it's a "barometric vent"; not a barometer. Could it just be a hole to make sure the internal and external pressure are the same?

I remember when the waterproof Yaesu VX-7 radio came out (hand-held amateur radio transceiver), and it had a problem with being too sealed.. The problem with anything that is waterproof and has a speaker and/or a microphone is that the pressure on the inside can be very different from the pressure on the outside. If you change altitude, you will find that the pressure difference inside can press on the speaker diaphragm and/or microphone diaphragm. This limits the diaphragm travel, and will result in distorted audio. When this happened on the VX-7, the users discovered that they could crack open the battery case to "burp" the unit, restoring normal audio (at least until they changed elevation again). The eventual solution from the manufacturer turned out to be (from what I understand) to actually put a hole in the case and cover it with Gore-Tex. Water still stays out, but enough air can get through to equalize the pressure.

Since the iPhone has both speakers and microphones, something like this is needed if you really want to make it waterproof. Since the interior then has the same pressure as the outside, that makes it easy to drop a barometric sensor anywhere there is space on the board.

The way the digital stations around here work, is they broadcast both - and the receiver in my car seem to be intelligent enough to downgrade if the digital signal is too weak.

Basically, the radio starts off sounding like poo as it starts off in analog, but then as it 'locks in' (for lack of a better term) it switches over to digital and thus sounds much better. If I drive into a tunnel or such, the digital signal will drop and the radio will (without gap, mind you) drop back to analog, and switch back up when the digital signal is again stable.

I think what it does is it receives both, and keeps a running error talley on the digital stream. It uses this to determine if the signal is stable enough to use. I would expect even better performance if the streams were buffered for a second or two, but this isn't the case (at least the analog signal isn't - verified with my "real" radio)

Hmm. Maybe my transceiver is just nice, but i have no reception issues when I'm 5kHz up or down - I obviously don't know how I sound, but I've had conversations before. I guess they just assumed I had a weak signal.

I was thinking of HF, not a 2M. A good mobile transceiver (say a Yaesu 897D) and a screwdriver antenna could reach Europe or anywhere in the Middle East easily.

send email using APRS to one of many available satellites, although you may only get a few good passes each day-
http://www.amsat.org/amsat-new/information/faqs/aprs.php

including the international space station-
http://www.ariss.net/

many APRS handheld radios are available-
yaesu vx-8r:
http://www.yaesu.com/indexVS.cfm?cmd=DisplayProducts&ProdCatID=111&encProdID=64C913CDBC183621AAA39980149EA8C6

kenwood th-d72:
http://www.universal-radio.com/catalog/ht/3072.html

The resurgence of American amateur radio equipment companies is one of the great untold stories recently. I mean, one still has Japanese industry stalwarts Icom and Kenwood, who led the Japanese domination of the industry in the 1970s, but even Yaesu was bought by Motorola a few years back. The real news, though, is the new, innovative startups, doing state-of-the-art, truly wonderful designs, with simultaneous high performance, high quality, and reasonable prices. Companies like Elecraft and software-defined radio pioneer FlexRadio Systems come to mind, producing products unmatched by any of the mainstream companies.

It's a refreshing change.

virtually all ham radios, even the new ones with the tiny pitch SMT soldered components, come with schematics. I'm on a mailing list for the Yaesu FT-817and people have broken it open to swap out resistors to improve performance. Ham radio operators complain that nowadays we are just 'appliance operators': computer users haven't been experimentalists/hobbyists for the most part for 20+ years, although a few still do tinker. I wonder if it will come full circle someday and computers will be more of a hobbyist build, with schematics and more possibilities.

here you go. But it requires a license and won't make phone calls unless you've prearranged an autopatch within your signal footprint. On the plus side, it includes an broadcast AM/FM reciever and a marine radio transceiver, is waterproof (to ~3' Don't take it scuba-ing), floats, and has numerous interesting accessories. No bluetooth, though.

The range is a bit better than a cell phone, though, so it's probably a better choice for fishing out in the middle of nowhere anyway.

I have been around Hams for twenty years and the tech has usually stayed interesting. During the late 80's packet radio was starting out. When most people were calling bbs's using modems, hams were sending wireless data. Check out Phil Karn's site. He has a lot of wireless experience as both ham and engineer responsible for much of the CDMA standard.

Want to start with some small radios and learn more about electronics at the same time? There are many interesting kits around if you look. You certainly don't have to spend huge amounts on radios to get started. I paid ~$120US for my VX-2R when they were first introduced. It makes a great general purpose scanner too.

Newer modes like PSK31 are incredibly efficient. A couple of watts of power and 31Hz of radio spectrum and you have error free world wide digital communication at 50wpm. It is difficult to audibly detect the signal while listening, even when you know it is there.

• Street-level maps of the city and surrounding regions.
  
• Medical history, for those with medical issues.
  
• Any actual medications that have a decent enough shelf life to store for a while.
  
• A pair of contacts or glasses if you need them.
  
• Dust mask (at least).
  
• Minimal first aid kit.
  
• As an amateur radio operator I would definitely have a repeater guide to access repeaters while traveling. It's a sure thing the cell service will be down or overloaded. I'd also include a small wide-band receive transceiver, like the Yaesu VX-2R.
  
• You know those kinetic flashlights we see advertised here at Slashdot by ThinkGeek all the time? Definitely one of those.
  
• Ditto with a human-powered radio.
  
• Some sort of food (granola bars at least).
  
• A water purifier. There are water purifiers that are like a thick straw. You can put it in any water source and as you suck water through the "straw" it is purified.
  
• A couple "space blankets".
  
• A hard-copy of War of the Worlds. Putting it on the USB drive doesn't count.
  
  
  Dan East

I use a Yaesu VX-2 (small ham radio) for the same purpose. It's got something like 900 memories, covers HF through 1GHz, and has a few features your average scanner doesn't like assigning names to memories, 10 dB attenuator, RF squelch, CTCSS/DCS decode, and -- get this -- very small size. (Throw out the stock antenna and put a real one on, though.)

As an added bonus, there's the experimental 'frequency counter,' which has come in useful a few times. (Though it's also proved utterly useless several times.) And it can be easily modified to transmit on frequencies such as FRS. (Disclaimer: it's only legal to transmit on ham frequencies with a ham radio license. Transmitting outside ham radio frequencies (via modification) is illegal even if you're licensed there -- the radio's not type certified.)

It doesn't do trunk tracking (or APCO project 25 digital voice), but this isn't a handicap in my case.

I picked mine up for around $125.

I also listened to the shuttle mission live on my VX2R handheld (about the size of an iPod), courtesy of NA6MF, the NASA Ames amateur radio club retransmitting their internal audio feed on 145.585 MHz.

And just for funsies, I made a sample PodCast RSS of W1AW Morse code practice.

It depends largely on what is popular in your area, but a 2meter/70cm dual handheld is usually a great first radio. Handhelds (HTs) have gotten extremely capable in the last few years.

There is even a programming library and some applications available to control various radios.

The ARRL has a quick guide to getting started. Buy Now You're Talking! All You Need For Your First Amateur Radio License ($19) from the ARRL or your local Radio Shack. Your local clubs may offer classes too. Read the book, get tested ($10), answer 35 multiple-choice questions that you've already seen in the book, and you will have a Technician Class license. Buy a hand-held radio (about $130) that you can use with repeaters for and you are in business.

While there are certainly some people who fit this criteria, many are not. There are people of all different ages, and weight categories, who are hams. The public should really try to visit something like Field Day sometime; people seemed to find it quite interesting that the back parking lot of a high school suddenly had four 70 foot towers and dozens of tents scattered around.

Also, as far as the equipment, the equipment is surprisingly modern, and we don't all make it out of scrap metal... Yaesu, Icom, Kenwood, and Alinco are all popular amateur radio manufacturers.

Also, hams have launched a ton of satellites; the newly-launched AO-40 satellite has a footprint that covers practically half the Earth at a time. Now I know, with your super-duper cell phone, you can contact anyone with a phone, even if you're in the middle of nowhere.

But suppose you're somewhere like California, with the power crisis. The cell towers suddenly lose power. Or worse yet, there's a major disaster. Experience has shown that cell towers quickly become extremely jammed; transmissions on trunking radio systems get queued; and the hams help out.

Also, even in normal conditions, there's a big difference between a cell phone and a ham radio. To paraphrase someone else (dont' remember who) - would you call complete strangers on complete cell phones? Would you ask them what type of cell phone they had? No, they'd think you're a nut and would hang up.

Of course, there's more to ham radio than contacting random people and asking what type of radio they have... There are actually a lot of neat things to do with ham radio, check out something like ARRL, which has a bunch of info about ham radio.
________________________________________________

First, "HAM" doens't have to be in all caps. This is a common misconception, I guess... I don't know any hams who capitalize it "HAM". (A similar phenomonen occurs with people who don't use Linux, and label it as "LINUX") It's not really *wrong*, it's just a pet peeve of mine.

Anyway, another misconception is that ham radio always goes around the world. It depends on a number of factors, but the fact is that a common ham radio handheld will not go around the world. However, "repeater" sites are very common -- they repeat your signal at a much higher power, from a great location. Thus, a user on a low-powered "HT" (handheld) could still have his voice heard for hundreds of miles.

I have never actually used packet, but it is possible to achieve great distances with this, also.

One additional note... You will, of course, need a license to transmit. And you can't use it for commercial purposes.

Yaesu has just come out with nifty new "rig", the FT-817. This little radio transmits on the "HF" ('shortwave') bands, and can, theoretically, be heard anywhere in the world.

Also, PSK31 is extremely popular. I don't know about using it for images; I'm not in a position to comment on it. I don't know if they have an official site, but PSK31.com is a very informative site.

For those interested, here are a few additional ham-radio related links.

ARRL: excellent resources for those interested in ham radio

Kantronics, one of the larger makers of TNCs ['packet modems']

"73" (Ham term for 'best regards')
________________________________________________

First, "HAM" doens't have to be in all caps. This is a common misconception, I guess... I don't know any hams who capitalize it "HAM". (A similar phenomonen occurs with people who don't use Linux, and label it as "LINUX") It's not really *wrong*, it's just a pet peeve of mine.

Anyway, another misconception is that ham radio always goes around the world. It depends on a number of factors, but the fact is that a common ham radio handheld will not go around the world. However, "repeater" sites are very common -- they repeat your signal at a much higher power, from a great location. Thus, a user on a low-powered "HT" (handheld) could still have his voice heard for hundreds of miles.

I have never actually used packet, but it is possible to achieve great distances with this, also.

One additional note... You will, of course, need a license to transmit. And you can't use it for commercial purposes.

Yaesu has just come out with nifty new "rig", the FT-817. This little radio transmits on the "HF" ('shortwave') bands, and can, theoretically, be heard anywhere in the world.

Also, PSK31 is extremely popular. I don't know about using it for images; I'm not in a position to comment on it. I don't know if they have an official site, but PSK31.com is a very informative site.

For those interested, here are a few additional ham-radio related links.

ARRL: excellent resources for those interested in ham radio

Kantronics, one of the larger makers of TNCs ['packet modems']

"73" (Ham term for 'best regards')
________________________________________________

In 2000. I guess you haven't seen this! 1.8 MHz through 450 MHz, all modes, self-contained AA batteries, and OK it's got a shoulder strap, but it's a handheld.

And no, I haven't missed articles on working satellites via FM. That's what I was talking about.

People can set their own challenge levels, and if they are interested they work from low to high. Having an easy satellite mode would have been a great starter for beginners and especially young people. You know young people, they look like other hams, but aren't bald with a limp :-)

People gave me the same argument about packet in the 80's, which came down to where's the sport in that? Not everybody is into Amateur Radio for the sport.

Thanks

Bruce