The average human is about 6 feet, which is approximately one wavelength in the VHF public service and business pools (150MHz). Standing up, you are a nicly resonating grounding device for that energy in the air. I guess I was unclear, the cells heating up is the result of the absorption of the energy, the cells themselves are not resonate but the entire structure, be it a human or an antenna.
The FCC has human exposure rules because this is a very real issue, and not just with GHz. KWNZ, located in Carson City, Nevada, was just fined $10,000 by the FCC for violating public exposure limits at their transmission site, and they are on 93.7MHz (almost 10 foot wavelength).
Especially since law enforcement, road crews, public works, etc. normally have 50w radios, and fire engines normally have 110w radios (for VHF anyway). Drive by one of these guys why they are talking and its going to be absorbed and heat your cells more than a cellphone will. No one worried about them, though, they are public safety!
I am semi-concerned, but there are so many places to get free access already. The library, schools, universities, internet cafe. Some even let you bring your own computer and just plug into their Cat 5 (thats the way we do it at my school if you don't have WiFi). So, it might make it easier, but its not already impossible.
Yeah, not to bash on the guy, but when I read scrubbed I was trying to figure out which moon rocket was up for launch. The blown dry part just made no sense at all and was disregarded. Granted, reading another 10 seconds cleared it up, but misleading headline none-the-less.
If you go to the main page, you can see that 0.9 RC has been released. Mozilla has a habit of updating their main page when a new firefox is out, but not updating their firefox page.
Local police will not touch anything involving the use of airwaves, they will refer you to the FCC. Most people think the FCC is into enforcement so they are happy to dump you on their lap; the FCC says they are into enforcement and take the case, but as this story and my own personal experience has found, they just don't do anything after that.
The problem is not every person wants to make money off airwaves. Amateurs use it for fun, public services use it because they have to to be effective. Would you buy the space for the portable phone in your house? Who would pay for the WiFi frequencies you are using? Bluetooth? All those other little fun things people use but no one body controls to buy the frequency for would go away. Sometimes things need to be set aside for people that don't have a way to pay for them but have a very good use. Should people have to buy their own roads because they want to drive around, or have a managed system of distribution and sharing? Land is limited in NYC but people can go elsewhere. If they sell all the usable spectrum (and no it isn't infinite) there is no where else to go, you just don't get wireless.
Digital can do wonders getting things narrowband, but the USFS narrowband setup is just as narrow as digital. Some say the digital (APCO P.25 specifically) sounds better after its slight compression, others say it sounds worse. I think it is just what you get used to. The main complaint I hear now is if there is a transmission that would be in the mud in analog mode it is completely lost with digital. The signal is either there to decode or it is not with digital, where at least with analog you would get bursts of noise, even if it was not understandable. In some lines of work (like my area of comms: law enforcement) that bit of noise getting out can be enough to summon help or not. There is also a delay with digial that is hard to get used to, and increases the occurances of people talking over eachother, which is inefficient use of the bandwidth.
Digital will get better but costs a ton ($1500 per radio isn't hard to do), but just taking every available analog channel and going narrow analog would effectivly double the "channels" to use while keeping costs low, which appeals to a lot of places, especially California right about now.
CB wastes spectrum? It is less than one half of one MHz. If you want to talk about wasted spectrum just by the size than broadcast TV is a waste. 75 channels at 6MHz each is 450MHz slotted for TV, and they are not all in use all around each other so most sit 100% idle. At least CB activity can pop up all over on all channels. The military has a monstrous chunk from about 200-400MHz that is a wasteland for everyone else. Should they have that much? Probably, they do a lot of wild stuff with it. Should I be able to step into their area because I don't seem to be hearing them at the moment? Probably not.
Digital communications does not make things use less bandwidth. The USFS just went narrowband this year on all their radios, but it is still analog voice. They are trying to lead by example. Digital is just a buzzword people use to make it sound like it is important and should get money.
Point to point (microwave style) communications is very easy because it takes low power and directional antennas so the signals don't mix. That is great for linking towers but try to operate a police force or other geographically diverse group with directional antennas. While extremely high-level and high-power repeater stations might not be the best answer, extremely small and lower power doesn't work well either. Spectrum IS scarce because there are only so many frequencies that will work for omni-directional area communications like so many public service and businesses want. Take out the 450MHz from TV and the 200MHz for military [(1000-150)-(450+200)] and you get about 200MHz of usable frequencies left over for everything else that people require in an omni-style broadcast. Cell phones, public service, business, fun, most of it all has to fit in there.
Hopping frequencies is great until one transceiver breaks the rules (either on accident or maliciously) and screws it for everyone else, who have no idea what is going on or who is the cause of it. Right now the breaks in the frequencies force people to stay out of each others areas. Amateurs have a chunk of "land" to screw around with because if they make a dirty-bomb of a transmitter it only screws up other amateurs nearby and not your local fire/medical dispatch centers.
Except from what I understand those buffers take a ton of battery power and if you could go right to the card fast enough it would eliminate some of the parts inside. Smaller, lighter, faster. It can be better.
Correct, but transmitting with a non-resonant antenna is not a very good thing to do, where car antennas only receive.
It was more of a joke, the math, depending on the size/type of antenna you want, is (# / frequency), which with 0Hz would cause some problems. We were talking about facual errors in the document, and reporting 0mhz as usable was one of them.
Well, open investigations leads me to not want to talk in details, but public knowledge is that he has a combination of grudges against the people using the frequencies as well as physical disabilities that leaves him little other entertainment than his radio.
For people that he doesn't have bad past history with he is decent with on the radio. I wouldn't call him a bad person as much as misaligned. While jail time probably wasn't the best solution for this case, I believe a temporary revocation of his radio license would have sent the message that the behavior is not acceptable and personal issues should be resolved in other ways.
On the other hand, I was once trying to radio in a bicyclist down on a back road and requesting medics respond and I was jammed. We belive it was "our guy" by signal strength readings from around the county during the incident and he has history of jamming the person I was reporting the medical call to. That case we don't have enough to legally proove it was him or not, but it sure made me mad either way; whoever did it directly delayed medical attention to an injured person.
Correct, while Very Low Frequency radios exist the bands are not usable. In the 50s there was much experimentation in these areas, but mosly listening to nature make noises and seeing how transmissions on these bands affected nature. Naturally occurring ELF & VLF radio phenomena make it very hard to reliably use this area for communications, especially when you can bump up a few hz and get much better results. Also, how would you transmit on 0Hz? Your antenna would be infinitely large...
The parent comment is right on. Considering how many people rely on wireless, very very few actually understand how it works (and in many cases, doesn't). I only hope articles like these & their comments teach people something instead of just make people argue and forget about the point. Oh wait, it is/.
Actually it is quite rare for people to go to jail for intentionall jamming. There have been two cases this year that I recall, and the involved multiple (30+) cases of jamming local law enforcement frequencies before they took action. One guy in LA is notorious for doing it, has even been to jail for it once, and continues.
In my jurisdictional area we have a guy that jams amateur frequencies any time they are being used to assist in emergencies. The amateurs working these situations are Disaster Service Workers under CA Office of Emergency Services and are either ARES or RACES affiliated, and he jams the nets. Our local law enforcement wanted to act, but it is a federal issue, so we gave it to Riley Hollingsworth at the FCC. After months of proof being sent in for review, swore statements by multiple officers that witnessed the crime, Riley sent a letter and told him to stop. Nothing ever came of it, it was a waste of time for everyone.
I wish people would actually go to jail for these things, but they normally don't. So go ahead, jam anyone you want, apparently the FCC only cares about getting money for the bands they can and never spending it on enforcement.
Nick Butte County Sheriff Communications [not presumed to be a statement of my employing agency]
Yeah except most people don't know to go looking for them, or don't want to keep checking every week to see if the plugin you want has been created or has been updated to actually work. It seems every time Pheonix/Firebird/Firefox is updated they break half the plugins.
I understand they (Firefox, Thunderbird) are still sub 1.0 and maybe some of the current extensions will make it into the full product because most people want them, I think the average user (not the slashdot user) out there will not want to go fishing for the features they want and will just continue to use IE. It just depends on what Moz/Firefox is going for here, and I can deal with either one.
Ahhh yes... there is a 1000' foot tower nearby my house on a hill that also has a friend's local amateur repeater housed in a vault. We go up to do work on his old machine and just look up 1000 feet into the air in amazement that they could build such a thing and have it stand on one point without falling. Then if you look real close at then end of the wave-guide way up there is the teeny part (or it appears from 1000 feet away) that actually does the transmitting. Quite a lot of work went into getting more people to watch commercials for that channel.
Actually the new digital HDTV channels do not take up any less bandwidth. A channel is 6MHz in the US. Analog and NTSC you get whatever crap 550x430 resolution on current TVs, but with HDTV the added refresh and scanlines increases the bandwidth, then digital compression brings it back down again to, guess where, just under 6MHz. 90% of an HDTV signal should fall into ~5.4MHz. Iteresting thing about digital "modulation" is it spreads the data evenly (or tries, anyway) over is available bandwidth, so you don't get quite the large spikes in power representing analog "loudness." You may notice that in the AM bands, especially CB where the equipment is EQ'ed very well, a person can actually overmodulate the channel and run out of bandwith for their transmission.
I agree the dynamic assigning of frequencies could be quite useful. Right now the system is setup akin to a company buying an entire road and then using it 30% of the time, meanwhile people that didn't pony up the money or have their roads jammed full just sit and look at all the open space they can't use one over.
Problem is, once you start dynamically assigning frequencies, who is to say which user is the highest importance? Every industry will yell they should be higher than everyone else. Also, it requires all the radios to play very nice and move over when someone else comes in. Trunking systems are a start, but anyone that has used one knows they are not as reliable as some would hope, and they are hell for interoperability (note: that is the DHS buzzword of the year).
The software defined radio should help a ton in getting this efficient method of frequency use into the mainstream, and they are still a few years off. Some people argue bandwidth is nearly infinite and people aughta just shut up about it... I ask them to try to use a 5GHz radio to talk out of a mountainous area or beam a microwave link using 5MHz. There always will be frequencies "worth" more than others, and the fights over them will always exist.
With good propigation you can talk, or "work" as most call it, all over the world. One time a friend and I were driving around in his truck when he got a phone call from another freind saying "6 just opened wide up!" We flipped on his 706 and talked from a drive-thru in northern CA to a guy in Greenland. It only lasted about 10 minutes, then the band closed, and we ate our burgers. You wouldn't want your TV signals doing that.
If the people we went after had as much as a bottle of water and a shirt they would be way better off. While most cases our SAR callouts are real needs where someone had multiple small incidents that created one big problem, or were compeltely prepared and still got in trouble, there are the ones that decided to hike 50 miles through snow in flip flops. I have been out on 10+ hour rescues for people that went to the snow with nothing more than a t-shirt. But hey, it is fun for me either way.
Nick, Butte County, CA SAR - http://www.buttesar.org
The laws vary from state to state, but it is normally all volly as others have said. In my county the sheriff deputies are not allowed to be on SAR, which is a bummer because there are several that would otherwise.
As for what is required, generally good shape and a willingness to spend some money and time. I have spent about $1500 on personal gear and I put in about 12-15 hours a week in training, unit support, and the ever random callout. Some calls are minutes long (responce canceled) and I have been out for a 12 hour snow rescue.
You can checkout my unit's website, which has pretty good info for at least a start of what is needed for our group: http://www.buttesar.org
It has taken way more time and money than I thought it would, but it has also been way more fun and rewarding. It keeps me balanced too, computer science classes by day and swiftwater rescues by night.
Nick - Butte County, CA
They don't take all the "search" out of Search & Rescue. First, if you get one, spend the cash and get one with GPS. The non-GPS cheaper ones work off the SARSAT system doing a doppler find on your signal, and it takes several passes of the sattelites to narrow the area down to about 5sq miles, which is still a huge search area.
Latest testing also shows several of the GPS models do not pick up their locations very well, even compred to "cheap" personal GPS devices. Also, the unit being under water or antenna placed in a bad location can attenuate the signal and degrate locating or even make the signal not get out at all. Meanwhile, someone pulled the big red handle on their SAVE ME box and eat all their food and don't set up shelter because help is on the way, and then no one shows up
They are great, but still not perfect. Marketing people coined the 'takes search out of search and rescue' and SAR teams are having to keep up with that impossible demand.
Slashdot Mirror
The average human is about 6 feet, which is approximately one wavelength in the VHF public service and business pools (150MHz). Standing up, you are a nicly resonating grounding device for that energy in the air. I guess I was unclear, the cells heating up is the result of the absorption of the energy, the cells themselves are not resonate but the entire structure, be it a human or an antenna.
The FCC has human exposure rules because this is a very real issue, and not just with GHz. KWNZ, located in Carson City, Nevada, was just fined $10,000 by the FCC for violating public exposure limits at their transmission site, and they are on 93.7MHz (almost 10 foot wavelength).
Especially since law enforcement, road crews, public works, etc. normally have 50w radios, and fire engines normally have 110w radios (for VHF anyway). Drive by one of these guys why they are talking and its going to be absorbed and heat your cells more than a cellphone will. No one worried about them, though, they are public safety!
I am semi-concerned, but there are so many places to get free access already. The library, schools, universities, internet cafe. Some even let you bring your own computer and just plug into their Cat 5 (thats the way we do it at my school if you don't have WiFi). So, it might make it easier, but its not already impossible.
Yeah, not to bash on the guy, but when I read scrubbed I was trying to figure out which moon rocket was up for launch. The blown dry part just made no sense at all and was disregarded. Granted, reading another 10 seconds cleared it up, but misleading headline none-the-less.
If you go to the main page, you can see that 0.9 RC has been released. Mozilla has a habit of updating their main page when a new firefox is out, but not updating their firefox page.
The FCC says they are into enforcement but Hollingsworth, from what I have seen, is all bark and no bite. It would be nice, but...
Local police will not touch anything involving the use of airwaves, they will refer you to the FCC. Most people think the FCC is into enforcement so they are happy to dump you on their lap; the FCC says they are into enforcement and take the case, but as this story and my own personal experience has found, they just don't do anything after that.
The problem is not every person wants to make money off airwaves. Amateurs use it for fun, public services use it because they have to to be effective. Would you buy the space for the portable phone in your house? Who would pay for the WiFi frequencies you are using? Bluetooth? All those other little fun things people use but no one body controls to buy the frequency for would go away. Sometimes things need to be set aside for people that don't have a way to pay for them but have a very good use. Should people have to buy their own roads because they want to drive around, or have a managed system of distribution and sharing? Land is limited in NYC but people can go elsewhere. If they sell all the usable spectrum (and no it isn't infinite) there is no where else to go, you just don't get wireless.
Digital can do wonders getting things narrowband, but the USFS narrowband setup is just as narrow as digital. Some say the digital (APCO P.25 specifically) sounds better after its slight compression, others say it sounds worse. I think it is just what you get used to. The main complaint I hear now is if there is a transmission that would be in the mud in analog mode it is completely lost with digital. The signal is either there to decode or it is not with digital, where at least with analog you would get bursts of noise, even if it was not understandable. In some lines of work (like my area of comms: law enforcement) that bit of noise getting out can be enough to summon help or not. There is also a delay with digial that is hard to get used to, and increases the occurances of people talking over eachother, which is inefficient use of the bandwidth.
Digital will get better but costs a ton ($1500 per radio isn't hard to do), but just taking every available analog channel and going narrow analog would effectivly double the "channels" to use while keeping costs low, which appeals to a lot of places, especially California right about now.
CB wastes spectrum? It is less than one half of one MHz. If you want to talk about wasted spectrum just by the size than broadcast TV is a waste. 75 channels at 6MHz each is 450MHz slotted for TV, and they are not all in use all around each other so most sit 100% idle. At least CB activity can pop up all over on all channels. The military has a monstrous chunk from about 200-400MHz that is a wasteland for everyone else. Should they have that much? Probably, they do a lot of wild stuff with it. Should I be able to step into their area because I don't seem to be hearing them at the moment? Probably not.
Digital communications does not make things use less bandwidth. The USFS just went narrowband this year on all their radios, but it is still analog voice. They are trying to lead by example. Digital is just a buzzword people use to make it sound like it is important and should get money.
Point to point (microwave style) communications is very easy because it takes low power and directional antennas so the signals don't mix. That is great for linking towers but try to operate a police force or other geographically diverse group with directional antennas. While extremely high-level and high-power repeater stations might not be the best answer, extremely small and lower power doesn't work well either. Spectrum IS scarce because there are only so many frequencies that will work for omni-directional area communications like so many public service and businesses want. Take out the 450MHz from TV and the 200MHz for military [(1000-150)-(450+200)] and you get about 200MHz of usable frequencies left over for everything else that people require in an omni-style broadcast. Cell phones, public service, business, fun, most of it all has to fit in there.
Hopping frequencies is great until one transceiver breaks the rules (either on accident or maliciously) and screws it for everyone else, who have no idea what is going on or who is the cause of it. Right now the breaks in the frequencies force people to stay out of each others areas. Amateurs have a chunk of "land" to screw around with because if they make a dirty-bomb of a transmitter it only screws up other amateurs nearby and not your local fire/medical dispatch centers.
Except from what I understand those buffers take a ton of battery power and if you could go right to the card fast enough it would eliminate some of the parts inside. Smaller, lighter, faster. It can be better.
MPC is the greatest. They have made WMP without the suck.
Correct, but transmitting with a non-resonant antenna is not a very good thing to do, where car antennas only receive.
It was more of a joke, the math, depending on the size/type of antenna you want, is (# / frequency), which with 0Hz would cause some problems. We were talking about facual errors in the document, and reporting 0mhz as usable was one of them.
Well, open investigations leads me to not want to talk in details, but public knowledge is that he has a combination of grudges against the people using the frequencies as well as physical disabilities that leaves him little other entertainment than his radio.
For people that he doesn't have bad past history with he is decent with on the radio. I wouldn't call him a bad person as much as misaligned. While jail time probably wasn't the best solution for this case, I believe a temporary revocation of his radio license would have sent the message that the behavior is not acceptable and personal issues should be resolved in other ways.
On the other hand, I was once trying to radio in a bicyclist down on a back road and requesting medics respond and I was jammed. We belive it was "our guy" by signal strength readings from around the county during the incident and he has history of jamming the person I was reporting the medical call to. That case we don't have enough to legally proove it was him or not, but it sure made me mad either way; whoever did it directly delayed medical attention to an injured person.
Correct, while Very Low Frequency radios exist the bands are not usable. In the 50s there was much experimentation in these areas, but mosly listening to nature make noises and seeing how transmissions on these bands affected nature. Naturally occurring ELF & VLF radio phenomena make it very hard to reliably use this area for communications, especially when you can bump up a few hz and get much better results. Also, how would you transmit on 0Hz? Your antenna would be infinitely large...
The parent comment is right on. Considering how many people rely on wireless, very very few actually understand how it works (and in many cases, doesn't). I only hope articles like these & their comments teach people something instead of just make people argue and forget about the point. Oh wait, it is /.
Nick, KG6NMP
Butte County Sheriff Communications
Actually it is quite rare for people to go to jail for intentionall jamming. There have been two cases this year that I recall, and the involved multiple (30+) cases of jamming local law enforcement frequencies before they took action. One guy in LA is notorious for doing it, has even been to jail for it once, and continues.
In my jurisdictional area we have a guy that jams amateur frequencies any time they are being used to assist in emergencies. The amateurs working these situations are Disaster Service Workers under CA Office of Emergency Services and are either ARES or RACES affiliated, and he jams the nets. Our local law enforcement wanted to act, but it is a federal issue, so we gave it to Riley Hollingsworth at the FCC. After months of proof being sent in for review, swore statements by multiple officers that witnessed the crime, Riley sent a letter and told him to stop. Nothing ever came of it, it was a waste of time for everyone.
I wish people would actually go to jail for these things, but they normally don't. So go ahead, jam anyone you want, apparently the FCC only cares about getting money for the bands they can and never spending it on enforcement.
Nick
Butte County Sheriff Communications
[not presumed to be a statement of my employing agency]
Yeah except most people don't know to go looking for them, or don't want to keep checking every week to see if the plugin you want has been created or has been updated to actually work. It seems every time Pheonix/Firebird/Firefox is updated they break half the plugins.
I understand they (Firefox, Thunderbird) are still sub 1.0 and maybe some of the current extensions will make it into the full product because most people want them, I think the average user (not the slashdot user) out there will not want to go fishing for the features they want and will just continue to use IE. It just depends on what Moz/Firefox is going for here, and I can deal with either one.
Ahhh yes... there is a 1000' foot tower nearby my house on a hill that also has a friend's local amateur repeater housed in a vault. We go up to do work on his old machine and just look up 1000 feet into the air in amazement that they could build such a thing and have it stand on one point without falling. Then if you look real close at then end of the wave-guide way up there is the teeny part (or it appears from 1000 feet away) that actually does the transmitting. Quite a lot of work went into getting more people to watch commercials for that channel.
Actually the new digital HDTV channels do not take up any less bandwidth. A channel is 6MHz in the US. Analog and NTSC you get whatever crap 550x430 resolution on current TVs, but with HDTV the added refresh and scanlines increases the bandwidth, then digital compression brings it back down again to, guess where, just under 6MHz. 90% of an HDTV signal should fall into ~5.4MHz. Iteresting thing about digital "modulation" is it spreads the data evenly (or tries, anyway) over is available bandwidth, so you don't get quite the large spikes in power representing analog "loudness." You may notice that in the AM bands, especially CB where the equipment is EQ'ed very well, a person can actually overmodulate the channel and run out of bandwith for their transmission.
I agree the dynamic assigning of frequencies could be quite useful. Right now the system is setup akin to a company buying an entire road and then using it 30% of the time, meanwhile people that didn't pony up the money or have their roads jammed full just sit and look at all the open space they can't use one over.
Problem is, once you start dynamically assigning frequencies, who is to say which user is the highest importance? Every industry will yell they should be higher than everyone else. Also, it requires all the radios to play very nice and move over when someone else comes in. Trunking systems are a start, but anyone that has used one knows they are not as reliable as some would hope, and they are hell for interoperability (note: that is the DHS buzzword of the year).
The software defined radio should help a ton in getting this efficient method of frequency use into the mainstream, and they are still a few years off. Some people argue bandwidth is nearly infinite and people aughta just shut up about it... I ask them to try to use a 5GHz radio to talk out of a mountainous area or beam a microwave link using 5MHz. There always will be frequencies "worth" more than others, and the fights over them will always exist.
With good propigation you can talk, or "work" as most call it, all over the world. One time a friend and I were driving around in his truck when he got a phone call from another freind saying "6 just opened wide up!" We flipped on his 706 and talked from a drive-thru in northern CA to a guy in Greenland. It only lasted about 10 minutes, then the band closed, and we ate our burgers. You wouldn't want your TV signals doing that.
KG6NMP
If the people we went after had as much as a bottle of water and a shirt they would be way better off. While most cases our SAR callouts are real needs where someone had multiple small incidents that created one big problem, or were compeltely prepared and still got in trouble, there are the ones that decided to hike 50 miles through snow in flip flops. I have been out on 10+ hour rescues for people that went to the snow with nothing more than a t-shirt. But hey, it is fun for me either way.
Nick, Butte County, CA SAR - http://www.buttesar.org
The laws vary from state to state, but it is normally all volly as others have said. In my county the sheriff deputies are not allowed to be on SAR, which is a bummer because there are several that would otherwise.
As for what is required, generally good shape and a willingness to spend some money and time. I have spent about $1500 on personal gear and I put in about 12-15 hours a week in training, unit support, and the ever random callout. Some calls are minutes long (responce canceled) and I have been out for a 12 hour snow rescue.
You can checkout my unit's website, which has pretty good info for at least a start of what is needed for our group: http://www.buttesar.org
It has taken way more time and money than I thought it would, but it has also been way more fun and rewarding. It keeps me balanced too, computer science classes by day and swiftwater rescues by night.
Nick - Butte County, CA
They don't take all the "search" out of Search & Rescue. First, if you get one, spend the cash and get one with GPS. The non-GPS cheaper ones work off the SARSAT system doing a doppler find on your signal, and it takes several passes of the sattelites to narrow the area down to about 5sq miles, which is still a huge search area.
Latest testing also shows several of the GPS models do not pick up their locations very well, even compred to "cheap" personal GPS devices. Also, the unit being under water or antenna placed in a bad location can attenuate the signal and degrate locating or even make the signal not get out at all. Meanwhile, someone pulled the big red handle on their SAVE ME box and eat all their food and don't set up shelter because help is on the way, and then no one shows up
They are great, but still not perfect. Marketing people coined the 'takes search out of search and rescue' and SAR teams are having to keep up with that impossible demand.
Nick, Butte County, CA Search & Rescue