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Ham Operator Sets New Miles-Per-Watt World Record
DoctorPepper writes "A ham radio operator in New London, North Carolina correctly copied an 80 meter CW beacon in Wappingers Falls, New York, a distance of 546.8 miles. The kicker is, the beacon station, an Elecraft K1, was putting out 40.6 uW (40.6 millionths of a Watt) -- which works out to 13,467,980 miles per watt!"
Even most directional antennas will not give you linear 'watt to distance' amplification.
In worst case it is a power^1/3. So for 40 milliwatts to 1 watt amplification you'll get some 30x distance (at worst), but never 2500x, unless some wicked atmospheric conditions happen.
According to the article, the receiving operator was using a 1,000 foot antenna. I'd be more impressed if the antenna were smaller.
"Lack of technical competence coupled with the arrogance of power, as usual, leads to no good end."
This seems an odd way to compare accomplishments. If you use this metric, then you reach the false conclusion that doubling wattage doubles distance. Since signal strength deteriorates with distance squared, a better metric might be miles^2 per Watt.
Example using round numbers. Philip transmits 10 miles using a 10W transmitter. Sally transmits 19 miles using a 20W transmitter. If you use miles per Watt to compare, it looks like Philip achieved better results, when in fact Sally did.
It's as sensible as measuring distance travelled/max acceleration of a car. There simply isn't a linear relationship between these things and so dividing one by the other doesn't give you anything interesting. If we start dividing random variables by each other and reporting the result on /. we'd never get to read any interesting news.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
The record is quite impressive given that there is more land and civilization between the new points of the new record. Still probably used ionsphere to bounce it forward, but there would be less ground effect in the new record than in the old.
These guys have advanced antennas but its still way cool that with a QRP rig and even a simple wire antenna, you can communicate over great distances with the juice of a 9 volt battery.
Here is a list of some famous hams
Pete Carr Owner Chatmag.com
The units here are watts per square mile. Your typical FM radio station has a range of maybe 50 miles and is running maybe 10 kwatts, so they're doing 4 watts per square mile. This guy is doing much better. My own power/distance record, back when I was active in ham radio, was 7000 miles on about 25 watts, or 5.10204082 × 10**-7 watts per square mile.
You might wonder how it's remotely possible for there to be a gap of seven to ten orders of magnitude. Why aren't we bothered by FM radio stations on the other side of the world? There is a qualitative difference between the behavior of radio waves above and below about 30-50 MHz (the FM band starts at 88 MHz). Conditions permitting, the lower frequencies can refract in the ionosphere and come back down to earth along non-straight-line paths. That's why shortwave radio stations on other continents can be heard.
WWJD for a Klondike Bar?
My cell phone can talk around the world on it's itty bitty power output.
No, it can't. That is why there are those little bars showing signal strength. You're lucky the newer digital units can get two miles to a tower (where it is then pumped thru an ATM link over a T-1 to the landline network).
Funny, fine. But to whomever modded that post "Informative" needs to go back to school.
-Charles
Learning HOW to think is more important than learning WHAT to think.
For maximum pessimism, say that it's currently putting its maximum 315 watts into "phoning home" -- I work this out to 26.1 million miles per watt. (My guess is that realistically it's more like 1e3 times that.)
Sorry HAM-guy, but Voyager still kicks yer butt.
Cheers,
Richard
It's more like hearing a whisper across a huge crowded stadium.
The listener had really good ears and was able to pick out the code from a lot of background noise, with a really good antenna setup.
/sig
Outmoded you say? Here's a recent example that may make you change your mind on that one.
f m
http://www.voanews.com/english/2005-01-05-voa24.c
Actually, this IS kind of neat. Most of the ham market is owned by Japanese radios: Icom, Yaesu, and Kenwood. It IS neat using American gear.
Plus, the Elecraft K1 is a kit. If you want one, you get a board, a metal box, and a bag full of parts. Some assembly required. For some people (like me), this is a feature, not a bug.
"-1 Troll" is the apparently the same as "-1 I disagree with you."
Miles per watt indeed! What tosh.
Try channels 11 and up. Amateurs only go up to 2.450GHz.
echo 33676832766569823265328479713269.8639857989Pq | dc
Right...the power drops off as the square of the distance, when you are operating in the far field.
The far field of an antenna starts at a point where the radiated wavefront is practically flat. One such measure of this distance is
2* D^2
R = ----------
wavelength
where D is the largest dimension of the antenna. With a satellite dish, this is the reflector diameter typically; with a monopole ("stick") antenna it is the antenna length. There are other measures that are also used to calculate the start of the far field, but I can't recall them now; I will say that whichever one yields the furthest distance is the thumbrule used.
Your orientation to the radiating antenna also plays a role. A "stick" antenna (dipole or monopole) has more energy radiated perpendicular to the mast than along the mast axis. In free space with no reflections, you can stand at either end of a stick antenna and not receive squat, as long as you are in the far field. Thus, you must also consider the gain of your antenna in the direction of interest. A stick antenna has about 3dB gain perpendicular to it, and negative infinity gain along the antenna axis.
The actual equation to get the power density Pr when distance r from the source is:
Pt * Gt
Pr = ----------
4pi*r^2
Pt = Power radiated
Gt = Gain of your antenna
That's why the change in power to distance isn't linear. May have been long-winded but I spent most of the afternoon doing power density calculations so it was fresh in my head.
Government's idea of a balanced budget: take money from the right pocket to balance...oh who am I kidding?
That is true, but the Technician license doesn't allow one to use the HF bands unless you have also passed the 5 words-per-minute code examination.
The General license, which requires passing another written exam beyond the Technician level and the 5 WPM code test, allows for far greater privileges on all the amateur bands.
I studied code and took the exam just so I could get HF privileges. I have not used it a whole lot since then. I only had to use it a few times to realize that I really dislike code. Not because it's obsolete (which it is beyond amateur radio) but because it's a slow way of holding a conversation, and I just don't have the patience for it.
On the up side, I was able to nab a couple of countries using CW (Morse Code) that I didn't yet have in my log book-- Australia and Poland.
What happens, though, is that the wavefront becomes larger , and you have to build antennas also larger to capture the same amount of energy.
But, for example, if you completely surround the transmitter with your antenna then you will reclaim all the transmitted energy. This is one of fundamental principles of the field theory. Mathworld has a very good explanation that leads into Maxwell equations.
Also, the path loss in a given direction does not depend on the antenna.
Friis formula is actually Pr=(Pt*Gt*Gr*lambda^2)/(4*pi*r)^2.h tml to verfiy.
Please reference http://www.ce-mag.com/archive/02/Spring/fogelle2.
Obviously if he had a very directonal receiving antenna then this is possible.
... in "miles per watt" anybody can beat this "record" pretty much anytime.
As many people have mentioned, the unit chosen is stupid. It is not about nitpicking, the unit has no meaning: this guy could easily beat his own record, not by going into space but simply by sitting half as far, or (even better) right next to the transmitting station. Indeed, all things being equal (hardware used, the ham's ear), the chosen measure increases linearly with the inverse of the distance, and more if the fall-off is higher (usually 3 or 4 in "real life").
As many people mentioned, power fall-off is inverse-square of distance in free space. That means that if the guy had stood half as far, all other things remaining equal, he would have received four times as much power. He could have then halved the transmitted power, he would still have received twice the power as in the reported experiment (making things easier for him to hear). But because the power halved and the distance halved in the process too, the "measure" of distance per power didn't change.
Is this a joke by radio amateurs trying to get the media or Slashdot to publish stupid claims?
Ham radio is not just about talking. Ham radio licences, at least my UK one (G4JZA), allows you to design, build and use transmitters without having to have them type approved.
Why in hell did you stupid moderators mod the parent insightful?
I think it's a glitch in the system... I've already been given 10 mod points this week. Christmas bonus? Whatever... I'll just be sure to fulfill my destiny to moderate as stupidly as possible. I'll post the links to the posts I moderate in my journal, if you'd care to bit^W complain about my mad mod skillz.
Stressed? Me? Of course not. Stress is what a rubber band feels before it breaks, silly.