I *do* however have a problem with hiring someone who is less qualified but will either work for less money [often the case in H1-B visa]
Really? If you had such a problem with it, why didn't you call the INS and tell them? I mean, after all, that's actually illegal for the hiring company to do.
Oh, you didn't do that? Why? No proof? No evidence? All supposition? Shame.
Hell, while we're at it - microchip all non-citizens in the country so we can keep track of them. They're not US citizens and should't be guaranteed certain rights at the expense of the safety and welfare of those of us who are citizens...
You can microchip me when you change the law to let me become a citizen without having to wait 7 years. That's 7 years *after* getting my green card, bub.
If you don't agree to that? Tough shit. You're not coming near *my* body with anything, unless I get to do the same thing to you with my dick. Capice?
Only if you wanted to redistribute the library for free. Today, you can't distribute the library for free at all: you or your customer must buy it.
I don't know if you've done much shopping for libraries lately, but most are royalty free. The developer pays once for the library, and then can redistribute that library in binary form for nothing. The end customer buys your software, not that individual library.
If Tower didn't overcharge for everything (compared their prices to, say, Wherehouse or even Borders), then they might not be in such bad shape. I for one avoid Tower wherever possible -- the extra $3 to $5 markup on DVDs make it pointless going there.
Not likely. Independent developers are known for innovative and new ideas. The game industry is only interested in sequels. Proof? Every popular game last year was a sequel. Every one.
Thanks. That was exactly the answer I was expecting. I suggest you take a look at this article [paulgraham.com] to start with.
Looked at it...
I still don't see any immense benefit over C++ with templates. Most engineering tasks involve little more than picking the best compromise from the massively combinatorial options available to you.
Not to mention that his comparison at the end of his talk is somewhat... stretched. After all, how often would one need to code an accumulator? The Python solution linked to later in the rebuttals is actually more easily understandable (and thus, better code) than the LISP solution.
Given that the most costly and most pervasive engineering work is code maintenance, it helps if your work is easy to understand. If you enjoy playing in the dark not-too-often-visited corners of the field, then be my guest. Knowing LISP, however, does not a great engineer make. Neither does knowing tuple notation for database normalization; an engineer with a solid foundation of the design choices behind database normalization may never use tuple notation -- but may get the same results.
The same thing applies to UML -- a system of notation which has always seemed clumsy to me.
For the record, I took my degree in Physics with a side order of Electronic Engineering. There was a good reason for this; it would have been at least 2 years of a 3 year course for me to have gotten anywhere even close to learning anything new. I chose education instead of an easy walk in the park. But you can look at my bookshelf right now, and see everything from texts on Generative Programming, to a walk through the Linux kernel, through the internals of SQL Server, K&R's book, Plauger's companion to it, the (showing its age) Lakos book on Large Scale C++ software architecture, a smattering of texts on UML, a 5 volume set of books examining most of the programming languages in use today (everything from LISP through Fortran, Cobol and Ada), books on Internationalization and User Interface design, books on debugging techniques including stack walking, compiler design, database theory et al. Oh, and Knuth. Can't forget Knuth.
A codified education in Computer Science does not a software engineer make. Continued learning and reading -- and preferably a passion for what you are doing, which includes the desire to better one's knowledge and abilities -- does.
Well sorry, but I don't want to "forget" all of these things. And I'm sorry but I don't buy into the idea that I have to sit passively and stoically accept that I am going to get fucked in the ass. I guess there are a lot of passive-agressive socially retarted Farscape marathon-watching dorks in the industry who will, but not I.
You might not be having as many employment issues if you would learn how to write correct English. Passive Aggressive? Socially Retarded? You're describing Star Trek fans - not Farscape fans.
No offense to the H1-Bs that come to this country seeking better wages, but there's more to engineering than being able to operate validation software...
No offense to you, but there's more to architecting software than running around in a room, playing with lego, and hitting yourself over the head with a skillet.
But, of course, being American you wouldn't know that because your education system absolutely sucks. A 4 year degree in the US gets you the equivalent of 2 years study in any European country.
Oh, sorry, you didn't mean to start a fight? Right. Well, get off your stupid fat bigoted ass and learn a little about the world around you. Or happily accept that you're a bigot. Pick one. Live it. Love it.
Programming is critical thinking, and that can't really be taught in a classroom. You either cultivate it yourself, or you don't. That's certainly a big part of it.
With this: "You can do it on your own, but classroom can provide a clear direction and help filter the stupid stuff from the essential stuff."
If you've got the critical thinking part down, just exactly why would you need a classroom to help you filter the wheat from the chaff?
The only things you have to do to teach yourself is to read, and to experiment. Or you can go the other route and learn from your peers. Either way, a classroom is not a prerequisite if you have any kind of curiosity about the field you're choosing as a career.
Stacker - Stolen compression technology, case later settled by MS.
Stacker was a PATENT INFRINGEMENT CASE, not a stolen IP case.
here's some words from an expert in the field of compression and patents:
http://www.ross.net/compression/
" Waterworth patented a LZ77 variant (US Patent 4701745). This algorithm is generally referred to as as LZRW1, because Ross Williams reinvented it later and posted it on comp.compression on April 22, 1991. The same algorithm has later been patented by Gibson & Graybill (US Patent 5049881). The patent office failed to recognize that the same algorithm was patented twice, even though the wording used in the two patents is very similar.
The Waterworth patent is now owned by Stac, which won a lawsuit against Microsoft, concerning the compression feature of MS-DOS 6.0. Damages awarded were $120 million. (Microsoft and Stac later settled out of court.) "
From his resume: "Consulting to Microsoft: In 1993 Stac initiated a software patent lawsuit against Microsoft over the doublespace data compression feature of MS-DOS 6. As part of its defence, Microsoft retained me as an expert in text data compression. Tasks involved searching for prior art and evaluating patents. "
Most importantly, however:
http://www.ross.net/compression/introduction.htm l
"Unfortunately, during this happy rollout, some patents popped out of the US patent system that cast a shadow over the LZRW series algorithms, and they became effectively unuseable in any practical application. If you want to use them in any product (whether free or commercial), you will have to do some in-depth patent homework and algorithm development/modification so as to avoid infringement. If you think that's easy, then you should be aware that Microsoft tried to use an LZ77/LZRW1/etc variant, specifically designed not to infringe existing patents, in its MS-DOS V6 operating system, and ended up having to pay Stac about $80m in the resulting patent lawsuit. For this reason, I would like to take this opportunity to state that the code provided in this web (and FTP site) is provided with the intention that it be used for educational and recreational use only. "
Miyamoto created this industry. After the gaming crash of the late 80's (Atari generation) it was the Famicom from Nintendo that reinvigorated the industry, bringing it back from the brink of extinction. And why was the Famicom (NES outside Japan) so successful? It was successful because of Super Mario Brothers and The Legend of Zelda, both coming from Shiggy. There was no side-scroller before Super Mario Brothers. There was no top-down adventure/RPG before Zelda. He invented the fscking genre and Seamus FSCKING Blackley is doubting him?
Super Mario Bros - released in 1985 (Nintendo)
Defender - released in 1980 (Williams). The *first* sideways-scrolling game.
Scramble - released in 1981 (Konami) - sideways scrolling shoot-em-up.
(http://www.klov.com/game_detail.php?letter=S&ga me _id=2725)
Or of course, there's Choplifter from 1982 (Broderbund). Or Defender (1983).
Or Splat (4 way scroller, 1983, Incentive Software Ltd)
Or heck, for 1984 there's Tir Na Nog from Gargoyle Games -- and a game which had much more depth than Super Mario Bros.
I spend a lot of time dealing with hiring for the IT staff at my company. These days, I pretty much instantly trash any resume doesn't include some sort of background with creating or maintaining an Open Source projust of reasonable size. It may be an unfair bias, but experience has shown me that OSS developers are almost always an order of magnitude more skilled and more responsible than applicants from other backgrounds.
The self-motivation, self-discipline, organizational skills, and willingness to write code that the author isnt ashamed to display to the whole world are exactly the sort of traits that employers look for (or should be, anyway).
And, of course, the willingness to work for next to nothing doesn't hurt when it comes to your balance sheet.
If anyone's still dumb enough to be smoking, that study should have put them off...
Unfortunately, there's the whole addiction side of it which kind of gets in the way.
Re:.. and in the darkness bind them
on
More on Longhorn
·
· Score: 3, Interesting
Tobacco harms you - you - far more than you see. It raises health care costs (and takes all that income going to health care out of the rest of the economy.) If you have a loved one addicted to tobacco, it's far more destructive than a loved one who uses Microsoft. If your co-workers smoke, then you get second-hand smoke. (If "quit your job" is an option for smokers, then it's also an option for people working at MS shops.)
Actually, the healthcare costs are minor compared to the taxation on cigarettes. Smokers have already paid for their healthcare many times over with the additional tax on cigarettes.
Add to that the fact that most smokers will never need long term geriatric care because they'll die young, and the net health care costs for smokers actually end up being lower.
Oh, I definitely think Open Source is the best, if that's what you mean by bias. What you need is an unbiased third party to evaluate both sides. Like Terry Bollinger at MITRE. His conclusion is really interesting reading. Bruce
Unbiased?
Terry Bollinger is as unbiased about open source as you are.
He's been pushing Open Source since at least 1998 in paper after paper after paper. Which means he's Pro Open Source -- he's not a neutral party.
Claim he's unbiased if you want, but you're wrong to do so.
Finnally, I apologize for the harshness of my reply. You seemed to oversimplify things so much that I thought you were talking out your ass after physics 101. Please accept this appology
Hey, no problem. I deliberately simplified things because the target audience most likely didn't know anything about radio; if they did, they'd already know what the deal was:)
The key thing for me in understanding how all this stuff works was when I realized that to receive and decode a radio signal, all you need to do is to introduce a non-linearity (the same way a cat's whisker set works). After that, it's all just a matter of fine tuning the filters.
So you're trying to tell me the billboard has a receiver so sensitive to pick up on the internal oscillator in my car radio. Not only will it pick up on this EXTREMELY low level signal, past all the noise and crap in the air, it will take an aggregate of all the cars in the area and figure the most listened to station.
Yes, it does. TV detector vans in the UK work on this principle -- and no, they don't work off vsync or hsync flyback voltages (well, ok; they use that to tell if you've got a TV) -- they can actually tell which channel you're watching, based on the carrier freq. you're using to decode the VHF/UHF signal.
No... First off your method of demodulating an FM signal is all wrong. You got the first stage right. The RF is broken down into an intermediate frequency (IF) by mixing it with a locally generated signal. But then you are all wrong. The IF is not rectified and filtered in an FM receiver. That is for AM.
In FM, the IF is run past a discriminator circuit. A change in frequency is interpreted as a change in amplitude and thus produces the audio.
Same difference. No; seriously. If you take the signal and pass it through an integrator, you get exactly the same net result. There are more elegant ways of decoding the signal which reduce noise, but this is decoding at its most basic. You did all the hard work when you mixed in the carrier frequency.
Now, if you're encoding stereo on the signal, then yes, you need a discriminator.
As I said, there's not much to it. Note the diodes for rectification of the signal.
If it was so easy to tell what radio frequency one was listening to, what would I (as a member of the US Navy) do? The enemy would know what frequencies we were listening to. That would get them one step closer to breaking our encryption and listening to our messages.
Yup... that's the case. That's why the Navy doesn't use FM for sensitive communications; they use spread spectrum.
So how exactly do these billboards figure out what radio stations people are listening to? Do radios emit EM signals that can be used to determine what they're tuned to (it's been a long time since I took a physics class, somebody help me out here)?
Yep - as do television sets.
It's called heterodyning, and is used to decode FM (frequency modulated) signals. Basically, you mix the signal coming in with the frequency you want to listen to, and the signal at that frequency gets amplified (due to the interference), and the outcome of that is rectified, amplified, and is ultimately what you listen to.
So the billboard picks up the frequency you're mixing the incoming signal with (because you need a frequency generator to create that frequency, and they will emit it -- there's not much you can do to stop it short of burying it in a completely metal box -- which kind of stops the incoming radio signal).
Slashdot Mirror
I *do* however have a problem with hiring someone who is less qualified but will either work for less money [often the case in H1-B visa]
Really? If you had such a problem with it, why didn't you call the INS and tell them? I mean, after all, that's actually illegal for the hiring company to do.
Oh, you didn't do that? Why? No proof? No evidence? All supposition? Shame.
Simon
Hell, while we're at it - microchip all non-citizens in the country so we can keep track of them. They're not US citizens and should't be guaranteed certain rights at the expense of the safety and welfare of those of us who are citizens...
You can microchip me when you change the law to let me become a citizen without having to wait 7 years. That's 7 years *after* getting my green card, bub.
If you don't agree to that? Tough shit. You're not coming near *my* body with anything, unless I get to do the same thing to you with my dick. Capice?
Only if you wanted to redistribute the library for free. Today, you can't distribute the library for free at all: you or your customer must buy it.
I don't know if you've done much shopping for libraries lately, but most are royalty free. The developer pays once for the library, and then can redistribute that library in binary form for nothing. The end customer buys your software, not that individual library.
Simon
If Tower didn't overcharge for everything (compared their prices to, say, Wherehouse or even Borders), then they might not be in such bad shape. I for one avoid Tower wherever possible -- the extra $3 to $5 markup on DVDs make it pointless going there.
Are they going to release command line versions of most of their administrative tools?
You know, maybe I'm smoking crack, but I'm pretty sure that most of the admin tools already had command line (or at least scriptable) versions.
WMI being the biggie.
Simon
Not likely. Independent developers are known for innovative and new ideas. The game industry is only interested in sequels. Proof? Every popular game last year was a sequel. Every one.
Waitaminute...
Halo's not a sequel.
Thanks. That was exactly the answer I was expecting. I suggest you take a look at this article [paulgraham.com] to start with.
Looked at it...
I still don't see any immense benefit over C++ with templates. Most engineering tasks involve little more than picking the best compromise from the massively combinatorial options available to you.
Not to mention that his comparison at the end of his talk is somewhat... stretched. After all, how often would one need to code an accumulator? The Python solution linked to later in the rebuttals is actually more easily understandable (and thus, better code) than the LISP solution.
Given that the most costly and most pervasive engineering work is code maintenance, it helps if your work is easy to understand. If you enjoy playing in the dark not-too-often-visited corners of the field, then be my guest. Knowing LISP, however, does not a great engineer make. Neither does knowing tuple notation for database normalization; an engineer with a solid foundation of the design choices behind database normalization may never use tuple notation -- but may get the same results.
The same thing applies to UML -- a system of notation which has always seemed clumsy to me.
For the record, I took my degree in Physics with a side order of Electronic Engineering. There was a good reason for this; it would have been at least 2 years of a 3 year course for me to have gotten anywhere even close to learning anything new. I chose education instead of an easy walk in the park. But you can look at my bookshelf right now, and see everything from texts on Generative Programming, to a walk through the Linux kernel, through the internals of SQL Server, K&R's book, Plauger's companion to it, the (showing its age) Lakos book on Large Scale C++ software architecture, a smattering of texts on UML, a 5 volume set of books examining most of the programming languages in use today (everything from LISP through Fortran, Cobol and Ada), books on Internationalization and User Interface design, books on debugging techniques including stack walking, compiler design, database theory et al. Oh, and Knuth. Can't forget Knuth.
A codified education in Computer Science does not a software engineer make. Continued learning and reading -- and preferably a passion for what you are doing, which includes the desire to better one's knowledge and abilities -- does.
Simon
Simon
How many would even know why Lisp is important?
I don't think programming Emacs plugins is all that important personally. Lisp is only really of use in the AI field.
You're talking esoterica and dusty cobwebbed corners of the field -- not anything that 99% of engineers will ever need to know.
Simon
Well sorry, but I don't want to "forget" all of these things. And I'm sorry but I don't buy into the idea that I have to sit passively and stoically accept that I am going to get fucked in the ass. I guess there are a lot of passive-agressive socially retarted Farscape marathon-watching dorks in the industry who will, but not I.
You might not be having as many employment issues if you would learn how to write correct English. Passive Aggressive? Socially Retarded? You're describing Star Trek fans - not Farscape fans.
Simon
No offense to the H1-Bs that come to this country seeking better wages, but there's more to engineering than being able to operate validation software...
No offense to you, but there's more to architecting software than running around in a room, playing with lego, and hitting yourself over the head with a skillet.
But, of course, being American you wouldn't know that because your education system absolutely sucks. A 4 year degree in the US gets you the equivalent of 2 years study in any European country.
Oh, sorry, you didn't mean to start a fight? Right. Well, get off your stupid fat bigoted ass and learn a little about the world around you. Or happily accept that you're a bigot. Pick one. Live it. Love it.
Compare this:
Programming is critical thinking, and that can't really be taught in a classroom. You either cultivate it yourself, or you don't.
That's certainly a big part of it.
With this:
"You can do it on your own, but classroom can provide a clear direction and help filter the stupid stuff from the essential stuff."
If you've got the critical thinking part down, just exactly why would you need a classroom to help you filter the wheat from the chaff?
The only things you have to do to teach yourself is to read, and to experiment. Or you can go the other route and learn from your peers. Either way, a classroom is not a prerequisite if you have any kind of curiosity about the field you're choosing as a career.
Simon
Stacker - Stolen compression technology, case later settled by MS.
m l
Stacker was a PATENT INFRINGEMENT CASE, not a stolen IP case.
here's some words from an
expert in the field of compression and patents:
http://www.ross.net/compression/
" Waterworth patented a LZ77 variant (US Patent 4701745). This algorithm
is generally referred to as as LZRW1, because Ross Williams reinvented
it later and posted it on comp.compression on April 22, 1991. The same
algorithm has later been patented by Gibson & Graybill (US Patent
5049881). The patent office failed to recognize that the same algorithm
was patented twice, even though the wording used in the two patents is
very similar.
The Waterworth patent is now owned by Stac, which won a lawsuit against
Microsoft, concerning the compression feature of MS-DOS 6.0. Damages
awarded were $120 million. (Microsoft and Stac later settled out of
court.) "
From his resume: "Consulting to Microsoft: In 1993 Stac initiated a
software patent lawsuit against Microsoft over the doublespace data
compression feature of MS-DOS 6. As part of its defence, Microsoft
retained me as an expert in text data compression. Tasks involved
searching for prior art and evaluating patents. "
Most importantly, however:
http://www.ross.net/compression/introduction.ht
"Unfortunately, during this happy rollout, some patents popped out of
the US patent system that cast a shadow over the LZRW series algorithms,
and they became effectively unuseable in any practical application. If
you want to use them in any product (whether free or commercial), you
will have to do some in-depth patent homework and algorithm
development/modification so as to avoid infringement. If you think
that's easy, then you should be aware that Microsoft tried to use an
LZ77/LZRW1/etc variant, specifically designed not to infringe existing
patents, in its MS-DOS V6 operating system, and ended up having to pay
Stac about $80m in the resulting patent lawsuit. For this reason, I
would like to take this opportunity to state that the code provided in
this web (and FTP site) is provided with the intention that it be used
for educational and recreational use only. "
Get a better DVD player. Yours is defective.
No problems with the menus on my system. (Pioneer, twin laser).
What's yours?
Simon
Miyamoto created this industry. After the gaming crash of the late 80's (Atari generation) it was the Famicom from Nintendo that reinvigorated the industry, bringing it back from the brink of extinction. And why was the Famicom (NES outside Japan) so successful? It was successful because of Super Mario Brothers and The Legend of Zelda, both coming from Shiggy. There was no side-scroller before Super Mario Brothers. There was no top-down adventure/RPG before Zelda. He invented the fscking genre and Seamus FSCKING Blackley is doubting him?
a me _id=2725)
m
Super Mario Bros - released in 1985 (Nintendo)
Defender - released in 1980 (Williams). The *first* sideways-scrolling game.
Scramble - released in 1981 (Konami) - sideways scrolling shoot-em-up.
(http://www.klov.com/game_detail.php?letter=S&g
Or of course, there's Choplifter from 1982 (Broderbund). Or Defender (1983).
Or Splat (4 way scroller, 1983, Incentive Software Ltd)
Or heck, for 1984 there's Tir Na Nog from Gargoyle Games -- and a game which had much more depth than Super Mario Bros.
http://www.luny.co.uk/sinclair/gargoyle/tirm.ht
Simon
I certainly hope that authors in the future don't recieve royalties for public library readers.
They already do. There is a world outside of the US, you know.
Simon
Is purify available for Linux?
Probably not, but I'm sure the open source community can come up with their own version given a few years and a copy of the original.
Simon
(Oh, I'm sorry... was that bitter and cynical? My mistake)
I'm gonna take a wild guess and say that was probably on purpose.
Murky Bucket for pointing that out.
Simon
He probably did not like to lie so much. I heard that if you don't lie to dozen people by lunch you get fired from MS.
You still work there then huh? Or did you start working for Sun when you got good at it?
I spend a lot of time dealing with hiring for the IT staff at my company. These days, I pretty much instantly trash any resume doesn't include some sort of background with creating or maintaining an Open Source projust of reasonable size. It may be an unfair bias, but experience has shown me that OSS developers are almost always an order of magnitude more skilled and more responsible than applicants from other backgrounds.
The self-motivation, self-discipline, organizational skills, and willingness to write code that the author isnt ashamed to display to the whole world are exactly the sort of traits that employers look for (or should be, anyway).
And, of course, the willingness to work for next to nothing doesn't hurt when it comes to your balance sheet.
If anyone's still dumb enough to be smoking, that study should have put them off...
Unfortunately, there's the whole addiction side of it which kind of gets in the way.
Tobacco harms you - you - far more than you see. It raises health care costs (and takes all that income going to health care out of the rest of the economy.) If you have a loved one addicted to tobacco, it's far more destructive than a loved one who uses Microsoft. If your co-workers smoke, then you get second-hand smoke. (If "quit your job" is an option for smokers, then it's also an option for people working at MS shops.)
Actually, the healthcare costs are minor compared to the taxation on cigarettes. Smokers have already paid for their healthcare many times over with the additional tax on cigarettes.
Add to that the fact that most smokers will never need long term geriatric care because they'll die young, and the net health care costs for smokers actually end up being lower.
Not that this is a good thing, mind you...
Simon
Oh, I definitely think Open Source is the best, if that's what you mean by bias. What you need is an unbiased third party to evaluate both sides. Like Terry Bollinger at MITRE. His conclusion is really interesting reading.
Bruce
Unbiased?
Terry Bollinger is as unbiased about open source as you are.
He's been pushing Open Source since at least 1998 in paper after paper after paper. Which means he's Pro Open Source -- he's not a neutral party.
Claim he's unbiased if you want, but you're wrong to do so.
Finnally, I apologize for the harshness of my reply. You seemed to oversimplify things so much that I thought you were talking out your ass after physics 101. Please accept this appology
:)
Hey, no problem. I deliberately simplified things because the target audience most likely didn't know anything about radio; if they did, they'd already know what the deal was
The key thing for me in understanding how all this stuff works was when I realized that to receive and decode a radio signal, all you need to do is to introduce a non-linearity (the same way a cat's whisker set works). After that, it's all just a matter of fine tuning the filters.
Simon
So you're trying to tell me the billboard has a receiver so sensitive to pick up on the internal oscillator in my car radio. Not only will it pick up on this EXTREMELY low level signal, past all the noise and crap in the air, it will take an aggregate of all the cars in the area and figure the most listened to station.
Yes, it does. TV detector vans in the UK work on this principle -- and no, they don't work off vsync or hsync flyback voltages (well, ok; they use that to tell if you've got a TV) -- they can actually tell which channel you're watching, based on the carrier freq. you're using to decode the VHF/UHF signal.
No... First off your method of demodulating an FM signal is all wrong. You got the first stage right. The RF is broken down into an intermediate frequency (IF) by mixing it with a locally generated signal. But then you are all wrong. The IF is not rectified and filtered in an FM receiver. That is for AM.
In FM, the IF is run past a discriminator circuit. A change in frequency is interpreted as a change in amplitude and thus produces the audio.
Same difference. No; seriously. If you take the signal and pass it through an integrator, you get exactly the same net result. There are more elegant ways of decoding the signal which reduce noise, but this is decoding at its most basic. You did all the hard work when you mixed in the carrier frequency.
Now, if you're encoding stereo on the signal, then yes, you need a discriminator.
Here's a basic mono-FM signal receiver.
As I said, there's not much to it. Note the diodes for rectification of the signal.
If it was so easy to tell what radio frequency one was listening to, what would I (as a member of the US Navy) do? The enemy would know what frequencies we were listening to. That would get them one step closer to breaking our encryption and listening to our messages.
Yup... that's the case. That's why the Navy doesn't use FM for sensitive communications; they use spread spectrum.
Simon
So how exactly do these billboards figure out what radio stations people are listening to? Do radios emit EM signals that can be used to determine what they're tuned to (it's been a long time since I took a physics class, somebody help me out here)?
Yep - as do television sets.
It's called heterodyning, and is used to decode FM (frequency modulated) signals. Basically, you mix the signal coming in with the frequency you want to listen to, and the signal at that frequency gets amplified (due to the interference), and the outcome of that is rectified, amplified, and is ultimately what you listen to.
So the billboard picks up the frequency you're mixing the incoming signal with (because you need a frequency generator to create that frequency, and they will emit it -- there's not much you can do to stop it short of burying it in a completely metal box -- which kind of stops the incoming radio signal).
Simon