Using wireless for one-way streaming of digital audio broadcasting?

802.11 doesn't do a mile, maybe a few hundred feet, unless you get into expensive fixed antennas, and then you are out of the league of your $10-20 reciever.

So get a low-power FM license and see how you do. Trying to make a silk purse (radio/tv broadcast) out of a sow's ear (802.11) isn't going to bring listeners flocking to hear you...

You could do it, but I'm not sure why you'd bother. Why not do podcasting or streaming audio/video over the Internet? Then you don't need to restrict your audience geographically, and could potentially have a larger audience. [If you want to yack about neighborhood issues, you can, just tell your neighbors where to listen...]

Higher frequencies have _more_ problems going long distances and generating high powers than lower frequencies.

Yes, it can. However, you still have legal limits on ERP, and it still won't go through trees, houses, or other obstacles.

Why do you think this? Have you priced WiFi gain antennas?

Why? If there's a market, and a pent-up listening audience, why should you care if it's licensed?

Look at any of the many path loss calculations that have been done in the newsgroup. You can't get blood out of a stone.

Third world poor people can put up low-power FM transmitters at least as easily as you can.

Again, look at the loss of RG6 at 2.4GHz. Look at the cost of low-loss coax at GHz frequencies.

But I could well be wrong, build your mousetrap and see if the world beats a path to your door.

For a while I've been thinking about the possibilities of 802.11 (or similar) for one-way streaming of non-licensed digital audio and possibly even digital video broadcasting. It could be received using a personal computer with wireless capability and running a special application, but could also be received and converted to audio by simple, very inexpensive, portable radio-like (Walkman-like) devices (such devices would not be PCs -- they'd have an 802.11 receiver and a simple means to extract the streaming digital broadcast and convert it to analog for listening the old fashioned way -- processor and other hardware needs should be quite minimal.)

Why the interest? Well, I've been interested for quite some time with legal, unlicensed radio broadcasting. It is little known by many that in the U.S., the FCC allows unlicensed radio stations both in the BCB (AM: 520 to 1720 kHz) and FM bands. The downside of course is transmission power, distance and even antenna size, which is severely limiting, especially for legal FM operation (which is the most suitable for analog broadcasting.) In fact, unlicensed operation is allowed in a lot of the rest of the radio spectrum, but is severely limited power-wise as to make it impractical for even localized radio broadcast use.

There is a definite need for unlicensed one-way broadcasting with a usable reception range of at least a mile. It bypasses the commercial broadcast stations run by corporate conglomerates, allowing for airing alternative news, views and music, and it would be oriented towards the needs of the local community without commercial filtering. There are actually quite a few unlicensed AM and FM stations serving many communities, despite the technical limitations (they are harried, though, by commercial broadcasters.) It is also of interest in third world situations, where very inexpensive radio systems to serve remote villages are useful, and where using Internet-connected computers is out-of-the-question.

But unlicensed analog broadcast also has its problems. As just noted, power and distance. There's also interference issues. And finally that analog simply sucks in audio quality (some would debate that, but achieving red book CD audio quality with FM is expensive on both the transmitter and receiver sides, and it is still analog subject to interference -- and anyway legal unlicensed FM broadcasting is way too limited in range, moreso than AM is.) There is the possibility of digitally broadcasting on the AM and FM bands, but again there are the legal power and distance limitations, and the digital will require compression.

So, it is very intriguing to latch onto 802.11 (or similar) technology for one-way streaming of digital audio broadcasting (greater range, very small antenna sizes, inexpensive equipment on both ends, full red book CD quality with no compression needed, etc.) I surmise that it is legally possible to do this, and that potential reception distances would be measured in miles (with a good receiving antenna)?

Assuming these to be correct, how would one use 802.11 or similar in practice? I'm not asking if this makes sense (I believe there is a need and market as noted above), but whether it is doable, both technically and legally.

Furthermore, it is important that reception and listening be done without the need for a PC-level or even PDA-level computer (although it could be.) I'm thinking of a "portable radio" using earbuds that costs no more than $10-20 to manufacture. Is this doable? (This brings up the idea of designing open source circuits and diy kits to build such "portable radios".) Note that streaming is one-way, so the "portable radio" would not broadcast back to the transmitter -- likewise the transmitter would only be a transmitter, streaming the digital audio content.

Am I stupid and clueless (I admit I know little about wireless technology)? Or are there some possibilities here?

Thanks.

Mark

Thanks for your feedback.

1. I did say 802.11 or *similar* (using gigahertz carriers). I am hoping experts such as yourself can clarify this particular matter of the various candidate wireless carrier technologies.

1. The broadcast antenna can be optimized by bringing it outside and raising it to higher ground, etc. (What are the legal power limits?) It need not be a receiving antenna, only a transmitting antenna. Why do I keep hearing about 802.11 (or similar) wireless operating (two-way) over quite long distances such as 30 miles using pretty cheap antennas? Won't some of that apply here?

2. Who says that *receiving-only* directional antennas need to be expensive? It seems like they could be built for a few dollars. They only need to be "receive only". A cheap small dish might be made out of an old car headlight reflector or something. *laugh*

It seems like a lot of limitations of wireless are due to the need for it to be two-way with low-packet loss for effective LAN communication. But I'm not talking about two-way -- I'm talking about one-way, and this should free up some inherent limitations (but not all of them.)

This is not acceptable. FCC licensing is not acceptable. Anyway FM is analog, and am interested only in digital broadcasting which directly integrates with laptops running wireless, but also allows inexpensive portable radio reception. I'm not sure if the FCC FM license will even allow digital broadcasting -- I think not.

Your premise is that the wireless approach will not allow more than a couple hundred feet of reception distance. For the reasons I give above, I have not yet been persuaded that this is true. That is, I believe there is an inexpensive "formula" to get the general concept to work (in a practical sense) for one mile or more of reception and maintain red book CD audio quality. One mile would be acceptable, in my estimation.

After all, the receiver need not communicate back to the transmitter.

Well, maybe using the phrase "802.11" is incorrect.

What other wireless carrier technologies could be considered? I've not hidden the fact that I know next to nothing about wireless technologies other than being a user of 802.11g (I have a wireless hotspot and my laptop is wireless enabled.)

True, but there is definite *third world* and remote applications for the general system as I envision it, particularly among the poor. Both the transmitting and receiving portions should be cheap to implement. Transmitting would probably be done using a very inexpensive laptop configuration connected to an external antenna that would probably not be much more than a wire on a tall pole connected by RG6 (such broadcasting can also simulcast over the Internet if desired.) Reception can be by wireless laptops and by (hopefully) the $20 portable radio receiver with earphones. What usually restricts usage of broadcast in local settings is the cost and complexity of the transmitting equipment. Plus, with wireless we are now talking about red book digital audio quality, not limited by analog (AM or FM) restraints. Heck, the broadcast can originate halfway around the world, and via the Internet feed to the locally broadcasting laptop connected to the transmitting antenna.

Anyway, I am not interested in debating whether there's a market for this or not. You may be right -- no one will be interested. But I beg to differ knowing the hobbyist and non-licensed broadcast market plus the third world market. I see some interesting possibilities among both hobbyists, serious local community broadcasters, and third world/remote usage. Mainly because a lot of the hardware (processors, etc.) is already developed for wireless systems, and I know it is quite inexpensive.

What I'm interested to know are the technical issues of doing this. Am I making some assumptions about technology which are wholly incorrect or offbase? Is it doable to jerry-rig 802.11 (or similar) wireless technology for unlicensed one-way streaming of digital audio, with a realistic reception distance of one mile with error free performance (no doubt there'd be error correction built-in to the digital signal)? And to do so relatively inexpensively? (I acknowledge there may be need for a directional receiving antenna to get out the full mile, but as noted above I just can't believe this would be more than a few dollars in cost.)

Thanks again.

Mark

Thanks for your reply. It is a good technical overview of some of the more important issues. This is what I'm seeking. But I won't go down without some fight to assure the idea is properly technically vetted as well as looking at "how to make it work". I follow the dictum that there's a hundred ways by which something can't work, but all it takes is one way to make it work. I see some interesting opportunities here, at least in principle, as I'll note at the end.

Regarding 802.11, I only mentioned that since it is well-known. Not being an expert in this area, I'm not sure what it is called in a general sense (is 802.11 a particular family of wireless protocols?)

Now, it is the FCC requirements which are of most interest to me. What does the FCC say about setting up a wireless "hotspot" (which is sort of what the transmitter would be)? Does the FCC specify that if interference occurs with a neighbor that it must be shut down even if it is working within legal limits of transmission power? Does the FCC, for the frequencies that 802.11 operates (and there are other wireless protocols as well) also regulate not only the carrier but the digital signal imposed on the carrier?

And what are the various gigahertz frequencies allocated for wireless LAN communication?

I am familiar with Digital Radio Mondiale, being a shortwave hobbyist myself.

And I did investigate using it in various ranges up to 30 mHz, but because of extreme FCC limitations for unlicensed use in the non-BCB band it just did not appear to be workable. There was one band next to the CB band that might be a candidate, but would require the FCC in opening it up. I don't see it working that well in the MW BCB band, and there's the issues of setting up efficient transmitting antennas to work in the MW band.

What interests me about wireless is that it operates in the gigahertz range (I believe) in a portion of the spectrum where the FCC appears to not be *that* anal about (maybe I'm wrong here.) The very high frequency makes efficient broadcast antennas very small (e.g. a few inches) as well as small and efficient reception antennas. No need for a ground plane antenna like one needs for MW and the longer SW bands.

And it is already used for digital communication.

And more importantly. It is now implemented in all kinds of consumer goods (wireless laptops), so taking advantage of the low cost of the hardware, the installed laptop base, etc., is intriguing.

Well, all I see are wireless hotspots popping up all over which already seamlessly integrate into laptops. Also I've heard that two-way wireless LAN communication can go for more than just a couple hundred feet (saw something on SlashDot), etc., etc. So, it became intriguing to me that this avenue at least be explored. If the real-world technical and legal issues make this idea impractical or impossible, then so be it. But until the various ways of taking advantage of the wireless technology revolution are examined, I won't give up that easily.

Thanks again.

Mark

I don't. If the central access point also has internet access, there's nothing to stop the user from connecting to

other sources of free streaming media and getting their entertainment fix for free.

I don't have time to explain all the legalities and technical limitations of every possible method of license free communications available. You can find that all over this newsgroup, the web, in weblogs, and in books. When you have something concrete, I'll be happy to analyze, calculate, or otherwise tear apart your proposal from a technical angle. Please do some reading and come back with some less general questions.

The FCC says nothing. The way it works is that the 915MHz, 2.4GHz,

5.7GHz, 24GHz, and 60GHz frequency bands were set asside for use by "intentional radiators". The FCC rules are in Part 15. For what you're doing, it's 15.204 and 15.247 that are important. There are no restrictions as to what you can do with the service as long as you stay within the emission requirements. On top of Part 15 is IEEE 802.11. This is a series of specifications as to how these "intentional radiators" are suppose to communicate and interoperate. 802.11 is NOT the only data protocol in use on these frequencies. In addition, there are several incompatible modulation methods (Frequency Hopping, Direct Sequence, OFDM, Bluetooth, HomeRF, etc) and lots of proprietary high bandwidth systems on the higher frequencies. You are not required to use 802.11 but you'll find that the cost of proprietary is rather substantial. you build will need to be FCC type certified as well as approved by whatever foreign Telecom or Ministry you decide to export.

No. The FCC does not care about interference on the unlicensed and un-coordinated frequency bands. Interference is the price of unlicensed operation.

No. The FCC only is only interested in the emission limits (occupied bandwidth, duty cycle, and xmit power) as well the usual spurious emissions limits. The FCC does not care what you do to modulate the signal.

Things change a bit if you get big. If you have over 200 customers, you gotta report it to the FCC on form 477.

Actually, there are a substantial number beyond the common variety. See FCC 15.245 through 15.255 for specifics. Each band tend to have seperate emission requirements so don't assume that if something is acceptable on one band, it will be acceptable on another.

Fine. Then you're aware that DRM and iBiquity requires a per-receiver license. Great way to kill a new technology.

More:

OK. You have a 3rd world audience, with no hardware, probably no money, a mythical pressing need for CD quality audio, and you're getting picky about the quality of the service. I was listening to some Canadian DRM station (forgot which one) on 18MHz a few nights ago. It wasn't CD quality, but the stereo sure sounded good.

guess 3rd world impoverished listeners have more discerning tastes.

I would love to unload my frustrations with the FCC EB (enforcement bureau). Let's just say that they only enforce high profile cases. Unless you're a very important person, they don't act on complaints. You can get away with just about anything as long as you don't piss off anyone important. That will be a serious problem if you start selling commerical airtime on your broadcasting system. The broadcasters might consider you a threat and complain to the FCC. That will surely bring down the wrath of the enforcement bureau.

Yeah, something like that. Methinks maybe reading a few things about antenna design might be helpful. I've posted how to do fade margin and link calculations at least a dozen times in this newsgroup. The method is the same no matter what technology or frequency you're using.

That's the problem. You won't find any two way land mobile users in the middle of the frequencies used by broadcasters. That's because the services are incompatible. The same applies to what you're proposing. In my never humble opinion, broadcasting on 2.4GHz is no better than jamming existing users.

So, you're going to buy me an affordable laptop for Hannukah? Somehow, my budget just can't seem to catch up with the current definition of affordable. I do have about 15 different laptops but they're all junk.

The surest sign of success is pollution and abuse. Your idea is very close to becoming a sign of success.

Basic lecture on dB's.

3dB is about 0.7 times the range and 2x the coverage area. 6dB is about 2 times the range and 4x the coverage area. 12dB is about 4 times the range and 16x the coverage area. Bigger antennas mean more coverage and range. There are legal limits to what can be done. It's not all that simple because there are different rules for point to point and point to multipoint. See FCC 15.247 or various interpretations online.

You ask some very good questions. However, they're all the wrong questions. What you should be asking is how *YOU* will make money from this service. There are plenty of ideas out there that can make money for others, or where you can only operate as a free service. Selling to a 3rd world market is something I can see you have never even investigated. I know of a few 3rd world communications horror stories. Let me know if you wanna hear them.

Go back and read the slashdot article. IIRC they used extremely high gain antennas on both ends (C-band satellite dishes?), lots of expensive hardware, and a line-of-sight path that doesn't exist anywhere else.

That 'path' is exclusively reflective. WiFi does not (IME) propagate through 8" concrete walls.

Then you don't know much about RF. Except for power handling (which is nil in the case of WiFi), rx and tx antennas are the same.

No, I mean the power budget calculations Jeff and others have done here on a nearly daily basis for the last several years. Output power minus connector losses, minus feedline loss, plus antenna gain minus free-space loss plus antenna gain minus feedline and connector loss compared to receiver sensitivity for a given bit-error rate. RTFNG.

I'm curious, then. What's the details behind the so-called 30 mile distance accomplished with wireless (details on Slashdot a while ago.) Was this due to high-quality directional antennas on both ends? Or running at some significantly lower frequency? Or what?

What about WiMax?

Well, it must have some penetrative power, otherwise I could not connect my laptop, with a reasonable signal, to my wireless router being 80 feet away, going through, at an angle, about 10 feet of dirt, then through 12 inches of concrete, then two sheetrocked walls. I suppose there might be some reflection, although at such high frequencies I'm not sure there is much reflectivity.

For reception only, they should be cheaper than a directional antenna designed for transmitting as well. I'm only interested in the reception side, at least when thinking of dirt cheap.

I assume what you mean is loss in air itself?

Yep, agreed. The transmitter circuitry would probably have to be quite close to the antenna to minimize high frequency losses when feeding the antenna.

Well, who knows? Maybe someone here might try to experiment with this. Maybe some more workable variation of the idea. I'm not setup to do this -- just offering the idea to the world to do or not do with it as it pleases. For now I just want to understand the various legal and technical issues, and variations on the theme, before I put it to rest.

Mark

Why? This is sort of like wanting to 802.11 protocols to move video from one room to another.

Instead, you can just buy a box called a video sender that does this. It works out of the box, requires no software and is far cheaper than walking around with a laptop.

Why use something for a mispurpose that will be hard to get going when there's something out there already that does what you want:-

a) Local FM transmitter b) Internet broadcasting

David.