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That said, RFI problems like you described are usually NOT the fault of Amateur Radio operators. More specifically:

1. Many times the source of interference is someone operating illegally. Illegal CB operation (I.E. big huge amplifiers - which are against FCC rules, etc. etc.) is probably the biggest cause. Believe me, most Ham radio operators would love to take these people out back and teach them about respect for the rules.

2. Even if the source of the interference is an Amateur radio operator, many times the problem is tracked down to a low-quality piece of consumer equipment at the person being interfered with's end. As long as the Ham radio operator is operating within the rules, the owner of the equipment is responsible to fix the issue - as it is their equipment with the technical problem.

3. If it is in fact the amateur radio operator's problem, it is their duty to fix it. The FCC can and does pull licenses for this type of stuff.

If you are having problems along this line, contact your local Ham Radio Club a call. In most cases, they have a vested interest in finding the source of the problem and helping fix it. You can see clubs in your area by going to The club search page on the ARRL site.

Remember that Ham radio operators provide a valuable service when the crap hits the fan. Most Amateur radio operators are actually skilled in what they do and take great pains to insure they don't cause unwanted interference, as interference only hurts the Ham radio community.

I'm N7ZTT. I can never get my extra class license now that they lowered the morse code test to 5wpm - the advanced class (which no longer exists) is my only proof that I can transmit data by hand at ~10 baud (yes, faster than some early modems! 13wpm = ~10 baud)

If you follow that link, you'll see I earned my advanced class in 1993; I received my first license in ~1991. But I'm not an old fark, I was homeschooled & did this for part of my curriculum. I'm only 23 :-)

I'll make another post in a few minutes that won't be a brag thread. It's actually sorta sad to see Ham radio fading out. You can do everything and more on the internet than you can on amateur radio. Of course, if we had wide-scale power outages & the sun was spewing crud at our atmosphere, morse code could potentially be the only way to quickly send information to other countries. Due to the nature of morse code, it can be deciphered even with a very low S/N ratio.

Anyway, I'll make a more intelligent post soon:

To become one yourself, consider:
Welcome to Amateur Radio!

And if you're less insensitive, I might volunteer use of my generator to keep your PC running while I radio the county office of emergency services.

To become one yourself, consider:
Welcome to Amateur Radio!

And if you're less insensitive, I might volunteer use of my generator to keep your PC running while I radio the county office of emergency services.

Other countries are already moving to adopt the new international regulation. However in the USA the old men at ARRL are trying to drag out the demise of the 19th century requirement as they have for the last twenty years.

They have done this at their own risk, since none of the new ham radio operators will join a organiztion that has done everything they could to keep them out of ham radio.

To make a comparison between ham radio and computers it would be like all college computer training schools requiring all students to know how to operate and program a UNIVAC to get a degree.

Also the way the US government insists on inserting itself into every aspect of our lifes.
In the early 1990s (like 93 I think) there was an effort to bring about phone and Internet over cable. Early broudband. This was done with out any fedral aproval.
At first cable companys wanted to do two way cable to bring us internet access and interactive TV. The FCC said "No you have one way data.. only the phone company can do two way" so the local phone carrers asked if they could run coax. Same no.. only cable companys.
Well the Internet was a big deal and everyone wantted in.
Phone companys and Cable companys started striking agreements so they could do two way cable. Cable companys could provide phone service phone companys could provide TV service both would have the data service it was the best of all worlds for the consummer and we'd have it quickly.

No... The fedral government had to get involved and new laws were past. Then they desided it was a good idea and past yet more laws. And today we have what we could have had almost 10 years ago.

Not to say the fedral government is entirely evil. Right now there is some debate over a preposal for brodband over powerlines. Short version is "Sure you can have it but dump all your radio equipment FOREVER Muahahahaha." I think that sums it up nice a sloppy... I hate cliff notes so read the link if you really want to know otherwise use my cliff notes and look like an idiot.
I think I understand. To bad you couldn't use that for 802.11[?] carrer signals but I'm going to guess the signal would degrade before it got very far.

The FCC absolutely pursues action against people who violate FCC regulations and they can be quite harsh.

Here are some samples of FCC enforement letters for the amateur radio spectrum: (Of course, interfering with commercial/service broadcasts will bring them down like a ton of bricks...)

http://www.arrl.org/news/enforcement_logs/

The Morse requirement is not a serious impediment to growth in the ham ranks, as we know with the success of the no-code technician license. Furthermore, five words per minute is so simple to learn and pass that anyone who wants to can pass it. You can practically look it up as it's sent at that slow speed. Kids as young as seven and eight routinely pass the 5wpm test; I've even worked a 10-year-old Extra.

True, ham radio isn't just about Morse, but when all else fails (hey, that sounds familiar), you can get a message through using it.

and these "covenants" are considered illegal by the FCC, if you own a home, you can put antennas up, or an antenna tower. check out this page from the arrl http://www.arrl.org/FandES/field/regulations/anten na-restrictions.html

Of course, "Adoption of the Article 25.5 modification would not mean the immediate disappearance of the Morse requirement to operate on the amateur bands below 30 MHz. Each administration, including the FCC if it chooses to do so, would decide whether to drop the requirement from its domestic regulations." (quote from the arrl.org article) Theoretically, the FCC could decide to keep the existing 5 wpm Morse requirement...and they do have more important things to do than fiddle with the amateur licensing requirements, so it could take a while. But it would be good news, if it comes to pass.

Not anymore, anyway. According to most interpretations, the letters don't stand for anything so don't write it in all caps! The actual origin of the term 'ham' has been lost to history.

And true, ham radio is not dying. (It could be, though, without younger people getting interested and bringing in the new technology.) This weekend should be a fine example.

-- Me, still wondering why the /. eds don't like me, since I posted the same topic three days ago and was rejected.

... a chance to learn how to push more buttons and operate more neat-looking equipment full of blinkenlights. A chance to learn how a lot of electronic circuits work. A chance to digitally communicate over thousands of miles with just 4 watts (which you're aware you could do with wires, but that would require the use of a lot more than 4 watts on a complex, expensive carrier network to accomplish the same result). Oh, and you also meet a lot of nice people (and the occaisional troll), and assist others, when you're not talking to people in the space station, sending television signals, or whatever it is you end up doing with ham radio.

I'm a 26-year-old Extra, which I'll admit is somewhat young for the hobby, but the older folks like me (despite the nose ring) because I posess two very important traits: When I do not know, I say so, and shut up and observe. When I do know, I help. If this sounds like you, you'll make a brilliant amateur radio operator, and you should pursue this license, because after only 35 multiple-choice questions, you are rewarded with a federal license to screw with more stuff.

For the interested, those 35 questions are divided into 10 objectives, only a few questions on each. And those questions come completely from this question pool (July, 2003 edition), which if you look at for a second, probably doesn't strike you as particularly difficult. The resulting Technician-class license lets you use up to 1500 watts on all amateur bands (VHF, UHF, and beyond) over 50MHz, or more simply, everything but shortwave (HF). That includes talking to astronauts, long-distance 802.11b, packet radio, and a bunch of other things I don't know about, aside from the usual voice communications.

So, come see us tomorrow, ask a lot of questions, and bring your own station next year instead of just watching.

At the high school physics level (i.e., no calculus), the first thing that comes to mind is the ARRL antenna book. It has a good chapter on theory, and another one on measurement techniques. A book more narrowly focussed on HF antennas is Carr's Practical Antenna Handbook, but it lacks the breadth of the ARRL book. A book devoted to the antennas and propagation common to handheld, portable products (including indoor propagation and measurement of the effects of the human body on radiation patterns) is Radiowave Propagation and Antennas for Personal Communications by Siwiak. I've used it for years; it's an excellent reference. If you'd like to "learn from the simulator," Makarov's book seems like a good introduction to antenna analysis with Matlab, but I've not used it. But really, the calculus you must have to get a mechanical engineering degree is sufficient for the general theory sections of most antenna texts, such as Bolanis, Kraus, or Stutzman and Thiele. The general rule, of course, is that in free space the radiation intensity goes down with the square of the distance, while in indoor environments the "path loss exponent" increases to something between two and and four.

Actually I'm pretty sure that mobile phones fall under Part 15 . So therefore any interference they cause IS their problem:

 15.5 General conditions of operation.
(b) Operation of an intentional, unintentional, or incidental radiator is subject to the conditions that no harmful interference is caused and that interference must be accepted that may be caused by the operation of an authorized radio station, by another intentional or unintentional radiator, by industrial, scientific and medical (ISM) equipment, or by an incidental radiator.

Mind you this is under the assumption that the avionics are not held to Part 15.

I was thinking the same thing. I didn't have much time to get into amateur radio, but I still had some fun with it. Just hope they don't decide to knock out everything but 2 meters or something... we can pray, at least, that this act is passed.

- KF6KBP

Maidenhead Grid Squares are used by the amateur radio community to give location. They can range from four to 8 characters in length, depending on the level of precision required. At four characters, you are looking at around a 110km by 160km square in the continental U.S. (gets squarer as you approach the equator). Add two more characters, and it gets down to a 5km by 6km square. Add two more and it gets even closer. As an example, my grid square to six characters (sufficient for my ham radio activities) is LN32at. Not long, not difficult to remember.

The only thing I find missing in this discussion is that the FCC and local power companies have enough problems taming the unintentional radiation from their equipment, without introducing intentional broadband radiation! Remember that those miles and miles of power lines make reeeally good antennas! The thought of possibly wiping out military, amateur, and fixed service HF allocations trying to run broadband over a broken power grid should make everyone think several times about "whether-we-really-should-be-doing-this."

Just for the record, our local mono^H^H^H^Hutility has let problems go for years before finally finding and addressing them: Link Here to Cinergy/WLW story

At least this time the problem was resolved. Multiply this by hundreds of power companies and you should see we *might* have a problem...

llamafresh

Funny, I thought they used an FM downlink...

Well, if it is FM, you sure can't use an AM antenna for it :-)

(Note to my fellow hams - the preceding was a joke, OK? I got my BSEE and my Extra over 30 years ago, so just chill...)

Seriously, a wideband scanner, a pair of crossed dipoles cut for 137.5MHz (that's MegaHertz; "mhz" isn't anything), and some wiring from the low-level audio output of the scanner to the line input on your sound card, and some software, and you've got pictures.

Visit the ARRL web page and visit their online bookstore for the appropriate books. And, don't worry about John Ashcroft - I'm sure he's got better things to do; most ships, fishing boats and large pleasure boats all get the weather maps in the same way...

474 THz 192.6 WB7VVD (DM34hb) -- KC7AED (DM43iq) 21-Sep-1997
678 THz 248 WA7LYI (DM34tf) -- KY7B (DM42ok) 08-Jun-1991

474 THz 192.6 WB7VVD (DM34hb) -- KC7AED (DM43iq) 21-Sep-1997
678 THz 248 WA7LYI (DM34tf) -- KY7B (DM42ok) 08-Jun-1991

You can't raelly go wrong with an amateur radio license. Not only does it give you a failsafe communications method (assuming your transceiver has batteries), it also gives you a new hobby. You get to tinker with electronics, broadcasting, and radio equipment. It is a great learning tool for understanding computers better.

For more information, I suggest you check out the American Radio Relay League website. You might want to check and see if your local area has any amateur radio clubs that you can go to and ask more detailed questions.

You can't raelly go wrong with an amateur radio license. Not only does it give you a failsafe communications method (assuming your transceiver has batteries), it also gives you a new hobby. You get to tinker with electronics, broadcasting, and radio equipment. It is a great learning tool for understanding computers better.

For more information, I suggest you check out the American Radio Relay League website. You might want to check and see if your local area has any amateur radio clubs that you can go to and ask more detailed questions.

In case you didn't know, Radio Shack no longer sells morse code training tapes. You'll have to buy them from the ARRL.

According to Section 97.313, there is no license class restriction on the power output allowed on the amateur microwave bands, making the limit 1500 Watts regardless of whether you are a technician class or extra. However, it also states that you must use the minimum power necessary to maintain reliable communications. My 5 watt 2-meter handheld is perfectly sufficient if I am on a hilltop, and my 50 watt mobile is more than adequate on level ground. So a 100 watt limit is probably a reasonable expectation both from the minimum power rule and a technical point of view, unless you are trying to bounce your signal off of the moon.

I didn't think this was true so I used google and found this:

Phone Patch, Autopatch and HF/VHF/UHF Operating Guidelines

2) Phone patches or autopatches involving the pecuniary interest of the originator, or on behalf of the originator's employer, must not be conducted at any time. The content of any patch should be such that it is clear to any listener that such communications are not involved. Particular caution must be observed in calling any business telephone. Calls to place an order for a commercial product may be made such as the proverbial call to the pizza restaurant to order food, but not calls to one's office to receive or to leave business messages since communications on behalf of ones employer are not permitted. Calls made in the interests of highway safety, however, such as for the removal of injured persons from the scene of an accident or for the removal of a disabled vehicle from a hazardous location, are permitted.

Now I know :)

US hams are still authorized for 2300-2310 MHz. See the ARRL band plan for the 13cm band. Actually, we used to have all of 2300-2450 in one big 150 MHz chunk. But 80 MHz of it has been lost, so it's now 2300-2310 MHz (mostly because that's where the DX work was done, although it does include things like repeater inputs input so as to have a wider frequency split) and 2390-2450 MHz. Hams do not have 2450-2483.5 MHz, so any operation there has to be strictly under Part 15 rules, including things like not interconnecting any Part 97 operations.

US Hams still have all of 5650-5925 MHz in a single 275 MHz chunk in case you might be interested in working some 802.11a.

US hams are still authorized for 2300-2310 MHz. See the ARRL band plan for the 13cm band. Actually, we used to have all of 2300-2450 in one big 150 MHz chunk. But 80 MHz of it has been lost, so it's now 2300-2310 MHz (mostly because that's where the DX work was done, although it does include things like repeater inputs input so as to have a wider frequency split) and 2390-2450 MHz. Hams do not have 2450-2483.5 MHz, so any operation there has to be strictly under Part 15 rules, including things like not interconnecting any Part 97 operations.

US Hams still have all of 5650-5925 MHz in a single 275 MHz chunk in case you might be interested in working some 802.11a.

Communication from Part 97 --> Part 15 is allowed.
Communication from Part 15 --> Part 97 is resrticted.
Read this.

73 de Sjaak KG4PVX / PA3GVR

A good article from the ARRL on building your own ham antenna.

And when you are done with that, check out the fun at Pajonet!

IIRC radio shack is going out of the shortwave business. I don't know about transceivers though. With that said, they got some deals on shortwave receivers. Shortwave is both fun and practical, these days you got no idea when "normality" will change on you, in an emergency it's *nice* to have the option to be able to at least listen to some "news" that might not be filtered through some government propoganda FEMA control box that are installed at the commercial broadcast stations. Even better is to have the ability to converse. HAM and shortwave are very interesting geekish hobbies. So is "alternative energy". Tons of interesting and practical gift ideas in those areas.

I'm not a ham (I'd like to be one, but haven't had time to study code exam or money to buy gear)

Just so you know, there's a level of license called 'Technician' that requires no code. As to your second issue, if you have $100, you can get a fairly decent mobile (car mount) radio, or even a nice used base.

For more info, check out the American Radio Relay League's Website

The 2.4 GHz area is at least 1/2 allocated to Amateur Radio (for now at least, remember 220 and 11m?)

All modes and licensees (except Novices) are authorized on the following bands [FCC Rules, Part 97.301(a)]:

2300-2310 MHz
2390-2450 MHz
...

The ARRL has a web page with some information on the subject.

You might ask the engineer at the local radio station for suggestions. Even though it is not the radio station's fault, he may be willing to offer some assistance. Local amateur radio clubs can also be sources of people who are willing to help.

Ask the support department of the manufacturer of your audio device for assistance. They may have technical bulletins on how to solve the problem.

If you are asking people for help, be nice, not confrontational. Remember that it is your audio equipment, not the radio station, that is at fault. Consumer electronic equipment manufacturers could avoid most of these problems by adding less than a dollars worth of parts to their equipment. Most do not, reasoning that it is cheaper to deal with some complaints of susceptibility to RF interference than to prevent the problem.

The ARRL has a web page with some information on the subject.

You might ask the engineer at the local radio station for suggestions. Even though it is not the radio station's fault, he may be willing to offer some assistance. Local amateur radio clubs can also be sources of people who are willing to help.

Ask the support department of the manufacturer of your audio device for assistance. They may have technical bulletins on how to solve the problem.

If you are asking people for help, be nice, not confrontational. Remember that it is your audio equipment, not the radio station, that is at fault. Consumer electronic equipment manufacturers could avoid most of these problems by adding less than a dollars worth of parts to their equipment. Most do not, reasoning that it is cheaper to deal with some complaints of susceptibility to RF interference than to prevent the problem.

It takes a fair amount of circuit boards to make it economical, however, corporations could easily reduce landfills and get paid for the circuit boards if they reclaimed these metals this way. Common metals recovered include GOLD, SILVER, and LEAD as well as others. It's more profitable than going through the trouble of mining for these metals.

It takes a fair amount of circuit boards to make it economical, however, corporations could easily reduce landfills and get paid for the circuit boards if they reclaimed these metals this way. Common metals recovered include GOLD, SILVER, and LEAD as well as others. It's more profitable than going through the trouble of mining for these metals.

It's called APRS (or here), and it's free... Get a Ham license!

Amateur radio operators have been doing stuff like this for years on frequencies above and below 2 Ghz. Here's a listing of distance records .

Nevertheless, a person who is seeking a TV antenna in a covenant-controlled area would be well served by getting in contact with a ham (One who, unlike myself, has more than a couple of years experience basically being licensed and occasionally talking with the local club repeater. Not _on_ the repeater. _With_ the repeater. Living in a RF hole sucks sometimes.), as they often have to deal with this sort of thing and therefore have valuable information about how to either negotiate an equitable solution or sneak in a suitable antenna. "Oh, no. No antennas here. That is a perfectly ordinary flagpole/electric fence/modern sculpture/crank-up tower mounted in the bed of a pickup truck with a funny license plate. I am a perfectly ordinary and compliant member of this idyllic community, and I would never even consider having odd or unusual hobbies that might disturb the delicate sensibilies of my neighbors. Nothing to see here, move along."

And yeah, I fail to see the advantage of these communities.
"So what do I get for painting my house the Official Beige?"
"Well, you get to live in a neighborhood where everyone else paints their house Official Beige."
"Woo freaking hoo."
I think I'll take the plane as a neighbor, thanks much. I get to have my antenna farm, and he gets to rotate -- and if he doesn't like the antennas, he can rotate anyway!

Something to look forward to in your old age?

BTW, ARRL = American Radio Relay League, an amateur radio organization, which publishes QST their monthly magazine.

You can assure me all you like, can you provide a actual regulation I can look up placing the 500's frequencies mentioned in the article in the emergency band? The restricted bands are too numerous to reproduce here, but they are available here. The 500 range is not a restricted band. It is also worth noting that Part 15.242, which covers the band in question, makes long and specific mention of "biomedical telemetry devices," and that they must accept any interference and must not cause interference to TV stations operating on the same frequency. Also, while it's not an FCC link but an ARRL one, this section makes specific mention of land mobile transmitters belonging to fire, police, maritine and nautical safety services falling under Part 15. And finally, there is a huge difference between jamming and unintentional interference.

I don't know about cell phones (because they operate on different frequencies and are under a different set of rules and regulations), but amateur radio operators are prohibited from using their equipment when an aircraft is operating under instrument flight rules (unless the equipment is FAA approved) (reference), and generally prohibited amongst the large commercial airlines (by the airlines themselves, not by the FAA or FCC).

With that said; I do agree that at least part of the problem is created by the fact that at a mile up; you can cover a huge area (I'm sure someone knows how to compute this).

If you want some electronics, you can study for an amateur radio license. The ARRL has a lot of plans for good radio-related equipment you can build from scratch. Plus, you can get in on developing and testing software radios.

For the aspiring metallurgist in you, you can do your own metal pouring and casting.

Summertime is a good time for stargazing. You can build your own telescope.

I'm not sure what radio modems they are using. But, it actually sounds a little archaic if you ask me. I mean you have to work with what you have when you're on a budget (or worse ... don't have one). But, it seems that this could be setup a lot better with some equipment donotions. HAMs (amatuer radio operators) are generally relatively generous people. And, all they would need is a couple HF radios since they have the computers already.

AX.25 is natively supported in Linux, and could easily be leveraged to make this whole thing a lot better. With some donated HF radios, they could have routable RF network up all the time in no time. They might even be able to use APRS instead of AX.25. But, AX.25 is a more proven protocol for this type of thing. See the AX.25 Linux HOWTO for details. Information about the protocol can be found at TAPR's website. They might even be able to get a little bit more speed, though not much, by using 10 Meter (28 MHz) FM. Though 10M can be probmatic sometimes, so I'm not sure I'd recommend that. 20M (14 MHz) and down are much better frequencies if you want something reliable. A DSP based noise filter would certainly help things in regards to speed, but they cost a bit of money.

As far as the modem goes... You can use a sound card and a small "control" box. All the box does is operate the PTT (push to talk) circuit. So, you might be able to do with out that if you wire things up just so. But, I have not played with that as of yet. You can also use a Terminal Node Controller (TNC) to get the signal to the radio. Some of the newer TNCs have a DSP filter built in, so that could be an advantage there. But, the best you can hope for on HF is about 2400 bps at half duplex, and 2400 is pushing it. There's just too much noise on Upper/Lower Side Band, and I'm not sure if you would want to use AM (though that might be an option).

There are a number of sites to check out if anyone is interested in digital commincations over amatuer radio. TAPR is a very good one, as is RATS. RATS works with a protocol known as ROSE. There is another one called NETROM, but I don't have a link readily available for that. TCP/IP is by far the best for this type of thing though. You can also check out the ARRL's site, and the FCC's amatuer radio page, for more information on amatuer radio in general here in the United States. BTW, you don't need to know morse code anymore to get on VHF/UHF. And, to get on HF you only need 5 wpm on the code, which is not all that hard.

Ok, I admit that last paragraph was a sales pitch. But, amatuer radio seems to be a dying hobby; at least here in the US. So, anything that can be done to increase interest is a good thing. :)

I'll step down off my soap box now.

ham radio buffs are a thing of the past

Uhhh, not quite.

what stops an unscrupulous person from spamming it and making it unusable to everyone else?

It happens. Also see this.

but what's to stop, say, Sadaam from having a party one day and jaming all short wave channels with a few hundred megawatts of propoganda

It would take a hell of a lot of transmitters and electricity, antennas, etc, and you could easily track the source of the transmission through triangulation.

The original Ham calls for the US were WnXXX - where n = 0 to 9 (depending on your region of the country) and X = A thru Z. The first letter was always W.

Once all of these call signs were used up (1940s, 50s?), the FCC assigned KnXXX using the same number and letter scheme.

By the late 1960's or early '70s, the KnXXX calls were used up, then the went to WAnXXX, then WBnXXX. By the 1980's, the FCC started issuing KAnXXX, KBnXXX, calls. There are other combinations, like WnXX calls, but they were reserved for Hams with Extra class licenses.

This is just a quickie answer -- check out ARRL.ORG for more detailed information.

From the ARRL website:

The effort, called the Commemorative 9/11 Net, is being spearheaded by Len Signoretti, N2LEN, of Brooklyn, New York. N2LEN's 440.050 MHz (CTCSS 114.8 Hz) internet-linked repeater covers the Greater New York City area. The linkup will rely on either EchoLink or eQSO Internet software connections. Signoretti said his UHF machine is used as a central hub to coordinate EchoLink and eQSO, so users on each can communicate. The net will attempt to interconnect repeaters in all 50 US states as well as in many other countries around the world.

Amateurs can download free EchoLink or eQSO software from the Internet. While there is no listen-only capability on the Internet, many local VHF and UHF repeaters are expected to take part in the commemorative linkup.

The Commemorative 9/11 Net is scheduled to get under way at 8 PM Eastern Daylight Time (0000 UTC September 12) on the EchoLink and eQSO servers and could run as long as two hours. Haynie (ARRL President) is scheduled to address the cyberspace and RF-linked gathering at around 9 PM EDT.

You won't need any external DSP resources, but the term "software-defined radio" is still a gross misnomer because you still need an RF front end to do anything really interesting.

At a minimum, this would consist of a mixer and 1st local-oscillator synthesizer, preferably with an RF preamp in front of it all depending on what frequencies you want to cover and what kind of antenna and feedline you're running.

The mixer and RF preamp can be off-the-shelf parts from Mini-Circuits or eBay.

The synthesizer is less convenient. I'm finishing an article on a "turnkey" octave-range VHF/UHF/microwave synthesizer design (http://www.qsl.net/ke5fx/synth.html that anyone with a decent soldering iron should be able to put together, but it's still not a trivial project.

A lot of software-defined radio efforts are targeted at relatively narrow bands like the 2.4 GHz ISM band, where a bandpass filter can theoretically be used to take advantage of ADC aliasing via undersampling. With a scheme like this, you can dispense with the mixer and synthesizer. I'm not optimistic about these kinds of ideas, though... to achieve competitive performance, every dollar you save on the mixer and 1st LO synthesizer will have to be spent on a super-high-quality ADC configuration. It seems like the sensitivity would be pretty crappy, not to mention the fact that plenty of interfering sources near other aliased frequencies would be likely to survive the trip through the front-end filter. (I will admit that I don't have any direct experience with this topology, though.... there are probably quite a few advantages that I'm glossing over.)

At any rate, though, by keeping the traditional front-end mixer and oscillator while letting software handle the IF processing, you can use an ordinary sound card in a direct-conversion scheme (see this month's QEX to demodulate just about anything in the entire spectrum -- FM, NBFM, AM, SSB, FSK, QAM, you name it. To me, that seems a lot more interesting than the "Antenna at the ADC" schemes that a lot of people are hyping.

http://www.arrl.org/arrlletter/audio/

http://www.tapr.org/newsline/

Many local zoning ordinances prohibit big (6~8 ft) satellite dishes.

If you are actually talking about government zoning and not covenants, conditions and restrictions (CC AKA deed restrictions), you're in luck. Get an FCC amateur radio license (anyone can get one for the $10 and a very basic understanding of electronics) and tell folks its a ham antenna. Don't mention TV reception.

The FCC's PRB-1 (here and here) is a limited preemption of zoning ordinances. Basically, local government must reasonably accommodate folks when it comes to antennas. A C-band dish in your back yard would certainly be reasonable.

(You may also want to bluff with Section 207 of the Telecommunications Act of 1996 which says that folks must allow dishes. It generally only applies to dishes less than a meter but some people won't read the entire document if you have a good poker face.)

Is it possible to use many smaller dishes to achieve the same effect as one big dish in picking up C-band transmissions?

Yes. Hams have beeing builing arrays for years to do moon bounce and whatnot. You can find some over the top pictures here. However, the infrastructure to create such a monster is substantial and is likely to run afoul of the same local ordinances you're trying to work around.

Overall, I don't see the point in using a big dish for TV anymore and an array of smaller dishes to act like a bigger dish seems pointless.

InitZero (k4mls)