Part 15 FM mw constellation network

Wi fi is something I have yet to try for any reason, but using it as a link in a part 15 chain is a very interesting thing to wonder about.

The constellation concept would require a computer at each transmitter to receive the wi fi signal? Or, would you need a wi fi radio at each transmitter to pass the audio along?

For multi-point transmission on FM a long leaky cable also might be good if you have a long stretch of ground available.

WiFi mesh net. stream over network with barix. each mesh node can contain a barix box, solar panel, battery, and one each p15fm and p15am transmitter.

these can be totally self contained and sufficient without need for public utilities, just a host willing to give up a little real estate. the backbone would run point to point on 5.8 GHz and the client side (if used) would run 2.4 GHz

Starting with what I know, I will ask for description about what I don't know.......

I know that the radio broadcast would start in the computer at home and be fed to a Barix transmission box, which would generate an internet stream. From Here on I have no cluce....

Would the Barix transmission go to a Wi fi transmitter? What does it look like, how is it tied to the computer?

Does the RF Output from the Wi fi go to an antenna for transmission up in the GHz range? Where is the antenna located?

At the receiving points, I assume there will be another Wi fi antenna mounted somewhere... then to the Barix receiver with audio lines to the FM transmitter.

The whole Wi fi part is a fog in my knowledge.... I would not know what parts or devices to order.

It's a great idea, and no different from using a dedicated POTS pair feeding each transmitter audio and control.

The only issue is the inherent stream delay to each transmitter point, meaning that since each TX point is incredibly limited to coverage distance, those TX's will be spaced out so close together you may end up setting up as many as two TX and Barix box on the same property! Oh and not to mention the daisy chain echo of delayed audio to each TX further down the line. Even with synchronized transmitters of the oscillator, your still going to face the stream delay factor which is unavoidable.

How many TX's in a typical setup like this will be needed and how many open frequencies do you have to do this?

Given the potential for the number of TX and boxes needed to have effective coverage, the costs involved will most likely exceed that of simply running some leaky coax from a single point transmitter and use of one single frequency everyone can easily find and remember. Oh and it would avoid people having to re-tune their radios while driving...sort of like the problem of cell phone use/text messaging and driving.

Its a good idea, but not one without some considerable problems that have to be addressed.

As to Carl's confusion about Wi-Fi....it is direct line of sight, point to point communications, also limited in their range as well as adhering to your (a) and (b) people. For effectiveness, the antennas will no doubt be outdoors, particularly the receiving points. Your main point..located at your studio, would use one of those outdoor Wi-Fi antennas or one placed in of all places...the WINDOW!

For the whole system to be effective, each remote located TX will have to be able to have a direct unobstructed line of sight to your studio location.

Got tall trees around? Tall Buildings? Large 2 or 3 floor houses anywhere in between? Hills, mountains, that sort of thing?

RFB

What kind of wi fi devices for this?

Make, model number, antenna name and number, other parts ????

These is some WiFi gear that can handle non-line of sight - it tends to be proprietary (such as the Trango 900 Mhz transmitters and subscriber units) and expensive. But they do work very well at much longer distances than the run of the mill consumer stuff.

And from a Canadian perspective, this setup wouldn't be legal. In Canada, you're not allowed to transmit with more than one transmitter using a single source (such as your computer). If you had a separate computer generated stream for each transmitter, that would be OK.

I've never really comprehended the advantage of using those expensive little Barix boxes.. It seems like the same thing is accomplished using the same method utilizing a couple of old computers hooked to the internet.

I don't get what the Barix units do, that a standard internet connection does not.

more compact. stable. less power usage. simple setup. if you don't need something compact and has small power drain than an old pc will do fine and be cheaper. if you can afford a microwave ip link setup a rangemaster, solar panel, battery and a 222, then chances are you can afford to add a barix box.

Good point, Rich Powers. The shoutcast stream I'm able to send from my computer is adjustable through a full range of bit-rate settings and stereo/mono options, so it could be downloaded by a batch of old computers out on the other end of the wi-fi.

When the Barix boxes were first announced, I thought that they could be used in conjunction with other web streaming, such as receiving the shoutcast stream on a distant computer so that it could be received minus a second computer, but that's not the way it works. Its streaming is proprietary and only works from Barix to Barix.

Thanks for the RE's ... lots to think about.

Yes, I was thinking about the Barix Extreamers when I posted. But the delay/sync problems can be dealt with simply with a base station. You should need only one digital source of origin point using a computer with a cable to a Bullet and wireless modem with WiFi omni antenna.

Each satellite might consist of a dish, Bullet, cable, Barix, Part 15 FM TX, solar-charged (with appropriate controller) battery power supply, spaced approx. equidistant from the base, maybe 600' each way.

Not especially cheap, but a heckuvva lot less than anything else for license-free FM coverage. Stringing leaky cable capable of FM propagation downtown is wholly impractical.

But, these are just rudimentary basics. Making measurements, choosing the right gear, getting permission from building/property owners to mount systems on their roofs, installation, tuning, and testing, financial arrangements, etc., all must be figured into the plan.

I just haven't found anyone who has implemented such a system.

Well, I think you need both an Extreamer and the Instreamer units just for a single feed to one transmitter.. That alone would be about $500, not counting any additional accessories you would need.

Whereas a used desktop pc can readily be got for well under $50 (or in many cases for free) and do the same thing... leave the monitor screen off when not needed and the electricity used would be minimal.
Good used and complete P3 and P4 laptops can be also readily be purchased for $40 to $100.

If I were a rich man I might opt for the Barix due to it's more straight forward approach... I'll let you know if I get rich, but for now I'm looking at using a standard internet connect.

Another thing.. Regardless which route is taken, it seems that to have a synchronized audio feed to multiple transmitters would require that ALL of them - including your primary transmitter would have to get it's feed via the internet to avoid delays -- What I mean is that your processed signal would not go directly to your main transmitter, but instead first go to the internet and then back to your pc which then would feed the transmitter.
I wonder how much that would degrade the audio quality?

For high audio quality you'll need high CPU speed, which might no longer be a cheap computer.

For FM audio bandwidth of 15kHz you can tailor the stream rates to 32kbps at a sample rate of 32kHz, stereo. That might be an exact quality match.

"For high audio quality you'll need high CPU speed, which might no longer be a cheap computer."

Not necessarily. An old P-233 can dish out a 320kps stereo mp3 stream to a co-located server with no sweat.

Now if your running the DNAS server off the same PC as the encoder...(AHEMM!!!)..ya well then you need some hefty PC power cuz not only your doing the encoding and sending to the server, but also being the server creating the buffer chain taking up not just physical and virtual RAM, but CPU power as well.

32kps 32khz sampling stereo sounds like hammered poo poo. At minimum I would not run the audio interlinking stream no less than 92kps 22.050khz for "real" good FM stereo audio.

But if this entire idea is for a reviving of downtown businesses venture, transmitting in stereo would make no sense as most of the program content will be focused on the downtown businesses announcing sales and such, all or most of nothing more than voice content over background music or effects. Be a waste of all the effort for attempting full fidelity FM stereo and mimic a commercial station.

Now for decent mono FM sound, then ya 32kps 32khz mono would work, but I would use the more standard sampling rate of 22.050khz instead of 32khz.

RFB

basically you need to run mono on part 15 fm to maximize s/n ratio and therefore achieve maximum range.