In general I want to feed audio to a few Part 15 transmitters using a longer range Part 15 device.
I know that even white spaces in 26-27 Mhz (CB Band) is off limits for this, but what about other bands / frequencies that are open to Part 15 continuous use.
49 Mhz sounds like it may be a good choice, but I don't want to risk interfering with someone's baby monitors or some of the old cordless phones that are still in use. Then there are those kiddo walkie talkies that could hijack the transmitters' input and open allow undesirable words to be broadcast.
I don't have a lot of money to put into this, but having a few Part 15 AM transmitters on hand, I would like to be able to space them out to cover a large stretch of a small town without people having to tune for another frequency (at least twice) just to listen while driving to work.
Of course I could do an AM-Translator in the middle on a different frequency, but the audio quality isn't going to be too good coming from the translator, and so the audio coming from the third transmitter is going to be terrible.
Then there is the idea of putting up some Part 15 FM transmitters and feeding them audio from an AM receiver, but I believe the FCC has a provision against "Cross Band Translators" at least for licensed stations (feeding FM to AM or vice-versa).
If I could legally feed AM receivers output into a Part 15 FM transmitter, and do this every 900 ft or so apart. AND use solar power to keep the batteries charged... but like I wrote above; this may be considered cross-banding, and I want to stay legal.
So this leaves me in search of a Part 15 service where I can achieve a few miles with highly directional and highly efficient receive antennas... Such a service that I can send studio audio over for 12 continuous hours at a time on a daily basis (legally).
Ideally the equipment would be inexpensive as in the most expensive part being highly efficient -- highly directional receive antennas, and I think I can make these antennas myself to lower the budget.
I can't find the thread right now, but I remember some talk of using 49 Mhz and solar? But I think I'm going to need a little more than what 49 Mhz is going to offer.
I would suggest using plain old WiFi, streaming into efficient, directional antennas. You'll need a computer at each transmitter to feed it, but not much of one (you can pick up older laptops cheap these days). You can also use the WiFi link to administer the computers from a central location.
Engenius (and others) make good, high power, Part 15 wireless access points and point to point transmitters that you can build your network from.
Another possibility is to use proprietary wireless technology, such as Trango or Barix. Not as flexible, and not as cheap, but you'll probably get greater range.
You can use up to 1 watt on the 2.4 Ghz band with a 6db gain antenna under Part 15, less power with more gain.
Of course, if you can pick up a remote internet stream at the transmitters, you won't even need your wireless audio feed - just internet connections at each transmitter. I don't know enough about your situation to know if that's possible.
I can still forsee problems. If you want to use the same frequency for the transmitters, you're going to run into interference at the range boundaries, and it could be noticeable (streaming introduces time lag). You might not see this as much with proprietary technology, but you're still going to get interference. Generally, using different frequencies is recommended for distributed transmitters due to this issue.
In any event, I would consider some form of streaming to distribute your signal before I'd consider using other methods. It's readily available, it's cheap and it works.
You will find it interesting Jim Dee that there IS a part 15 frequency in one of the CB white spaces that is open for use...
I will return later with more details, right now I am working on another project.
Artisan's suggestions are rock solid, and would be less experimental than part 15.
1 watt on 2.4 Ghz (microwave?) band with a 6db gain (directional) antenna sounds doable enough.
Of course the receive antenna is probably going to be a monster, will need an unobstructed view of the TX antenna, and a perfect aim to the TX. I'm getting about 3,000 ft in one direction using a stock Part 15 Talking House that is mounted inside of a weather tight container on the ground. Poly Twine supports the wire antenna in an almost vertical position. Yes the signal fades to almost unusable on the road, but I can listen for approximately 3,000 ft.
So I need to double this 3,000 ft using Part 15 techniques, and have a strong desire to stay as analog as possible while doing so.
Having said all that. I might be able to relocate the transmitter to that distant (3,000 ft) location and beam my audio to it by using the 2.4 Ghz link, while still being able to monitor the station (transmitter output) from the inside of the studio.
Except: there are a lot of unknown factors regarding placing my transmitter there. Security being one of those concerns. But not just security. I'd have to locate the transmitter atop a building, away from the ground, and thus reducing it's effective range. Then it'd be smack in the middle of the land of pavement.
If I can double that 3,000 ft with 2.4 Ghz at 1 watt, then I have better options for locating a 2nd transmitter at ground level in a more secure location, and (in theory) achieve better range.
Now if the 2.4 Ghz unit will do 9,000 ft or so... I could add a 2nd receiver to the third transmitter and grab the largest part of the main business district. Come to think of it 6,000 ft and proper transmitter location could get me there too, but i foresee overlapping signals, noise, and cancellation if I try to situate in a triangular pattern with only 6,000 ft. Better to go the 9,000 ft or so if it can be done.
My primary goal is highway coverage, but the more households that could possibly tune in from in-or-outdoors the merrier.
I know there will be "dead spots" but as an avid AM listener, I ignore those, and I'm sure that others will ignore a few coverage gaps the same as me.
Wonder how hard it will be to find a couple of old analog satellite receivers? because I don't think the receivers that come with those 2.4 Ghz links are going to be sensitive enough to pull a signal from those distances.
I'm very interested in your solution. Right now I have an FM TX i transmit my computer's Internet station to and need something other than an old cellphone that receives the Internet station and then simply re transmits it because when Google does its updates to the phone the audio will stop.
Bluetooth only goes about 30 feet and I'm about 50 FT or so from the TX. Analog probably would be the best case for me and I want to be Stereo. Any AV sender/receivers capable of operating at a good range?
This technique could also be used to have multi transmitters as well.
CB band? Are you talking about the in between channels AKA RC channels? I don’t think that would be good but what about the channels below 1? I don’t know of any FM TX/RX combo’s being built that would allow FM Stereo down there.
15.217 Long Wave 160-190 kHz 1 Watt 50-foot antenna;
15.225 Shortwave 13.553-13.567 MHz 15,848 microvolts/meter @ 30 meters;
15.227 Shortwave/CB band 26.96-27.28 MHz 10,000 microvolts/meter @ 3 meters.
15.235 As far as your concern that someone might have a baby monitor up in the 49.9 MHz region, drive around in your desired footprint and monitor... if you don't hear a baby monitor than monitor yourself by claiming the frequency.
You could just use one of those video senders used for TV, I've used that in the past with success. Otherwise Ubiquiti makes an affordable access point system.
above Artisian "suggest using plain old WiFi, streaming into efficient, directional antennas. You'll need a computer at each transmitter to feed it.."
That's not neccisarily true, there are methods to stream via witi from your pc to Roku devices without going through the internet. Therefore you would only need a small Ruko at each transmitter. I suspect that even the older models would serve the purpose, I see earlier models on ebay as cheap as $15 each.
Yes, you can use an Internet radio at the transmitter site.
Trango also has a Part 15 900 Mhz solution that doesn't require line of sight (although it will increase range).
You shoulld be able to get at least several miles point to point with either 2.4Ghz or 900 Mhz with line of sight and decent antennas.
I have been using Ubiquiti equipment for PTP and PTMP links for years. It's very do-able and not pricey.
I think 900 Mhz, highly efficient RX antennas, and a few old analog satellite tuners will give me what I'm looking for.
As for running the old SAT tuners from a solar charged battery battery (?) I have some researching to do there.
Thank You Everybody!
I will report back on this.
Hmmm if those older AV senders work nicely I may try that one day. I did get a hold of a cell phone to use for now. Works pretty good for receiving my Internet station so I can transmit it via the TX.
One aspect to all this that's going unspoken...
It aint gonna be cheap.