I recently moved into a concrete & steel apartment tower, and located my transmitter in a room that I use as my studio/office. However, its location is not ideal, as it gives a clear, line of sight view in a direction that I don't care about as much as others.
So I moved my transmitter to another room, facing south, and overlooking my primary coverage area, which includes the Pitt Meadows municipal offices and the recreation center. It was impractical to run an audio cable across the length of the apartment, so I used WiFi as a STL. I set up a stream within my (at least now) private network, capture that stream with an Internet Radio, and then output the audio to the transmitter.
It's working great, and gives me the flexibility to change the stream as I deem fit. For example, I can change the now mp3 stream to AAC or anything else, as long as the capture device at the other end can handle it.
I know others use Bluetooth for this purpose, but there were several disadvantages to this method, at least in my situation:
- The required length and obstructions made a solid bluetooth signal iffy
- Bluetooth security is not as great as WiFi, particularly in an apartment setting
- I've tried Bluetooth in the past, and had issues with the audio volume (and no means to increase it).
So far, I've had no issues, and I hear no difference in the quality of the FM signal from a straight audio cable connection (mind you, I'm running a high bitrate mp3 stream).
Wi Fi Casting
This is a very interesting achievement, Artisan, and sparks the imagination...
Can your Wi Fi radio transmission be opened up for direct listening by other Wi Fi users within range?
Are we on the brink of a new age of part 15 radio on the Wi Fi Band?
Yeah, I wouldn't recommend that. Other than in-house listeners, unless you have a wonderfully robust firewall and some heavy-duty password protection, expect someone in your listening area to go back up through your Wi-Fi appliance and turn your station's computer into a porn server.
My own home Wi-Fi password is 26 characters long -- in an easy-to-remember format but not an easy-to-guess one -- and by my reckoning, there are 254 million combinations a hacker is welcome to try before he gets old and dies. I urge everyone to do the same.
If all you're doing is giving access to a music stream through your wifi (and that can easily be done through an app without giving out your password), then there shouldn't be any issue. To be really safe, you could use a separate wifi network for your music stream (and only the music stream), and then you could freely give out the password.
It's a lot more difficult to hack into a network and other computers from that network than what might be portrayed in the media and elsewhere, particularly if you are security conscious, and keep software and hardware up to date. Most publicized security breaches are from inside information, and/or physical access. It just doesn't work like the movies.
I've often thought of building a radio-like wifi public network. It would be easy to do, even within the confines of Part 15 (you're allowed up to 1 watt with a 6db antenna), and hardware, including antennas, is readily available and relatively inexpensive. The difficult part is finding locations (with access to power) for the nodes, access points, etc. Certainly, you could build a network that could easily (and solidly) cover a community.
Maybe one day...
I'm the chief engineer at the local Community FM station and believe it or not that's what we use to get the signal to our transmitting facilities 6 miles away. Not too dependable but its all they can afford at this time.
With the right equipment, and more importantly, the right antennas (highly directional), and the right location, long distance point to point Part 15 wifi communication is certainly possible.
With a good point to point backbone, and then some decent access points, you can create a wifi network that will greatly outperform any legal Part 15 FM transmitter.
Oddball Wi-Fi
Few years ago I purchased a suit of small devices from MCM Electronics called simply "Wireless Stereo Audio Kit". The part # is not shown on the box but it wouldn't matter anyway because the unit was discontinued right after I bought mine.
It is in constant use, consisting of a USB dongle that transmits at 2400MHz - 2483MHz, and a black-box receiver with switching power supply.
It boasts CD quality 16-bit/44.1 kHz stereo, and sounds as good as a plain wire cable.
Up to 150-feet range is claimed, I am using it at 35-feet with never a drop-out.
Using USB Audio Out from the computer I am able to send KDX program audio to the SStran AMT5000 and Wholehouse 2.0 FM Transmitters. located at the rear wall of the building.
Back then I purchased a 2nd one so I could use the receiver of the 2nd unit to reach a second location, but it doesn't work that way. Each transmitter/receiver is a closed system and two of the units cannot be used in the same place. MCM refunded and allowed a return of that 2nd unit.
On my Wi-Fi dongle, which shows all the Wi-Fi's in the neighborhood, this MCM unit does not show its presence. Whether it is crowding someone's spectrum space or perhaps cordless phone I have no way of knowing.
BUMP
If you have the ability to connect to the Internet via copper at both the studio and Transmitter locations, there is a free software package literally designed to be an STL link:
https://jamesharrison.github.io/openob/
Your Receive end can be something as simple and cheap as a Raspberry Pi (with the Wolfson audio board). Take a look.
I've played with idea of wifr STL for a while and even experimented using Rukos as the transmitters audio feed, and had some success with that, but that w's back when streaming music was cheap.. But anyway, and I'm not sure if I'd already mentioned it in another thread, but there's a free software that I'd come across recently, and wonder if anyone has ever used MB RECASTER FREE?
"MB RECASTER FREE is a freeware application allowing to stream over the internet the audio input/outputs of the soundcard. ....internal server: stream directly from your computer without a stream host server with up to 10 simultaneous connections.."
The paid version allows up to 200 connections and can send metadata and some other features, but for my own purposes I think the free version having only 10 connections would be plenty.
What I have in mind is to use MB Recanted Free to feed multiple non overerlapping transmitters via internet, with the Rokus as the receivers which feed each transmitter.
The only problem I see is if one of the Ruko's loose a connection which result in that particular transmitter broadcasting dead air.. Ruko has some apps which can help to counteract that, but it still means dead air for a period of time until the stream gets restored..
So, to correct that scenario starts getting a little more expensive by preparing for it with additional items like a silence sensor coupled to an MP3 player, but it all still comes out considerably cheat than using the much more dependable and established method of using Barix boxes and such which can run into thousands quite rapidly depending on how many transmitters you'll be feeding.
I'm thinking looking at the silence detector found at the Angry Audio site which Carl mentioned recently. It's $229, which sounds kind of expensive but it does a lot:
And for the MP3 player maybe something quality like the Panasonic Digital Audio Player for $125, although a cheap $25 MP3 player could probably serve the purpose, but I figure if you're going to have this stuff outdoors enclosed in a box at the transmitter sites you're going to want quality builds that can withstand the weather tempature changes and so forth.
Anyway, that's the ideas I'm playing around with in my head. Any thoughts?
Useful Ideas
What Rich Powers is doing with Wi-Fi audio STL (Studio-Transmitter-Link) experimentation is in the same class as my ongoing experiments with open source radio streaming software (B.U.T.T., Altcast, Icecast) and appeals to me very much.
I will also take a look at MB RECASTER although I don't have Roku, but maybe I should think about getting it.
I would think of ways to keep as much of the equipment indoors as possible and for this balanced audio lines can be strung from the house out to the tower.
There are boxes that convert unbalanced to balanced or self-built chip circuits can accomplish the task. The point is that balanced audio cable can be longer without signal loss.
Control and voltage cables would also be required, so it basically means running a miniature telephone company.
The wireless portion of the run would be from the radio studio to the dispatching station at the closest wall to the outdoor tower.
Well you wouldn't really need a Ruko as the receiver, it's just that they are very portable, cheap, use almost no energy, and capable of receiving the stream wirelessly - but of course they need a WiFi signal to work. You could just use a laptop or something as the receiver instead.
Any ruko would work, I've even paid under $10 used on eBay for one of their earliest models when they still were all metal chassis. But if you go that route just make sure its a model that also have RCA connections, not all do.
Edit To clarify: I'm just out to cover several individual sections/areas within about a two mile area using multiple transmitters and allowing dead spots between them. I've abandoned the idea of blanketing a mile or two with just one transmitter, and the expense involved using Barix appears way to expensive to sync multiple transmitters -Might go that route in the future, but now considering cheaper ways.
Oh.. and they would probably be solar powered
Plans
Three towers are due to be built on the grounds of the Internet Building, home of KDX.
The front of the building previously had a 3-leg bamboo tower for 1550 kHz which served also as a flower vine tower, but the vines got top heavy in the wind and that tower went crashing to the ground, so needs to be re-built with better weight at the base.
A tower near the back wall on a ridge just above the patio table will support an outdoor loudspeaker and maybe a vertical antenna for 13.560MHz shortwave, although that would be in excess of 17-feet tall so maybe it would look out of proportion at that location... it's not far enough out to support a horizontal wire from the house... thinking remains to be done.
The most significant tower will be about 100' way back in the back for 1680 kHz, and tentatively it will be connected by overhead cables supported on bamboo telephone poles, with possibly some wireless channels, a wide-angle security cam and a yard light.