Ideas? I need to travel about 1 mile.
I operate/program the Community Radio system for the City of Cuyahoga Falls, Ohio. The station is part of an outdoor siren warning system. When you hear the sirens, tune to 1650 AM for an emergency message.
Our programming runs on ZaraRadio automation at my office/shop. Using a dedicated IP audio streamer, the programming is carried over the City's intranet about three miles to where our transmitter is located.
The streaming devices are called the Extreamer (transmitter) and Instreamer (receiver.) They were expensive but very stable having never crashed in over a year now.
The bit rate and compression are adjustable as MP3 allows.
I started out using Windows Media Encoder on my desktop PC and the receiving end was a laptop running Windows Media Player. The stream would occasionally stop usually due to Windows forced updates.
When no emergency exists, I run weather and local activities information. The station is allowed up to 10 watts provided the signal does not exceed the specified strength measured at 1.5 km from the antenna.
You could use something like Shoutcast and WinAmp to stream over the internet if you have reasonable bandwidth at both ends. I use Shoutcast for my webcasting.
I used a Ramsey FM25B to relay from my computer audio out to the back of the building where an FM receiver demodulated and fed to SStrans3000 for re-transmission. That was just 30-feet, but the FM signal could be heard all over the neighborhood even though I had antenna shortened as much as possible (8") and the power control lowered. I gave up because I didn't want such a large presence on FM.
Do you have line of sight to your destination? That makes a huge difference and if you could directionalize the transmission antenna from the FM25B and used a high gain FM receiving antenna the FM25B is a thought.
I use my part15 FM signal from my Maxell FMT-1 and pick it up at the AM transmitter with a modified little "Dollar store" FM receiver.
But I'm only going 60, maybe 100 ft at most with that, I don't think it would work at a mile even with a great location and a really *really* good receiver.
For short range though, it gets the job done.
Daniel
I'm using a Radio Shack 2.4GHz transmitter/receiver that is used to send wireless audio and video signals around a house. I have the transmitter module sending the audio signal from my studio out to the receiving module in my garage about 100 feet away. I have the audio output of the receiver connected to the audio input on my sstran transmitter. This is a temporary arrangement I'm using to monitor and evaluate the reliability of the Radio Shack units for this application. I thought there would be interference from other 2.4 GHz sources in my area, but so far everything has been as quiet as a mouse! If this continues to work, I will be using this to feed my ground mounted Procaster transmitter in my back yard, if I ever get a chance to do that!
That's inspiring, gronsk! What is your frequency response like in that system? Better than AM, I'd guess.
If there's a way you can test its distance limits that would be useful to know!
I know there are plans out there on the web to modify the antennas for better range.
I must confess that I am new to radio technology and I am not exactly certain what you mean by "frequency response". I can tell you that the monitored on air signal is as strong, clear, and free of interference as any of our 50 kW AM stations here in the Milwaukee, Wisconsin area. In terms of your request for testing the system for "distance limits" it is my intention to perform these tests. Many of the Part 15 activities that I would like to pursue is frequently very difficult to accomplish – I have really bad arthritis. I'll keep you posted here if I can come up with a way to provide distance testing information. What I can tell you is the 2.4GHz signal from the studio to transmitter links are traveling through drywall, wood studs, insulation, and aluminum siding from the indoor studio and then again at the receiving end of the link. The accurate distance measured in between the two units is 103 feet. I hope this helps a little!
You could probably set up internet streaming with a directional antenna at both ends (as well as bridges) to get a legal one mile range - you're allowed one watt, I believe, for wireless networking with directional antennas in the 2.4 GHz range. You would have to have some form of small internet radio to receive your signal and transfer it to your transmitter via audio cables at the other end. If the location is outdoors, the wireless bridge, internet radio (such as a Roku or Squeezbox) and transmitter would all have to fit into a weatherproof box).
Yes, gronsk, your information tells a lot. If it works so well through walls, it is the nature of microwaves to work much much better in open space. And your experience of a pleasing sound tells me that the "frequency response," a term you will run into again, refers to the audio response from lowest notes up to the highest dings.
I tried to find the 2.4GHz on the radio shack website, but the site is not easy to figure out. I did find a number of such devices in the Markertek catalog (markertek.com), all of which also had video channels.
The reply about using computer-type wi-fi equipment is a whole new world to explore!
Carl,
Thanks for your explanation of "frequency response". That finally clears up a question I've had for a while now.
The Radio Shack homepage is jammed with information that makes searching specific products difficult (at least for me anyways). The unit I'm using is called the Terk Leapfrog (LF-30S) Wireless 2.4GHz Remote Extender. I found this product by entering "TV transmitters" in the search window at the top of the homepage. When the next page opens scroll down to the seventh unit on the page to see the Leapfrog (don’t ask me why a catalog number search doesn’t work - but it doesn’t!) By the way, as you scroll down there is a 5.8GHz unit that may be of interest as well. It was more expensive so I went with the lower priced 2.4 GHz unit just to see if this would work at all. Can you tell me if higher frequency radio waves penetrate through objects more effectively than lower frequency waves? If that’s the case, would 5.8GHz be a better solution for distance and penetration of objects in the signal path? Thanks again!
.
gronsk, et. al.,
I have used 27 MHz, 49 MHz, 900 MHz, 2.4 GHz, and 5.8 GHz cordless telephones around here over the years. The quietest unit is the 5.8 GHz phone, but it also has the spottiest coverage. If I am positioned so that the refrigerator is between me and the base unit, I lose the signal. The greatest range I achieved was with a 27 MHz unit with a 49 MHz back channel and that was about 300 feet using stock equipment.
At 5.8 GHz the signals tend to be line of sight and don't bounce around obstacles and my phone does have several dead spots around the house. It could work well for line of sight outdoors but I don't know that.
I have done experiments at 932 MHz with OEM tx and rx units using a 1/4 wave antenna (only 8 cm long) and have had good results with full quieting signals inside and outside the house up to 100 feet. I haven't had a chance to go farther for testing. I have also used 10.5 GHz for doppler experiments and this, with a horn antenna, is very directive. Hams report reliable ranges on this X microwave band of up to 6 miles line of sight. I don't know much about the part 15 restrictions in this band.
From what I have tried, the 900 MHz and 2.4 GHz bands seem to hold promise and they are both part 15 bands. The 900 MHz equipment I use is simple FM but I believe the digital phones at 2.4 and 5.8 GHz are both spread spectrum.
Neil