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This was received on October 18th, 2006 from inside my living room on my AOR AR-3000 communications receiver at 927.600 MHZ and recorded on my PC computer using line in on a Creative Audigy 4 soundcard. In addition I used a directional beam antenna capable of receiving 902 MHZ to 928 MHZ with up to 13 db gain. The transmitter appeared to be west of my location and I’m guessing up to a mile away, but most likely as close as a few blocks. Sometimes while monitoring this transmitter a barking dog could be heard and then an echo of the same sound outside my house less than a second later.
This baby room monitor has considerably better fidelity than the other at 49.845 MHZ (previous post in Baby Room Monitors) mainly because it seemed to be transmitting in wide band FM instead of narrow band FM like police and fire departments. In other words it tuned in just like an FM broadcast station and setting the receiver to narrow FM would produce loud distorted sound. In fact, I think the receiver was almost at “full quieting,” meaning the signal was as strong as possible with the least amount of noise. In spite of that, there was still a substantial amount of white noise and possibly some digital noise from cell phones. I did a lot of processing with Adobe Audition. I eliminated 10 megabytes of the original wav file where there was no talking, and then applied noise reduction to the entire file. After that, I used amplification and hard limiting to bring up low level audio. Also, I normalized the whole file to just under 0db. Lastly, the file was converted to standard stereo 128 kb per second MP3, although the sound is actually monaural. It still isn’t that great but it is a fun little story.
900 Megahertz Directional Beam Antenna
