Direct mp3 download or play: Very Bad Reception
Here is a little thing I made using a cordless phone and a radio. I discovered that my cordless phone appears to transmit on several different frequencies. In addition I’m using a wireless phone extender, the same type cable TV companies used to use for digital cable boxes to automatically call in billing data for pay-per-view movies. I have several of these units and they work fine for regular telephone use. The phone extender has a main frequency of 3.5 MHz and weaker signals at 7 MHz and 14 MHz and transmits in wide band FM. The cordless phone handset transmits on 46.6 MHz to 47 MHz and its base unit is on 49.6 MHz to 50 MHz. The handset can change frequencies in its range depending on reception. The phone itself transmits on narrow band FM.
I connected an inexpensive RadioShack multiband radio (model SW-100) to my small Yamaha mixer (model MG10/2). I then connected one of my DBX 161 compressors to send and return on the mixer. The mixer line out connected to my PC computer with a Soundblaster SE soundcard. The output from the computer soundcard feeds into an Alesis Nanocompressor and from there into my H.H. Scott A426 integrated amplifier. The Speakers are older Pioneer model CS-63 with the woofers replaced with Electro-Voice DL-15 speakers. I have added to each speaker a JBL 075 tweeter and a JBL 2402 tweeter. Model 2402 is a newer version of the 075 and looks identical from the front. There are four additional tweeters in all.
Now for the recording. I set the the threshold on the Nanocompressor quite low (-20db) so there could be a lot of feedback without the need to have the speakers very loud and to prevent damage to the amplifier or speakers. The radio was tuned up and down the dial on shortwave and then to about 7 MHz where the wireless phone extender transmits even when the phone is hung up. Then I switched on the cordless phone, waited until the dial tone stopped, listened on the radio and sure enough there was a signal. It was very loud and distorted, but very controlled with audio compression on the mixer and on the output of the soundcard as well. Then I realized the radio was receiving on AM and the wireless phone extender transmits on FM. When you try to receive a broadcast in the wrong mode it will come through very distorted. Once this was established, I just started recording the feedback from my cordless phone. I did not process the recording in any way except since the recording is monaural I’m presenting it here at 80KB mp3 mono.
