Testing a homebrew direct conversion dual-band side WSPR transceiver 30 yards. WSPR is so narrow bandwidth digital slow speed that can be decoded, even if the signals are below the noise level. WSPR takes 2 minutes to send two words. It's too slow for the purposes of the conversation that is increasingly used as a signaling system to test the propagation and research. WSPR milliwatts can be decoded thousands of miles and the drivetrain is needed is very simple as shown in this video. Thetransceiver that connects to a laptop, only four transistors. One of them is the crystal oscillator, one to the receiver's audio amplifier and two in the pilot of the issuer and the final. The balanced modulator is used as a detector device and the receiver uses two diodes IN4148. This is a very memory. The concept is similar to the platform W3PM (see website below), but only double-sideband (SSB not) and use the manual transmission / reception switching. The receiver is prone to false pointsand requires more work (probably because of interference from the computer.) However, the transmitter works very well, reports indicate that long distance. Anyone wishing to build something like that should start with the design W3PM transceiver for well designed, but simple, with good performances (link below). This project was inspired by an article in the Soldersmoke podcast / blog WSPR OSD. Even better is that 30 meters was the activity around a frequency which was in the glass...

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I did not write this, but can probably see me at the end of the receiver. I was on the computer B. both built the transmitter and receiver, but anyway, our transmitter was better, and the recipient was better, if the result was 300 feet above still work. Tho time of fun, love of laboratory projects.

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