VHF/UHF

摘要

Joe Taylor, K1JT, has published a new version of WSJT which is now ready for download: WSJT 7.0 Beta. The main change to earlier versions is the introduction of a new mode 'WSPR', (pronounced 'whisper'). It stands for 'Weak Signal Propagation Reporter'. WSPR generates and receives signals using structured messages, strong forward error correction and narrow-band 4-FSK modulation. Its principal design goal is reliable copy at very low signal levels. Total bandwidth is about 6Hz, so WSPR signals are about 1/60th the bandwidth of JT65b signals and one quarter the bandwidth of 20 wpm CW.rnIn practice, it works well at signal-to-noise ratios down to at least -27dB in a reference bandwidth of 2500Hz. WSPR has some 3 - 4dB gain over JT65 KV decodes and is about 1dB better than JT65 DS decodes.