WSPR

WSPR (1270 AM, "Power 1270") is a radio station licensed to serve Springfield, Massachusetts, USA. The station is owned by Davidson Media Group and licensed to Davidson Media Station WSPR Licensee, LLC. It airs a Spanish Tropical music format. Throughout the 1960s and 1970s, the station had a Top 40 format. Later decades, the station had a talk/news approach before its current format.

The station was assigned the WSPR call letters by the Federal Communications Commission.

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WSPR (amateur radio software)

WSPR (pronounced "whisper") stands for "Weak Signal Propagation Reporter". It is a computer program used for weak-signal radio communication between amateur radio operators. The program was initially written by Joe Taylor, K1JT, but is now open source and is developed by a small team. The program is designed for sending and receiving low-power transmissions to test propagation paths on the MF and HF bands.

WSPR implements a protocol designed for probing potential propagation paths with low-power transmissions. Transmissions carry a station's callsign, Maidenhead grid locator, and transmitter power in dBm. The program can decode signals with S/N as low as -28 dB in a 2500 Hz bandwidth. Stations with internet access can automatically upload their reception reports to a central database called WSPRnet, which includes a mapping facility.

The WSPR Protocol

The type of radio emission is "F1D", frequency-shift keying. A message contains a station's callsign, Maidenhead grid locator, and transmitter power in dBm. The WSPR protocol compresses the information in the message into 50 binary digits. These are encoded using a convolutional code with constraint length K=32 and a rate of r=1/2. The long constraint length makes undetected decoding errors less probable at the cost, that the highly efficient Viterbi algorithm must be replaced by a simple sequential algorithm for the decoding process.