WSPR

WSPR implements a protocol designed for probing potential propagation paths with low-power transmissions.  Normal transmissions carry a station’s callsign, Maidenhead grid locator, and transmitter power in dBm.  WSPR can decode signals with S/N as low as -28 dB in a 2500 Hz bandwidth.

iWSPR TX by Federico, IW2MVI, is a WSPR implementation for iPhone and iPad that allows you to transmit and receive WSPR signals with just your iOS device and a simple audio cable connected to your radio.    It’s great for checking an antenna during a SOTA operation, field day, or making adjustments to your home antenna system.

iWSPR TX is very to use: just insert your Callsign and Grid Locator and then change the “Power” and the “Dial Frequency” in relation of your working condition. Once you are ready click “Generate TX” and then “Enable TX”. The button will become red and a popup window will appear during transmission.  To avoid distortion and overload of your radio keep the audio level as low as possible.

Instructions on how to use iWSPR TX and information on building an audio interface cable are available  as a PDF here.

You can find more info about the WSPR protocol on the K1JT’s official WSPR website