Radio transmission timing calibrator

1. Field of the Invention A signal calibrator () for a software-defined communications device () that enables device communications signals to be transmitted in a manner that maximally decouples the calibrator () from the device hardware (), and that simplifies the design and reduces the cost of the communications device (). The calibrator () includes a software modulator () for generating a nonstop stream of samples including zero valued samples and non-zero valued waveform bursts, and a software demodulator () connected to the software modulator () via a closed loop feedback path () that receives a nonstop stream of samples. The non-zero valued samples create radio emissions. The software demodulator () is for determining a timing error of the transmission sample and for transmitting a timing error correction value to the software modulator () via the closed loop feedback path (). The timing error correction value enables the software modulator () to adjust a transmission time of a subsequent waveform burst to compensate for both unknown hardware delays and RF signal propagation delays.