System for the automatic establishment of a shortwave telegraphy signal connection

摘要

A system for the automatic establishment of a shortwave telegraphy signal connection between two transmitter-receiver stations within a frequency range subdivided into several channels. Both stations use their receiver to determine objective measurement values reflecting the transmission conditions over the individual channels. Active and passive channel analysis of the actual quality of the signal transmission is determined at each channel. The transmitter of the calling station is automatically tuned to the channel which corresponds to the best channel quality stored in its memory. A predetermined time after transmitting the call signal, the calling station switches to reception and upon reception of an acknowledgment signal from the counter station automatically begins the message transmitting-and-receiving operation. If after a predetermined time no acknowledgment signal is received, the transmitter automatically switches to the channel stored in its memory with the next best channel quality value.