In order to heighten the grade by the present mobile wireless telegraphy system, through the experimentation and research on both data transmission and error correction methods, both data and facsimile transmission were confirmed to be possible together with the following result: In the character transmission by a CPU connection and other encoded transmissions in which even an error by one bit considerably influences the contents of data, 1200bps, as able to be widened in service area, is profitable. While the data transmission in the mobile wireless telegraphy generates many errors due to phasing and noise along the propagation route. To attenuate those errors, error correction encoding is effectively applied with a correction method to be selected by kind of data. Further the 150MHz band, as more largely influenced by urban noise than the 400MHz band, narrows service area in the urban district. While the mobile wireless telegraphy is restricted in frequency band region. 12 refs., 26 figs., 9 tabs.