System for automatic radio transfer of digital information and for distance computation

Claim 1

IN A SYSTEM FOR TRANSFERRING DIGITAL INFORMATION SIGNALS BETWEEN A FIRST AND A SECOND STATION, SAID INFORMATION BEING CODED IN A SPLIT-PHASE TRANSITIONAL PULSE MODULATION BINARY CODE WHEREIN ONE BINARY NUMBERATION DIGIT IS REPRESENTED BY A FIRST TIME INTERVAL BETWEEN ADJACENT TRANSITIONS, SAID TIME INTERVAL DEFINING A PRESCRIBED KEYING RATE OF THE INFORMATION SIGNALS, AND THE OTHER BINARY NUMERATION DIGIT IS REPRESENTED BY A SECOND AND SUBSTANTIALLY SHORTER TIME INTERVAL BETWEEN ADJACENT TRANSITIONS; THE PROVISION IN AT LEAST ONE OF SAID FIRST AND SECOND STATIONS OF THE COMBINATION COMPRISING: RADIO RECEIVER MEANS FOR RECEIVING CODED INFORMATION SIGNALS FROM THE OTHER STATION; A DIGITAL FILTER UNIT HAVING AN INPUT CONNECTED TO THE RECEIVER MEANS AND HAVING A FIRST AND A SECOND OUTPUT, SAID UNIT INCLUDING: MEANS DELIVERING A PULSE AT SAID FIRST OUTPUT IN RESPONSE TO THE APPEARANCE OF CONSECUTIVE TRANSITIONS AT ITS INPUT SEPARATED BY A TIME INTERVAL WITHIN A FIRST PRESCRIBED RANGE THAT INCLUDES SAID FIRST TIME INTERVAL; AND MEANS DELIVERING A PULSE AT SAID SECOND OUTPUT IN RESPONSE TO THE APPEARANCE OF CONSECUTIVE TRANSITIONS AT ITS INPUT SEPARATED BY A TIME INTERVAL WITHIN A SECOND PRESCRIBED RANGE THAT INCLUDES SAID SECOND TIME INTERVAL WHEREBY SAID SECOND OUTPUT PULSES ARE REPRESENTATIVE OF SAID OTHER BINARY DIGITS IN THE RECEIVED SIGNALS;