A device for protecting an aircraft turbomachine computer against speed measurement errors, comprising: - on a speed regulation channel: • a speed sensor of the turbomachine gearbox shaft, • a speed measurement circuit, • a speed regulation circuit, - on a monitoring channel: • a speed sensor of the turbomachine gas generator shaft, • a speed measurement circuit, • a turbomachine stop control circuit, configured so that: - the two speed sensors (21, 31) are two sensors facing teeth of two wheels (20, 30) of different technologies and having different numbers of teeth, - each speed sensor (21, 31) delivers a pseudo-sine frequency signal, - each channel (10, 11) uses dissimilar characteristics able to eliminate the common mode errors, - the speed regulation channel comprises a speed monitoring circuit which carries out a comparison of the frequency signal to a minimum threshold and which delivers a speed error signal when the measured frequency is lower than this minimum threshold, - the monitoring channel comprises a speed monitoring circuit which carries out a comparison of the frequency signal to a minimum threshold and which delivers a speed error signal when the measured frequency is lower than this minimum threshold, and configured so that it further comprises: - a circuit for cross checking the two obtained speeds, configured to detect an abnormal deviation between both speeds, by detecting the loss of a period on one of both signals or even of both signals simultaneously, and which delivers a speed problem signal, in case of an abnormal deviation between both speeds; - a circuit for possibly controlling the turbomachine stop in case of a speed problem. - on a speed regulation channel: • a speed sensor of the turbomachine gearbox shaft, • a speed measurement circuit, • a speed regulation circuit, • a speed sensor of the turbomachine gearbox shaft, • a speed measurement circuit, • a speed regulation circuit, - on a monitoring channel: • a speed sensor of the turbomachine gas generator shaft, • a speed measurement circuit, • a turbomachine stop control circuit, • a speed sensor of the turbomachine gas generator shaft, • a speed measurement circuit, • a turbomachine stop control circuit, - the two speed sensors (21, 31) are two sensors facing teeth of two wheels (20, 30) of different technologies and having different numbers of teeth, - each speed sensor (21, 31) delivers a pseudo-sine frequency signal, - each channel (10, 11) uses dissimilar characteristics able to eliminate the common mode errors, - the speed regulation channel comprises a speed monitoring circuit which carries out a comparison of the frequency signal to a minimum threshold and which delivers a speed error signal when the measured frequency is lower than this minimum threshold, - the monitoring channel comprises a speed monitoring circuit which carries out a comparison of the frequency signal to a minimum threshold and which delivers a speed error signal when the measured frequency is lower than this minimum threshold, - a circuit for cross checking the two obtained speeds, configured to detect an abnormal deviation between both speeds, by detecting the loss of a period on one of both signals or even of both signals simultaneously, and which delivers a speed problem signal, in case of an abnormal deviation between both speeds; - a circuit for possibly controlling the turbomachine stop in case of a speed problem.