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 are two sensors facing teeth of two wheels of different technologies and having different numbers of teeth, - each speed sensor delivers a pseudo-sine frequency signal, - each channel 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 (S1) 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 (S2) 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 (S3), 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 are two sensors facing teeth of two wheels of different technologies and having different numbers of teeth, - each speed sensor delivers a pseudo-sine frequency signal, - each channel 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 (S1) 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 (S2) 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 (S3), in case of an abnormal deviation between both speeds; - a circuit for possibly controlling the turbomachine stop in case of a speed problem. <EOS>