The T-ASJ20 is a timing security isolation device designed for scenarios such as GNSS interference and spoofing. It features automatic BeiDou switching, simulated signal generation, and system isolation. Its built-in local clock discipline and holdover mechanism ensures timing accuracy better than 100ns even in the presence of external anomalies. It supports anti-forwarding interference, real-time monitoring, seamless switching, and remote upgrades, with fast interference response and guaranteed time security. It is suitable for applications in the power, finance, communications, and defense sectors.