They can be sonar guided, or they can be wire guided. Before these technologies were developed, torpedoes were unguided.
A torpedo guidance system is a mechanism used in torpedoes to navigate and steer towards a target. It typically consists of sensors, such as sonar or acoustic arrays, that detect the target and measure the torpedo's position and orientation. The data from these sensors is processed by a guidance algorithm, which provides commands to control the torpedo's propulsion and steering, allowing it to intercept the target accurately.
Germany
They were not really codes. It was a communications system for torpedo guidance that was resistant to enemy jamming. Bits of signals were sent over different frequencies.
Torpedoes are typically controlled remotely and autonomously. They are equipped with various sensors and guidance systems, such as sonar, to detect and track targets. The guidance system then calculates the desired trajectory and control surfaces, such as fins, are activated to steer the torpedo towards its target.
Type 95 torpedo, aka Long Lance; best (and deadliest torpedo of WWII).
Red Torpedo was created in 2009.
PCP Torpedo was created in 1998.
Torpedo Service was created in 1870.
Torpedo Service ended in 1978.
Torpedo - petroleum - was created in 1865.
Torpedo Sofia was created in 2006.
Spearfish torpedo was created in 1992.
Torpedo Rīga ended in 2000.