Wobbling Mechanism and Evolution

Wobbling Mechanism and Evolution

1. Signal Origin and Temporal Injection (Original Mode)

Originally, the region code (SCEx) is physically engraved on the CD as a track oscillation called wobbling. This specific area is located in the Lead-In of the disc, a sector normally used to calibrate the focusing and reading system of the optical block.

On the first revisions of the console (older motherboards), the analog signal extracted from this wobbling was simply converted into a digital format (0 or 1) using a comparator circuit.

• The nominal duration of a region bit in this raw signal is 4 ms.
• To bypass the security, it was enough to inject a continuous signal reproducing this code at the exact moment the console attempted to read the wobbling: a forced low level (0) or a high level (1) maintained for 4 ms per bit.

2. Evolution of the Security Circuit: WFCK Chopping

To counter the first modification devices, Sony complexified the security signal processing chain on later revisions of the console. The rectified signal from the wobbling was logically combined with the internal WFCK (Subcode Clock).

This modification radically changes the shape of the injected wave:

• Bits at 0 remain unchanged (maintenance of a continuous low level).
• Bits at 1, instead of remaining stable for 4 ms, end up chopped into 30 pieces synchronized with the WFCK frequency, which oscillates around 7.3 kHz.

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P.S. Tests confirm that the chopped signal at 7.3 kHz (WFCK Sync) is not backward compatible.

If you attempt to send this chopped signal into a first-generation console that expects a continuous 4 ms signal (Fixed Delay), the original circuit fails to validate the region code and blocks reading. This historical divergence requires keeping or precisely selecting the correct injection mode (temporal or synchronized) based on the targeted motherboard revision.