• C1 and C2 Error Correction

The LC78620E writes EFM demodulated data to internal RAM to compensate for jitter and then performs the

following processing with uniform timing based on the crystal oscillator clock. First, the LC78620E performs C1

error checking and correction in the C1 block, determines the C1 flags, and writes the C1 flag register. Next, the

LC78620E performs C2 error checking and correction in the C2 block, determines the C2 flags, and writes data to

internal RAM.

Note: 1. If the positions of the errors determined by the C2 check agree with those specified by the C1 flags, the correction is performed and the flags

are cleared. However, if the number of C1 flags is 7 or higher, C2 correction may fail. In this case correction is not performed and the C1 flags

are taken as the C2 flags without change. Error correction is not possible if one error position agrees and the other does not. Furthermore, if

the number of C1 flags is 5 or under, the C1 check result can be seen as unreliable. Accordingly, the flags will be set in this case. Cases

where the number of C1 flags is 6 or more are handled in the same way, and the C1 flags are taken as the C2 flags without change. When

there is not even one agreement between the error positions, error correction is, of course, impossible. Here, if the number of C1 flags was 2

or under, data that was seen as correct after C1 correction is now seen as incorrect data. The flags are set in this case. In other cases, the C1

flags are taken as the C2 flags without change.

2. When data is determined to have three or more errors and be uncorrectable, correction is, of course, impossible. Here, if the number of C1

flags was 2 or under, data that was seen as correct after C1 correction is now seen as incorrect data. The flags are set in this case. In other

cases the C1 flags are taken as the C2 flags without change.

No. 5130-30/34

LC78620E

C1 flag

Error correction and flag processing

No errors

No correction required · Flag reset

1 error

Correction · Flag reset

2 errors

Correction · Flag set

3 errors or more

Correction not possible · Flag set

C2 flag

Error correction and flag processing

No errors

No correction required · Flag reset

1 error

Correction · Flag reset

2 errors

3 errors or more