HDB3 - clock recovery????

[5hinka]

Im designing Jitter Measurer for 2Mbit (HDB3) signal.
Input signal must be decoded from HDB3 to recover clock signal.
Is there any easy (or little bit hard) way to decode it (with error
correction)????

I was thinking about putting hdb3 signal into serial-in parallel-out shift
register
clocked with 11,12,13 * 2Mbit. Analizing Parallel out of this register will
enforce
11-13 multiply.
Maybe you know/see any easier solution??
Maybe sb seen anywhere in net some good publications about jitter
measurment??

Thx for help
Greetings from Poland
5hinka

 

[Tony Thomas]

Im designing Jitter Measurer for 2Mbit (HDB3) signal.
Input signal must be decoded from HDB3 to recover clock signal.
Is there any easy (or little bit hard) way to decode it (with error
correction)????

I was thinking about putting hdb3 signal into serial-in parallel-out shift
register
clocked with 11,12,13 * 2Mbit. Analizing Parallel out of this register will
enforce
11-13 multiply.
Maybe you know/see any easier solution??
Maybe sb seen anywhere in net some good publications about jitter
measurment??

Thx for help
Greetings from Poland
5hinka

There are chips on the market for decoding HDB3 such as the MV1442
from Zarlink. HDB3 was not designed for error correction. The decoder
circuit has to remove the "B00V" code sequences (B=Binary (0 or 1); V=
Violation)which have been encoded at the far end and replaces them
with "0000". The "B" is introduced, as required, to keep the
violations alternating in polarity. Error detection takes place by
looking for other violations of the normally alternating Pos Neg pulse
sequence which will cause a double violation of the same polarity.
This may occur due to an extra "1" being changed from a "0" in the
code - remove?? or a "0" being changed from a "1" - producing a
violation in an adjacent bit position - can't remove. How do you find
out which type it is??
Hope this helps
Tony

 

[5hinka]

There are chips on the market for decoding HDB3 such as the MV1442

from Zarlink. HDB3 was not designed for error correction. The decoder
circuit has to remove the "B00V" code sequences (B=Binary (0 or 1); V=
Violation)which have been encoded at the far end and replaces them
with "0000". The "B" is introduced, as required, to keep the
violations alternating in polarity. Error detection takes place by
looking for other violations of the normally alternating Pos Neg pulse
sequence which will cause a double violation of the same polarity.
This may occur due to an extra "1" being changed from a "0" in the
code - remove?? or a "0" being changed from a "1" - producing a
violation in an adjacent bit position - can't remove. How do you find
out which type it is??
Hope this helps
Tony

My mistake. I DO NOT need to decoder HDB3. I NEED to RECOVER clock.
All chips i found decode hdb3. :-(((

Greetings
5hinka

 

[Tony Thomas]

My mistake. I DO NOT need to decoder HDB3. I NEED to RECOVER clock.
All chips i found decode hdb3. :-(((

Greetings
5hinka

The MV1442 does provide clock recovery using an external 16.384MHz
clock if you are operating at 1.5 or 2MBit/s. See the following link
http://products.zarlink.com/product_profiles/MV1442.htm. You don't
say what speed you want - is this not suitable? The conventional way
of recovering clock is to feed the recovered data stream (not the one
which has been HDB3 decoded, but the combination "OR" of the positive
and negative input data) and stick it into a low Q tuned circuit.
Amplify the resulting sine wave and square off. The second stage in
the process is to feed into a narrow band phase locked loop in order
to generate a highly stable clock which will then allow you to do
jitter measurements.
Best Wishes
Tony