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RS Errors
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Old 19-12-2012, 08:53   #1
chienmort
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RS Errors

I have lots of pre and post RS errors, Cam anyone explain what they are?
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Old 19-12-2012, 10:44   #2
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Re: RS Errors

the superhub reports errors even if there are none
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Old 20-12-2012, 14:57   #3
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Re: RS Errors

RS = Reed Solomon - An algorithm for inserting error correction data prior to transmisssion to assist correction when received. It's a type of Forward Error Correction (FEC)

http://en.wikipedia.org/wiki/Reed%E2...ror_correction

The pre and post error counters should show how well the error correction is performing i.e. Pre-RS may be non-zero but Post-RS should be very low, ideally zero.

If the values reported by the SH are incorrect then the counters are, of course, useless!
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Old 20-12-2012, 15:07   #4
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Re: RS Errors

As Ferret says. VM have admitted that, in R36 at least, the counters are "unreliable". But, IMO, not that unreliable.

The pre-RS count will be higher on your SH where the SNR is lower. So, if DS1 was 41 db and DS2 was 37 dB, you'd see higher pre-RS errors and possible higher post-RS errors.

Post-RS errors should only occur if:

1 Your SNR is too ow for your modulation (say below 33 dB on 256QAM)

2 Your SH is playing up. This is unlikely.

The RS checking occurs right at the front of the modem section because it has to be able to sort out what's intended for your modem and discard the rest.
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