Kitz Forum

Broadband Related => Broadband Technology => Topic started by: Weaver on August 24, 2020, 02:20:12 PM

Title: Bits per bin and SNRM difference
Post by: Weaver on August 24, 2020, 02:20:12 PM

Question: In DSL, if you improve the SNR on a tone by x dB so as to get a 1 bit increase in bit-loading, what is x ?

Title: Re: Bits per bin and SNRM difference
Post by: burakkucat on August 24, 2020, 04:15:16 PM

I presume that you are asking about the absolute SNR and not the SNRM for a particular frequency?

It's a good question and I feel there must be some "rule of thumb" (or paw) which would allow an estimate to be made.

I suspect that either ejs or Kitz may be able to assist . . .

Title: Re: Bits per bin and SNRM difference
Post by: digbey on August 24, 2020, 04:56:02 PM

https://kitz.co.uk/adsl/adsl_technology.htm

~ Bit Loading

• If the signal is good then 15 bits (maximum) can be allocated to that tone.
• Each 3dB of SNR equates to 1 bit (of data),

Title: Re: Bits per bin and SNRM difference
Post by: burakkucat on August 24, 2020, 05:36:43 PM

  :thumbs:  Thank you. That is what I could not fully recall. Team work prevails, once again.  :)

Title: Re: Bits per bin and SNRM difference
Post by: Weaver on August 24, 2020, 08:29:03 PM

Thanks! Measurements taken from SNR and bits-per-bin graphs suggested 3dB to me, but I wanted another opinion. Thanks to Kitz also.

Title: Re: Bits per bin and SNRM difference
Post by: 4candles on August 24, 2020, 10:52:41 PM

Interesting parallel - that 3db is generally accepted as the smallest difference in level that is easily heard by most people listening to speech or music.

Title: Re: Bits per bin and SNRM difference
Post by: Weaver on August 24, 2020, 11:49:45 PM

That is what I have read too. Indeed, an interesting point. Approximately double the power.