Kitz Forum

Broadband Related => Broadband Technology => Topic started by: Weaver on November 15, 2020, 09:19:15 AM

Title: Pilot tone
Post by: Weaver on November 15, 2020, 09:19:15 AM

I don’t understand the pilot tone in DSL; Is it meant for detecting the presence of the service ?

I read in a Huawei document that the downstream pilot tone is supposed to be tone 64 and there’s supposed to be an upstream tone at tone 16. I am seeing a drop down to bit loading=2 on tone 69, not tone 64, and I’m not seeing any bit loading drop on tone 16 so I don’t understand where that has disappeared to.

Title: Re: Pilot tone
Post by: licquorice on November 15, 2020, 04:41:02 PM

At the risk of teaching grandma to suck eggs, the purpose of a pilot tone is to give a standard reference frequency for setting/measuring signal levels.

Title: Re: Pilot tone
Post by: Weaver on November 15, 2020, 07:22:38 PM

Thank you. I’m not qualified as a grandma. Do you know why I’m not seeing the upstream one ? Or why the downstream carries 2 bits?

Title: Re: Pilot tone
Post by: licquorice on November 15, 2020, 07:56:22 PM

I'm afraid I have no answer to that. I was just speaking in generic terms as to the purpose of pilot tones in systems.