US 12,261,978 B1
Detecting a loop length change in a digital subscriber line
Feiyu Fang, London (GB); Lykourgos Kekempanos, London (GB); and Daniel Gilks, London (GB)
Assigned to BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY, London (GB)
Appl. No. 18/848,778
Filed by BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY, London (GB)
PCT Filed Feb. 6, 2023, PCT No. PCT/EP2023/052881
§ 371(c)(1), (2) Date Sep. 19, 2024,
PCT Pub. No. WO2023/179953, PCT Pub. Date Sep. 28, 2023.
Claims priority of application No. 2204091 (GB), filed on Mar. 23, 2022.
Int. Cl. H04M 3/30 (2006.01); H04B 3/46 (2015.01)
CPC H04M 3/30 (2013.01) [H04B 3/46 (2013.01); H04M 2201/14 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A method of detecting a loop length change in a digital subscriber line, said method comprising:
generating a test echo response from the digital subscriber line using a single ended line test, wherein said test echo response comprises a frequency domain trace;
retrieving a historical echo response associated with the digital subscriber line, wherein the historical echo response comprises a frequency domain trace previously taken from the digital subscriber line;
applying each of a plurality of scale factors to the frequency axis of the test echo response or to the frequency axis of the historical echo response to generate a corresponding plurality of adjusted test echo responses or adjusted historical echo responses respectively;
calculating a difference between each of the adjusted test echo responses and the historical echo response or the adjusted historical test echo responses and the test echo response; and
identifying the scale factor that resulted in the lowest calculated difference;
comparing the identified scale factor to a threshold; and
determining if there is a loop length change in dependence on the comparing step.