Excavating
Patent
1991-05-02
1994-10-25
Baker, Stephen M.
Excavating
370 14, 370 15, 371 205, H04L 124
Patent
active
053596099
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in a general way to the quality check of a digital transmission link in the presence of real traffic. More particularly, the invention relates to quality check equipments complying with the CCITT recommendations on this matter, indicating transmission errors at bit level and in which the error detection preferably uses a cyclic redundancy coding (CRC).
2. State of the Prior Art
The gradual implementation of the integrated services digital telecommunications networks such as French ISDN network "NUMERIS" and the advent of the associated digital services point to increased demand from users with regard to quality in the forthcoming years. All-digital systems theoretically authorize precise quantitative measurements of transmissions quality and it is desirable to do away with all quality criteria of a subjective type in both data transmission and voice transmission.
In the recommendation G-821, Geneva 1980, pages 30 to 40 the CCITT International Telegraph and Telephone Consultative defined quality parameters for digital sections, links and paths throughout a network with or without switching exchanges. The measurement of these quality parameters currently requires the link in question being temporarily turned off and the injection into the link of a pseudorandom digital sequence of which the composition is known in advance. A comparison between the transmitted sequence and the received sequence enables rigourous bit-level detection of the transmission errors, and the quality parameters according to the CCITT recommendation are then calculated.
In the state of the art, there is no equipment available for measuring the CCITT quality parameters in a link in the presence of real traffic. Moreover, the errors detected by using cyclic redundancy codes generally concern a set of channels carried by the checked link and these errors cannot be specifically attributed to said channels.
OBJECT OF THE INVENTION
The main object of this invention is to meet the new quality check requirements of the above-mentioned digital links and to provide equipments for checking the quality of the links at bit level and in the presence of real traffic.
SUMMARY OF THE INVENTION
Accordingly, an equipment embodying the invention for checking the quality of a digital transmission link in the presence of real traffic, in which are provided first and second checking stations connected to first and second ends of the link for calculating first and second check information relating to groups of transmitted frames and to groups of received frames respectively, and for detecting transmission errors after comparisons between the first and second check informations, is characterized in that it comprises a service link connecting the first and second stations for transmitting notably the check information and the frame groups concerned by the transmission errors, and means distributed among the first and second stations for analyzing at bit level the frame groups concerned by the transmission errors, and for producing statistical informations and recordings relating to said errors.
Preferably, the distributed means comprise means for synchronizing the operating of the first and second stations, means for numbering the frame groups concerned by the transmission errors and the corresponding check information, first means for temporarily storing the frame groups and the check information, means for comparing bit-by-bit the first and second frame groups concerned by the transmission errors, and second means for storing the results of the comparison of the frame groups as well as informations relating to the instants of occurrence of the transmission errors, and means for processing the results and information contained in the second storing means thereby deriving said statistical information and recordings.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood from the following description of several preferred embodiments of the quality ch
REFERENCES:
patent: 3605091 (1971-09-01), Tong
patent: 3934224 (1976-01-01), Dulaney et al.
patent: 4439859 (1984-03-01), Donnan
Bonnifait Michel
Garandel Rene
Tremel Jean-Yves
Baker Stephen M.
French State Represented by the Minister of the Post, Telecommun
LandOfFree
Quality check equipments for digital transmission links does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Quality check equipments for digital transmission links, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quality check equipments for digital transmission links will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-141163