The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 08, 2001
Filed:
Apr. 21, 1999
Jyri Suvanen, Helsinki, FI;
Nokia Communications Oy, Espoo, FI;
Abstract
In some call-switching systems, transmitted speech samples may be sent back (back-looping) to the sender from a telephone switching center if the switching center is unable to send the speech samples forward. When supplementary information is sent with the speech sample, back-looping may cause a problem if the sending device interprets the signal as originating from another device. To avoid this problem, transmitted samples are subjected to a check value calucation such as a checksum or a cyclic redundancy check. The check value is stored in memory and any received samples are subjected to a check value calculation and compared to the stored samples. If the comparison yields a match, then the device will know that the received samples originated from itself and can be properly handled.