Pad and CODEC detection
AssigneeIntel Corporation
InventorsJeffrey Allan Green, Vedavalli Gomatam Krishnan
Life of this patent
Estimating the term…
Abstract
A Digital Impairment detection scheme which is designed for providing reliable estimate of digital impairments such as PAD, and CODEC type in the presence of digital impairments such as Robbed Bit Signalling and non G.711 complaint network CODECs and analog impairments such as IMD, noise and changing line conditions. This estimate is used to derive optimum transmit symbol constellations for a modem connected digitally to a trunk so as to maximize its data transmission rate.
Claims22
In a digital communications system including a first modem operatively connected to a second modem through a digital communications network with possible digital impairments of repetitive nature, with repetition frame (RF) size of one or more slots, said first modem including pad detection means for detecting and measuring an actual value of programmed attenuation (PAD) in a digital trunk, a PAD and CODEC detecting means for detecting the type of Network CODEC at the digital trunk to analog loop interface in the signal path from the second modem to the first modem, said PAD and CODEC detection means comprising:
- a. means for selecting a plurality of test values, where each said test value corresponds to a PAD value;
- b. means for selecting one or more CODEC types, each of said CODEC types corresponding to a particular CODEC type at the digital truck to analog loop interface at the network;
- c. means for calculating a minimum error between preprocessed received signal values and the type of CODEC linear values for a test PAD value;
- d. means for calculating a PAD estimate based on the minimum error;
- and
- e. means for identifying CODEC type based on the minimum error.
A method of operating a first modem operatively connected to a second modem through a digital communications system with possible digital impairments of repetitive nature, with a repetition frame (RF) size of one or more time slots, to measure communications system programmed attenuation (PAD) and the network CODEC type at said first modem for signals sent from said second modem, said method comprising:
- selecting a test PAD value,
- selecting a CODEC type,
- carrying out at said first modem a calculation of summing absolute errors between average received values multiplied by said test PAD value and the nearest CODEC linear values for the CODEC type,
- selecting a minimum absolute error based upon said calculation,
- calculating a PAD estimate based on said minimum absolute error, and
- identifying a network CODEC.
Dependencies are inferred from the claim text.