摘要:
A method of estimating background noise in a signal (10). The signal is divided into blocks (SB) of equal predetermined length. The minimum energy (A-E) of the signal during the length of each block is determined. The minimum energy determined for the current block is compared to a previous determination of minimum energy. If the current minimum energy exceeds a predetermined maximum energy level, the current block minimum energy is discarded and the previous determination remains unchanged. If the current block minimum energy is below the previous determination, the previous estimate is reduced by the difference between the previous determination and current minimum energy. If the current energy is above the previous determination but below the maximum, the previous estimate is increased by half of the difference between the current energy and the previous estimate.
摘要:
A method for designing an equalizer (32) and tracking performance for upstream PCM in a digital communications network is described. The invention optimizes upstream data rates for data transmissions in a network between a client modem and a server modem. During training, the upstream channel impulse response (46) is identified compensating for any robbed bit signaling. The upstream transmit equalizer (32) is computed in closed form based on the identified channel (34). An equalizer in the receiver (41) is also used to track timing and channel variations. The invention approximates bit error rate performance by looking for code violations in the trellis code decoder and tracking their frequency. The bit error rate is used to determine if the current modem parameters need to be re-designed.
摘要:
Providing facsimile communications in a system wherein an originating facsimile terminal equipment (FTE) connects to an intermediate digital network of unknown and unpredictable delay via an originating facsimile interface unit (FIU) and wherein a destination FTE connects to the network via a destination FIU. The originating FTE sends data to the destination FTE via the originating FIU. the originating FIU sends the data to the destination FIU. While the destination FIU is waiting for data from the originating FTE, the destination FIU sends made-up data to the destination FTE to prevent protocol timeouts of the destination FTE. The FTEs operate under the G3 protocol. The made-up data is either fill data or stall data, depending on the amount of data accumulated at the destination FIU and on the types of network delays.
摘要:
A method of estimating an echo return loss of a communication link measures the peak power value of a signal received from a far end of a communication link and the corresponding peak power value of a signal received from the near end of the communication link. When the near end signal is free from near end voice and excessive noise, the near end corresponding peak will be the echo of the far end power. The far end power is monitored and when a peak is detected, a period, which can be equal to a filter length period, is initiated. When the period has run, the delay line attached to the near end is polled to determine the peak power in the delay line. This peak power will correspond to the far end peak. If a peak, exceeding the first peak is detected before the period has run, the period is reinitiated. The echo return loss estimate is calculated as a ratio of the far-end peak power value to the near-end peak power value. The measured far-end signal is the payload information that the communication link was established to convey and the measured near-end signal is the echo of the payload.
摘要:
A method of detecting control tones in a digital signal by using a tone detection unit (11) (TDU) and a packet voice protocol unit (12) (PVPU) in a network over which the signal is transmitted. The TDU (11) detects the presence of a control tone in the signal within the first 5 ms of transmission and generates an alert signal (23) to the PVPU (12) to cease further transmission of the signal. Upon confirmation, the PVPU (12) may halt the transmission and buffer or delete the voice signal packets. Alternatively, if the control tones are not present in the signal, the PVPU (12) may continue transmission of any buffered packets. The method further incorporates the sending of the control tone signal to the receiving end of the transmission of the voice packets following transmission of the control tone to the receiving end.
摘要:
A method of estimating background noise in a signal (10). The signal is divided into blocks (SB) of equal predetermined length. The minimum energy (A-E) of the signal during the length of each block is determined. The minimum energy determined for the current block is compared to a previous determination of minimum energy. If the current minimum energy exceeds a predetermined maximum energy level, the current block minimum energy is discarded and the previous determination remains unchanged. If the current block minimum energy is below the previous determination, the previous estimate is reduced by the difference between the previous determination and current minimum energy. If the current energy is above the previous determination but below the maximum, the previous estimate is increased by half of the difference between the current energy and the previous estimate.
摘要:
A telecommunications gateway allows packets to be sent over a TDM system and allows TDM traffic to be sent over a packet switched network. The gateway is a universal port that includes a plurality of Digital Signal Processors (DSPs) that are controlled by software. The controlling software determines what single function the DSP will perform over multiple channels. Each DSP handles multiple channels, however, each DSP is restricted such that all of its multiple channels are permitted to handle the telecommunications traffic according to one signaling protocol.
摘要:
A cooperative feedback system (210) is provided for a compensation system associated with a transmitter or codec, for enabling the compensation system to improve the accuracy of digital signals transmitted to a digital network (113). The cooperative feedback system is particularly suited for providing feedback to a compensation system (130) for correction distortion resulting from rob bits signaling (RBS), digital loss, or other types of digital signal degradation. The cooperative feedback system includes a compensation selector (204) in a transmitter (181) that combines compensations with frames of digital data by way of an addition mechanism to produce modified digital data frames. A receiver (214) is configured to receive the modified digital data frames (118b) from the digital network (113), to determine if accuracy of each of the modified digital data frames has increased based upon a corresponding compensation, and to communicate one or more quality feedback signals (118a) to the transmitter (181) via the digital network (113). The transmitter (181) receives the quality feedback signal(s) and selects and implements the compensation that yields a highest accuracy based upon the quality feedback signal(s).
摘要:
Disclosed are methods for determining the reasons for packet loss in a wireless local area network, such as an IEEE 802.11 network. The methods use the strength of received signals at a wireless station, such as the received signal strength indicator (RSSI), noise levels (e.g, non-802.11 energy in the 2.4 GHz frequency range), and packet loss information together to determine the network status. In most implementations, the 802.11 implementation (e.g., the 802.11 driver) is responsible for maintaining statistics on the RSSI and the noise whereas the measure of the packet loss is the responsibility of the application. The network status is determined by the endpoint station independent from the access point.