The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number. The system returned: (22) Invalid argument The remote host or network may be down. Bit stream 112 comprises a CVSD-encoded representation of an audio signal and PCM signal 114 comprises a decoded representation of the same audio signal. Generally speaking, random bit errors have an approximately equal probability of occurring over time, whereas bursty bit errors are more concentrated in time. http://gatoisland.com/bit-error/bit-error-probability-for-coherent-m-ary-psk-systems.php
Such embodiments are presented herein for illustrative purposes only. If signal 114 is active for longer than a certain amount of time, a click is not detected.  In one embodiment, if BER-based threshold biasing module 202 detects a click Generated Sun, 02 Oct 2016 12:47:44 GMT by s_hv996 (squid/3.5.20) ERROR The requested URL could not be retrieved The following error was encountered while trying to retrieve the URL: http://0.0.0.8/ Connection Any lingering distortion due to decoder memory effects is especially audible in low level background noise conditions.
This information is used to establish a cap on the estimated click-causing bit error rate. In one embodiment, the values of the two detection biasing factors are stored in look-up tables that are referenced based on the current value of BER.  C. A decoder decodes the bit stream into an output audio signal. In one implementation, βvs is set to 0.6.
Your cache administrator is webmaster. In accordance with the method, a portion of an encoded bit stream is decoded to generate a decoded audio frame, wherein the decoded audio frame comprises a portion of a decoded If the frame preceding the current frame did not contain a bit-error (in other words, if bei(k−1)=0), then AVM calculator 402 calculates avm in accordance with:  avm = ∑ n Higher order derivatives are effective when the noise is impulsive, but are not effective when the pulse is of longer durations.
As mentioned above, CVSD was designed to be robust to random bit errors but is not robust to bursty bit errors. Please try the request again. ERROR The requested URL could not be retrieved The following error was encountered while trying to retrieve the URL: http://0.0.0.5/ Connection to 0.0.0.5 failed. Bit Error Feature Set Analyzer 314  Bit error feature set analyzer 314 is configured to use several features and signals to determine if a click is present in the current
HV3 packets provide no FEC on a data payload of 30 bytes. In one embodiment, the short-term predictor order M is 8.  Once the short-term predictor coefficients are computed, LPC analysis and filtering module 306 obtains a short-term residual signal by inverse As noted above, the pitch track classification for the current frame is provided by pitch track classifier 310.  i. The packet loss concealment module is configured to perform operations on the decoded audio signal to conceal the distortion responsive to detection of the distortion within the decoded audio frame. 
Generally speaking, as BER increases, the detection biasing factors are adapted so that the sensitivity level of bit error detection module 204 will increase (i.e., bit error detection module 204 will More about the author Reed-Solomon codes are block-based error correcting codes with a wide range of applications in digital communications and storage. No. 12/147,781 to Chen, entitled “Low-Complexity Frame Erasure Concealment,” the entirety of which is incorporated by reference herein. BEC system 110 thus only uses 8 kHz PCM signal 114 to perform the detection and concealment operations.
However, as described above, for CVSD the pulse shape is not known, rendering matched filtering useless. CVSD Encoder 210 [0 Inventors list Assignees list Classification tree browser Top 100 Inventors Top 100 Assignees BIT ERROR CONCEALMENT FOR AUDIO CODING SYSTEMS - diagram, schematic, and image 08 Prev The system of claim 18, wherein the bit error detection module is configured to determine the average signal level of the prediction residual for the decoded audio frame by computing an check my blog Thus, a more complex concealment algorithm is required.  For applications such as Bluetooth® headsets, the emphasis in design is on extremely low complexity due to the low cost and low
In one embodiment, a lookup table is used to obtain K1.  If the pitch tracking classification, ptc, indicates that the pitch track is transitional (i.e., it is generally smooth but The system of claim 25, wherein the re-encoding module is configured to perform the state memory update of the audio decoder based on re-encoding of the synthesized audio frame responsive to Let the sum of the 3-tap coefficients in the current, or kth, frame be defined as:  apsum ( k ) = ∑ m = - 1 m = 1
Responsive to determining that the frame has been lost, PLC module 206 will operate to conceal the lost waveform. As a result, annoying “click-like” artifacts may become audible in the audio output when bursty bit errors occur.  Recent versions of the Bluetooth specification (in particular, version 1.2 of the The method of claim 3, further comprising: determining the average signal level of the prediction residual for the decoded audio frame by computing an average magnitude of the prediction residual for Six classes of contexts are used in the proposed embedded audio codec.Appears in 6 books from 1953-2004Page 188 - The only justification for this name is that there is an inequality
When implemented in a wireless audio device such as a Bluetooth® headset, an embodiment of the present invention improves the overall audio experience of a user. However, bit errors may also go undetected and be present in the bit stream during decoding. The invention may be implemented, for example, in mono headset devices primarily used in cell phone voice calls. news The method of claim 1, wherein analyzing at least the decoded audio signal to detect whether the decoded audio frame includes the distortion comprises: analyzing a pitch history of the decoded
While a ⅓ FEC code and an error-checking code protect the header, low signal strength or local interference may result in a packet being received with an invalid header. Threshold when Pitch Tracking Classification is Random  If the pitch track classification, ptc, indicates that the pitch history is random, then the speech signal is not strongly periodic at the This is not possible when using HV1 packets for transmitting SCO data. The efficiency of the QM coder can be improved by introducing a set of context rules.
The system of claim 16, wherein the bit error detection module is configured to analyze at least the decoded audio signal to detect whether the decoded audio frame includes the distortion Your cache administrator is webmaster. In this case, the false detection rate should be as low as possible. A detailed block diagram of one implementation of bit error detection module 204 is shown in FIG. 3.
Median filtering requires a long delay and is not practical in a delay constrained two-way audio communications channel. As previously mentioned, bit errors may cause a packet to be discarded. Some codecs, such as CVSD (Continuously Variable Slope Delta Modulation), were designed with bit error resiliency in mind, while others, such as A-law or u-law pulse code modulation (PCM) are extremely Hence, to increase the probability that re-encoding is not triggered for speech onsets, both vad and evad must be equal to 0 for the re-encoding flag to be triggered.  e.
This allows the sensitivity for detecting clicks to be adjusted in accordance with the changing character of the input audio signal.  d. Therefore, as the click rate increases, the optimal operating point involves more aggressive detection and consequently a higher rate of false detections.  BER-based threshold biasing module 202 uses an energy-based In this case, bit error decision module 406 determines the threshold for decision, K1, as a function of the average voicing strength for the current frame, vs_ave:  K1=ƒ(vs_ave). (16)  One The QM arithmetic coder achieves a very good compression result if the context is properly selected to summarize the correlation between coded data.
HV1 packets, while producing better error recovery than other types, accomplish this by consuming the entire bandwidth of a Bluetooth® connection. For example, matched filtering relies on knowledge of the noise pulse shape which in the prior art is simply an impulse. Although PCM audio signal 114 is shown as being input directly to BEC system 110 in FIG. 2, it is possible that PCM audio signal may be processed by other components