US 6807524

Here's a concise summary of US Patent 6,807,524:

US Patent 6,807,524: Perceptual weighting device and method for efficient coding of wideband signals

• Title: Perceptual weighting device and method for efficient coding of wideband signals
• Current Assignee: Saint Lawrence Communications LLC
• Inventors: Bruno Bessette, Redwan Salami, Roch Lefebvre
• Filing Date: October 27, 1999
• Issue Date: October 19, 2004
• Abstract: The patent describes a perceptual weighting device and method for processing wideband signals (0-7000 Hz) to improve coding efficiency and quality. It involves a signal pre-emphasis filter to boost high frequencies, a synthesis filter calculator to determine coefficients, and a perceptual weighting filter with a fixed denominator. This design aims to substantially decouple formant region weighting from the spectral tilt of the wideband signal, making it suitable for fixed-point implementation and improving the encoding of higher frequency content. The pre-emphasis filter typically uses a transfer function P(z)=1-μz⁻¹, where μ is between 0 and 1 (e.g., 0.7), and the perceptual weighting filter uses W(z)=A(z/γ₁)/(1-γ₂z⁻¹), where 0 < γ₂ < γ₁ ≤ 1 and often γ₂ is set equal to μ.

Plain-Language Overview of Independent Claims:

• Claim 1 (Perceptual Weighting Device): This claim describes a device that takes a wideband speech signal and creates a perceptually weighted signal. It does this using three main parts:

  1. A "pre-emphasis filter" that boosts the high frequencies of the incoming speech signal.
  2. A "synthesis filter calculator" that uses this pre-emphasized signal to figure out certain filter settings (synthesis filter coefficients).
  3. A "perceptual weighting filter" that then processes the pre-emphasized signal using those filter settings. The key feature is that this perceptual weighting filter has a fixed denominator in its mathematical description, which helps separate how the device handles the main sound characteristics (formants) from the overall tone balance (spectral tilt) of the wideband speech.

• Claim 8 (Perceptual Weighting Method): This claim outlines a method (a series of steps) to achieve the same goal as the device in Claim 1. It involves:

  1. Filtering the wideband speech signal to boost its high frequencies (pre-emphasizing it).
  2. Calculating synthesis filter coefficients from this pre-emphasized signal.
  3. Filtering the pre-emphasized signal based on these coefficients using a perceptual weighting filter. Like the device, this filter has a fixed denominator, ensuring that formant weighting and spectral tilt are largely handled independently.

• Claim 15 (Encoder): This claim describes an encoder for wideband speech signals, which includes the perceptual weighting device defined in Claim 1. In addition, this encoder has components for:

  1. A "pitch codebook search device" that analyzes the perceptually weighted signal to find pitch-related parameters and create a target signal for the next stage.
  2. An "innovative codebook search device" that uses the synthesis filter coefficients and the target signal to find innovative codebook parameters.
  3. A "signal forming device" that combines these pitch, innovative, and synthesis filter parameters to produce the final encoded wideband speech signal.

• Claim 22 (Cellular Communication System): This claim describes a cellular communication system for a large geographical area divided into cells. It includes mobile devices, base stations, and a control terminal. The key part is a bidirectional wireless communication sub-system (found in both mobile units and base stations) which contains:

  1. A "transmitter" with an encoder as described in Claim 15 (which includes the perceptual weighting device) and a circuit to transmit the encoded signal.
  2. A "receiver" with a circuit to receive encoded signals and a decoder to convert them back into speech.

• Claim 29 (Cellular Mobile Transmitter/Receiver Unit): This claim defines a cellular mobile device itself. It comprises:

  1. A "transmitter" that includes an encoder as described in Claim 15 (with the perceptual weighting device) and a circuit for transmitting the encoded wideband speech signal.
  2. A "receiver" that includes a circuit for receiving transmitted encoded wideband speech signals and a decoder for decoding them.

• Claim 36 (Cellular Network Element): This claim describes a cellular network element, which is a component within the cellular network (e.g., a base station). It includes:

  1. A "transmitter" that has an encoder as defined in Claim 15 (with the perceptual weighting device) and a circuit for transmitting encoded wideband speech signals.
  2. A "receiver" that has a circuit for receiving transmitted encoded wideband speech signals and a decoder for decoding them.

• Claim 43 (Bidirectional Wireless Communication Sub-system): This claim focuses specifically on the bidirectional wireless communication sub-system found within a cellular communication system (as described in Claim 22). This sub-system, present in both the mobile unit and the cellular base station, contains:

  1. A "transmitter" that includes an encoder as described in Claim 15 (with the perceptual weighting device) and a circuit for transmitting the encoded wideband speech signal.
  2. A "receiver" that includes a circuit for receiving transmitted encoded wideband speech signals and a decoder for decoding them.

USPTO and CAFC 2026 Dockets Search:

• USPTO Database: The patent US6807524B1 has a legal status of "Expired - Lifetime" with an anticipated expiration date of 2019-10-27. This means the patent is no longer in force. The current assignee is Saint Lawrence Communications LLC, based on Google Patents data. Without direct access to USPTO assignment records, I cannot definitively confirm current ownership beyond what is publicly available on Google Patents, though it's typically accurate.
• CAFC 2026 Dockets: Searching for "US6807524" and "6807524" within CAFC 2026 dockets does not return any results for ongoing litigation at the Court of Appeals for the Federal Circuit as of today's date, April 26, 2026. Given the patent expired in 2019, it is highly unlikely there would be active infringement litigation in 2026. However, prior litigation is noted in the Google Patents record, with cases filed in various District Courts and one PTAB case between 2014 and 2019, though none appear to be ongoing at the CAFC in 2026.