GSM Buzz Removal
Today’s GSM handsets use high power amplifiers to increase the communication distance with the base station. These amplifiers produce bursts of high currents at low frequencies causing the objectionable “GSM buzz” in nearby audio equipments. When a device such as an iPod accessory plays from an iPhone, an incoming GSM call can create annoying bursts of noise from the speakers if the accessory hardware is not properly shielded.
We have created a software solution to reduce the effects of this GSM buzz in audio equipments. Our GSM buzz removal software can run in the DSP or MCU that is contained in the audio equipment and process the incoming audio to eliminate the buzz. This reduces the time and cost involved in hardware shielding for the audio equipment.

Typical GSM buzz waveform:

interference noise pulses

Highlights
  • High performance: More than 99% detection rate; Near-flawless pulse removal (More than 40dB suppression)
  • Practical: Consumes approximately 70Mhz on Coldfire MCU when operating on 44.1kHz, stereo audio; expected to be lower on ARM9e
  • Proven: Licensed to a Tier1 Auto OEM in Europe

Case studies

Developing an Asynchronous Sample Rate Converter

Designing an Asynchronous Sample Rate converter that offers high THD and low ripple across a range of frequencies is no mean achievement. We not only designed the ASRC but implemented it with low MHz on a fixed point processor.

Video codecs on a multi-core highly-parallel custom core

We worked with SiliconHive (now part of Intel) to develop High Definition video codecs that are designed to run optimally on a multi-core environment. Our contribution also included efficient coding for a VLIW core and algorithmic innovations to address memory bandwidth constraints.

Showcase

Android Auto projection on Telechip TCC8930 running WinCE 7.0
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RACE Media & Connectivity IVI suite
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