In-Line Module

The bhi DSP noise cancelling In-Line Module cleans up noisy signals and works on most radios and receivers. It comes with the latest bhi DSP noise cancelling technology which brings improved audio quality to the listener when operating in noisy conditions across all radio bands.  The audio is clearer and more intelligible as a result.

Easy to connect in-line with your radio

The In-Line Module has a 5W audio amplifier and connects in between your radio and loudspeaker. The loudspeaker audio is muted when headphones are connected, and when the unit is switched off the audio bypass feature routes the signal directly through to the loudspeaker.

Simple control of all features

The In-Line Module is powered from a suitable 10 to 16V DC power supply and has a three-position switch that turns the unit on and switches the noise cancellation on and off. The “Status” LED illuminates red when power is applied and changes to green when the noise cancellation is active. The unit has an audio input overload LED, an audio output level adjust control and is supplied with a 3.5mm mono plug lead, fused DC power lead, User manual and 4 small rubber feet. 

Features

• 8 noise cancelling levels 8 to 40dB
• Tone reduction up to 65dB
• Bespoke 5W audio amplifier
• Audio bypass feature when switched off
• Speaker output connection 3.5mm mono jack socket
• Headphone socket 3.5mm mono jack socket
• Audio input overload indicator
• DC power 10 to16V DC (500mA min)
• Compact unit, 135mm x 65mm x 46mm, weight 0.3Kg

What’s inside the unit

The In-Line Module makes use of a  powerful programmable DSP audio processing chip which utilises bhi’s DSP noise cancelling technology. This high−performance chip delivers exceptional sound quality and incorporates a full audio signal chain with 16−bit A/D converters and digital interfaces to accept the signal through the fully flexible digital processing architecture to analog line−level.

The audio amplifier stage is provided by a Texas Instruments TPA3111D1PWPP 10W Filter-Free Mono Class-D audio power amplifier chip which is 94% efficient, eliminating the need for heatsinks, saving space on the pcb.

Audio DSP chip key features

• A Complete DSP−based, Mixed−signal Audio System Consisting of a 16−bit Fully Programmable Dual−Harvard 16−bit DSP Core, a Patented, High−resolution Block Floating−point WOLA Filterbank Coprocessor, and an Input/Output Processor (IOP) along with Several Peripherals and Interfaces which Optimize the Architecture for Audio Processing
• Integrated Converters and Powered Output
• Ultra−low Power Consumption: Under 5 mA at 20 MHz to Support Advanced Operations; 1.8 V Supply Voltage
• “Smart” Power Management: Including Low Current Standby Mode Requiring Only 0.05 mA
• Excellent Fidelity: 88 dB System Dynamic Range, Exceptionally Low System Noise and Low Group Delay.

DSP Noise Cancelling:

The DSP noise cancelling in all our products uses techniques that study signals in both the time and frequency domains simultaneously.  The algorithm looks for signals with speech and noise characteristics.  Signals with modulated speech characteristics pass through and other sounds with higher or lower modulation frequencies than speech are removed depending on the filter level selected (8 to 40dB).  There is virtually almost no distortion of the speech signal, even for extremely low signal-to-noise ratios of 0 dB and below, and the technology is self-adapting to changing noise environments, so no training of the noise filter required. If the signal-to-noise ratio is extremely low, and/or a high level of noise suppression is selected, the system may yield artefacts in the form of slightly robotic speech.  Customers can adjust the level of noise suppression to suit their own needs.