How does the Nortek AVAS system work?

The system uses a VMMS-AVAS controller connected to the vehicle’s CAN-BUS system, along with V-AMP amplifier units and external speakers. It uses vehicle speed information to control the playback of the alert sound so that the vehicle gives an appropriate audible warning at low speeds.

AVAS Acoustic Vehicle Alerting System

The Nortek AVAS Acoustic Vehicle Alerting System is a UK-manufactured acoustic vehicle alerting system for electric and hybrid vehicles. It is designed to generate an external warning sound at low speeds, helping pedestrians, cyclists and visually impaired road users detect the presence, direction and movement of quieter vehicles.

The system is suitable for electric buses, hybrid buses, commercial vehicles, public transport fleets, specialist vehicles and vehicle builders that need a compliant AVAS solution. The Nortek AVAS system is modular, allowing vehicle manufacturers and installers to configure coverage using the VMMS-AVAS controller, V-AMP amplifier units and external horn speakers.

Nortek’s AVAS system is designed to meet the requirements of UN ECE 138 and is suitable for vehicles that require a compliant acoustic warning system. It can be configured with the TfL London Urban Bus Sound or with custom vehicle sounds, depending on the application and operating requirements.

What does an AVAS system do?

An AVAS, or Acoustic Vehicle Alerting System, produces an external vehicle sound to alert pedestrians and other road users to the presence of a quiet electric or hybrid vehicle. This is particularly important at low speeds, where electric and hybrid vehicles may produce very little natural engine noise.

The Nortek AVAS system uses vehicle speed information to control the playback and attenuation of the alert sound. This helps the sound respond appropriately to the movement of the vehicle, giving clearer cues about the vehicle’s presence, direction and speed.

Nortek Electronics Acoustic Vehicle Alerting System (AVAS)

A UN ECE 138 compliant, UK Manufactured modular AVAS acoustic vehicle alerting system for all Electric & Hybrid Vehicles.

AVAS Acoustic Vehicle Alerting System Brochure Download (available soon)

With the constant roll out of quiet, virtually silent Hybrid & Electric Vehicles onto our roads, so arises the complex issue of the removal of traditional engine sounds which served as an warning of an approaching vehicle to cyclists & pedestrians alike.

The visually impaired in particular heavily rely on audible environmental cues to assist
with their mobility and orientation, whilst Mobile phones also play a part in modern everyday lives which in turn can serve as a distraction when crossing the street or stepping off the pavement, and may otherwise focus visual attention away from any approaching vehicle.

The solution is an AVAS Acoustic Vehicle Alerting System, an Electronic Safety Device which generates a focused sound below a preset upper speed which can be played from speakers fitted to any external position on a vehicle providing distinct indications of the vehicle’s location, direction and speed.

The Nortek AVAS system can be programmed to play a sound customised to your requirements for vehicle or manufacturer based individuality or can use any sound adopted by Country or City based legislation (subject to licencing).

In addition, the Nortek AVAS Acoustic Vehicle Alerting System is approved and licenced for use with the TFL “London Urban Bus Sound” and a policy of continuous development ensures that our system remains compliant with the changing requirements of Transport for London so it can be used with confidence by vehicle builders in vehicles intended for use in London, on some of the busiest bus routes in Europe.

Nortek Electronics were early adopters to the requirements of Regulation ECE R138 which legislated that all vehicle manufacturers must install an Acoustic Alerting System to all quiet electric and hybrid vehicles registered from July 2021.

In addition to meeting ECE R138 our system is also regulation R10 approved (E-Mark) for EMC compliance and the Nortek Electronics Factory undergo regular VCA based audits to ensure that our manufacturing processes remain within the requirements of Regulation 10 certification.

The finer requirements of ECE R138 require that the AVAS Acoustic Vehicle Alerting System system reduces or increases its playback speed automatically in proportion to the vehicle’s speed, at a rate of 0.8% per km/h. The sound level remains constant from 0 km/h to the specified speed, then decays away to nothing as demonstrated on the graph below.

The modular design of the Nortek System, not only facilitates easy servicing and quick, cost effective end of life parts replacement, but also provides some Engineering redundancy fall back, so in the event of a partial Electronic failure, the vehicle will likely retain at least some AVAS coverage from the remaining functional parts of its system to enable it to return to the depot, rather than having to be recovered from the road side.

This design approach compares favorably with all-in-one or stand alone AVAS systems, where a partial fault or internal component failure may in turn result in complete power supply failure or a supply fuse blowing, rendering the entire AVAS safety system inoperative and completely silent.

The Nortek AVAS system consists of Three Main Component Parts.

VMMS-AVAS – this is both the ‘brains’ and ‘heart’ of the system and connects to the vehicle J1939 Can-Bus system in order to accurately control the playback speed and Attenuation based on the vehicle road speed. The VMMS-AVAS may be connected to any number of external Amplifiers (V-AMP) in order to give the required coverage based on the vehicle type and size.

V-AMP Amplifier – This takes the audio output from the VMMS-AVAS and amplifies it to a level suitable to drive a single, dedicated external 8 ohm horn speaker. The V-AMP uses efficient, reliable Class D integrated amplifier technology to produce the AVAS Audio and also features comprehensive & extensive protection circuits to protect against Electrical and Thermal Overload, Short and Open Circuit as well as Speaker Monitoring.

The V-AMP also has an external diagnostic output, which in the event of the built in protection circuits activating can be used to separately trigger our VMMS or VARU message unit in order to play a warning message to the driver, immediately alerting them to any failure of the AVAS system or loss or disconnection of any connected speaker. This driver alert functionality exists to fully meet the current requirement of the TFL specification.

AVAS Speaker – A IP67 High Quality 8 Ohm compact Horn Speaker with excellent SPL rating and exceptional Directional Audio Coverage characteristics, which has been fully tested in commercial vehicle AVAS applications when partnered with a VMMS-AVAS & V-AMP amplifier. The configuration design is based on one speaker per V-AMP amplifier.

In the majority of applications, two speakers and two V-AMP’s are fitted (Front & Rear) however any number of V-AMP & Speaker combinations can be fitted to ensure full vehicle coverage or to comply with different or changing Legislation.

Nortek Electronics can also produce a custom wiring harness for its AVAS system for Vehicle Builders buying in quantities & based on customer supplied schematics.