Be a rockstar

09 June 2009

Wireless guitar system streams uncompressed audio using pair of nRF24Z1s.
Wireless guitar system streams uncompressed audio using pair of nRF24Z1s.

Wireless guitar system for amateurs claims new transceivers provide native CD-quality audio.

Targeted at amateur and professional guitar and bass guitarists performing live on stage at small venues, clubs and houses of worship, the Radian Gold Series wireless guitar system from WaveAngle operates using a small form factor attachment that plugs directly into the output jack of any electric guitar and then transmits audio wirelessly back to a partner attachment plugged into the input jack on any guitar amp. This completely eliminates the underfoot clutter of trailing cables common to on-stage performers, and makes it simpler for multiple acts to get on and off stage quickly.

The WaveAngle Radian Gold Series wireless guitar system streams uncompressed audio from an electric guitar to an amplifier to free performers from traditional trailing wires when on stage. This is achieved without loss of audio quality or reliability compared to a traditional wired link and at a pricing level that makes the solution accessible to both amateur and professional performers

Nordic Semiconductor announced that WaveAngle has specified a pair of its nRF24Z1 transceivers to provide the wireless audio link at both ends of its Radian Gold Series wireless guitar system.

“Wireless guitar audio is nothing new, but it has yet to take off in a big way in the mid-range market,” said Sean Michaud, president of WaveAngle. “Low end analogue solutions based on UHF and VHF radio have existed since the late 1970s, but there has not until now been a mid-range, digital audio solution priced at an affordable level that does not noticeably sacrifice audio quality and reliability (i.e. immunity to dropouts and fuzz-outs) for wireless convenience. This has hindered the widescale adoption of wireless among performing guitarists.”

While other mid-range wireless guitar products do exist, Michaud said these invariably employ some form of compression which degrades sound quality compared to a wired link. In comparison, the Nordic nRF24Z1 2.4 GHz transceiver-based WaveAngle products are capable of streaming clear uncompressed stereo audio at up to 4 Mbit/s with native ‘CD-quality’ 16-bit, 48 kHz resolution.

“Using the Nordic nRF24Z1, we were able to develop a product that delivers completely uncompressed audio with enough bandwidth headroom to allow us to engineer out latency to an imperceptible level to the human ear,” continued Michaud. “All digital audio wireless solutions are susceptible to latency issues – particularly standards-based solutions that have to be able to operate with the ‘rest of the world’. But the Nordic nRF24Z1 is designed specifically for digital audio and as such supports a degree and precision of latency tuning that simply does not exist on generic [i.e. non-audio specialised] chips.”

In addition, the nRF24Z1 is designed ‘out-of-the-box’ to cope with other 2.4 GHz interferers (such as Bluetooth wireless technology and Wi-Fi) that may be operating in the vicinity. It does this via a proprietary frequency agility protocol that automatically looks for an adjacent clear channel to swap to before interference becomes so severe that too many packets are being lost for audio quality to remain unaffected.

“The Radian system also pairs automatically which means the end user doesn’t have to worry about choosing channels, making the product quite literally ‘plug and play’,” added Michaud. “And up to 10 Radian Gold Series attachments can be used alongside each other in the same room. All of these achievements are directly attributable to the Nordic nRF24Z1, and help to distinguish the WaveAngle products from those of competitors.”

As a result, Michaud claimed the Radian Gold Series achieves a sound quality and connection solidity as good as wired. This includes: a class-leading battery life (20 hours continuous usage from a single AAA cell); a small form factor (competing systems are much bulkier); excellent range (up to 30 m); and the ability to succeed in a direct audio quality (wireless to wired) comparison.

“We did actually start our product development using a generic 2.4 GHz transceiver from a Nordic competitor,” admitted Michaud. “But when we evaluated the nRF24Z1 we concluded it was worth going back and doing a redesign because of the integrated protocol and other features. The Nordic solution and the excellent support they have provided to WaveAngle saved us an awful lot of work on the software debug and validation side and helped us deliver an excellent product.”

“The Nordic nRF24Z1 is helping to make high quality wireless audio products that can genuinely serve as cable replacement technologies affordable and viable,” concluded Geir Langeland, Director of Sales & Marketing at Nordic Semiconductor. “The Radian Gold Series is an excellent application example in the musical instrument segment.”

The nRF24Z1 is a single chip solution for wireless streaming of CD-quality stereo audio up to16-bit, 48 kHz without using compression. The nRF24Z1 also features input support of up to 24-bit, 96 kHz.

The nRF24Z1 uses Nordic Semiconductor’s 4 Mbit/s MegaZtream platform embedding Quality of Service (QoS) subsystem with a low power robust 4 Mbit/s wireless 2.4 GHz transceiver and all appropriate digital audio interfaces creating a complete digital wireless audio streamer solution in a 6 x 6 mm package. In addition to streaming audio up to 4 Mbit/s, the nRF24Z1 also boasts a digital control information channel for transfer of control information such as volume, balance and display details.

Using industry standard I2S and S/PDIF interfaces for audio, the nRF24Z1 can interface without glue logic to virtually any digital audio source, or external industry standard low cost analogue-to-digital and digital-to-analogue converters for analogue audio input and output. Control information uses SPI or 2-wire (I2C compatible).

The nRF24Z1 features a design where attention is paid to every detail of the audio interface and the challenging tasks of streaming CD-quality audio with no glitches and degradation in performance in the presence of other 2.4 GHz sources such as Bluetooth. The circuit has embedded voltage regulators, giving maximum noise immunity and operation from a single 2.0 V to 3.6 V supply.

Nordic Semiconductor’s nRF24xx range of 2.4 GHz transceiver and transmitter devices are aimed at applications such as PC peripherals such as wireless keyboards/mice, game controllers, intelligent sports equipment and wireless audio (for example, mp3 and portable CD player headphones and PC speakers). The latest nRF24L01 family, for instance, is targeted at ultra-low cost and power applications such as wireless desktops and intelligent (for example, wristwatch-based) sports equipment.


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