Avnera has released a set of application-specific standard product (ASSP) chips aimed at the audio market. Avnera's chips, implemented in CMOS, transmit and receive stereo audio (close to CD quality) over the 2.4 GHz wireless ISM band assigned internationally for industrial, scientific and medical uses. Avnera claims a typical range of 45 feet, with longer range if an optional external power amplifier is used.
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Figure 1. Avnera implements wireless audio with a transmitter chip and a receiver chip.
As shown in Figure 1, the AudioMagic AV71x1 are wireless transmitter chips, paired with the AV71x2 receiver chips. The transmitter sends stereo audio at a sample rate up to 48 kHz, with close to 16-bit quality. Within the AV71x1 family, the AV7111 offers an I2S input, and the AV7101 includes a USB input (both interfaces are shown in the figure). To facilitate integration with other audio hardware which may be capable of handling higher-quality audio, the Avnera transmitter chips accept audio at sample rates up to 96 kHz, and samples up to 32 bits wide.
BDTI conducted informal tests of the A-R AWD210 wireless headphones provided by Avnera. These headphones provided clean sound for a non-audiophile product. They were easy to set up and use. A small transmitter box connects to a computer via a USB connection. The headphones feature on-off and volume controls on the left earpiece. In a home setting, the headphones received a clear signal when the listener was in motion, with no audible clicks or pops or dropouts. The signal traveled well through some walls and floors. When the audio did fail, for example due to increasing distance from the transmitter, it tended to fail suddenly and completely. The headphones did interfere with the operation of a Panasonic 2.4 GHz cordless phone, although the phone had no effect on the headphones. A microwave oven (which operates in the same frequency range) did not affect the headphones.
Wireless consumer audio is a field with demanding specifications, highly critical listeners, and an unforgiving environment: if data is dropped, the speaker cone keeps moving, and the listener hears a click. In this market, ASSPs often make sense, because potential volumes are high, and system designers need low-cost, low-power solutions. Avnera's offerings are worth considering for short-range wireless audio applications.
For more details on the recent releases of Avnera, see InsideDSP.
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