The wireless revolution has been in full force for several years. Many of us use wireless connections for computer networking, hands-free cell phone communications and many other day to day activities. We all get the benefits of wireless connectivity.
So why has high quality wireless audio been missing?
The short answer is bandwidth. High quality audio takes lots of bits delivered in a timely consistant manner. Unlike WiFi, you may not have the opportunity to retransmit the data again if the data fails the first time. The second, less obvious answer is economics. Let's explore each of these in turn.
Most wireless audio solutions aim very low. The thought is that convenience is everything and that 16 bit 48k stereo is more than enough. Anyone who has listened to MP3s understands this point of view. Suffice to say, this is not an area that we are interested in pursuing.
If you set the bar much higher, then it is reasonable to require higher sample rates and certainly much wider bit depth. This limits the playing field to only a few candidates. If you also extend the requirements so that multichannel solutions are supported, then the field narrows even more. Imagine you would like to support either wireless surround sound for a home theatre application or a system with multiple subwoofers for a stereo application or both?
Summit Semiconductor has a premium wireless audio platform that meets these basic requirements. It supports up to a 7.4 system, sampled at 96k and 24 bit uncompressed bit depth. The Summit solution uses 24 RF channels in the 5-5.8 GHz band. It is adaptive to minimize interference from competing wireless solutions.
This is a great start and the basic solution is supported by an industry consortium called WiSA (Wireless Speaker & Audio) Association.
So it would seem like Summit has done a great job of addressing the "bits" problem and they have. But there is still more to creating a great wireless audio system and this is where "economics" comes into play. If we can insure that bits are delivered error free, then any platform, wired or wireless should have equivalent results given the same sample rate and bit depth. This is true as long as the bits arrive at precisely the right time. The right data at the wrong time is the wrong data!. This is why jitter performance is so important. If the data stream is improperly sample rate converted, you can permanently encode jitter into the stream and this cannot be fixed. If the data is correct but not jitter free, it can be fixed by jitter attenution techniques.
So lets get back to economics. If you are a chip manufacturer, it follows that you need to sell your products to a sufficently large audience. This means that you will need to create a sufficient least common denominator of features, performance and cost that insures that your devices are both affordable and meet the primary needs of your target audience. Summit has done this quite well. But due to economic realities, there is more that can be done.
Danville wireless audio technology uses SHARC DSPs and very low phase jitter clocks to complete the solution. There is a SHARC DSP in our transmitter implementation and SHARC DSPs in each receiver circuit. The SHARC also implements our dspCrossover functions. We complete the process with high quality DACs and related single conditioning circuits.
At the 2013 CES show, we had a well known audio reviewer state that the wireless speaker we were showing was a wireless system that didn't sound wireless. Isn't that the way its supposed to work?
Our wireless audio implementations are available to loudspeaker manufacturers. Let's start a conversation.
Learn more about the WiSA Association here.