Portable audio devices such as MP3 players and tablets are becoming more and more popular. In fact, the PC market has been declining due to the increase in portable devices. One killer application which has contributed to the popularity of these portable devices is streaming of audio. Let me go into detail what this entails. Streaming usually refers to moving or broadcasting some information in particular audio information from one device to some other location such as loudspeakers. In fact, streaming can be used for a lot of contacts but in this post I’m referring to sending audio data from a storage device to some speakers.
Streaming can be done by using a network cable or by using a wireless signal. You can think of streaming as simply transferring data. However, streaming has some challenges which have to be addressed which are less rigid when it comes to simply transferring data packets. In particular, streaming audio typically requires having low latency. Latency determines how long it takes for the data to arrive at the speakers. The longer the delay the more severe is the loss of sync between video that might be playing in the audio that is being heard over the speakers. For practical applications, the delay should be less than 50 ms. Ideally, it should be less than 20 ms to be less noticeable.
However, having a low delay poses some challenges. In particular, if there other devices in the area which are also streaming on a similar frequency there can be conflicts caused by the interference. Let’s say that you are streaming data packets and at some point some other transmitted is also sending data wirelessly on the same frequency. In that case chances are the speaker is not able to decipher the data which was sent from our transmitter because it was jammed by the other transmitter. Therefore, manufacturers have spent time to come up with some methods for avoiding such problems. Obviously, there’s never any guarantee that there won’t be another transmitter sending a data packet at the exact same frequency at the exact same time. Therefore, most streaming devices employ some data buffering. The speakers are smart enough to recognize if some data is missing or corrupted. If that is the case, they can request a data package which was not received properly.
Obviously, if the data packet is being disrupted the second time around then another request would have to take place. To keep the latency at a reasonable level, this cannot be done indefinitely. So in order to avoid very severe interference, most streaming devices can coordinate frequencies. If you’re using a wireless router to connect to the Internet than the router enables you to set specific frequency for the signal. By choosing a frequency that differs from the frequency used by other nearby devices, you can avoid a lot of conflicts.