Why aren't their headphones that use wireless network tech?

[Gannon]

I was thinking about this today, most wireless headphones on the market do not use digital transmission for audio, they use old RF method (radio method). It would make much more sense to send packets of an audio file, store it in memory on the headphone chip somewhere and play it locally on the headphone.

Especially when it comes to computer headphones, headphones with an wireless network card and flash memory built into the headset would be a godsend. Finally "true digital wireless" without radio interference.

What is so hard about this that people haven't done it?

 

[f95toli]

I think there are a few bluetooth headphones around. However, AFAIK they aren't very good.
The problem is that you need quite a lot of electronics to decode a digital signal. You need a bluetooth chip (or something similar), DAC, amplifier, power supply etc. This means that the weight and price goes up.
So, I suspect the answer is that plain old RF is more efficient in this case.

 

[Gannon]

Originally posted by: f95toli
I think there are a few bluetooth headphones around. However, AFAIK they aren't very good.
The problem is that you need quite a lot of electronics to decode a digital signal. You need a bluetooth chip (or something similar), DAC, amplifier, power supply etc. This means that the weight and price goes up.
So, I suspect the answer is that plain old RF is more efficient in this case.

That explanation does not seem congruent, I mean what are cell phones?? hmmm.

 

[PottedMeat]

What do you mean 'digital' audio?

Aren't most digital transmission chains like:

Analog or Digital Audio -> A/D Converter -> Encoding/Processing ( QPSK/FSK/PSK Whatever ) -> Up Conversion -> RF Amplification -> Antenna

AIR

Antenna -> Filtering -> RF Amplification -> Down Conversion -> Decoding -> D/A Converter -> Audio Freq Amp. -> Speaker

As to radio interference, encoding/decoding/filtering techniques can minimize that. More processing/filtering will cost more.

I dont know much about wireless headphones, but did they even do simple Analog straight to RF modulation? Those little RF modulators for ipods->cars do that.

 

[CycloWizard]

Originally posted by: Gannon
That explanation does not seem congruent, I mean what are cell phones?? hmmm.

Most people aren't going to pay as much for a set of headphones as they would for a cell phone, especially if they can get something 99% as good for 25% of the price.

 

[f95toli]

Exactly, it can be done but I doubt there is a market for >$300 wireless headphones unless the sound quality is ok, meaning the DAC, amplifier and power supply needs to be pretty good AND be able to drive even "difficult" headphones.

 

[Who Me]

WiFi uses a lot more power than Bluetooth - so battery life is a first stumbling block.
It's also a much more complex technology - so more hardware and cost.
Basically, a commercial non-starter.

 

[ninjayeti]

a long time lurker's thoughts...

Wireless headphones don't have to be expensive or power-hungry. I've been working with the nRF24Z1 on a project for a while. It only uses <10mA at 4.5V (regulated to 3), and costs 6 bucks. WLAN in particular is higher powered and has more overhead, so it uses more power.

Another thing to consider as to why they don't exist is latency. That signal path takes a while to convert to digital and back, and the delay could conceivably be uncomfortably long. We're talking 5-25ms for the wireless link and more for the codecs (I can't find a number right now from the codecs we're using -- TI tlv320aic23b).

Specifically on wireless networking technology-- if you used something like TCP for audio, you guarantee that all the packets get there in the right order, but you sacrifice transmission time (and have to add buffers to re-order the packets before being output). If you go with something like UDP, you get the packets there fast, but not necessarily in the right order, and some may not arrive at all. The real question is what do you do with lost packets or delays in transmission, (esp. when your highest priority is high-fidelity continuous audio)? I'm honestly not sure. The chip we're using just ends up clicking a lot. Maybe someone's figured this out, but it would definitely require some amount of extra processing / memory ( == $$) .

 

[imported_Seer]

Originally posted by: ninjayeti
a long time lurker's thoughts...

Wireless headphones don't have to be expensive or power-hungry. I've been working with the nRF24Z1 on a project for a while. It only uses <10mA at 4.5V (regulated to 3), and costs 6 bucks. WLAN in particular is higher powered and has more overhead, so it uses more power.

Another thing to consider as to why they don't exist is latency. That signal path takes a while to convert to digital and back, and the delay could conceivably be uncomfortably long. We're talking 5-25ms for the wireless link and more for the codecs (I can't find a number right now from the codecs we're using -- TI tlv320aic23b).

Specifically on wireless networking technology-- if you used something like TCP for audio, you guarantee that all the packets get there in the right order, but you sacrifice transmission time (and have to add buffers to re-order the packets before being output). If you go with something like UDP, you get the packets there fast, but not necessarily in the right order, and some may not arrive at all. The real question is what do you do with lost packets or delays in transmission, (esp. when your highest priority is high-fidelity continuous audio)? I'm honestly not sure. The chip we're using just ends up clicking a lot. Maybe someone's figured this out, but it would definitely require some amount of extra processing / memory ( == $$) .

++
latency doesn't matter in cell phones, but with headphones its a killer. RF give syou the benefit of going straight from EM waves to the audio signal, if im not mistaken.

OT: Interesting choice to delurk on.

 

[Casawi]

There is a rule in the EM world, why design an antenna if you can run a wire. Designing an antenna that is reliable for a system can costt a lot of money, so proposal for such project will be riplied to with, why can't just run a wire.

 

[Aluvus]

Originally posted by: Seer
++
latency doesn't matter in cell phones, but with headphones its a killer. RF give syou the benefit of going straight from EM waves to the audio signal, if im not mistaken.

OT: Interesting choice to delurk on.

Latency is very carefully controlled in cell phones (and in phones in general), because excessive latency is disorienting and makes it hard to carry on a conversation. If you say "hello" you expect the other person to say "hello" back fairly quickly. For an example of what happens to communications under high latency, look at "live via satellite" interactions, where latency can be very significant. Local anchor asks a question, field reporter pauses visibly, then starts his answer. For a more extreme example, try the space shuttle or Mars rovers, where latency can be several minutes.

But yes, a "dumb" RF conversion incurs less latency than a digital packet link.

Originally posted by: yassine
There is a rule in the EM world, why design an antenna if you can run a wire. Designing an antenna that is reliable for a system can costt a lot of money, so proposal for such project will be riplied to with, why can't just run a wire.

Wireless headphones systems using various infrared, proprietary RF, and Bluetooth solutions exist and are readily available. They can be convenient.

The OP seems to be asking why none of them use a WLAN standard like WiFi, to which the answer appears to be that other wireless systems already perform the task with less complexity and, one would expect, less cost. Though something with more range than typical Bluetooth solutions would be nice.