Datasets:
kkboy1
/
LeAudio

Dataset card Data Studio Files
xet
 Community
1
text
stringlengths
1
112
modifications to the adp specification at the audio source thats a problem as it means
that earbuds or speakers that didnt adopt them wouldnt be compatible to be successful in
the market there needed to be a solution which would wor k with any audio source which
effectively meant that the solutions needed to be implemented solely in the audio sinks the
earbuds
section limitations and proprietary extensions
the solution that csr came up with is known as the replay or forwarding approach as shown
in figure
figure replay scheme for tws
before they connect to the phone the two earbuds pair with each other which may be done
at manufacture one is set to be the primary device the other as a secondary to receive an
adp stream the primary device pairs with the audio source appearing as a single device
receiving a stereo stream when audio packets arrive it decodes the left and right channels
and in the example shown above relays the left channel directly to the second ary earbud
this may be possible using bluetooth technology but if the earbuds have small antennas this
may be problematic as the head absorbs the ghz signal ver y well many companies
discovered this when they first tested their devices outside indoors reflections from walls
and ceiling s will generally ensure that the bluetooth signal gets through outside with no
reflecting surfaces to help they may not to compensate for this a second radio is typically
added which gets around the absorption problem the most popular option is near field
magnetic induction nfmi which is an efficient low power solutio n for short range audio
transfer other chip vendors have used similar low band retransmission lbrt schemes
as the primary device is in charge of the timing for the audio relay it knows exactly when the
secondary earbud will render it it needs to delay the rendering of its audio stream to match
that is one of the issues with the relay approach as the relay process and buffering adds to
the latency of the audio connec tion for most applications it is unlikely to be noticed by the
user not least because adp latency will normally dominate
the relay approach also works for hfp although in most cases only the primary device is
used for the voice return path
chapter the background and herita ge
volume a nd content control such as answering a call or pausing music still uses the
audiovideo remote control profile avrcp over the connection to the primary earbud
the second radio when present can also be used to relay user interface and avrcp controls
such as pause play and volume between the primary and secondary device
more recently companies have started moving to a sniffing approach illustrated in figure
figure the sniffing approach for tws
here the added latency of the relay approach is removed by both earbuds listening to the
primary adp stream only one of the earbuds the primary device acknowledge s receipt of
the audio data to the phone normally the secondary device wouldnt know where to find
the audio stream or be able to decode the audio data in this case the primary device provid es
it with that information either through a bluetooth link or a proprietary sub ghz link that
link is configured by the manufacturer so theres no chance of other devices being able to
pick up the adp stream
as both earbuds receive the same adp stream directly this is potentially a far more robust
scheme particularly if implemented as a bluetooth only solution where there is no relaying
of the audio stream the latency is appreciabl y better
both of these schemes require clever extensions at a fairly low level of the bluetooth stacks in
the earbuds so have largely been the domain of chip vendors apples success has spurred
competing silicon providers to innovate with the result that around a dozen different true
wireless schemes are now in existence built on vari ants of these two techniques with some
including additional features like primary swapping so that the two earbuds can change roles
if one loses the link
section whats in a hearable
the problem with these proprietary approaches is that they can fragment the market apple
qualco mm and others have all filed patents for their solutions which results in their
competitors spending time and effort looking at how to get around the se patents rather than
innovating to drive the market forward it also means that it is almost impossible to mix
earbuds from two different manufacturers as theyre likely to use different tws schemes
that may not be an issue for consumer tws earbuds where they are always bought as a paired
set but it is for hearing aids where different types may be nee ded for left and right ears it
makes it difficult to extend the scheme to speakers where surround sound systems often
combine speakers from different manufacturers although proprietary solutions can spur
market growth in its early stages they rarely help its long term development which is where
bluetooth le audio comes in
shared listening
sharing audio isnt just about sending signals to a pair of earbuds and hearing aids its also
about extending the number of people who can listen to the signal whilst public installations
can cater for large numbers of people listening simultaneously theres a more personal
application where you want to share your music with a friend the white paper on multiple
headphones referred to above sets out how shared listening with one other person is possible
with adp but the solution i t suggests never seems to have made it into products instead
this segment of the market has largely been owned by tempow a paris based bluetooth
software com pany they have developed a phone based audio operating system which they
call dual adp which generates a separate left and right synchronised stream allow ing two
separate pairs of earbuds to render the streams at the same time although this is usefu l it is
limited and has only been taken up by a few manufacturers bluetooth le audio goes beyond
this by providing a scalable solution to transition from one to many listeners
whats in a hearable
the relatively recent arrival of wireless earbuds was limited by the availability of chips which
could provide a way to support separate left and right stereo streams but thats not the only
reason as all of the original startup companies who entered this market discovered packing
all of the functionality that you need to reproduce decent audio into something as small as an
earbud is hard in fact its v ery hard adding bluetooth technology to that along with any
additional sensors to support it becomes incredibly hard only around of the
crowdfunded hearable companies ever managed to ship a product even companies like
apple had to commit almost five years of development to bring about the airpods they
even resort ed to designing their own bluetooth chips to get the performance which made
airpods such a success thats something that only the largest earbud companies apple and
huawei have had the resources to do
its a story that hearing aid manufacturers know well as theyve been perfecting the
miniaturization of hearing aids for many years they also work with customised chips to
optimise performance resulting in devices which run for days on small primary zinc air
chapter the background and heritage
batteries there are a surprising number of e lements in a bluetooth hearing aid as shown in
figure which represent s a fairly basic design its a very similar architecture to an earbud