The Firehouse

While it does contain most of the ad-hoc stack, the recently announced Wi-Fi Direct standard is actually an attempt to become more like Bluetooth. Ever since Wi-Fi was invented, ad-hoc mode allowed two or more adapters to form a peer-to-peer network without an access point (AP) running the show. In certain scenarios, there would be connectivity problems when adapters were not configured for automatic IP assignment in the auto-discovery range, or had static IPs setup. Saving these, the user would then have to make sure his operating system had enabled the appropriate sharing protocols so that meaningful things could happen, such as sending files from one machine to the other.

Ever since Bluetooth was invented, it provided a communications stack, and a protocol stack, which encompassed a growing number of profiles. An application only had to talk to the right profile in order to establish communication with another Bluetooth device supporting the same profile, for example, serial port, audio gateway or FTP. During device discovery, a Bluetooth device would query the other about its available profiles, and would then choose the right one as needed. As a practical and recent example, the iPhone initially supported the handset profile, which provides very rudimentary headset functionality and leaves out things like address book access. Over time, the iPhone has been upgraded with more profiles, some as complex as A2DP which allows highish-definition audio to be sent to stereo headphones or speakers. I say “highish” as it uses an audio bandwidth of 16kHz, way below the normal audio response of a set of headphones, leading to a noticeable decrease in quality. But I digress.

In my view, the press release was very badly worded, making it appear as a re-branding of old-time ad-hoc, when it really implies adding a number of protocol stacks and profiles to the standard ad-hoc mode. It is also an attempt to take Bluetooth head-on, with the argument that Wi-Fi is a gateway to a bigger number of services – Bluetooth DSL router, anyone? no? I rest my case. Having such a set of profiles would obviate the need to have Bluetooth chipsets on top of Wi-Fi, which are always an added cost and source of radio interference. We would then have to see how audio accessories cope with this, but then again, I’ve not seen many people carrying Bluetooth headsets around, while car kits can accommodate a Wi-Fi chipset thanks to their board space and bigger battery.

I already wrote about the extreme lack of support for most of Bluetooth’s possibilities in the original iPhone, but it seems Apple has improved things a bit with the release of the iPhone 3G.

Looking over the PICS again, the Phonebook Server Equipment (PSE) mode in the Phonebook Access Profile (PBAP) is now supported, which means that phonebook download, browsing and other functions are available, but not contact uploads, which would require a Phonebook Client Equipment role in the profile. A very clear and simple explanation of PBAP can be found on Microsoft’s MSDN Library.

All this mumbo-jumbo means that carkits such as the Parrot MINIKIT SLIM can download and use the iPhone’s contact list for training-free speech recognition and dialing, which is very cool and works wonders! For those interested, PSE makes support for vCard 2.1 and 3.0 mandatory.

Additionally, Hands-Free Profile 1.5 is also supported on top of the much more limited Headset profile in the original iPhone. They still don’t support inband ringtones, for reasons that escape me, as it’s not like you can steal the ringtones in hi-def over speech-quality Bluetooth. In any case, a good step in the right direction!

Just today UPS dropped off (well, I intercepted the driver in mid-flight, but that’s a different story) the Jawbone Bluetooth headset I was waiting for – and boy, does it work wonders! This has to be the best implemented piece of DSP technology I have seen. If you don’t believe in ‘official’ demos and blurb from jawbone.com (they are true), just check out this audio recording [WAV, 48kHz, 1.7MB]. The first part is recorder using my Mac with an unsquelched radio about 30cm from the headset, with the DSP turned off. I then turn it on, and the audio is recorded perfectly, with barely a hint of the background noise.

How do they do it? I’ve not opened this baby up, as it’s too good-looking (and expensive), but it seems that they combine two directional microphones with a vibration sensor (the small white dot you see on the picture) that picks up bone-transmitted voice from your jaw (thus the name). By matching the vibrations, which are not enough to actually record sound, with the incoming audio from the microphones, they can take away the extra noise very effectively. I should know, as in my previous job, one of our biggest problems was noise and echo cancellation (I was responsible for electronics R&D at SouthWing, designing and testing Bluetooth headsets and other accesories) – and we could never completely kill feedback echo, and noise – forget it. Our designs were in the top league as far as audio quality and noise went, but try what I just did today and the whole recording would have been like the first half.

Good job, Aliph!

I ordered a Jawbone Bluetooth headset on the August 1st. By about the 9th, I should be getting it in my hands. This would not be too bad, were it not that UPS Worldwide Expedited was paid for, at almost $50! Aliph’s site quotes 3-4 business days, but this will be more like 6-7. From now on, I think I’ll request USPS Air, as it costs a fraction, it usually arrives quicker, and has never been held up in customs (I can tell UPS horror stories of packages held for days while some stupid customs inspector felt like having a look at the paperwork…).