Transcript USB for Audio

USB for Audio
There are also several USB Audio chips.
You install a custom driver on the host computer, and the USB
sound device appears as a Windows (or Linux, or Mac) sound
device.
The downside of this is that you have to do this install for every
device you might use the USB sound device with.
C-media single chip USB Audio system
Bluetooth
Bluetooth is a wireless cable replacement standard.
After a slow start, Bluetooth technology is taking off. Sales for
2005 should exceed 200 million units, and is roughly doubling
each year.
Bluetooth comes in two flavors:
Class 2: for personal devices or in-vehicle use, around 10-20m
(try 10-20 feet in practice)
Class 1: For longer range up to 100m, e.g. in a household or
office.
Bluetooth Data Rates
Bluetooth also comes in two versions.
Version 1 (usually you see 1.1 or 1.2) has data rates up to 723
kb/s.
Version 2 (aka EDR or Extended Data Rate) triples the data rate
up to about 2 Mb/s.
Bluetooth shares the 2.4GHz spectrum with WiFi (802.11a,b,g
etc.).
Bluetooth Profiles
One of the most useful innovations in the Bluetooth standard is
the use of device profiles.
A profile is an abstract device spec. that has to be supported at
both ends of a connection.
If you like, it’s the kind of cable(s) that Bluetooth connection
supports. Each connection can support several profiles at once.
Profiles eliminate the need for custom drivers on the host, and
allows a Bluetooth device to connect to any host (PC, PDA, cell
phone) that supports the profile(s) it uses.
Bluetooth Profiles
Bluetooth Chips - CSR
Cambridge Scientific Radio (CSR) manufactures a large number
of Bluetooth chips, probably more than half of those shipped.
This is a diagram of their Bluecore2 series.
This chip fits
in a 1cm2
package
Developing with Bluetooth
• The newest modules make it pretty easy to go wireless. Most
modules can be used as serial cable replacements.
• The next simplest step is to add a microprocessor to act as
controller (PIC etc.), using the module’s serial profile. But
since new BT chips have a powerful, energy-efficient
processor on-board already, this is rather wasteful.
• You can develop for the native processor, but you will need to
buy some expensive development tools. CSR and some
module vendors provide virtual machines so your code can’t
void the module’s qualification.
Semantic Web
• Tim Berners-Lee originally expressed the vision of the
semantic web as follows:
• I have a dream for the Web [in which computers]
become capable of analyzing all the data on the
Web – the content, links, and transactions between
people and computers. A ‘Semantic Web’, which
should make this possible, has yet to emerge, but
when it does, the day-to-day mechanisms of trade,
bureaucracy and our daily lives will be handled by
machines talking to machines. The ‘intelligent
agents’ people have touted for ages will finally
materialize.
– Tim Berners-Lee, 1999
• Humans are capable of using the Web to carry
out tasks such as finding, reserving a library
book, and searching for a low price for a DVD.
However, a computer cannot accomplish the
same tasks without human direction because
web pages are designed to be read by people,
not machines. The semantic web is a vision of
information that is understandable by
computers, so that they can perform more of
the tedious work involved in finding,
combining, and acting upon information on
the web.
• The Semantic Web is an evolving
development of the World Wide Web in which
the meaning (semantics) of information and
services on the web is defined, making it
possible for the web to "understand" and
satisfy the requests of people and machines to
use the web content. It derives from World
Wide Web Consortium director Sir Tim
Berners-Lee's vision of the Web as a universal
medium for data, information, and knowledge
exchange.
• Some elements of the semantic web are
expressed as prospective future possibilities
Other elements are expressed in formal
specifications. Including
• Resource Description Framework (RDF),
– Describes the data about resource
– a variety of data interchange formats (e.g.
RDF/XML, N3, Turtle, N-Triples), and notations
such as RDF Schema (RDFS)
• The Web Ontology Language (OWL)
• Describes the relationship between the data (Knowledge
Domain)
• Formal description of concepts, terms, and relationships
within a given knowledge domain.
• The Resource Description Framework (RDF) is
a family of World Wide Web Consortium
(W3C) specifications originally designed as a
metadata data model. It has come to be used
as a general method for conceptual
description or modeling of information that is
implemented in web resources, using a variety
of syntax formats.
• The Web Ontology Language (OWL) is a family of
knowledge representation languages for authoring
ontologies, and is endorsed by the World Wide Web
Consortium. This family of languages is based on two
(largely, but not entirely, compatible) semantics:
OWL DL and OWL Lite semantics are based on
Description Logic, which have attractive and wellunderstood computational properties, while OWL
Full uses a semantic model intended to provide
compatibility with RDF Schema. OWL ontologies are
most commonly serialized using RDF/XML syntax.
OWL is considered one of the fundamental
technologies underpinning the Semantic Web, and
has attracted both academic and commercial
interest.