Very Low Bit Rate Vocoder Released
Low bit rates would allow audio over low bandwidth mesh networks.
are flexible, high integration, high performance,
half-duplex RALCWI (Robust Advanced Low Complexity Waveform
Interpolation) Vocoders, offering near toll quality voice at very
low bit rates. A Forward Error Correction (FEC) engine provides
optimum performance in real life applications. The RALCWI Vocoder
comprises four independent functions which are selectable by the
host: Voice Encoder, FEC Encoder, Voice Decoder and FEC Decoder.
In encode mode, the voice encoder uses a 20ms voice frame
size with 3 programmable bit rates: 2050bps, 2400bps or
2750bps. The optional FEC encoder performs channel coding of the
encoded voice (2050bps, 2400bps or 2750bps, depending on the
selected mode) and forms an encoded, interleaved bitstream of
3600bps (216 bits per 60ms packet or 288 bits per 80ms packet).
The FEC operation utilises a packet of either 3 or 4 x 20ms Vocoder
frames to provide optimum error correction performance.
Source: CML Microcircuits.
ZigBee video Doorbell
The article 32-bit processors
have a place in low-power, low-bandwidth ZigBee designs shows
an example application of building a Video-Doorbell System, built with
Analog Devices Blackfin processor.
The example doorbell mentions the uses the JPEG format for video.
JPEG has patent licensing issues when used in embedded devices. I
would avoid JPEG in my own designs, which they do by using more
advance codecs in the doorbell.
...While standard low-bit-rate video encoding is an easy task for
today's media processors, it does pose challenges to low-bit-rate
ZigBee networks. The most bandwidth-efficient media codecs are the
most computationally intensive. The nominal rate of the underlying
IEEE 802.15.4 standard is 250 kbps. Because of the CSMA/CA
architecture, the realistic maximum is on the order of half the
nominal rate. In practice, one can expect to achieve upwards of 60
kbps with large packet sizes in a low-frills configuration without
security. With network bandwidth of this order, a good-quality
VGA-sized JPEG image can be transmitted every second. One way to
increase the frame-rate when transmitting images over a low-bit-rate
link like ZigBee is to implement a more advanced codec that yields a
higher compression ratio than JPEG...
Source: EDN Magazine.
Building Wireless Sensor Networks (WNS)
"Wireless sensor networks (WSNs) dramatically reduce the cost of
installing and commissioning instrumentation in industrial
facilities. More instrumentation means better visibility into
operational and environmental variables that affect overall uptime,
safety, and compliance.
WSNs connect critical processes and assets with the systems or
experts that can interpret the data or take immediate action. At
the end of the day, operational teams with more visibility into
their processes can prevent unplanned shutdowns, increase
efficiency, and keep workers safe...
Synchronized Mesh Protocol (TSMP)
provides a mechanism for WSN
intelligence. By defining how a wireless node utilizes radio
spectra, joins a network, establishes redundancy and communicates
with neighbors, TSMP forms a solid foundation for WSN applications.
TSMP Overview TSMP is a media access and networking protocol that
is designed specifically for low power, low-bandwidth reliable
networking. Current TSMP implementations operate in the 2.4 GHz ISM
band on IEEE 802.15.4 radios and in the 900 MHz ISM band on
The article continues with practicle tips on how to design the
network for operation after installation, not just after start
Source: Robert Shear, Dust
Networks, Courtesy of Industrial
Control Designline, via embedded.com.
Speech via IEEE 802.15.4
new IEEE 802.15.4
voice reference design enables secure full duplex transmission of
speech with long battery life for use in point to point and large
wireless sensor networks (WSN).
Source: Jennic Press Release.
Sorting out ZigBee power options
...ZigBee's RF power specification comes from IEEE 802.15.4, which
specifies a minimum power output rating of 1 mW, with no
specified maximum. The de facto 100 mW "high power" level
relates to the European limit of 100 mW EIRP, including antenna
...100 mW radios offer an indoor range of around 300 feet (100 m) and
an outdoor line-of-site range of about 4000 feet (1200 m). The much
longer ranges make these products suitable for industrial
applications in large factory settings and in outdoor
installations, where nodes are often at intervals that cannot be
spanned by unamplified ZigBee radios...
Source: Wireless Net Design Line.
Ezurio pushes Bluetooth range to 1 km
LONDON: Wireless chip and module specialist Ezurio
has pushed out the
boundaries of Bluetooth with a module that gives the short-range
wireless protocol a range of 1 km.
Source: E.E. Times Europe, by John Walko.
Introduction to Bluetooth Ultra Low Power
Bluetooth's ULP (ultra low power)
mode is expected to consume about
10% to 25% of the power of normal Bluetooth operation, which opens
to the door to networking with small, battery operated devices and
Source: Wireless Net Design Line.
IEEE Publication, New Second Edition of Low-Rate Wireless Personal Area Networks: Enabling Wireless Sensors with IEEE 802.15.4tm
Low-Rate Wireless Personal Area Networks: Enabling Wireless Sensors with IEEE 802.15.4 (Second Edition)
This book will be an update to the existing book with the title
Low-Rate Wireless Personal Area Networks - Enabling Wireless
Sensors with IEEE 802.15.4
by Josť Gutierrez, Edgar
Callaway, and Raymond Barrett.
The book will introduce the reader to the concept of low-rate
wireless personal area networks based on the newly revised IEEE Std
802.15.4-2006, which includes the amendment IEEE 802.15.4b, its
application, as well as implementation and system design
Wibree Radio Technology/Ultra low power Bluetooth
Wibree is intended for ultra low
power applications, which is now being referred to as Ultra
low power Bluetooth technology, due to the merging with the Bluetooth SIG.
is a new interoperable
radio technology for small devices. It can be built into products
such as watches, wireless keyboards, gaming and sports sensors, which
can then connect to host devices such as mobile phones and personal
computers. It is essential the missing link between small devices and
mobile devices/personal computers.
Bluetooth Body Area Network
Single chip "wire replacement" based on Bluetooth from National Semiconductor, will be
released later this year. It is currently under Non-Disclosure to get
the data sheets. Samples are available. Should work well
as a Body Area Network.
Passive Optical Networking
is now available from http://www.one-net.info/
"ONE-NET is an open design standard for low power wireless
optimized for residential and small business control
applications. The ONE-NET wireless standard is specifically
optimized for very low power, very low cost and very good
security. ONE-NET can be implemented with a variety of off the
shelf wireless transceivers and microcontrollers."