DirectBand
Encyclopedia
DirectBand is a North American wireless datacast
network owned and operated by Microsoft
. It uses FM radio broadcasts in over 100 cities to constantly transmit data to a variety of devices, including portable GPS devices, wristwatches and home weather stations.
leased by Microsoft from commercial radio broadcasters. This subcarrier delivers about 12 kbit/s (net after ECC) of data per tower, for over 100 MB per day per city. Data includes traffic, sports, weather, stocks, news, movie times, calendar appointments, and local time.
) subcarrier. RDS is a different system and has much lower data rate (~730 bit/s after ECC, including framing). Its much narrower subcarrier is primarily used for radio station information and traffic. DirectBand and RDS can co-exist on the same FM station.
The initial DirectBand products were a series of data watches. These had mild success, but never met expectations and production of new watches was discontinued in 2008. Recently, several other applications have surfaced, the most visible being the traffic data/local info market, particularly to auto GPS sets for Garmin and Avis. This competes directly with older RDS-based services, which operate at a substantially lower data rate.
(SPOT) team at Microsoft. System hardware was designed for Microsoft by SCA Data Systems of Santa Monica, CA. MSN Direct
is the consumer brand that Microsoft uses for devices that receive content from the DirectBand network.
Although this clearly indicates Microsoft's intent to cease usage of the service, it is not yet known whether the DirectBand technology will be sold to another company, such as one of the hardware licensees of MSN Direct (e.g. Garmin
) -- or whether the technology will be put in the public domain as an open source technology.
Datacasting
Datacasting is the broadcasting of data over a wide area via radio waves. It most often refers to supplemental information sent by television stations along with digital television, but may also be applied to digital signals on analog TV or radio...
network owned and operated by Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
. It uses FM radio broadcasts in over 100 cities to constantly transmit data to a variety of devices, including portable GPS devices, wristwatches and home weather stations.
How it works
DirectBand uses the 67.65 kHz subcarrierSubcarrier
A subcarrier is a separate analog or digital signal carried on a main radio transmission, which carries extra information such as voice or data. More technically, it is an already-modulated signal, which is then modulated into another signal of higher frequency and bandwidth...
leased by Microsoft from commercial radio broadcasters. This subcarrier delivers about 12 kbit/s (net after ECC) of data per tower, for over 100 MB per day per city. Data includes traffic, sports, weather, stocks, news, movie times, calendar appointments, and local time.
Not like RDS
DirectBand does not use the RDS (Radio Data SystemRadio Data System
Radio Data System, or RDS, is a communications protocol standard for embedding small amounts of digital information in conventional FM radio broadcasts. RDS standardises several types of information transmitted, including time, station identification and programme information.Radio Broadcast Data...
) subcarrier. RDS is a different system and has much lower data rate (~730 bit/s after ECC, including framing). Its much narrower subcarrier is primarily used for radio station information and traffic. DirectBand and RDS can co-exist on the same FM station.
Forward Acting Error Correction
Since many DirectBand uses are mobile, and there is no opportunity to request retransmission of a broadcast signal, DirectBand utilizes an advanced error-correction strategy that allows for reconstruction of messages even when sizable portions of the message are lost due to buildings, tunnels or other obstructions of the FM signal. Error correction is 3/4ths rate Trellis with time diversity, soft-decision decode. The DirectBand data rate is in excess of 12 kbit/s after ECC.Push network
DirectBand is a push network—new content is delivered every 2 minutes. Users pre-select the virtual channels that they are interested in.Receivers
There are a variety of DirectBand receivers. All use a small (2.794 mm x 2.794 mm x 860 µm) radio receiver. Some designs add an ARM7-based processor.The initial DirectBand products were a series of data watches. These had mild success, but never met expectations and production of new watches was discontinued in 2008. Recently, several other applications have surfaced, the most visible being the traffic data/local info market, particularly to auto GPS sets for Garmin and Avis. This competes directly with older RDS-based services, which operate at a substantially lower data rate.
Microsoft design
DirectBand is a product of the Smart Personal Objects TechnologySmart Personal Objects Technology
Smart Personal Object Technology was developed by Microsoft to personalize household electronics and other everyday devices, through "smart" software and hardware that would make their uses more versatile....
(SPOT) team at Microsoft. System hardware was designed for Microsoft by SCA Data Systems of Santa Monica, CA. MSN Direct
MSN Direct
MSN Direct is an FM radio-based digital service which allows 'SPOT' portable devices to receive information from MSN services. Devices that support MSN Direct include wristwatches, desktop clocks, in-car GPS satellite navigation units, and even small appliances such as coffee makers...
is the consumer brand that Microsoft uses for devices that receive content from the DirectBand network.
FM subcarrier usage
RDS uses a portion of the FM station spectrum immediately above the stereo signal, centered at 3x19 kHz (the stereo pilot frequency). RDS extends between about 55 and 59 kHz. DirectBand is above RDS, extending from about 59 kHz to 75 kHz.Future
On October 26, 2009, Microsoft announced that MSN Direct service would end on January 1, 2012.Although this clearly indicates Microsoft's intent to cease usage of the service, it is not yet known whether the DirectBand technology will be sold to another company, such as one of the hardware licensees of MSN Direct (e.g. Garmin
Garmin
Garmin Ltd. , incorporated in Schaffhausen, Switzerland, is the parent company of a group of companies founded in 1989 by Gary Burrell and Min Kao , that develops consumer, aviation, and marine technologies for the Global Positioning System...
) -- or whether the technology will be put in the public domain as an open source technology.
See also
- RDSRadio Data SystemRadio Data System, or RDS, is a communications protocol standard for embedding small amounts of digital information in conventional FM radio broadcasts. RDS standardises several types of information transmitted, including time, station identification and programme information.Radio Broadcast Data...
- PSIP
- Error correction
- ModemModemA modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
- FM broadcastingFM broadcastingFM broadcasting is a broadcasting technology pioneered by Edwin Howard Armstrong which uses frequency modulation to provide high-fidelity sound over broadcast radio. The term "FM band" describes the "frequency band in which FM is used for broadcasting"...