DirectBand
From Wikipedia, the free 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.
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[edit] How it works
DirectBand uses the 67.65 kHz subcarrier 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.
[edit] Not like RDS
It is important to note that DirectBand does not use the RDS (Radio Data System) subcarrier. RDS is a different and lower bandwidth (~730bps net after ECC) subcarrier primarily used for radio station information and traffic. DirectBand and RDS can co-exist on the same FM station.
[edit] 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.
[edit] 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.
[edit] 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.
[edit] Microsoft design
DirectBand is a product of the Smart Personal Objects Technology (SPOT) team at Microsoft. MSN Direct is the consumer brand that Microsoft uses for devices that receive content from the DirectBand network.
[edit] FM subcarrier usage
RDS uses a portion of the FM station spectrum immediately above the stereo signal, centered at 3x19Khz (the stereo pilot frequency). RDS extends between about 55 and 59 kHz. DirectBand is above RDS, extending from about 59KHz to 75 kHz.
[edit] See also
Related technologies
Related topics
[edit] External links
Official websites
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