Universal Serial Bus: Difference between revisions
(pasted USB 1.1 info from other article (no need for two seperate USB articles!)) |
m (fixed link) |
||
| (9 intermediate revisions by the same user not shown) | |||
| Line 1: | Line 1: | ||
The '''Universal Serial Bus''' ( |
The '''Universal Serial Bus''' ('''USB''') is a serial 4-wire bus (GND, Power and a differential Data Signal transferred over 2 wires). A quite clever designed protocol for communication between the PC Host and peripheral devices like e.g. DVB Receivers. Since devices are defined as dumb clients that get polled by the USB Host Controller, USB device chipsets can be very cheap compared to [[IEEE1394]] chips that provide essentially the same functionality. |
||
Governed by the USB Consortium, USB specifications are openly available to the public on [http://www.usb.org usb.org]. |
|||
Many USB DVB devices are available from an wide assortment of different [[List of Device Vendors|vendors]]. |
|||
Different USB DVB Devices are available on the Market by different [[DVB Card Vendors]], only High-Speed USB2.0 devices are able to transfer the full [[MPEG2 Transport Stream]] or high-datarate [[Transponder]]s, Full-Speed are limited to a overall datarate (incl. Protocol overhead) of about 12MBit. |
|||
===USB 1.1=== |
===USB 1.1=== |
||
This older Universal Serial Bus variant specifies data transfer rates of 1.5 Mbps (Low-Speed devices) and 12 Mbps (Full-Speed devices). |
|||
USB DVB devices adhering to the USB 1.1 standard will operate at the Full-Speed specification. However, because Full-Speed devices are limited to a overall datarate (incl. Protocol overhead) of about 12 Mbps, this essentially prevents these devices from receiving [[HDTV]] steams and makes it impossible to receive some high-datarate services. Only High-Speed USB 2.0 DVB devices are able to transfer the full [[MPEG-2 Transport Stream]] or high-datarate [[Transponder]]s. |
|||
===USB 2.0=== |
===USB 2.0=== |
||
In terms of reception of digital TV (DTV) services, the 480 Mbps transfer rate of USB 2.0 overcomes several of the limitations of earlier USB 1.1 devices. |
|||
== Links |
==External Links== |
||
*http://www.usb.org/ |
*http://www.usb.org/ |
||
*[[wikipedia:USB]] |
*[[wikipedia:USB]] |
||
Revision as of 22:14, 6 January 2008
The Universal Serial Bus (USB) is a serial 4-wire bus (GND, Power and a differential Data Signal transferred over 2 wires). A quite clever designed protocol for communication between the PC Host and peripheral devices like e.g. DVB Receivers. Since devices are defined as dumb clients that get polled by the USB Host Controller, USB device chipsets can be very cheap compared to IEEE1394 chips that provide essentially the same functionality.
Governed by the USB Consortium, USB specifications are openly available to the public on usb.org.
Many USB DVB devices are available from an wide assortment of different vendors.
USB 1.1
This older Universal Serial Bus variant specifies data transfer rates of 1.5 Mbps (Low-Speed devices) and 12 Mbps (Full-Speed devices).
USB DVB devices adhering to the USB 1.1 standard will operate at the Full-Speed specification. However, because Full-Speed devices are limited to a overall datarate (incl. Protocol overhead) of about 12 Mbps, this essentially prevents these devices from receiving HDTV steams and makes it impossible to receive some high-datarate services. Only High-Speed USB 2.0 DVB devices are able to transfer the full MPEG-2 Transport Stream or high-datarate Transponders.
USB 2.0
In terms of reception of digital TV (DTV) services, the 480 Mbps transfer rate of USB 2.0 overcomes several of the limitations of earlier USB 1.1 devices.