DVB-T

Digital Video for Broadcasting - Terrestrial (DVB-T) is a set if standard for sending digital multi-media content via Radio Frequency transmissions.

DVB-T transmissions consist of a single MPEG Transport Stream (TS) which can contain multiple MPEG Program Streams (PS) or channels. A DVB-T tuner tunes in the single TS and then the receiver can de-multiplex (de-mux) a PS to be viewed.

In Australia, the DVB-T TS's are typically transmitted using QAM64 (or 64-QAM) modulation, with either a 2/3 or 3/4 internal convolution (FEC) coding rate on a 7MHz carrier. With a 1/8 or 1/16 guard interval, this results in an overall TS bitrate of between 20 and 26Mbps, enough for a single HD and multiple SD channels, as well as some radio (audio only) channels.

USB receivers

A number of USB connected DVB-T receiver "dongles" exist for receiving DVB-T signals for display on personal computers. Many of these devices use Software defined radio, with some type of programmable device inside the USB dongle.

DTV-2go

DTV-2go is a DVB-T USB dongle with an integrated IR remote receiver.

It identifies itself on the USB bus as:

  idVendor           0x14aa WideView Technology Inc.
  idProduct          0x022b WT-220U DVB-T dongle

Under Linux, the device firmware needs to be loaded at USB enumeration time. The firmware is not available as open-source and so needs to be distributed separately in most distributions. The required firmware is: dvb-usb-wt220u-zl0353-01.fw and needs to be copied into /lib/firmware before the device is inserted/enumerated.

The firmware is available from http://www.chandlerfamily.org.uk/files/dvb-usb-wt220u-zl0353-01.fw.

Scanning for DVB-T signals

A number of applications exist for scanning for DVB-T stations. Under Linux, one that works well is w_scan, in the w-scan package for Debian.

w_scan -c AU -x -t 2 > w_scan.out

Scans DVB-T signals in Australia at medium speed and writes the output in dvb-scan format.

External Links

• DVB-T at Wikipedia