Blind scan
Blindscan is a special channel search function for DVB receivers , i.e. satellite receivers , digital cable TV receivers and set-top boxes .
Receivers with BlindScan function have been on the market since 2003 . They enable a search that searches the complete frequency spectrum of a satellite without entering frequencies , symbol rates or using presets.
With satellites designed for direct reception, such as Astra , the station search is controlled via a transponder table (NIT = Network Information Table), which the satellite operator provides on several transponders. Some satellite operators do not or only insufficiently maintain this network table. A blind scan is recommended here, but for satellites such as Astra and Eutelsat it rarely brings advantages.
The blind scan also finds transmissions that have been added and are not recorded in the network table. Even (often uncommented / uncut) material from live broadcasts , broadcast vehicles, external studios or other broadcasters can be found with a blind scan (see Feedhunting ). Since all possible frequencies and symbol rates are tried out, this scan can take a long time.
Receivers for terrestrial and cable reception are based on the same technical principle; However, the changes are not only significantly less frequent than with satellite reception, but also channel parameters such as transponder bandwidth, FEC, bit rate, etc. are almost never changed and the channel grid is specified.