format such as that of the NBC feeds (AMC 1 at 103°W, now requires 8PSK, DVB-S2 and HDTV support to receive anything) can remove a channel from virtually all standard FTA receivers. Receiver obsolescence Many receivers will provide options for hardware expansion (such as to add 8PSK reception or DVB Common Interface TV subscription cards) and firmware upgrade (either officially or from nominally third-party sources). Most often, once the individual receiver model is discontinued, this support and expandability rapidly disappears from all sources. The migration of existing feeds to formats such as MPEG-4, HDTV, or DVB-S2 (which many current receivers do not support) may also result in viewers losing existing free programming as equipment becomes rapidly obsolete. Unlike digital terrestrial set-top boxes, most standard-definition DVB-S receivers do not down-convert HD programming and thus produce no usable video for these signals. There have also been incidents where existing receiver designs have been "cloned" or copied by competing manufacturers; a manufacturer will often reduce support for a widely copied receiver design. In some cases, malware has been released, ostensibly in the same format as existing third-party firmware, in an attempt to interfere with the further use of a widely cloned receiver's design. Legal issues FTA receivers are ostensibly designed for free-to-air use but can be adapted for other purposes. In some jurisdictions, this dual-use nature can cause problems. Thus, combatting piracy involving FTA receivers has been difficult using legal means. Popular brands Peripheral equipment Satellite dish LNB DiSEqC Universal Satellites Automatic Location System References External links Free to air TV channels Free to air radio stations Channel Master editor (archived, last update October 2008) Channel finder for Astra satellites Set-top box Television technology