Abstract: A power supply for a satellite receiver system includes a dual input supply voltage arrangement. When a higher output voltage is selected, a source of a lower supply input voltage is coupled to an input main current conducting terminal of a series pass transistor. On the other hand, when a lower output voltage is selected, a source of a lower supply input voltage is coupled to the input main current conducting terminal of the series pass transistor. A comparator senses a magnitude of an output voltage produced by the series pass transistor. When, as a result of an over current condition, the output voltage is lower than a reference threshold level, any selection of the higher output voltage is automatically overridden and the source of the lower supply input voltage, instead, is coupled to the input main current conducting terminal of the series pass transistor.

Abstract: Hacking of a class of Set-Top Boxes known as Integrated Receiver-Decoders (IRDs) used to receive satellite broadcasts for display on television sets is prevented by use of connections to the reprogramming enable pin of a flash memory. If a user attempts to reprogram the boot sector of the flash memory in order to obtain free service via privacy, the set-top box is destroyed. The invention relates to the design and manufacture of IRDs that are resistant to hacking via unauthorized reprogramming.

Abstract: The compression of composite video data is provided in order to reduce bandwidth and thereby increase the amount of bandwidth available for transmission. Composite video signals that include a plurality of fields are received at a selected clock frequency. A first selected number of fields is stored and a second selected number of fields is dropped. In a Frequency Division Multiplexing mode, the data is read out at a fraction of the selected clock frequency corresponding to the stored portion. In a Time Division Multiplexing mode, the data is read out at the selected clock frequency during selected intervals having a duration corresponding to the time it took to receive the stored fields. No data is read out during an interval having a duration equal to the time it took to scan the dropped fields, such time being allocated to the compressed information from other users of the same shared transmission medium.

Abstract: A television receiver includes apparatus for stabilizing an on-screen character display by which the deflection signal source is controlled for operating in a free-running mode, substantially unaffected by signal variations on the sync input line, rather than in a synchronized mode when sync is unreliable or otherwise undesirable. As another feature, the deflection signal source is caused to operate at substantially the same frequency in either mode.