A channel selector for selecting one from among a predetermined number of received signals (e1 . . . en), and which may be used in a mobile radio system to improve the radio traffic between a mobile and a central station. The channel selector includes a summator for summing the received signals in accordance with respective weight factors (G1 . . . Gn), and an evaluation circuit for determining the weight factors on the basis of an evaluation of a characteristic, such as channel quality or signal energy, of the received signals.

The invention relates to a method for determining the strength of a signal (18) at the input of a tuner (1a.) In this, the frequency-dependent amplification characteristic for the tuner is measured and stored in a memory assigned to the tuner. With the help of this characteristic the frequency-dependent variation of the amplification can be compensated during tuner operation, in order that the input signal strength can be deduced more precisely. For a tuner with automatic gain control (AGC), the frequency dependence of the AGC can also be recorded and stored in the memory by representative characteristics. The consideration of the AGC characteristics results in a further improvement to the precision of estimation of the input signal strength.

In one embodiment, the commercial insertion system includes, at a control center, a source of commercial inserts and a processor for generating various command signals based upon monitoring a plurality of programmed channels signals on a per channel basis. A stream of commercial insert video signals and the command signals are sent via a satellite up link to regional cable systems generally grouped as East Coast stations and West Coast stations. A multiple input/output video switch system is located at the video head of each cable system. This video switch system includes a local video signal generator and a video switch for each channel having local available commercial time slots. The video switch applies, at its output, either the programmed channel signal received by the cable system from a first telecommunications network, the commercial insert signal received from the second telecommunications network or the local video signal, all dependent upon switch commands sent from the control center via the second telecommunications network. A mechanism is provided for producing a frame blanking signal intermediate the application of the programmed channel signal, the commercial insert signal and the local video signal and for generating characters for each particular spot commercial.

The video switch system remotely controls on a per switch, and hence a per channel, basis the insertion of a programmed channel video signal sent over one telecommunications network, a commercial video signal sent with the switch commands over another network or a locally generated video signal compiled from digitally stored video signals located on a digital storage device by insert locator data sent with the switch commands and the commercial insert video. The video switch system, in preferred embodiments, can generate a plurality of third video signals based upon a plurality of insert location information that is part of the insert locator data and apply respective third video signals to one or more of the video switches dependent upon switch commands and insert locator data generated remotely and received at the cable head end. The digitally formatted video signals can be sent to the video switch system via the second telecommunications network or via phone lines or be hand delivered on compact disc-read only memory (CD ROMs), magnetic tape, or other transportable media capable of storage of digital data.

A power control method for a set top box is disclosed. The method includes a first step for setting a time reserving and recording function for recording a broadcasting signal received from a set top box, a second step for recording the broadcasting signal in accordance with the time reserving and recording function of the first step, a third step for judging whether or not a synchronous signal is inputted into a broadcasting signal recording apparatus through a signal cable connected with the set top box during the operation of the second step, a fourth step for continuously performing a time reserving and recording function when it is judged that the synchronous signal is inputted into the broadcasting signal recording apparatus as a result of the third step, a fifth step for outputting a power code or channel code to the set top box when it is judged that the synchronous signal is not inputted into the broadcasting signal recording apparatus as a result of the third step, and a sixth step for performing the fourth step when the synchronous signal is inputted as a result of the judgment that the synchronous signal is inputted into the broadcasting signal recording apparatus after the fifth step, for thereby controlling the power of a set top box in accordance with whether there is a synchronous signal applied to the broadcasting signal recording apparatus when the power of the set top box is OFF.