Abstract: A matrix-shaped display device with a display foil in which display elements are punched out in the form of tabs. The tabs are positioned in rows and columns, and depending on the desired display, can be positioned by a positioning device in front of or behind a strip having a contrasting color. The display elements are oriented alternately upward and downward from one row to the next. Pairs of oppositely oriented display elements support a strip.

Abstract: A matrix-type advertising device having a circulating transport band with flap-like advertising elements, positioned in rows and columns, which are connected with the transport band on one side in the direction of transport. Dividing strips are positioned in an advertising area, coordinated with the individual rows which have a color contrasting to the transport band provided with the advertising element. The advertising elements in front of or behind the coordinated dividing strips can be brought into the advertising position. In one previously known advertising device of a similar type, the dividing strips are rigidly constructed and accommodated in and fixedly attached to a casing. The advertising device, in the case of a large advertising field, is thus correspondingly large and heavy.

Abstract: In a radio broadcoast channel, an additional message is superimposed on the normal message so as to be inaudible to the listener. To accomplish this, the additional message, consisting of digital signals, is modulated on a subcarrier lying in the ear-physiological masking range of the normal message. During breaks and very quiet intervals of the normal transmission, the signal transmission is interrupted because no masking occurs during those times. To make this possible, the transmission of the normal message is delayed by at least one signal length.

Abstract: An FM receiver has a first pair of signal mixers for receiving an RF signal and a local oscillator for providing a signal to said mixers at a frequency near the center frequency of the received signal. A phase shifter shifts the phase of the local oscillator signal to one mixer by 90.degree.. The outputs of the first pair of mixers are connected to low pass filters having cut-off frequencies equal to approximately one-half the bandwidth of the received signals. A second pair of signal mixers receive the filtered signals and an oscillator signal at a frequency equal to at least twice the cut-off frequency of the low pass filters. The oscillator signal to one of the mixers is phase shifted 90.degree.. The outputs of said second pair of mixers are added together, amplified, limited and thereafter demodulated to provide an audio signal. Automatic frequency control is also provided for the local oscillator.