DE2223432A1 - AUTOMATIC STEREO DISPLAY - Google Patents

Description

State of the art

It is known in radio receivers for stereophonic playback to attach a display device that shows the operator a stereo broadcast. The indication is controlled by the pilot carrier, his presence or absence Should be an identifier for a stereo or mono broadcast.

In practice it has been found that for the reasons stated here are not to be discussed in more detail, the pilot carrier often remains switched on, even then, when broadcasting a mono broadcast.

By means of a display device according to the prior art, the Operator thus sometimes misinformed.

OBJECT The invention is based on the object of a stereo display to create that is independent of the pilot carrier in principle and that only gives an indication when stereo playback is actually taking place. The task is achieved by the invention specified in claim 1, which in principle is based on it is based on the fact that a display occurs when different channels in the amplifier Information is transmitted and the display turns off when the transmitted Information is the same.

Advantages The independence from the decoder of the radio receiver enables the application of the invention also for records or tape playback. It can also be used on multi-channel amplifier arrangements, such as quadrophonic, etc.

can be used and in principle allows any display, which channel against which or which other different or identical information reproduces.

An advantageous further development of the invention lies in a link with the switching voltage of the decoder set up to receive stereo broadcasts Radio receiver to the effect that both pilot voltage for a stereo display as well as various information must be available in the two audio channels, to effect an advertisement. This avoids the presence of a single sound source exactly in the middle between left and right the stereo display switches off, because in this rare special case, both Amplifier channels have the same information in the same amplitude and phase position hold true.

This in principle existing disadvantage of the method according to the present In an advantageous further development, the invention can thereby be circumvented or greatly mitigated that a shutdown by means of an integration element of high time constant the stereo display only takes place after such a period of time, after experience has shown one exactly in the middle only one standing between left and right Sound source has already changed its position again.

To be generated when operating the amplifier with purely low frequency Stereo information, e.g. when playing records, tape recorders or the like in which a switching voltage of a pilot carrier is not available stands to be able to operate, the switching voltage is in a further development of the invention the decoder circuit is simulated by a fixed DC voltage that is applied to the logic Linking circuit by means of a changeover switch, which is mechanically connected to the changeover switches is coupled to the various sources of low-frequency voltages, acts.

A very advantageous development of the invention is a simple one Display for stereophonic and quadrophonic with a 4-channel low-frequency amplifier, in which the equality or inequality of the 1, front left "and" front right " flowing information and the equality or inequality of the "front left" - or the "front right" with the associated "rear left or or" rear right "amplifier channel scans, the yes / no statements obtained from the two test circuits in logic circuits with the addition of a decoder switch if necessary The information given is linked in such a way that it is a separate display for quadrophonic and stereophonic results.

Explanation of the invention Fig. 1 shows an embodiment of the present invention Invention based on a two-channel stereo amplifier. The test circuit (1) is with its clamp (2) to the "right" channel and with clamp (3) to the left channel connected to the stereo amplifier. The test circuit (1) contains the same matching elements (4) for the "right" and 5 for the "left" channel. Behind one of the two adjustment links, in the embodiment in series with the. Adapter (4) in the "right" channel a phase reversing stage (6) is attached, which while maintaining the amplitude the Phase rotates around 1800. To the outputs of the adapter (5) and the phase inverter (6) a series circuit of two identical resistors (7 and 8) is connected, at the connection point A there is an alternating voltage if the information in the "Left" and "Right" channels of the stereo amplifier are different and on which the AC voltage is zero if the information is in the 11Left "and" Right "channels of the stereo amplifier are the same, e.g. in the case that a radio station sends out a pilot carrier, but internally sends the two channels "left" and "right" are connected and a mono program is being broadcast. The presence or the absence of an alternating voltage at point A is thus a real criterion for the presence of stereo or mono information on both channels.

To get a yes or no statement in digital form (L or 0), the voltage at point A only needs to be amplified (9), rectified (lo), possibly limited and integrated (11). Turning on a The integration link also has the purpose of eliminating short-term information differences be bridged in mono operation, which can arise, for example, from the fact that when playing a mono record due to the presence of dust particles a stereo information is simulated, and that in a stereo transmission also the seldom occurring, short-term operating condition that a single sound source exactly in the middle between the microphones for "left" and for "right" longer Time should be transferred, and in this special case the information in "left" and "right" channels are the same, this does not change the display.

The desired digital output is then at output A = of the test circuit (1) Display voltage, either directly or as shown in Fig.

1 is shown by means of an AND circuit (12) with the output voltage a decoder switching stage (13) of a radio receiver set up for stereo reception is linked, so that only when both display voltages are present the optical Display means, in the exemplary embodiment a lamp (14) displays. In the exemplary embodiment a further lamp (15) is connected via an isolating amplifier (16), which is shown in known way indicates the pilot carrier itself. By means of a switch (17) is used when playing records instead of the then nonexistent output voltage of a decoder Switch (13) the substitute DC voltage source (18) switched on.

Fig. 2 shows the possibilities that the invention for the various Displays with a 4-channel amplifier Quadrophonic amplifier offers. The 4 connection points The 4 channels are labeled VL (front left), VR (front right) HL (rear left) and Labeled HR (back right). Each connection point is over with every other a test circuit according to the present invention connected, with the representation Not to confuse, the matching links have been left out. The respective connection points of the two resistances at which the presence or absence a different AC voltage is queried are A, B, C, D and F denotes.

The table attached to FIG. 2 shows which logical information at the outgoing digital information belonging to the connection points A to D. Connection terminals A = to F = of the test circuits depending on the equality or inequality of the information transmitted in the 4 channels arise.

With the help of appropriate logic circuits, it is possible to for all stereophonic possibilities (left - right, front - back, cross, respectively 1 channel against 3 others) as well as the monophonic and quadrophonic display by means of display means, whereby it makes sense to arrange these advertisements in such a way that they face the viewer make a clear impression of the existing state of transference.

The simplified application example can easily be seen from the table in FIG. 2 Derive according to FIG. 3. Here it is shown with which relatively simple means with a 4-channel amplifier one for stereo and quadrophonic reproduction separately Display can be effected.

A first test circuit (1) protrudes as in Fig. 1, the channels "in front right "and" front left "and wins a yes / no statement about a difference the left-right information at terminal A. A second test circuit (20) asks the channel "front left" and the channel "back left" and wins a yes / no statement about the presence of "front" and rear information at terminal D =.

From the table of Fig. 2 it can be seen that at terminal A = as well at terminal D = the voltage L is when quadrophone playback takes place, and that only a "left / right" stereophonic transmission takes place if at terminal A = voltage L and voltage 0 at terminal D ~.

In the latter case, the voltage at terminal D = becomes zero a negation circuit (21) inverted, then result in the AND circuit (22) and optical display means connected to the AND circuit (23) such as light bulbs a ge.

separate display for quadrophony (22, 24) and stereophony (23, 25). In mono operation none of the light bulbs 24 and 25 light up.

As in the embodiment of Fig. 1 is also game in Ausführungsbei Fig. 3 shows the output voltage of the decoder switch (26) for multi-channel reception set up radio receiver with the voltages A = and D = from the input linked reasons and it is also here for the operation of the amplifier a DC voltage equivalent source on a record player or on a tape recorder (27) is provided, which delivers the same voltage as the decoder switch in Position L.

An incandescent lamp (28) shows the presence of a in a known manner Pilot carrier.

L e r s e i t e

Claims (5)

Automatic stereo display P a t e n t a n s p r ü c h e circuit arrangement for monitoring and displaying the presence of an inequality of alternating voltages in the channels of a multi-channel low-frequency amplifier, characterized in that that a test circuit (1) with both of them is connected to 2 channels to be monitored Inputs (2) and (3) is connected, the output A = a digital voltage L or 0 delivers, depending on the presence or absence of such an inequality, that at this output directly or indirectly via connecting links (12) optical Display means (14) are connected and that the test circuit itself exists from a bridge circuit of 2 equal resistors (7, 8), a phase reversal stage (6) with gain (l) connected in series with one of the two resistors is, and 2 equal adapter members (4, 5) that connect to the two channels to be monitored, and an amplifier, limiter, rectifier and integration arrangement (9, lo, 11) with its input to the connection point A of the two resistors belonging to the bridge circuit is connected and whose output A = the output of the test circuit. 2. Circuit arrangement according to claim 1, characterized in that the output A = the test circuit and the output of a decoder switch (13) one Radio set up for multi-channel reception of radio broadcasts is and that the presence of a pilot carrier for establishing a switching voltage used, with the inputs of a conjunctive logic circuit (12) are connected, at the output of which the optical display means (14) are connected are. 3. Circuit arrangement according to Claims 1 and 2, characterized in that that with a quadrophonic amplifier both on 2 channels, the right-left information serve as well as a test circuit on 2 channels, which are used for front-back information (1, 20) is connected and that the outputs of the two test circuits with the Inputs of a first conjunctive logic circuit (22) connected are, at the output of which optical display means (24) for the quadrophone operating status and that the outputs of the two test circuits with the interposition of a negation element (21) in the test circuit (20), which is connected to the two channels, the serve the front-back information to the inputs of a second conjunctive link Logic circuit (23) are connected, at the output of which optical display means (25) are connected for stereophonic operating status. 4. Circuit arrangement according to claim 1 to 4, characterized in that that the test circuit or several identical test circuits and / or the connected Logical circuits are combined to form an integrated circuit. , 5. Circuit arrangement according to claims 1 to 4, characterized in that the Time constant of the integration element in the test circuit (11? So large is chosen that relatively seldom and only briefly occurring accidental Equalities of the alternating voltages of two monitored channels in the case of non-monophonic Operating state can be bridged.