DD131608B1 - DIGITAL PLACTER WITH REDUCED ERRORS IN THE STEL - Google Patents

Description

20007 1 -ch-

Title of the invention

Digital controller with reduced disturbances during the setting process

Field of application of the invention

The invention is particularly applicable in the audio engineering of digital level controls. It can also be used to reduce pops in the digital setting of filters and equalizers or other functional units of the audio channel in which quantized changes in attenuation, gain, frequency or the like are made.

Characteristic of the known technical solutions

Digital control elements for the sound studio technology are usually constructed in the form of a chain circuit of Dämpfungsgliederη and / or gain stages (DD-PS 100 600), the Dämpfungsbzw. Gain factors only a few discrete fourth - two with the use of a switch per stage - can accept. Corresponding coding of the switchable amplifications or attenuations in the chain ensures that the signal level can be varied in equal-quantized steps, preferably 1 dB, over the entire adjustment range of approximately 100 dB. The sudden level change generates unwanted secondary spectra, which are subjectively perceived as annoying pops ·

200071

A known arrangement for reducing such interference (DD-PS 117 953) mixes digital and analog circuit principles by supplementing the quantized actuator with an assembly representing analog circuitry. This leads u.a. problems with matching and reproducibility. There is also the risk of undesired level jumps due to overlapping. The recharging of the capacitor must be done in a time corresponding to the switching time of the quantized actuator. Another disadvantage is the fact that the analog complementary circuit also works when no signal voltage is applied. As a result, the clacking caused by the crosstalk of the switching pulses in the signal path are increased.

Object of the invention

With the invention, a reduction of cracking noise is sought, without causing amplified noise in the transmission breaks.

Statement of the invention

The clunking noises in the gain change, which can be heard disturbingly during the operation of a digital level controller, are ultimately due to the large quantization jumps. In order to achieve sufficiently small click disturbances, the maximum level jump must not be greater than about 0.2 dB.

The invention has for its object to supplement the known quantized actuator with an assembly that leads to a finer Quantelung in the attenuation ZVerstärkungsänderung. In principle, this problem can be solved by a corresponding increase in the clock frequency (Sehalthäufigkeit) in conjunction with a finer quantized control path. This, however, an increase of such noise is connected, which have their cause in the crosstalk of the switching pulses in the Tonsignalweg. These noises interfere with the lack of signal voltage the more, the higher the clock frequency. Analog circuits and their disadvantages should be avoided.

200071 з

This object is achieved by using a further series-connected control element according to the invention that the further control element 4 is also a quantized Stelleleraent with finaler Quantelung than the first control element 1, that for the second control element 4 also in a known manner, a counter and a logic logic. 5 is provided, wherein the counter is connected to the Riehtungssignal R of the control unit 1, that it has an additional reset input S1, at which the basic clock signals T " and the clock input CP is connected to a trigger 7, which in turn connected to a Nutzsignalspannungsanschluß in combination stands·

The clock frequency must be at least ten times greater than the basic clock frequency if ζ · Β. a change of 1 dB in 0.1 dB jumps should be realized. In certain applications it is therefore advantageous or necessary to switch a filter - preferably a high pass filter in audio engineering - in front of the trigger.

In order to obtain optimal time courses in the sense of minimal click disturbances, the lower limit frequency of the high-pass filter can be controlled via a control input, which is connected to the basic clock signal of the control unit. With each basic clock signal, the counter of the modules according to the invention is reset to a defined initial state.

embodiment

With reference to the drawing, the invention will be explained in more detail using the example of a digital level controller.

Show it:

Fig. 1: a block diagram of the arrangement

FIG. 2 shows three time courses of the quantized attenuation or gain change. FIG

In Fig. 1, the modules give control distance coarse Quantelung 1, counter and logic 2 and logic controller 3rd

200071

schematically reflects the known technical solution of a digital level controller. The modules control section with fine Quantelung 4, counter and logic logic 5, filter 6 and threshold element 7 represent the circuit arrangement according to the invention for reducing the cracking noise.

In the known embodiment, the control unit 3 generates the signals: direction R and basic clock T _& , controlling the counter in FIG. 2, which in turn controls the switch components in the control section with coarse quantization 1 via the associated logic in FIG. Each basic clock pulse T ~ causes, for example, an increase of the gain in the control range with coarse quantization 1 by 1 dB. The associated curve is shown in Fig. 2a.

According to the invention, the coarse quantization line 1, which likewise processes the useful signal Un, is connected in series to the control path 4 of fine quantization 4, whose attenuation or amplification factor can be varied in smaller steps, for example 0.1 dB. The adjustment range corresponds to the attenuation or gain jump of the control path with coarse quantization 1. FIG. 2b shows the curve profile realized by the control section with fine quantization 4. Fig. 2c reflects the resulting waveform of the derailleur.

The control section with fine Quantelung 4 is controlled by its control input S3 of the counter and the logic logic, the '-Taktimpuls T are obtained by a suitable triggering of the useful signal voltage Un in a threshold value 7. Each basic clock pulse T _& sub6 sets the counter in Fig. 5 via an appropriate one. Set input S1 to a defined initial state. The counting direction of the counter in FIG. 5 and its defined initial state are dependent on the direction of adjustment predetermined by the direction signal R of the control unit 3.

The clock frequency T must be at least ten times greater than the basic clock frequency Tp when a change of 1 dB, as in

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Fig. 2a, for example, provided that the inventive arrangement in 0.1 dB jumps to be realized. For this purpose, a filter 6, in the sound studio technique preferably a high-pass filter, is connected in front of the threshold value element 7.

The representation in Fig. 2Ъ and 2c assumes that the clock frequency T is equal to twenty times the basic clock frequency T ^. In order to obtain optimal curve progressions in the sense of minimal click disturbances, the cutoff frequency of the filter 6 can be changed as a function of the basic clock frequency T "via the control input for changing the cutoff frequency S2»

Claims (3)

1. digital actuator, which contains as a control section a quantized control element and a further control element in series, wherein the quantized control element is controlled by a counter and a logic logic of a control unit for the generation of basic clock and direction signals, characterized in that the Another control element (4) is also a quantized control element with finer Quantelung than the first control element (1) that for the second Stelleleraent (4) also in a known manner, a counter and a logic logic (5) is provided, wherein the counter with the direction signal (R) of the control unit (1) is connected to have an additional reset input (S1) at which the basic clock signals (T _& ) are located and whose clock input (CP) is connected to a trigger (7) which in turn is connected to a payload voltage terminal communicates 2, digital controller according to item 1, characterized in that in the supply of the Mutzsignalspannung (Un) to the trigger (7), a high-pass filter (6) is turned on. 2 0 00 7 1 -β- Invention claim: 3. Digital controller according to item 1 and 2, characterized in that the high-pass filter (6) in its lower limit frequency via a control input (S2) which is connected to the basic clock signal (Tq.) Of the control unit (1) is variable. For this 1 sheet drawings