CN1064157C - Track-optimized tone generator for cycle recording - Google Patents

Abstract

The invention relates to a tone generator for track-dividing optimized periodic recording, in particular to a tone generator for recording tones in a track-dividing manner and adopting an optimized period number to achieve frequency accuracy.

Description

Track-optimized tone generator for cycle recording

The invention relates to a tone generator for track-separated and optimized cycle recording, especially a tone generator for track-separated recording and optimal cycle number to achieve frequency accuracy.

Press, in the dual-segment frequency generator of electronically synthesized music or telecommunication, it is necessary to have a tone generator (Tone Generator) to generate various tone frequencies to provide workers with further synthesis and application of various tones. A traditional tone generator (as shown in Figure 1) uses a fixed signal source 10 to generate a reference timing (fs), and this signal (fs) is divided by a programmable counter 11 (ProgrammableCounter) to obtain the desired tone frequency N times, you can program the counter 11 to output a frequency of N*F. After this frequency is divided by a fixed number of N counters 12, the corresponding tone digital waveform is obtained through the address look-up table, and then the waveform is converted into digital and analog. After conversion by device 13 (DAC), the desired tone can be obtained.

Since the tone frequency is evenly distributed by 12, that is, f*2 ^N/12 , the frequency difference between each scale is only 7%, so if you want to get a more accurate pitch, for example, the error is less than 0.5%, you can program The number of counting stages of the counter 11 must be up to eight (i.e. the divisor is from 128 to 256). At this time, the frequency of the signal source 10 should be greater than 256*N*f. If the tone waveform table is completed with 64 addresses, that is, N is 64, To generate a tone of 2000Hz, the frequency generated by the system signal source 10 needs to be greater than 256*64*2KHz=32MHz, which is generally produced by a quartz oscillator, and the high-frequency quartz oscillator is very expensive, and its The power consumption is also proportional to the frequency, and the programmable counter 11 requires at least eight levels, so the hardware cost is very high. Therefore, how to achieve the audio generator of the bottom frequency system timing has always been the goal of various researchers.

The main purpose of the present invention is to use an extremely low system frequency to complete a new tone generator with low power consumption, low cost and high precision by means of a simple and regular hardware structure.

According to the foregoing, the present invention is a tone generator that records the tone in separate tracks and uses an optimized number of cycles to achieve frequency accuracy. Due to the use of the track-based recording method, the sampling frequency will be reduced, and the recording length is optimized. The number of cycles is the standard, so it can have accurate frequency requirements, and at the same time, the system time base can be greatly reduced with more storage space, thereby reducing current consumption and hardware costs.

The tone generator for track-divided optimization period recording of the present invention includes: a signal generator, an address counter, a memory and a digital-to-analog converter. It is characterized in that the signal source generates a system time base, and the system time base is sent simultaneously to the address counter; the address counter is to select the corresponding address to the designated memory address according to the desired tone, and read out the relative data repeatedly; the memory is to store the time base sampling of each tone system and record each different tone. The data in the address is pointed to by the above-mentioned address counter, and then sent to the digital-to-analog converter to restore the tone to the original analog signal; the system time base is based on a 32768Hz clock quartz or a ceramic oscillator. Generate; the address counter and memory can be used to generate more than two groups of tones as a dual-tone multiple frequency generator and a multi-tone accompaniment tone generator; the data stored in the memory for sampling and optimizing the number of cycles can be used by time-sharing In the reading mode, the column address and the row address are staggered and read, and respectively latched into the temporary register inside the memory, and converted by a digital-to-analog converter and added to form a multiple-frequency tone.

In order to enable further understanding of the purpose, features and effects of the present invention, the present invention is described in detail by means of the following specific embodiments, and in conjunction with the accompanying drawings, as follows:

Fig. 1 is a circuit block diagram of a conventional tone generator;

Fig. 2 is a circuit block diagram of the present invention;

Fig. 3 is another embodiment diagram of the present invention;

According to the sampling principle, the sampling frequency only needs to be greater than twice the highest frequency of the signal to faithfully record and restore the original sound. Therefore, the present invention uses this principle to separately sample and record each tone, and its system reference timing only needs to be more than twice the highest frequency, so that the system timing can be down-frequency, and the power consumption can be reduced without using a high-frequency quartz oscillator. quantity and hardware cost.

As shown in Figure 2, be the circuit block diagram of the present invention; Signal source 20 is to utilize quartz oscillator or ceramic oscillator to produce system time base (fs), and this system time base (fs) is also sent in the address counter 21; The address counter 21 is to select the corresponding address to the designated memory 22 address according to the desired tone, so as to read out the relative data; the memory 22 can adopt a read-only memory (ROM), which is to store the data that each tone is sampled and recorded with fs. The length is determined by the allowable range of the required frequency to determine the optimal number of cycles for recording. The data in the address is pointed to by the above-mentioned address counter 21. After reading, it is sent to the digital-to-analog converter 23 to restore the tone to an analog signal of the original sound.

The data stored in the memory 22 is planned as shown in Table 1:

Table I musical alphabet frequency f 32768/f Recording cycle number C record pointsN error% A6 1760.00 18.618 3 56 +0.3 A6# 1864.66 17.573 53 88 -0.1 B6 1975.54 16.587 5 83 -0.1 C7 2093.01 15.656 3 47 -0.1 C7# 2217.47 14.777 4 59 +0.2 D7 2349.32 13.948 1 14 -0.4 D7# 2489.02 13.165 6 79 -0.0 E7 2637.03 12.426 5 62 +0.2 F7 2793.83 11.729 4 47 -0.2 F7# 2959.96 11.070 14 155 -0.0 G7 3135.97 10.449 9 94 +0.0 G7# 3322.45 9.863 7 69 +0.1

Table 1 is a comparison table of relevant information for generating tones A6, A6#, ..., G7, G7#, etc. by using the 32768 clock with a quartz oscillator as the system time base (fs). The first line in the table is the name of the sound, that is, in The treble mark on the music, the second row is the main frequency value, the third row is the multiple relationship that the total frequency is 32768, the fourth row is the number of cycles recorded by the present invention corresponding to the relative note name at 32768Hz, and the fifth row is the relative number of points , and the sixth line is the frequency-corresponding error percentage. Take A6 as an example, its frequency is 1760Hz, sampling at 32768Hz (that is, 32768/1760) is 18.618 samples (sample), because the actual record is an integer, so the sampling can be 19, and the frequency error at this time is: $\frac{18.618-19}{18.618}=\frac{-0.382}{18.618}=-2.0\%$ That is to say, using 19 data to restore A6 will reduce the error by 2.0%. Therefore, I use the best cycle number recording method to solve this problem, that is, record three cycles. At this time, the number of sampling points should be 55.845 ( 18.618*3), taking its integer as 56, the error is: within the reasonable demand range. Therefore, 56 points can be recorded, and the error can be limited to -0.3% by repeated reading. Using this kind of individual tone sampling and recording with the optimal number of cycles to meet the precise frequency requirements can greatly reduce the system time base fs (from 32Mhz to 32768Hz), and the frequency is proportional to the power consumption, which in turn can Reduce current consumption.

Table II address Data content: 0123::55 D0(A6)D1(A6)D2(A6)D3(A6)::D55(A6) 565758::143 D0(A6#)D1(A6#)D2(A6#)::D87(A6#) 144145146::227 D0(B6)D1(B6)D2(B6)::D82(B6) 228229230::273 D0(C7)D1(C7)D2(C7)::D46(C7) 274 D0(C7#)

As shown in Table 2, it is a schematic table of memory address and content of the present invention, and the data stored in the memory 22 is stored according to the sampling and the best cycle record obtained as shown in Table 2. As shown in Table 2, the The data are arranged in order, such as the number of points sampled by the sound name A6 is 56 points, so from address 0 to 55 is to record the data of each point of A6, when the tone of A6 is to be generated, the address counter 21 is controlled by the selection input to send the address 0 Data, when being added to 55 in sequence, automatically by reverting to 0, can represent the output of each sampled signal of pitch A6 like this, and be converted into the original sound (TONE) output by digital analog converter 23, same, if desire Output B6 tone, then the initial position of address counter 21 points to address 144, and take the data in order until the last piece of data D82 (B6) at address 277, then return to address 144, so that tone B6 can be obtained by repeating this cycle, and the rest Tones are analogous.

As shown in Figure 3, it is another embodiment figure of the present invention; This embodiment is applied to the dual-tone complex frequency generator (DTMF GENERATOR) of telecommunication, wherein includes: a signal source 30, is to utilize crystal oscillator Or the ceramic oscillator generates the system time base (fs), and the system time base (fs) is sent to the first address counter 31 and the second address counter 32 respectively; the first address counter 31 is controlled by row address selection, and the second address counter 31 The second address counter 32 is selected and controlled by the column address; the memory 33 stores the tone content of the optimized number of cycles, and uses a time-sharing read method, that is, the column address and the row address are read in a staggered manner, and are respectively latched into (Latch) In the temporary register inside the memory 33; the digital-to-analog converter 34 is to convert the read row and column address data into analog signals respectively, and send the multiple frequency tone after adding the two signals. The methods of sampling and optimizing the number of cycles adopted in this embodiment are the same as those described above, and will not be repeated here.

To sum up, the tone generator for track-separated and optimized cycle recording provided by the present invention adopts a track-separated recording method that will reduce the sampling frequency, and the recording length is based on the number of optimized cycles, which can It has precise frequency requirements, and at the same time, the system time base is greatly reduced with more storage space, thereby reducing current consumption and hardware costs. Not only has practical function, but also has a new design that has never been seen before, and has the improvement of function and progress.

The above-mentioned contents and illustrations of the cited embodiments are only preferred embodiments of the present invention, and the various changes and modifications made by those who know this technology according to the spirit of the present invention should still be included in the patent of this case. within range.

Claims (3)

1. A tone generator for track-divided optimization cycle recording includes: a signal generator, an address counter, a memory and a digital-to-analog converter; it is characterized in that: The signal source is to generate the system time base, which is sent to the address counter; The address counter selects the corresponding address to the specified memory address according to the desired tone, and reads out the relative data repeatedly; The memory is to store the time base samples of each tone system, and record the optimized cycle number of each different tone, point to the data in the address by the above address counter, read it and send it to the digital analog converter to restore the tone to the original tone analog signal. 2. The tone generator for track optimization cycle recording according to claim 1, wherein the system time base is generated by a _32768Hz clock quartz or ceramic oscillator. 3. The tone generator for track optimization cycle recording according to claim 1, wherein the address counter and the memory can be used to generate more than two groups of tones to produce as a dual-tone multiple frequency generator and multi-tone accompaniment tone device.

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