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Talking about the Reasonable Use of Audio Processor

With the continuous development of science and technology, radio programs from editing, production to the dissemination, transmission, are using more advanced technology and equipment, the quality of the program is also greatly improved. Even so, if the use of equipment to understand the method is not comprehensive, it will cause the broadcast quality decline. The audio processor is one of the key equipment in the broadcast transmission system, and it has a great impact on the broadcast quality. In the daily work of radio technical staff are most concerned about the problem: First, the launch antenna and network matching problem. Second, the three major technical indicators of radio transmitter. Third, the audio signal in the transmission process of noise and attenuation problems. Little concern about the working state of the audio processor and set the problem, I Taiwan this year to participate in Xinjiang Taiwan, the Central People's Broadcasting Station jointly << let candle light lit the sun tomorrow >> live on the audio and some aspects of the problem, Combined with some of my experience in the actual work, talk about their own views.

The reasonable use of audio processor requirements, principles, benefits

Broadcast audio signal in the process of the existence of a large non-linear, for audio processing equipment, it not only includes the signal compression, limiting, clipping, expansion and other processing methods, but also on the audio processing equipment installed location, lead Length, as well as in the high electromagnetic field radiation environment, anti-interference ability, and so have strict requirements. In response to this situation, I work on the audio processor, Cheap Beats Headphones set the method, place the location, additional features to explore, in order to use a variety of effective measures to make the audio processor in the future work to play a greater role.

1, the requirements of audio processing: (1) broadcast transmission with the audio processing is more complex, mainly on the human ear audible frequency range to be compressed or limited, to prevent it from being modulated at the same time, but also to ensure that audio Get the best signal to noise ratio and audio bandwidth. So that the audio signal to maintain the characteristics of the original program material on the basis of its larger deal, making it a new look, with the characteristics of the sound for the audience to receive appreciation.

2) In the broadcast program, the loudness of the audio signal is improved by reducing the ratio (peak / flat ratio) of the "peak" to "average" in the dynamic audio. Within the allowable modulation range, adjust the relationship between the peak and the average, to avoid the audio signal processing process due to clipping and other harmful effects such as distortion, the audio processing, so that the peak modulation in the range, Try to increase the subjective sense of loudness effect.

2, the basic principles of audio processing:

Audio processing equipment, mainly by reducing the dynamic range of the way to suppress noise, including the program signal compression, peak limiting and clipping, multi-band compression and frequency selectable limit and equalization. The main purpose of compression is to narrow the program dynamic range, increase the density of the sound, as far as possible to make the audio signal peak amplitude uniform. The peak limit is an extreme form of compression, but its compression ratio is high, the start and recovery times are faster, and the main purpose is to protect the subsequent channel transmission from overloading.

The peak clipping process is to prevent the distortion caused by the overheating of the channel processing circuit, and "cut off" the processing of the high-level crest portion exceeding the threshold value instantaneously. If the peak limits and clipping are perfectly matched, the problem of the negative effects of harmonic distortion and intermodulation distortion and signal bandwidth can be handled between the density and loudness of the audio program signal.

During the audio processing, the audio spectrum is divided into several frequency bands, and each band is compressed and limited separately. Ie "multi-band compression and selectable limits", if set correctly and reasonably, will effectively eliminate the intermodulation of the spectral gain. For the balance in audio processing, the effect is to use an equalizer to change the balance of the correlation frequency in the overall frequency band of the audio signal on Cheap Beats Headphones" href="/">Cheap Beats Headphones the one hand and to create a sound feature by changing the beats solo loudness of the "sensitive frequency" And it can also be used as a frequency response correction in the transmission system.

3, the rational use of audio processor method

Radio program audio processing success or not, is its actual effect that the auditory effect to judge, such as broadcast broadcast effect can be accepted by the audience, this approach we think that is successful, otherwise it is a failure. In this regard, I audio processor from its principle, combined with the actual use of the situation, and fully tap their potential advantages, more effective and reasonable to play its effectiveness, should proceed from the following three aspects:

1 Keep the signal without distortion

At the front of the mid-wave broadcast transmitter, the audio processor highly processed audio signal, will contain many similar square wave flat-top waveform. The waveform of the square wave is relatively high for the amplitude and phase response of the transmission path through which it passes. In principle, if the flat amplitude and the group delay occur in the frequency range of the program's main energy, the flattened top of the processed audio signal is tilted, thereby increasing the peak modulation voltage, but the average level does not increase The From the peak / flat ratio, the average level of the path is reduced, and the loudness is reduced accordingly. In this regard, we want to maintain the shape of the signal waveform after processing, the first method is used in the transmission of signal cables, try to choose high quality, excellent performance of the transmission cable, requiring its distribution parameters, frequency bandwidth, Coarse, low attenuation, shielded copper core transmission line. This is very important and very effective. In addition, in the transmission connection, try not to add any additional equipment and branch parts, such as intermediate amplifiers, distributors, etc., to reduce the signal waveform distortion, to ensure good transmission quality.

(2) audio processing system settings

a for the audio processor, it consists of two circuits, one is the slow moving AGC, the second is the action and recovery time moderate compressor, for each band as needed to set the best time constant adjustment. We have concluded in actual use that the low frequency band time constant is set to be slower (about 200锟斤拷s) than the high frequency band, which has a greater effect on increasing the signal density of the program

b audio processor in the basic system also adds some additional components, enabling the audio processor installed in the slow motion AGC and multi-band compressor between the frequency equalization processing components to compensate for the medium wave broadcast signal typical presence of the sound Frequently bad situation. Properly enhance the distribution of 600HZ-1.2KHZ sound energy throughout the audio spectrum, so that the sound becomes "larger" in the auditory sense (the most sensitive range of human ear hearing is 2KHZ-8KHZ). Can make the audience feel the sound becomes real and pleasant.

C We also use the "breakout distortion" device called the audio processor to provide absolute negative peak control to prevent the audio signal from overflowing to eliminate distortions in some bands that the audience is most likely to hear The

(3) the location of the audio processor in the system placed in the system placed on the location of the audio processor, but also pay attention to, in order to effectively protect the waveform processed by the audio processor to limit the waveform, The transmitter does not change during the process, the audio processor should be placed near the transmitter, and the distance is as short as possible. So as to avoid changes in the distribution parameters during the transmission process, causing the parasitic modulation peak, so that the waveform has been processed to limit the peak changes, resulting in audio signal waveform distortion.

4, the rational use of audio processor benefits

The use of audio processors, in addition to reducing the peak level, improve the average modulation, increase the sideband wave power to increase the loudness of the advantages, there are four benefits:

(1) It is possible to solve the problem that the program level difference is large due to recording, switching, different program contents, and the use of different recording and reproducing apparatuses, which is difficult to solve satisfactorily when manually adjusting the program level.

锟斤拷 for the establishment of language programs and music programs between the volume balance to create the conditions.

锟斤拷 can be low on the program when the weak signal to a certain amount of amplification, so that the components are not submerged by submerged. Usually the program in the treble component of the low level, after processing can be an appropriate upgrade, high audio components not only determines the clarity of the program, but also with the loudness between the heart and the physiological complex relationship, due to clarity Raise the audience so that the loudness is also increased.

锟斤拷 Stereo broadcast, which covers half of the monaural radio with a radius of about the same power level. After using the audio processor, it is also possible that the received carrier field is slightly lower than the required area due to the increase of the sideband wave power Received a higher quality signal, expanded coverage.

The data shows that the average power of the processed music increases by 8.2 dB compared to the pre-processed music, which is 5.9 dB compared to the normal limit of 15 dB, beats by dr dre which is actually equal to the increase in the emission 4 times the power. With the audio processor to increase the coverage, compared to other ways, can save a lot of electricity, equipment investment and maintenance costs, is a very economical and feasible way. Of course, the audio processor on the program content of the appropriate amount of compression, too much compression will damage the content of the program, affecting the artistic effect of music, will make the stereo broadcast lost its due characteristics. In summary, in the transmitter program input, should use high-quality audio processor to compress the program's dynamic range, increase the loudness, expand the program coverage, to ensure high-quality stereo broadcast. On the current level of audio processor technology, fully able to meet the requirements of high-fidelity radio, so that after processing the sound can not hear the sound processing, that is, in the absence of processing traces, still retain the original sound of high Quality, even more than the original sound more sweet, clear, sounds.

In short, the rational use of audio processors, give full play to its role in our future work is very important, but also make our radio program icing on the cake.