Abstract:
Methods and systems for reducing noise relating to an electronic system are disclosed. The methods and systems determine a noise signature, which characterizes a targeted noise of the electronic system. A cancellation signal is then generated based on this noise signature, so that if the cancellation signal is transmitted, the targeted noise is at least partially reduced.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the present invention relate generally to audio processing and more specifically to reducing noise in electronic systems. 
     2. Description of the Related Art 
     Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section. 
     The continued trend in integrated circuit (IC) technology is to increase operating frequencies, data transfer rates, and the average number of transistors per IC, while decreasing IC package sizes. Unfortunately, the rising power density of the ICs results in higher operating temperatures of each IC. As electronic systems include a growing number of ICs to perform ever-increasing complex functions, the aggregated heat dissipation from the ICs can be significant. 
     A common approach to address the high operating temperatures within these electronic systems is to use fans and air ducts to provide airflow over the heat-generating ICs. Heat is transferred to the air as it flows over the ICs, thus cooling the ICs. Another approach is to transport a reservoir of liquid (e.g., water) to heat spreaders that are connected to the heat-generating ICs. Heat is then transferred to the liquid within the heat spreader, and the liquid circulates back to the reservoir where the heat is dissipated. 
     However, these cooling approaches generate noises at levels that sometimes can be irritating to the users of the electronic systems. For example, fans typically vibrate due to mass imbalance in their rotors, and air ducts also vibrate when air flows at certain velocities. Such vibration causes sound to be produced. As for a liquid cooling system, sound is mainly generated from operating the pump to circulate the liquid. 
     As the foregoing illustrates, what is needed in the art is a way to reduce the noises generated by the subsystems used to cool electronic systems. 
     SUMMARY OF THE INVENTION 
     Methods and systems for reducing noise relating to an electronic system are disclosed. The methods and systems determine a noise signature, which characterizes a noise produced by the electronic system. A cancellation signal is then generated based on this noise signature, so that if the cancellation signal is transmitted, the produced noise is at least partially reduced. 
     One advantage of the disclosed methods and systems is that they ameliorate the undesirable side effects of deploying the various cooling solutions in electronic systems by reducing the noise produced by these cooling solutions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  is a simplified block diagram of a noise reduction subsystem, according to one embodiment of the present invention; 
         FIG. 2A  is a flow chart illustrating a static noise reduction process that a noise reduction subsystem may be configured to implement, according to one embodiment of the present invention; 
         FIG. 2B  is a flow chart illustrating a dynamic noise reduction process that a noise reduction subsystem may be configured to implement, according to an alternative embodiment of the present invention; 
         FIG. 3A  is a conceptual diagram of a noise reduction subsystem residing inside the chassis of an electronic system, according to one embodiment of the present invention; 
         FIG. 3B  is a conceptual diagram of a noise reduction subsystem integrated in a standard subsystem in an electronic system, according to one embodiment of the present invention; 
         FIG. 3C  is a conceptual diagram of a noise reduction subsystem residing near a user of an electronic system, according to one embodiment of the present invention; and 
         FIG. 3D  is a conceptual diagram of a noise reduction subsystem with at least one sensing device residing inside of an electronic system and at least another sensing device residing outside of the same electronic system, according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Methods and systems for reducing noise in electronic systems are described. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details. 
     Throughout this disclosure, a “media processing unit” refers to a processing unit that mainly handles multimedia data. Some examples of a media processing unit include, without limitation, a graphics processing unit, an audio processing unit, and a signal processing unit. An “electronic system” broadly refers to any system that includes electronic components. Some examples of an electronic system include, without limitation, a computer, a server, a portal device, a multimedia player, a set-top box, and a game console. 
       FIG. 1  is a simplified block diagram of a noise reduction subsystem,  100 , according to one embodiment of the present invention. Specifically, noise reduction subsystem  100  includes analog/digital (“ND”) converter  104 , memory module  106 , processing block  108 , amplifier  110 , and at least one output device  112 . Depending on the type of noise reduction process employed by noise reduction subsystem  100 , noise reduction subsystem  100  may further include at least one sensing device  102 . The different noise reduction processes will be discussed in subsequent paragraphs. Sensing device  102  is mainly responsible for capturing sound waves produced by noise sources that are within its detection range and converting the captured sound waves into analog signals. An example of sensing device  102  is a microphone. A/D converter  104  converts analog signals into digital signals and vice versa. Memory module  106  stores instructions for processing block  108 , data, certain noise signatures, and intermediary values resulting from the processing performed by processing block  108 . Memory module  106  is however not required to be dedicated to computations performed by processing block  108 . Processing block  108  mainly performs noise reduction algorithms to compute cancellation signals that can be used to remove or dampen the various noise signals. Some examples of processing block  108  include, without limitation, a microprocessor, a digital signal processor, an embedded processor, analog circuitry, and non-processor based dedicated hardware. Amplifier  110  generates electrical signals that are based on the computations of processing block  108  to drive output device  112 . Output device  112  transmits the cancellation signals. An example of output device  112  is a speaker. Alternatively, each of sensing device  102  and output device  112  can be implemented as a single unit, which may include a logic component that switches between the input and output functionality of this unit. It should be apparent to a person with ordinary skill in the art to physically place output device  112  and sensing device  102  anywhere that processing block  108  is able to reach via either wired or wireless communication channels. 
       FIG. 2A  is a flow chart illustrating a static noise reduction process,  200 , that the static version of noise reduction subsystem  100  may be configured to implement, according to one embodiment of the present invention. In particular, the static version of noise reduction subsystem  100  does not have sensing device  102 , because it generates and transmits a cancellation signal based on a predetermined noise signature and does not attempt to identify a noise signature from a noise source. In step  202 , a predetermined noise signature representative of a targeted noise, which is associated with an electronic system, is selected. This noise signature can be determined by systems other than noise reduction subsystem  100  in a controlled setting, such as a laboratory. For instance, engineers could simulate the environment in which the electronic system would operate. Then different testing schemes can be devised to capture and characterize the various noise signals introduced by the electronic system or the subsystems of the electronic system. Some examples of the testing schemes are described in the subsequent paragraphs. Generally, the testing schemes may change from time to time to establish different predetermined noise signatures. 
     In one implementation, a testing scheme may include steps of decomposing a predetermined noise signature into its constituent components. For example, a noise signature representative of the noise resulting from the operations of the entire electronic system may be further dissected into individual components, each of which corresponds to a non-negligible source of noise within the electronic system and having a distinct noise signature. In another implementation, a testing scheme may also include steps of varying the operating conditions of the electronic system. Some examples include, without limitation, varying fan speed of the cooling subsystem in the electronic system, varying the clock speed of the processing units in the electronic system, accessing different peripheral devices external to the electronic system, and executing software programs with varying levels of complexity on the electronic system. 
     In one implementation of the static version of noise reduction subsystem  100 , the predetermined noise signatures are stored in memory module  106 . The selection of a particular predetermined noise signature may be triggered by the occurrence of an operating condition. As an illustration, suppose three predetermined noise signatures, A, B, and C, have been determined, each of which corresponds to a fan speed, speed (A), speed (B), and speed (C), respectively. Suppose further that the processing unit in the electronic system tracks the fan speed and communicates such information to noise reduction subsystem  100 . Thus, when the fan speed of the electronic system is at speed (B), the processing unit informs noise reduction subsystem  100  and causes the predetermined noise signature  8  in memory module  106  to be selected and retrieved by processing block  108 . In an alternative embodiment, the cooling subsystem of the electronic system, as opposed to the processing unit, tracks and communicates the fan speed to noise reduction subsystem  100 . It should be apparent to one with ordinary skill in the art to recognize that the selection mechanism discussed above applies to other operating conditions of the electronic system. 
     After having selected the predetermined noise signature, a cancellation signal is generated in step  204 . This cancellation signal has approximately the same amplitude and the opposite polarity to the noise signature. In one implementation, processing block  108  is programmed to generate the cancellation signal based on the predetermined noise signature stored in memory module  106 . After processing block  108  establishes the digital representation of the cancellation signal, the digital cancellation signal is converted to an analog signal by A/D converter  104 . Amplifier  110  then generates appropriate electric signals based on the analog information to drive output device  112 , so that output device  112  can transmit the cancellation signal in step  206 . In one implementation, output device  112  continues to transmit the cancellation signal for as long as the electronic system is up and running. Alternatively, similar to the noise signature, the cancellation signal may be pre-computed by systems other than noise reduction subsystem  100 . In other words, instead of generating the cancellation signal in step  204 , noise reduction subsystem  100  can select the pre-computed cancellation signal corresponding to the noise signal for output. 
       FIG. 2B  is a flow chart illustrating a dynamic noise reduction process,  250 , that the dynamic version of noise reduction subsystem  100  of  FIG. 1  may be configured to implement, according to another embodiment of the present invention. The dynamic version of noise reduction subsystem  100  includes sensing device  102 . Specifically, sensing device  102  captures sound waves, and processing block  108  analyzes the captured information in step  252 . Based on this captured information, processing block  108  generates the noise signature in step  254  and generates a corresponding cancellation signal in step  256  for output device  112  to transmit in step  258 . The process then loops back to step  252 . By capturing and analyzing sound waves, the dynamic version of noise reduction subsystem  100  is able to dynamically and iteratively adjust the generated noise signature and also the corresponding cancellation signal to improve the quality of noise reduction. It should be apparent to one with ordinary skill in the art to implement noise reduction subsystem  100  described above in the analog domain. For example, specific analog waveform generation circuits can be implemented to output the pre-computed cancellation signals. Also, such an analog system does not need to employ ND converter  104  and memory module  106  shown in  FIG. 1 . 
     The physical locations of noise reduction subsystem  100  of  FIG. 1  vary depending on the type of noise the subsystem is configured to address.  FIG. 3A  is a conceptual diagram of noise reduction subsystem  100  residing inside the chassis of electronic system  300 , according to one embodiment of the present invention. In this implementation, noise reduction subsystem  100  is configured to target the noise inside the chassis of electronic system  300 . Thus, noise reduction subsystem  100  is placed near the edge of electronic system  300  and away from media processing unit  302 , central processing unit  304 , memory subsystem  306 , input/output subsystem  308 , power subsystem  310 , and cooling subsystem  312 . Such placement allows the dynamic version of noise reduction subsystem  100  to capture the aggregated sound inside the chassis and generate a cancellation signal by following the aforementioned dynamic noise reduction process  250  to counter such noise. Alternatively, if the static version of noise reduction subsystem  100  following the aforementioned static noise reduction process  200  is utilized, then the aggregated sound may be captured and analyzed in a controlled setting so that a corresponding predetermined noise signature can be established. For example, one way to determine this aggregated sound may be to calculate the difference between the sound inside the chassis when electronic system  300  is powered on and operating and the sound inside the chassis when electronic system  300  is powered off. Then, the noise signature is stored in memory module  106  for processing block  108  to process. 
     In another implementation, noise reduction subsystem  100  of  FIG. 1  can be configured to target the specific noise generated by a particular component in electronic system  300 . For example, noise reduction subsystem  100  can reside near media processing unit  302  to cancel the noise generated by the cooling subsystem used to cool media processing unit  302 .  FIG. 3B  is a conceptual diagram of noise reduction subsystem  100  integrated in a standard subsystem in electronic system  300 , such as graphics subsystem  322 , according to one embodiment of the present invention. One example of graphics subsystem  322  is a graphics card. Specifically, graphics subsystem  322  includes, without limitation, media processing unit  302 , memory controller  326 , and video memory  328 . Graphics subsystem  322  further couples to central processing unit  304  and memory subsystem  306  via chipset  320 . Graphics subsystem  322  also couples to display device  324 . One way to establish the noise produced by media processing unit  302  is to directly measure and estimate the sound generated by the cooling subsystem used to cool media processing unit  302 . For the static version of noise reduction subsystem  100  following static noise reduction process  200 , this direct measurement and estimation may be conducted with media processing unit  302  or graphics subsystem  322  operating in a standalone fashion to establish a predetermined noise signature that can be stored in memory module  106  of  FIG. 1 . On the other hand, if dynamic noise reduction process  250  is followed, then the dynamic version of noise reduction subsystem  100  may be used to iteratively evaluate the noise signal produced by media processing unit  302  during operation and generate the appropriate cancellation signal. Similarly, noise reduction subsystem  100  can also reside near any other noise-generating components in electronic system  300 , such as, without limitation, power subsystem  310  or cooling subsystem  312  of  FIG. 3A . 
       FIG. 3C  is a conceptual diagram of noise reduction subsystem  100  of  FIG. 1  residing near user  350  of electronic system  300 , according to one embodiment of the present invention. Specifically, noise reduction subsystem  100  in this implementation is configured to target the aggregated noise generated by electronic system  300  in a certain environment. This aggregated noise includes at least the internal noise and the chassis noise of electronic system  300  and the ambient noise of this environment. Thus, by placing noise reduction subsystem  100  near user  350 , the noise that is perceivable by the user can be removed or dampened. Noise reduction subsystem  100  may embed in a number of items including, without limitation, a peripheral device of electronic system  300 , such as a desktop/desk side module, a keyboard, a mouse, or a remote control, a portal device, such as a cellular phone, a personal digital assistant, or a multimedia player, a piece of furniture, a display device, or a game console. One way to determine this aggregated noise may be to separately determine the noise produced by electronic system  300  and the ambient noise of the environment and then combine the two types of noises. 
       FIG. 3D  is a conceptual diagram of noise reduction subsystem  100  of  FIG. 1  with at least one sensing device residing inside of electronic system  300  and at least another sensing device residing outside of electronic system  300 , according to one embodiment of the present invention. Specifically, noise reduction subsystem  100  in this implementation is configured to target both the noise generated inside the chassis of electronic system  300  and also the noise experienced by the user that is “external” to electronic system  300 . This external noise includes both the noise generated by the chassis vibrations as well as the ambient noise of the user&#39;s environment. Sensing device  360  and sensing device  364  are thus responsible for capturing the aggregated sound inside and outside the chassis of electronic system  300 , respectively. Suppose the aggregate sound inside the chassis is considered as the internal noise, and the aggregated sound outside the chassis represents an approximate sum of the internal noise and the noise external to electronic system  300 . Output device  362  may generate a cancellation signal to offset the internal noise. Moreover, processing block  108  of noise reduction subsystem  100  subtracts the internal noise from the aggregate noise outside the chassis of electronic system  300  to obtain the approximate noise external to electronic to electronic system  300 . With this approximation, a corresponding noise signature and a cancellation signal are generated, and output device  366  transmits the cancellation signal for the external noise. 
     In an alternative embodiment, sensing device  360  and output device  362  belong to an internal noise reduction subsystem, and sensing device  364  and output device  366  belong to an external noise reduction subsystem. These two subsystems reside inside and outside the chassis of electronic system  300 , respectively. In one implementation, the external noise reduction subsystem resides near the user of electronic system  300 . Furthermore, since these subsystems reside in two different locations, the subsystems further include communication links to exchange relevant noise information. It should be apparent to a person of ordinary skills in the art to utilize any number of noise reduction subsystems inside or outside of electronic system  300 , generate and manipulate various noise signatures, and target any number of types of noises without exceeding the scope of the claimed invention. 
     The above description illustrates various embodiments of the present invention along with examples of how aspects of the present invention may be implemented. The above examples, embodiments, and drawings should not be deemed to be the only embodiments, and are presented to illustrate the flexibility and advantages of the present invention as defined by the following claims.