Solutions
Ambient noise cancellation test during a callYou are here: Home > Solutions > Consumer Electronics
Ambient Noise Cancellation Test During a Call
1、Program Overview
Active Noise Cancellation and Environmental Noise Cancellation are different noise cancellation technologies. Active Noise Cancellation is to offset ambient noise to the greatest extent, allowing people using earphone to enjoy a quiet environment. While Environmental Noise Cancellation is an application in the other direction, which allows people to use noise-canceling earphones to make a call on the side of a noisy road, on a speeding motorcycle, in a moving car with music on, or in a car with the windows open. People on the other side of phone can also hear your speech clearly with almost no noise passing though. To put it simply, Active Noise Cancellation means that the person using the headset is pleased, and Environmental Noise Cancellation means that the person on the other end of the phone is pleased.
There are three main technologies in Environmental Noise Cancellation tecnology:
l Beamforming directional enhancement technology
l Adaptive filtering technology
l Uplink bone conduction technology
These three technologies are not recent. Our mobile phones have two microphones (one is next to the charging port and the other is next to the camera), which have been silently helping us make calls and noise reduction for many years (so, sometimes We are accustomed to turning off the earphones and using the mobile phone directly when making a phone call with earphones for fear of being unclear. This is the main reason.) uplink Bone Conduction technology is to transmit the call content by collecting the vibration signal of face or vocal cord. The noise conduction medium is air, and the vibration of face or vocal cords are directly collected by the acceleration sensor, which can isolate the environmental noise. This technology is widely used in the military, making a phone call in a tank or a helicopter.
Now, the form of TWS earphones has accelerated the application of these three technologies in earphones. The golf club shape of the TWS earphones allows the distance between the dual microphones to be arranged farther, which improves the algorithm effect of beamforming. The shape of the TWS semi-in-ear allows
the vibration of the ear cartilage to be transmitted to the acceleration sensor
more efficiently. Bone conduction can get a signal with a higher SNR. At the same time, the optimization of the computing power and power consumption of the Bluetooth chip enables these algorithms to run better in the TWS chip.
Today we are going to discuss the Uplink Bone Conduction Technique. At the same time, we also hope that this article can help you avoid repeated investment in equipment. Because noise reduction in calls will become the standard for mid-to-high-end TWS earphone. Factories need to grasp this trend sensitively and choose the investment in testing equipment carefully. You need to choose a system that can be upgraded easy to conduct Environmental Noise Cancellation Test. Otherwise, you may have to spend a lot of money to upgrade the existing Bluetooth audio test system or buy a new one that supports call noise reduction test. As long as the planning is good, conventional Bluetooth acoustics and Environmental Noise Cancellation can be done on one station, which is supported by MegaSig system.
1.1、Overview of bone conduction technology in call
Bone conduction can be divided into uplink and downlink bone conduction communication technology. The former is to enable the other party to hear clearly, and the latter is to enable themselves to hear clearly. Today, we mainly introduce the technology of uplink bone conduction of the former.
1.2、Overview of uplink bone conduction technology in call
In the process of talking, the sound of our own speech is the useful signal we really want to transmit, but in addition, there are various noises generated by machinery and equipment, wind, surrounding people, etc., which can be called useless signals.
The essence of the uplink bone conduction technology is to transmit the content of the call by collecting the vibration signal of the cheek. Because the ambient noise conduction medium is air, the vibration of cheek is directly collected by the acceleration sensor to achieve the effect of of noise filtering in air.
When we speak, in addition to the vibration of the face, the vibration of the nose bridge is also stronger. So, this technology is not only used in the field of headphones but also can be used in VR or AR smart wearable devices to improve the effect of calls.
1.3、MegaSig complete bone voiceprint testing system
The testing of uplink bone conduction technology in call can be divided into three parts: IQC chip incoming test, Bone voiceprint test in semi-finished product stage, and Bone voiceprint test in finished product stage. These three tests are all supported by our system compatibility.
1.3.1、IQC chip incoming test
If the defective products flow into the manufacturing process, they may result in manufacturing product being dismantled to replace parts, or scrapped directly, which will cause huge economic losses.
The incoming IQC chip can be divided into chip with digital format microphones or chip with conventional analog silicon microphones from the signal type. Let us analyze the working principle from the architecture diagram.
The analysis and introduction of the first kind of IQC incoming chip with digital format microphones test system architecture diagram:
PC software AudioExpert control the acquisition card push a signal to the exciter SK 505 making it vibrate. The IQC chip's incoming material corresponds to the customized fixture pin, communicating with U903, demodulating the received vibration signal by U 924 in digital TDM format, and then transmits it to PC software AudioExpert for analysis.
IQC chip incoming stage - Test architecture for chip with digital mic
The analysis and introduction of the second kind of IQC incoming chip with analog microphones test system architecture diagram:
PC software AudioExpert control the acquisition card push a signal to the exciter SK 505 making it vibrate, and lead out the four points corresponding to the pins of the custom fixture to U 922, the semi-finished bone voiceprint microphone transmits the signal back to the acquisition card AI channel through the U922, and then analyzes it through the PC software AudioExpert.
IQC chip incoming stage - Test Architecture for chip with analog mic
1.3.2、Bone voiceprint test in semi-finished product stage
When the acceleration sensor is attached to PCBA, it may have a poor contact caused by false soldering, which may lead to sometimes be on or off. So it is also very important to conduct test for semi-finished bone voiceprint.
The bone voiceprint test of semi-finished products, like the incoming IQC test, is also divided into chip with digital format microphones or with conventional analog silicon microphones in terms of signal types.
The chip with digital format microphones is through I2C communication and TDM format data demodulation, so the overall test logic can refer to the IQC incoming chip with digital format microphones.
Semi-finished product stage - digital format PCBA board test architecture
The second form of semi-finished bone voiceprint analog silicon microphone testing system architecture diagram, the overall test logic can refer to the logic of IQC incoming chip with analog microphones test system.
Semi-finished product stage – analog format PCBA board test architecture
1.3.3、Bone voiceprint test in finished product stage
After the test of incoming materials and semi-finished products, it comes to the part of dispensing and assembling the earphones. In this case, the position of the microphone may deviate from the designed position during assembly and rotation, or more or less glue is applied at the place where glue is needed, which will affect the effect of the microphone. And it is necessary to test the finished product after assembly.
The following is the analysis and introduction of the structure diagram of the finished bone voiceprint earphone test system. The finished bone voiceprint earphone is tested by wireless transmission:
AudioExpert -> Acquisition card AO -> vibration exciter SK 505 -> Internal acceleration sensor of the finished product -> SPP/HFP protocol of Bluetooth dongle -> AudioExpert
Finished product stage - test architecture for uplink bone conduction technology
One thing to note is that in the finished earphone with bone voiceprint, the bone voiceprint microphone and the other normal microphones exist independently of each other. So, the test system also needs to be equipped with other hardware that can test the normal microphone, such as: SB-05 speaker, AM 581 artificial mouth.