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tyogav
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Consider two adjacent people speaking in cell phones. Why the signals don't interfere with one another? Does each phone communicate with a distinct frequency? If so, how?
An analogy to the problem of multiple access is a room (channel) in which people wish to talk to each other simultaneously. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different languages (code division). CDMA is analogous to the last example where people speaking the same language can understand each other, but other languages are perceived as noise and rejected. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can communicate.
Electromagnetic interference (EMI) is the disruption of electronic devices caused by the presence of electromagnetic waves from other nearby devices or sources. This interference can lead to the malfunctioning of electronic devices, including cell phones.
EMI can affect cell phones in various ways, such as causing dropped calls, poor signal strength, and distorted sound quality. It can also interfere with the functioning of other components in the cell phone, leading to malfunctions or even permanent damage.
While there is ongoing research on the potential health risks of EMI from cell phones, the current evidence suggests that exposure to EMI does not pose a significant health risk. However, it is recommended to limit exposure to EMI by keeping a safe distance from cell phones and using hands-free devices.
To reduce EMI on your cell phone, you can try keeping your phone away from other electronic devices, using a headset or speakerphone when making calls, and avoiding using your phone in areas with poor reception. Additionally, using a protective case or shield can also help reduce EMI.
Yes, there are regulations in place to limit EMI from cell phones. In the United States, the Federal Communications Commission (FCC) has set limits on the amount of EMI that electronic devices, including cell phones, can emit. Manufacturers are required to comply with these regulations before their devices can be sold in the market.