User Visit Certification and Visit Trace System Using Inaudible Frequency
This study proposes a user visit certification and visit trace system using inaudible frequencies in the range of audible frequencies but not those audible to people. The signal frequency consists of inaudible frequencies in the range of 18 kHz to 20 kHz, which can be generated by normal speakers. T...
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| Main Author: | |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-05-01
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| Series: | Signals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2624-6120/6/2/24 |
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