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by adrian_b
93 days ago
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In general, it is very easy to detect that radio signals are present. A better comparison is with radio signals for which a method of spread-spectrum modulation has been used, chosen such as to have a bandwidth so wide that the averaged signal falls below the thermal noise level. Such radio signals will also not be detectable without special detectors. WiFi and Bluetooth use spread-spectrum modulation methods but they have relatively low bandwidths, so they can be easily distinguished from thermal noise. Much wider bandwidths are required to prevent detection. |
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