from the wiki about the "capture effect":

The capture effect is defined as the complete suppression of the weaker signal at the receiver limiter (if it has one) where the weaker signal is not amplified, but attenuated. When both signals are nearly equal in strength, or are fading independently, the receiver may switch from one to the other and exhibit picket fencing.

Following is my understanding, for the receiver side, it can distinguish the two of the different arriving signal and determine which is the stronger one thus only decode the stronger one.

But, on the other hand, in the signal interference (such as, WIFI is interference protocol, and the ZigBee is the intended signal protocol), the interference power would superposition the intended signal power. Is it means that under this condition, the receiver can not distinguish two of the different arriving signal and just amplified the superposition of the two different signal (intended signal power and interference power)?

Well, there is obviously a conflict understanding about the above two, and is there misunderstanding? Thanks!


The capture effect applies strictly to frequency modulation (FM) receivers. Because FM reception requires "following" the changing frequency of the received signal, only one signal at a time can properly effect this output. This will not apply to the more complex signal encoding used in WiFi (802.11-series). Much different signal analysis is required to calculate the usable bandwidth for WiFi under adverse signal conditions.

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  • \$\begingroup\$ Thanks for the explanation. While in some article, "The capture effect is not a phenomenon limited to FM transmissions. Ash [1] showed that it is possible to obtain an equivalent and even stronger effect in AM receivers."[2]. -- [1] D. L. Ash. A comparison between ook/ask and fsk modulation techniques for radio links. Technical report, Technical report, RF Monolithics Inc, 1992. [2]Sharing a Medium Between Concurrent Protocols Without Overhead Using the Capture Effect, EWSN'16. \$\endgroup\$ – desword May 31 '16 at 3:44
  • \$\begingroup\$ Interesting references. From the looks of it, it's really that the capture effect is a fairly simple phenomenon, but has more complicated implications in more advanced communication. \$\endgroup\$ – user2943160 May 31 '16 at 20:15

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