[Discuss-gnuradio] Energy Detection output incorrect

[Tellrell White]

Hello All

I'm working on a project involving signal detection of an IEEE 802.15.4 waveform using energy detection.
The algorithm for energy detection goes as follows:

          A/D conversion ->  FFT -> mag^2 -> (1/N) ^ M -> threshold comparison

Currently, I'm doing simulations in gnuradio companion with a focus of just trying to construct the the algorithm and get an output. Below I've attached the current flowgraph i'm using along with screen shots of the flowgraph and the outputs from the fft sinks.

In the flowgraph i'm using gaussian noise as my source. I send this noise to both an FFT sink and also through the energy detection algorithm. My expectation is that both sinks will give me the same result, however, the output coming from the algorithm doesn't match the other sink and I'm currently now sure why this is. Are there some blocks I'm currently missing and/or is the FFT sink an incorrect way of trying to display the power coming from the energy detection algorithm?

Any suggestions are welcome.

Regards

Tellrell

threshold.grc
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Screenshot from 2017-09-20 11_53_10.png
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Screenshot from 2017-09-20 11_51_11.png
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