Signal Power Calculations
This week, we worked on computing reliable estimates of signal power from the received WiFi signals. Vrishab carried out some theoretical calculations from which we verified that undersampling the captured signals would not affect the received power. The implementation of these calculations in software was carried out by Enock.
Downconverter Debugging
In computing correlations between our captured WiFi signals, we found that one of the signals appeared to be corrupted by a high degree of noise. To debug this, we first determined that the source of the noise was not one of the SDRs. Txanton wrote a script to set the VCO output to a frequency that could be captured by the SDRs, which we were able to use to confirm that the SDRs were not the source of the problem. We found that one of the outputs from the downconverter board we were using was faulty, so we replaced our downconverter with the additional one that we had.
Server Implementation and Correlation Analysis
We implemented a simple UDP server to facilitate real-time data transfer from our data capture apparatus to a computer for processing. The server implements a correlation script that can ascertain the sample delay between signals from each antenna.
Progress Since Last Week
We have greatly improved our signal capture pipeline for two antennas, which was quite slow last week and suffered from incorrect correlations induced by a faulty downconverter.
Tasks for Next Week
We will add two additional RTL SDRs to our system. For now, we will use the faulty downconverter since one of its two lines still works. We will seek a replacement on monday if it cannot be fixed. We will also finish implementing angle of arrival estimation, which is a simple equation applied to the delay between the two signals which we have already obtained