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Improvements","user":{"login":"russellmsilva","id":29031462,"node_id":"MDQ6VXNlcjI5MDMxNDYy","avatar_url":"https://avatars3.githubusercontent.com/u/29031462?v=4","gravatar_id":"","url":"https://api.github.com/users/russellmsilva","html_url":"https://github.com/russellmsilva","followers_url":"https://api.github.com/users/russellmsilva/followers","following_url":"https://api.github.com/users/russellmsilva/following{/other_user}","gists_url":"https://api.github.com/users/russellmsilva/gists{/gist_id}","starred_url":"https://api.github.com/users/russellmsilva/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/russellmsilva/subscriptions","organizations_url":"https://api.github.com/users/russellmsilva/orgs","repos_url":"https://api.github.com/users/russellmsilva/repos","events_url":"https://api.github.com/users/russellmsilva/events{/privacy}","received_events_url":"https://api.github.com/users/russellmsilva/received_events","type":"User","site_admin":false},"labels":[{"id":732082205,"node_id":"MDU6TGFiZWw3MzIwODIyMDU=","url":"https://api.github.com/repos/jakapoor/AMRUPT/labels/enhancement","name":"enhancement","color":"84b6eb","default":true},{"id":883908856,"node_id":"MDU6TGFiZWw4ODM5MDg4NTY=","url":"https://api.github.com/repos/jakapoor/AMRUPT/labels/problem","name":"problem","color":"b21e2d","default":false},{"id":732082212,"node_id":"MDU6TGFiZWw3MzIwODIyMTI=","url":"https://api.github.com/repos/jakapoor/AMRUPT/labels/question","name":"question","color":"cc317c","default":true}],"state":"open","locked":false,"assignee":{"login":"vha3","id":5074226,"node_id":"MDQ6VXNlcjUwNzQyMjY=","avatar_url":"https://avatars0.githubusercontent.com/u/5074226?v=4","gravatar_id":"","url":"https://api.github.com/users/vha3","html_url":"https://github.com/vha3","followers_url":"https://api.github.com/users/vha3/followers","following_url":"https://api.github.com/users/vha3/following{/other_user}","gists_url":"https://api.github.com/users/vha3/gists{/gist_id}","starred_url":"https://api.github.com/users/vha3/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/vha3/subscriptions","organizations_url":"https://api.github.com/users/vha3/orgs","repos_url":"https://api.github.com/users/vha3/repos","events_url":"https://api.github.com/users/vha3/events{/privacy}","received_events_url":"https://api.github.com/users/vha3/received_events","type":"User","site_admin":false},"assignees":[{"login":"vha3","id":5074226,"node_id":"MDQ6VXNlcjUwNzQyMjY=","avatar_url":"https://avatars0.githubusercontent.com/u/5074226?v=4","gravatar_id":"","url":"https://api.github.com/users/vha3","html_url":"https://github.com/vha3","followers_url":"https://api.github.com/users/vha3/followers","following_url":"https://api.github.com/users/vha3/following{/other_user}","gists_url":"https://api.github.com/users/vha3/gists{/gist_id}","starred_url":"https://api.github.com/users/vha3/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/vha3/subscriptions","organizations_url":"https://api.github.com/users/vha3/orgs","repos_url":"https://api.github.com/users/vha3/repos","events_url":"https://api.github.com/users/vha3/events{/privacy}","received_events_url":"https://api.github.com/users/vha3/received_events","type":"User","site_admin":false},{"login":"skoviraj","id":6086555,"node_id":"MDQ6VXNlcjYwODY1NTU=","avatar_url":"https://avatars3.githubusercontent.com/u/6086555?v=4","gravatar_id":"","url":"https://api.github.com/users/skoviraj","html_url":"https://github.com/skoviraj","followers_url":"https://api.github.com/users/skoviraj/followers","following_url":"https://api.github.com/users/skoviraj/following{/other_user}","gists_url":"https://api.github.com/users/skoviraj/gists{/gist_id}","starred_url":"https://api.github.com/users/skoviraj/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/skoviraj/subscriptions","organizations_url":"https://api.github.com/users/skoviraj/orgs","repos_url":"https://api.github.com/users/skoviraj/repos","events_url":"https://api.github.com/users/skoviraj/events{/privacy}","received_events_url":"https://api.github.com/users/skoviraj/received_events","type":"User","site_admin":false},{"login":"jakapoor","id":23314448,"node_id":"MDQ6VXNlcjIzMzE0NDQ4","avatar_url":"https://avatars0.githubusercontent.com/u/23314448?v=4","gravatar_id":"","url":"https://api.github.com/users/jakapoor","html_url":"https://github.com/jakapoor","followers_url":"https://api.github.com/users/jakapoor/followers","following_url":"https://api.github.com/users/jakapoor/following{/other_user}","gists_url":"https://api.github.com/users/jakapoor/gists{/gist_id}","starred_url":"https://api.github.com/users/jakapoor/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jakapoor/subscriptions","organizations_url":"https://api.github.com/users/jakapoor/orgs","repos_url":"https://api.github.com/users/jakapoor/repos","events_url":"https://api.github.com/users/jakapoor/events{/privacy}"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first tests were performed with the coherent receiver placed in the middle of a baseball field. Preliminary angle of arrival tests with 2 antenna elements resulted in unstable sporadic angles. It was found shortly after that there was an RF signal in the environment transmitting at 431 MHz (we were using 433 MHz). It is debatable whether this would be an issue with the small receiving bandwidth being used (~1 KHz).\r\n\r\nI was not able to test the MUSIC/root MUSIC algorithms sufficiently outside because the power supply only lasted one hour (with a signal generator and low-battery laptop connected). Further tests were made indoors in Duffield. For the root MUSIC/MUSIC algorithm tests indoors, the resulting angle took ~5 seconds to stabilize once the transmitter was put in a fixed position (see improvement 1). 433 MHz transmissions resulted to NULL values from the root MUSIC algorithm; however, 866 MHz transmissions never resulted in a NULL value (see improvement 2).\r\n\r\n866 MHz transmission tests:\r\nIndoor multi-path effects (resulting in a clearly unexpected angle) resulted when the transmitter was pointed more than 30 degrees away from the line of sight. Towards the end of testing last night, stable angles within 10 degrees of the actual angle of arrival (measured by protractor/string) were observed. These last observations are premature though, and further testing must be done to see if these were fluke values.\r\n\r\nImprovements to be made:\r\n\r\n1. The GUI Compass may have an instability issue with reported issues [here](https://github.com/EttusResearch/gr-doa/issues/3) and [here](https://github.com/samwhiting/gnuradio-doa/issues/4). Therefore, the following tests will be done using the console or a GUI float sink (displaying the float value result of MUSIC/root MUSIC on the GNU Radio GUI) in addition to the GUI Compass to see if there is disparity between the end AoA results.\r\n\r\n2. The testing mast contained a platform for the coherent receiver, Raspberry Pi, and usb hub. This platform was placed within the near field of antenna array elements. The platform was specifically placed 2 feet from the antenna array (near field is one wavelength - ~2.3 feet for 433 MHz). This platform will be placed further from the near field (an additional 1.5 feet lower) to reduce EM interference with electronic devices. \r\n\r\n3. No matter the frequency, gain, or bandwidth setting, RTL SDR 1 receives the greatest sinusoidal amplitude, RTL SDR 2 receives a lower sinusoidal amplitude, RTL SDR 3 receives an even lower sinusoidal amplitude, and RTL SDR 4 receives the lowest sinusoidal amplitude. This effect occurs when sending sinusoidal waves to the coherent receiver from the CC1310 and the signal generator. Please see [this video](https://www.youtube.com/watch?v=KZ1ehw_afNY) which displays the sinusoidal waves received from a CC1310 transmitter. Since this was a high power disparity, the RF gain of each receiver had to be increased from 35 to 50 dB in order for RTL SDR 4 to receive enough power for testing. This phenomenon may adversely effect beamforming (as implemented in Whiting's system). Since RTL SDR 1 always receives a signal of much greater power than RTL SDR 4, the MUSIC/root-MUSIC algorithms may be adversely effected as well.\r\n\r\nPlease feel free to shoot me any suggestions or ideas. A next set of tests will be performed after the above improvements have been made or reconciled."},"comment":{"url":"https://api.github.com/repos/jakapoor/AMRUPT/issues/comments/425177073","html_url":"https://github.com/jakapoor/AMRUPT/issues/24#issuecomment-425177073","issue_url":"https://api.github.com/repos/jakapoor/AMRUPT/issues/24","id":425177073,"node_id":"MDEyOklzc3VlQ29tbWVudDQyNTE3NzA3Mw==","user":{"login":"russellmsilva","id":29031462,"node_id":"MDQ6VXNlcjI5MDMxNDYy","avatar_url":"https://avatars3.githubusercontent.com/u/29031462?v=4","gravatar_id":"","url":"https://api.github.com/users/russellmsilva","html_url":"https://github.com/russellmsilva","followers_url":"https://api.github.com/users/russellmsilva/followers","following_url":"https://api.github.com/users/russellmsilva/following{/other_user}","gists_url":"https://api.github.com/users/russellmsilva/gists{/gist_id}","starred_url":"https://api.github.com/users/russellmsilva/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/russellmsilva/subscriptions","organizations_url":"https://api.github.com/users/russellmsilva/orgs","repos_url":"https://api.github.com/users/russellmsilva/repos","events_url":"https://api.github.com/users/russellmsilva/events{/privacy}","received_events_url":"https://api.github.com/users/russellmsilva/received_events","type":"User","site_admin":false},"created_at":"2018-09-27T17:29:50Z","updated_at":"2018-09-27T17:29:50Z","author_association":"COLLABORATOR","body":"A video overview of the testing conducted 9/23/2018 can be found [here](https://www.youtube.com/watch?v=DcbEhXReK4k).  Please bear with the video quality/stability (it was difficult to record a video of the generated phase differences in real-time when holding the transmitter and my laptop).\r\n\r\nOriginally, the testing was performed with the sole purpose of video documenting the technical issues of our phase interferometry system. This was done so that experts who were able to implement similar direction-finding systems could help us debug these issues. However, the testing resulted in unexpected observations that necessitate further experimentation to isolate what the specific technical issues are.\r\n\r\nTesting was conducted outdoors on the baseball field. I placed the transmitter at distances perpendicular to the antenna array (90 degrees) to decrease the testing parameters to tag-to-array distance, movement, transmitter gain, and receiver gain. Notable findings include:\r\n\r\n1. Based on the transmitter and receiver gains, there was a distance from the antenna array at which the received signal would dissipate lower than a visible amplitude on the waveform display in GNU Radio. This is a beneficial quality of the testing environment, because the transmitted signal can be attenuated to a negligible amount by the time it reaches buildings/objects near the baseball field with low transmitter gains. The receiver gain can also be lowered to an amount to which reflected signals from nearby buildings/objects would not be detected by the receivers. Due to the brevity of testing time available, the exact transmitter gain/distance/received amplitude relationship of the CC1310 could not be determined.\r\n\r\n2. At a ⁓35-meter distance from the antenna array, the phase difference had a stable measurement close to 0 degrees when crouching down. When standing up with my body near the transmitter, the measured phase difference fluctuated to a different value. Also, the phase difference varied more than expected when the transmitter pole was tilted to the left or right from its vertical position.\r\n\r\nBecause of this second finding, I am going to modify the transmitter setup so that I can stay away from the CC1310 during testing and to more effectively record the system’s performance. The modifications will include building a base for the transmitter pole and programming the CC1310 to send an unmodulated 433.92 mHz signal without a connection to my laptop. These modifications will be done so that the system can be debugged and improved incrementally, adding interfering objects once our system can generate accurate AoAs without interfering objects (such as myself)."}}
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