an rfi mitigation strategy for the allen telescope array geoffrey c. bower uc berkeley
TRANSCRIPT
![Page 1: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/1.jpg)
An RFI Mitigation Strategy for the Allen Telescope Array
Geoffrey C. Bower
UC Berkeley
![Page 2: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/2.jpg)
The Allen Telescope Array
350 element interferometer
6.1 m offset Gregorians 0.5-11.2 GHz Science goals
– SETI– HI survey machine– Transient radio sources
![Page 3: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/3.jpg)
Strategy Overview
Know the enemy Put many arrows in the quiver
– No Magic Bullets
Exploit large N capability Implement at all levels
![Page 4: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/4.jpg)
Available Tools
Modeling of environment Measurement Real time strategies
![Page 5: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/5.jpg)
RFI Modeling: Hat Creek Terrain
![Page 6: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/6.jpg)
RFI Modeling: Free Space
3 x 3 degree region centered at Hat Creek Contours of path loss Visualyse simulation
![Page 7: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/7.jpg)
RFI Modeling: ITU-R P.526
Model includes topography, diffraction, tropospheric scatter, ducting/layer reflection, fade
Future modeling: frequency, scale, model parameters, Longley-Rice
![Page 8: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/8.jpg)
RFI Monitor
Simple design– Discone antenna– Broadband amp– Spectrum analyzer– Linux PC on ‘net
0.1 to 10 GHz– 0.3 to 3 GHz currently
Isotropic sensitivity
![Page 9: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/9.jpg)
… (One of) the Enemies is Us
![Page 10: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/10.jpg)
Is Glonass Present at 1612 MHz?
![Page 11: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/11.jpg)
Tracking Glonass
![Page 12: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/12.jpg)
…The Enemy is Us, Part 2
![Page 13: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/13.jpg)
And Tracking GPS
![Page 14: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/14.jpg)
Aircraft DME
![Page 15: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/15.jpg)
RFI Sources Detected at Hat Creek
Self-interference Satellites --- GPS, Iridium, DARS Aircraft Radar TV, cell phone, pager Microwave ovens
![Page 16: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/16.jpg)
Real Time RFI Mitigation
Monitoring Artificial horizons around known interferers
Time Blanking Adaptive canceling Interferometric Nulling Postcorrelation Analysis
![Page 17: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/17.jpg)
Time Blanking: Radar
![Page 18: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/18.jpg)
Time Blanking: DME
![Page 19: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/19.jpg)
Time Blanking Implementation
Done in backends Correlator will have
– 100 sec precision– External & Internal Triggers– Channel, Antenna Configuration Undetermined
![Page 20: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/20.jpg)
Adaptive Canceling
![Page 21: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/21.jpg)
Rapid Prototyping Array
![Page 22: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/22.jpg)
Cancellation of Glonass
![Page 23: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/23.jpg)
Cancellation of GPS
![Page 24: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/24.jpg)
ATA Implementation of Canceling
Multiple reference antennas (~10) Correlator/black box operating on phased-
array signal Wiener or LMS solutions
![Page 25: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/25.jpg)
Interferometric Nulling: Two Slits
![Page 26: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/26.jpg)
Interferometric Nulling
![Page 27: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/27.jpg)
Nulls with the ATA
![Page 28: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/28.jpg)
Muliple Nulls
![Page 29: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/29.jpg)
Nulls in Frequency Space
![Page 30: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/30.jpg)
The Wages of Nulling
Requires large-N to be effective
Loss in SNR with number of nulls
Must be able to update complex gains at ~100 Hz
Matrix inversion is computationally expensive
![Page 31: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/31.jpg)
Postcorrelation Analysis
Examine output of correlator/visibility matrix ~100 element PC cluster Data rate:
– 350x349/2– 4 Stokes– 1024 Channels– 16 bit– 100 Hz sampling
400 Gbits/sec: too much!
![Page 32: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/32.jpg)
How to Use the Tools
Blanking– Radar, Aircraft, intermittent signals
Adaptive Canceling– Reference antenna(s) on transmitter
Interferometric Nulling– Predictable trajectories: satellites, fixed transmitters
Postcorrelation Analysis– Broadly adaptable
![Page 33: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/33.jpg)
Future Steps
Algorithm development More modeling of environment Implement canceller, external blanker Angle of arrival methods
![Page 34: An RFI Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower UC Berkeley](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649e865503460f94b8912b/html5/thumbnails/34.jpg)