| 1. |
- Johansson, Gustav, et al.
(författare)
-
Picosecond level error detection using PCA in the hardware timing systems for the EISCAT_3D LAAR
- 2010
-
Ingår i: Radio Science Bulletin. - 1024-4530. ; :333, s. 45-50
-
Tidskriftsartikel (refereegranskat)abstract
- While developing the timing system for the receiver arrays for the EISCAT_3D system, several approaches to detect and adjust for timing errors within the array have been explored. The demand on the timing error between all elements in the array is to have a standard deviation of less than 120 ps, thus requiring high quality error detection systems to guarantee radar operation. This paper investigates the qualities of a secondary error detection system based on statistical analysis of captured data. The measurements are assembled with a Signal-to-Noise Ratio (SNR) of -30 dB implying that the elements in a 2112 element array need to be grouped into sub-arrays of 48 elements each. The captured data is then evaluated by Principal Component Analysis (PCA) and averaged over 20,000 measurements, or about half a second. Timing errors between sub-arrays of down to ~120 ps and a percentage of faulty sub-arrays of up to 20% are detectable. As a secondary error detection system PCA is cheap to implement since the only need of the analysis is a small amount of computer time. It also provides a valuable detection system for hardware errors in the primary timing system that can otherwise be hard to find.
|
|
| 2. |
- Johansson, Gustav, et al.
(författare)
-
Projekt: ESiS EP
- 2009
-
Annan publikation (populärvet., debatt m.m.)abstract
- Sammanfattningsvis är forskningsmålet att optimera kretskortsproduktion för små och medelstora serier. Huvudsakligen handlar det om att undersöka och modellera det termiska systemet mellan kretskort och lödugn. Modellen kommer sedan att användas för att ge bättre konfigurationsparametrar för produktionslinjen. En bra modell kommer inte bara att öka lödningskvalitén och minska antalet kasserade kretskort men kan också även användas för att hitta avvikelser redan i kretskortsdesignen.
|
|
| 3. |
- Johansson, Gustav, et al.
(författare)
-
Simulation of post-ADC digital beamforming for large aperture array radars
- 2010
-
Ingår i: Radio Science. - 0048-6604 .- 1944-799X. ; 45:RS3001
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents simulations and methods developed to investigate the feasibility of using a Fractional-Sample-Delay (FSD) system in the planned EISCAT_3D incoherent scatter radar. Key requirements include a frequency-independent beam direction over a 30 MHz band centered around 220 MHz, with correct reconstruction of pulse lengths down to 200 ns. The clock jitter from sample to sample must be extremely low for the integer sample delays. The FSD must also be able to delay the 30 MHz wide signal band by 1/1024th of a sample without introducing phase shifts, and it must operate entirely in baseband. An extensive simulation system based on mathematical models has been developed, with inclusion of performance-degrading aspects such as noise, timing error, and bandwidth. Finite Impulse Response (FIR) filters in the baseband of a band-pass-sampled signal have been used to apply true time delay beamforming. It has been confirmed that such use is both possible and well behaved. The target beam-pointing accuracy of 0.06° is achievable using optimized FIR filters with lengths of 36 taps and an 18 bit coefficient resolution. Even though the minimum fractional delay step necessary for beamforming is ∼13.1 ps, the maximum sampling timing error allowed in the array is found to be σ ≤ 120 ps if the errors are close to statistically independent.
|
|
| 4. |
|
|
| 5. |
- Johansson, Jonny, et al.
(författare)
-
Project: EISCAT 3D
- 2007
-
Annan publikation (populärvet., debatt m.m.)
|
|
| 6. |
- Wannberg, Gudmund, et al.
(författare)
-
EISCAT_3D - a next-generation European radar system for upper atmosphere and geospace research
- 2010
-
Ingår i: Radio Science Bulletin. - 1024-4530. ; :333, s. 75-88
-
Tidskriftsartikel (refereegranskat)abstract
- The EISCAT Scientifi c Association, together with a number of collaborating institutions, has recently completed a feasibility and design study for an enhanced performance research radar facility to replace the existing EISCAT UHF and VHF systems. This study was supported by EU Sixth-Framework funding. The new radar retains the powerful multi-static geometry of the EISCAT UHF, but will employ phased arrays, direct-sampling receivers, and digital beamforming and beam steering. Design goals include, inter alia, a tenfold improvement in temporal and spatial resolution, an extension of the instantaneous measurement of full-vector ionospheric drift velocities from a single point to the entire altitude range of the radar, and an imaging capability to resolve small-scale structures. Prototype receivers and beamformers are currently being tested on a 48-element, 224 MHz array (the "Demonstrator") erected at the Kiruna EISCAT site, using the EISCAT VHF transmitter as an illuminator.
|
|
| 7. |
|
|
| 8. |
- Beckman, C., et al.
(författare)
-
Design Considerations for the EISCAT_3D Phased Array Antenna
- 2014
-
Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014. - Piscataway, NJ : IEEE. - 9788890701849 ; , s. 1700-1704
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a background and an overview of the initial design considerations for phased array antenna being designed for the New Generation multi-static, incoherent-scatter radar station - EISCAT-3D - in Northern Scandinavia. Its anticipated electrical, mechanical and environmental design requirements are given both by the physics as well as by the extreme climate in the subarctic region of northern Scandinavia.
|
|
| 9. |
- Bocchetta, Carlo, et al.
(författare)
-
Project Status of the Polish Synchrotron Radiation Facility Solaris
- 2011
-
Ingår i: Proceedings of IPAC2011. - 9789290833666 ; , s. 3014-3016
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Abstract in Undetermined The Polish synchrotron radiation facility Solaris is being built at the Jagiellonian University in Krakow. The project is based on an identical copy of the 1.5 GeV storage ring being concurrently built for the MAX IV project in Lund, Sweden. A general description of the facility is given together with a status of activities. Unique features associated with Solaris are outlined, such as infrastructure, the injector and operational characteristics.
|
|
| 10. |
- Borg, Johan, et al.
(författare)
-
An ultrasonic transducer interface IC with integrated push-pull 40 Vpp, 400 mA current output, 8-bit DAC and integrated HV multiplexer
- 2011
-
Ingår i: IEEE Journal of Solid-State Circuits. - 0018-9200 .- 1558-173X. ; 46:2, s. 475-484
-
Tidskriftsartikel (refereegranskat)abstract
- We present an ultrasonic transducer interface IC that includes an 8-bit, 40 V pp , 400 mA current output DAC for arbitrary waveform transducer excitation and a ±25 V analog multiplexer. The IC was fabricated using a 0.35 μm, 50 V CMOS process. The design eliminates the need for an external power amplifier as the piezoelectric transducer is driven directly from a segmented push-pull current output DAC, which simplifies the overall system design. This approach has the advantage of simple and rapid glitch-free power-up/down, which is especially important in integrated high-output-power drivers. The DAC has been evaluated when operating at a 150 MHz sampling rate with a ±400 mA output current and a 50 Ω load. Measured performance includes 37 dB SNDR and 46 dB SFDR at 10 MHz output frequency. By implementing an additional reference DAC and extending the receiver isolation switch into an analog multiplexer, we enable on-line calibration for the purpose of reducing the driver and receiver signal path uncertainty. Measurements show a greater than ten-fold improvement in delay uncertainty to approximately 20 ps for temperature variations of 0 to 70 degrees Celsius.
|
|
