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| 2. |
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| 3. |
- Djupsjöbacka, Anders, et al.
(författare)
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Estimating Eye-opening Penalty with Aid of the Ripple Function of Fiber Bragg-gratings
- 2007
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Ingår i: Journal of Optical Communications. ; 28, s. 91-95
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Tidskriftsartikel (refereegranskat)abstract
- We investigate six different methods presented in litera-ture to estimate eye-opening penalty for dispersion-com-pensating fiber Bragg gratings with aid of the grating’s ripple function. The investigation is based on theoretical ripple functions as well on measurement results of three continuously chirped gratings. The gratings in question offer full wavelength coverage between 1530 nm and 1565 nm. We will show that the eye-opening penalty de-pends on the phase and frequency of the grating’s ripple function as well as to pattern length and to pulse form of the signal used. Since the estimation methods do not ac-count for these properties, their accuracy is shown to be limited.
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| 4. |
- Djupsjöbacka, Anders, et al.
(författare)
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Measured Temporal statistics of the DGD RMS-Value in Buried Optical Fibers
- 2009
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 21:24, s. 1801-1803
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Tidskriftsartikel (refereegranskat)abstract
- The behavior of the differential group delay (DGD)root-mean-square (rms) value is investigated for a buried G.652fiber line in a metropolitan fiber plant outside Stockholm, Sweden.This study presents measurement results from two different mea-surement periods where the same fiber and the same measurementequipment was used. In total,2800 hours of measurements wereperformed. As expected, the recorded DGD rms-value variedwith time. The measured standard deviation for the statistics ofthe DGD rms-value fits reasonably well with values presentedin literature. The fiber line, which showed a DGD rms-value of0.45 ps in average, had an extremely long time constant. Evenafter2800 hours of measurements we have not closed in on theexpected asymptotic distribution of the measured DGD rms-value
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| 5. |
- Forzati, Marco, et al.
(författare)
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40-gb/s field transmission through 540 km ssmf using the aprz modulation format
- 2005
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Ingår i: Optics InfoBase Conference Papers. - : Optical Society of America. - 1557527849 - 9781557527844
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Konferensbidrag (refereegranskat)abstract
- We report the first field transmission experiment using the APRZ modulation format for 40-Gb/s transmission through 540 km SSMF, which confirms the improved nonlinear tolerance of APRZ. The optimum phase-modulation amplitude in this experiment is p/2.
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| 6. |
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| 7. |
- Forzati, Marco, et al.
(författare)
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Asynchronous Phase Modulation for the Suppression of IFWM
- 2007
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Ingår i: IEEE transactions on intelligent transportation systems (Print). - 1524-9050 .- 1558-0016. ; 25, s. 2969-75
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Tidskriftsartikel (refereegranskat)abstract
- Intrachannel four-wave mixing (IFWM) represents main source of impairments in fiber transmission at 40 Gb/s. A number of phase modulation techniques have been proposed to suppress the IFWM. In this paper, we study a cost-effective way of increasing the nonlinear tolerance of a 40-Gb/s wavelength division multiplexing transmission system by asynchronous phase modulation (APM). This can be achieved with one phase modulator placed after the wavelength multiplexer so that cost is shared by all channels. We show, by means of numerical simulations and laboratory experiments, that APM greatly improves the performance of ON-OFF-keying transmission.
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| 8. |
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| 9. |
- Forzati, Marco, et al.
(författare)
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Reduction of intra-channel four-wave mixing using the alternate-phase RZ modulation format
- 2002
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 14:9
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Tidskriftsartikel (refereegranskat)abstract
- —The authors propose a modulation format in which the phase of the signal pulses alternates, in order to reduce the intrachannel four-wave mixing. They demonstrate numerically that the performance of a 40-Gb/s transmission link can be substantially improved.
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| 10. |
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| 11. |
- Mårtensson, Jonas, et al.
(författare)
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Improvement of Nonlinear Tolerance in 40 Gbit/s Transmission by Phase Modulation at 10 GHz
- 2002
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Ingår i: 2002 28TH European Conference on Optical Communication. - 8790974638
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Konferensbidrag (refereegranskat)abstract
- We propose to suppress intra-channel four-wave-mixing (IFWM) in 40 Gbit/s optical transmission by applying a phase modulation at 10 GHz. Both numerical simulations and experiments show that the penalty induced by IFWM is significantly reduced
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| 12. |
- Mårtensson, Jonas, et al.
(författare)
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Phase Modulation Schemes for Improving Intra-Channel Nonlinear Tolerance in 40 Gbit/s Transmission
- 2003
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Ingår i: Conference on Optical Fiber Communication, Technical Digest Series. - : Institute of Electrical and Electronics Engineers Inc.. ; , s. 662-663
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Konferensbidrag (refereegranskat)abstract
- Several schemes for suppressing infra-channel non-linearities by introducing phase shifts between pulses are compared. Simulations and experiments show that sinusoidal phase modulation at 10 GHz provides a simple and effective means for improving the nonlinear tolerance in 40 Gbit/s transmission.
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| 13. |
- Mårtensson, Jonas, et al.
(författare)
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Suppression of intra-channel four-wave mixing by phase modulation at one quarter of bit rate
- 2002
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Ingår i: Electronic Letters. - : Institution of Engineering and Technology (IET). - 0013-5194. ; 38:23, s. 1463-65
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Tidskriftsartikel (refereegranskat)abstract
- A proposed improvement of the nonlinear tolerance in 40 Gbit/s optical transmission by applying a 10 GHz phase modulation is presented. The improvement is obtained because intra-channel four-wave mixing (IFWM) is suppressed. It is shown, both by numerical simulations and experiments, that the penalty induced by IFWM is significantly reduced.
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| 14. |
- Roelens, M. A. F., et al.
(författare)
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High quality pulse and device characterisation using EAM-based frequency resolved optical gating
- 2005
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Ingår i: IET Conference Publications. - : Institution of Engineering and Technology. ; , s. 397-398
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Konferensbidrag (refereegranskat)abstract
- We report on the versatility of frequency resolved optical gating using an electro-absorption modulator to accurately characterise the pulse shape and phase of high speed telecommunication pulses, as well as properties of optical components.
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| 15. |
- Roelens, M. A. F., et al.
(författare)
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Linear frequency resolved optical gating as a line monitoring tool
- 2006
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Ingår i: 2006 Optical Fiber Communication Conference, and the 2006 National Fiber Optic Engineers Conference. - : IEEE Computer Society. - 1557528039 - 9781557528032
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Konferensbidrag (refereegranskat)abstract
- We demonstrate the use of spectrograms for pulse monitoring. The technique can characterize the phase and intensity of data modulated pulses after transmission over a fiber span including a tunable dispersion compensating grating. © 2006 Optical Society of America.
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| 16. |
- Öhman, F., et al.
(författare)
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Measurements and simulations of nonlinear noise redistribution in an SOA
- 2005
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 17:1, s. 16-18
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Tidskriftsartikel (refereegranskat)abstract
- Measurements and numerical simulations of the noise statistics after a semiconductor optical amplifier (SOA) demonstrate nonlinear noise redistribution. The redistribution, which relies on self-modulation due to gain saturation and carrier dynamics, shows a strong power and bandwidth dependence and can be important for SOA-based regenerators. © 2005 IEEE.
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| 17. |
- Öhman, F., et al.
(författare)
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Measurements of non-linear noise re-distribution in an SOA
- 2004
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Ingår i: Conference on Lasers and Electro-Optics, 2004. (CLEO)..
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Konferensbidrag (refereegranskat)abstract
- Measurements of the noise statistics after a semiconductor optical amplifier (SOA) demonstrate non-linear noise re-distribution with a strong power and bandwidth dependence.
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| 18. |
- Andersson, L. I., et al.
(författare)
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10 Gb/s Optical Transmission using a Silicon Bipolar Chipset
- 1995
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Ingår i: IEEE/LEOS 1995 Digest of the LEOS Summer Topical Meetings. Flat Panel Display Technology. ; , s. 59-60
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Konferensbidrag (refereegranskat)abstract
- A 10 Gb/s silicon chip set including a 8:1 MUX, a 1.8 DMUX, a dynamic divider, and circuits for clock recovery is described. Results from optical transmission experiments utilizing dispersion compensation techniques such as prechirp and MSSI, and bridging distances from 50 to 100 km, will be presented.
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| 19. |
- Benedetto, S., et al.
(författare)
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Multilevel polarization modulation using a specifically designed LiNbO/sub 3/ device
- 1994
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Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 6:8, s. 949-951
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Tidskriftsartikel (refereegranskat)abstract
- Binary and multilevel optical polarization modulation (POLSK) is an innovative transmission technique, suitable for both coherent and direct detection. To prove its feasibility, we have built a flexible polarization modulator based on a specifically designed LiNbO/sub 3/ device. We show that it can generate any state of polarization and therefore it is suitable for transmission of any binary or multilevel POLSK constellation. Once electrically equalized, the modulator has a 4 GHz bandwidth. To test the modulator with actual digital modulation, we set up a coherent binary experiment at 800 Mbit/s, and attained a sensitivity 1.5 dB away from the noise limit of the receiver.
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| 20. |
- Borg, Tina, 1982-, et al.
(författare)
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Perceived muscular tension in healthy subjects : a cross-sectional study
- 2016
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Ingår i: PREMUS2016. - 9780969972679 ; , s. 411-411
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Konferensbidrag (refereegranskat)abstract
- Background. Perceived muscular tension (PMT) has been suggested to predict development of neck/shoulder pain. It has been hypothesized to be an early sign of musculoskeletal disorder and a possible mediator of stress on symptoms. However, the content of the concept of PMT is not clear. This study examined the association between PMT and physical and psychosocial factors and physical activity in a group of healthy students.Methods. This cross-sectional study was conducted on the baseline measurements of an ongoing longitudinal case-control study. A total of 63 healthy university students without complaints of neck/shoulder pain were included (21 males, 42 females, mean age 24 years). PMT was measured by asking the question “Have you, during the past month, experienced muscular tension (for example, wrinkled your forehead, ground your teeth, raised your shoulders)?” with the following response options: never, a few times, a few times per week, or one or several times per day. Self-reports on symptoms in the neck, anxiety, depression, stress, mental health, physical health, sleep and physical activity were collected with questionnaires, as well as by tenderness on palpation of neck muscles and trapezius pressure pain threshold. This produced a total of 15 variables. The relationship between these variables and PMT were analyzed using Spearman’s rank correlation coefficient.Results. Positive correlations were found between PMT and temporomandibular complaints (rho= .34, p < .001), neck crepitus (rho= .33, p < .001), anxiety (rho= .33, p < .001), depression (rho= .31, p < .05), tenderness on palpation (rho= .25, p < .05). There was a negative correlation between PMT and mental health (rho= -.26, p < .05). Frequent experience of PMT had weak to moderate correlations with frequency of symptoms and higher psychosocial strain, but not with stress. This suggests some covariance between PMT and both physical and psychosocial factors.
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| 21. |
- Brunnström, Kjell, 1960-, et al.
(författare)
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Objective video quality assessment methods for Video assistant refereeing (VAR) Systems
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report describes the work and conclusions drawn after phase 4 in the project “Assessment methods for Video assistant refereeing (VAR) System”.The performance of six different video quality models have been evaluated, that were identified during phase 1, against the subjective video quality database that was created during phase 3. The results are slightly different for 1080p compared to 1080i. For 1080p the models VQM_VFD, SSIM and VMAF performs the best with Pearson Correlation Coefficients (PCC) above 0.9. For 1080i the PCC drops a bit overall and then VMAF and VQM_VFD are close in performance and performing the best. The overall performance for both formats VMAF an VQM_VFD stands out as the best models. In this comparison VQM_VFD has the added advantage to also be able to perform its own registration i.e. to fix any misalignment between the reference video and the distorted one.
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| 22. |
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| 23. |
- Brunnström, Kjell, 1960-, et al.
(författare)
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Quality measurement methods for video assisting refereeing systems
- 2023
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Ingår i: Sports Engineering. - : Springer Science and Business Media Deutschland GmbH. - 1369-7072 .- 1460-2687. ; 26:1
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Tidskriftsartikel (refereegranskat)abstract
- Changes in the footballing world’s approach to technology and innovation, along with major advancements in broadcasting contributed to the decision by the International Football Association Board to introduce Video Assistant Referees in 2018. The change meant that under strict protocols referees could use video replays to review decisions in the event of a “clear and obvious error” or a “serious missed incident”. At the time of writing 48-Member Associations have introduced the Video Assistant Referees protocol in at least one of their tournaments and there are many technology providers who work with organisers to implement the Video Assistant Referees systems. To ensure that the use of Video Assistant Referees has a positive effect on the game, Fédération Internationale de Football Association collaborated with the RISE Research Institutes of Sweden to develop objective test methods that could be used to ensure that a system can provide an adequate solution. Each provider must be able to pass requirements that ensure that they can deal with the challenges of processing, coding, decoding, synchronising, and re-formatting of the broadcast feeds. This article will describe the development of the test methods and illustrate some initial results from a test event on Video Assistant Referees system candidates. The methods have shown to be robust and appropriate for their intended purpose and will be developed over the years to ensure the quality of Video Assistant Referees. The developed measurement methods are general and can be applied to other broadcast and video systems as well as to other sports. © 2023, The Author(s).
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| 24. |
- Brunnström, Kjell, 1960-, et al.
(författare)
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Recommended precautions because of Covid-19 for perceptual, behavioural,quality and user experience experimentswith test persons in indoor labs
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Based on the recommendations from the Public Health Agency of Sweden(Folkhälsomyndigheten; FHM) and a set of internal rules from RISE, the followingrules are published for how to conduct experiments involving test persons in the timesof the pandemic Covid-19. The recommendations are for non-invasive and non-medicaltests, e.g. perceptual, consumer, ergonomic and human-computer interaction teststaking place in an indoor laboratory.Specifically, in this document we are specifying how experiments with test personstargeting audio and visual presentations should be done considering necessaryprecautions imposed by the Covid-19 pandemic. Laboratory experiments with testpersons, as it involves inviting people to the lab, require particular planning and carefulconsideration, if they are to be carried out safely because of the risks imposed by theCovid-19 pandemic. The safety aspects are valid for both the invited test persons andare equally important for the health of the test leaders.
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| 25. |
- Brunnström, Kjell, 1960-, et al.
(författare)
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Video expert assessment of high quality video for Video Assistant Referee (VAR) : A comparative study
- 2024
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Ingår i: Multimedia tools and applications. - : Springer Nature. - 1380-7501 .- 1573-7721. ; 83:20, s. 58783-58825
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Tidskriftsartikel (refereegranskat)abstract
- The International Football Association Board decided to introduce Video Assistant Referee (VAR) in 2018. This led to the need to develop methods for quality control of the VAR-systems. This article focuses on the important aspect to evaluate the video quality. Video Quality assessment has matured in the sense that there are standardized, commercial products and established open-source solutions to measure it with objective methods. Previous research has primarily focused on the end-user quality assessment. How to assess the video in the contribution phase of the chain is less studied. The novelties of this study are two-fold: 1) The user study is specifically targeting video experts i.e., to assess the perceived quality of video professionals working with video production. 2) Six video quality models have been independently benchmarked against the user data and evaluated to show which of the models could provide the best predictions of perceived quality. The independent evaluation is important to get unbiased results as shown by the Video Quality Experts Group. An experiment was performed involving 25 video experts in which they rated the perceived quality. The video formats tested were High-Definition TV both progressive and interlaced as well as a quarters size format that was scaled down half the size in both width and height. The videos were encoded with both H.264 and Motion JPEG for the full size but only H.264 for the quarter size. Bitrates ranged from 80 Mbit/s down to 10 Mbit/s. We could see that for H.264 that the quality was overall very good but dropped somewhat for 10 Mbit/s. For Motion JPEG the quality dropped over the whole range. For the interlaced format the degradation that was based on a simple deinterlacing method did receive overall low ratings. For the quarter size three different scaling algorithms were evaluated. Lanczos performed the best and Bilinear the worst. The performance of six different video quality models were evaluated for 1080p and 1080i. The Video Quality Metric for Variable Frame Delay had the best performance for both formats, followed by Video Multimethod Assessment Fusion method and the Video Quality Metric General model.
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