| 1. |
- Ahlin, Kjell, et al.
(författare)
-
Comparing Road Profiles with Vehicle Perceived Roughness
- 2004
-
Ingår i: International Journal of Vehicle Design. - Geneva, Switzerland : Inderscience Enterprises. - 0143-3369 .- 1741-5314. ; 36:2-3, s. 270-286
-
Tidskriftsartikel (refereegranskat)abstract
- Accurate road profiles are useful in vehicle design, such as for simulation of durability and ride quality. Laser/inertial profilometers typically record I mm wide profiles. The question is how well such a profile matches perceived vehicle wheel roughness. The objective here was to create a more representative wheel track longitudinal profile. Simulated and measured wheel vibration was compared on a 6km long road. Simulations were made for several definitions of the profile. Results for single laser sensor profiles showed reasonable likeness to truck perceived roughness. By far the best likeness (14.5% better) was achieved when the profile was based on triangular 25%-50%-25% weighted data from three sensors in the wheel track. Clearly, vehicle engineers can benefit from using multiple laser profile sensors, instead of a single sensor. This will improve test accuracy, thus reducing vehicle design project lead times and costs.
|
|
| 2. |
- Lindström, Fredric, et al.
(författare)
-
A Computational Efficient Method for Assuring Full Duplex Feeling in Hands-free Communication
- 2003
-
Konferensbidrag (refereegranskat)abstract
- This report proposes a method for obtaining satisfying "full-duplex feeling" in hands-free communication units at low computational cost. The proposed method uses a combination of an acoustic echo cancellation unit and an adaptive gain unit. The core of the method is to perform the processing of the speech signal into two separate frequency bands and to process these in different manners. Acoustic echoes in the low frequency part of the signal are cancelled by means of an acoustic echo cancellation unit, while acoustic echoes in the high frequency part are suppressed by an adaptive gain unit.
|
|
| 3. |
- Lindström, Fredric, et al.
(författare)
-
A Computational Efficient Method for Assuring Full Duplex Feeling in Hands-free Communication
- 2003
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report proposes a method for obtaining satisfying "full-duplex feeling" in hands-free communication units at low computational cost. The proposed method uses a combination of an acoustic echo cancellation unit and an adaptive gain unit. The core of the method is to perform the processing of the speech signal into two separate frequency bands and to process these in different manners. Acoustic echoes in the low frequency part of the signal are cancelled by means of an acoustic echo cancellation unit, while acoustic echoes in the high frequency part are suppressed by an adaptive gain unit. The proposed method is well suited when extending the bandwidth of an existing hands-free phone. A real-time implementation of a conventional hands-free phone is compared with a real-time implementation according to the proposed method, where the later is an extended version of the first. The evaluation of the two implementations shows that the proposed method can be used to increase the quality, i.e. extended bandwidth, of a hands-free phone with only a small increase in computational demand.
|
|
| 4. |
|
|
| 5. |
- Lindström, Fredric, et al.
(författare)
-
A Computational Efficient Method For Bandwidth Extension of a Conference Phone
- 2003
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a computationally efficient method for extension of the bandwidth of a conference telephone. The proposed method allows an improvement in quality, i.e. increased bandwidth, at a negligible extra computational cost. This is performed by a combination of an acoustic echo cancellation unit and an adaptive gain unit. The proposed method was implemented in a real-time system. Frequency analysis in combination with subjective tests showed that the proposed method extends the bandwidth with high quality.
|
|
| 6. |
- Lindström, Fredric, et al.
(författare)
-
A Finite Precision LMS Algorithm for Increased Quantization Robustness
- 2003
-
Konferensbidrag (refereegranskat)abstract
- The well known Least Mean Square (LMS) algorithm, or variations thereof are frequently used in adaptive systems. When the LMS algorithm is implemented in a finite precision environment it suffers from quantization effects. These effects can severely degrade the performance of the algorithm. This paper proposes a modification of the LMS algorithm that reduces the impact of quantization at virtually no extra computational cost. The paper contains an off-line evaluation of a system identification scheme where the presented algorithm outperforms the classical LMS algorithm yielding a better modelling of the unknown plant. This approach is well suited for adaptive system identification, e.g. beam-forming, electrocardiography, and echo cancelling.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Lindström, Fredric, et al.
(författare)
-
On audio hands-free design
- 2004
-
Konferensbidrag (refereegranskat)abstract
- High-quality audio hands-free systems involve rather complex signal processing. The development of such a system is not a straightforward task. This paper proposes a step-by-step approach to the design and implementation of an audio hands-free system. The proposed design method facilitates the implementation process and leads to a robust audio hands-free system solution. The paper also provides an overview of the problems encountered when designing an audio hands-free system. State-of-the-art solutions as well as recently proposed solutions are referred to in addition to the hands-free system design problems.
|
|
| 11. |
|
|
| 12. |
- Lindström, Fredric, et al.
(författare)
-
The two-path algorithm for line echo cancellation
- 2004
-
Konferensbidrag (refereegranskat)abstract
- The two-path algorithm is an algorithm for line echo cancellation based on two parallel filters. This paper proposes a modification of the two-path algorithm that improves its performance. In the two-path algorithm a background filter is used for continuously adaptive estimation of the line echo, while a foreground filter is used for the actual cancellation. The coefficients of the background filter are copied into the foreground filter when the background filter is proven to perform better. A robust algorithm for line echo cancellation is thereby achieved. In this paper, the benefits and the drawbacks of the two-path algorithm are evaluated and demonstrated through simulations. A modification is proposed that reduces the negative effects of the two-path algorithm. This modification is compared to the original two-path algorithm. Simulations using real speech signals indicate that the proposed modification can improve the performance of the two-path algorithm. © 2004IEEE.
|
|
