| 1. |
- Magesacher, Thomas, et al.
(författare)
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An adaptive mixed-signal narrowband interference canceller for wireline transmission systems
- 2001
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Ingår i: The 2001 IEEE International Symposium on Circuits and Systems, ISCAS 2001.. - 0780366859 ; , s. 450-453
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Konferensbidrag (refereegranskat)abstract
- Narrowband radio transmitters like radio amateurs and broadcast radio stations are considered to be a serious problem for high-bitrate data transmission over twisted pairs. Due to its high power level, radio frequency interference (RFI) has the potential of overloading the receiver's analog-to-digital converter (ADC). Once the ADC is in saturation, any countermeasure taken in the digital domain will fail, so the problem has to be faced at least partly in the analog domain. This paper proposes an adaptive, mixed-signal, narrowband interference canceller employing a modified recursive least-squares (RLS) algorithm which is split into an analog and a digital part. The mixed-signal approach enables the circuit to generate an interference-cancelling signal of several MHz while operating the adaptive algorithm at some kHz. The structure is fast enough to prevent the ADC from overloading due to radio amateur interference, thus protecting the data transmission from interruption. Simulation results as well as measurements indicate a practical disturbance rejection potential of about 40-50 dB
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| 2. |
- Nilsson, Rickard, et al.
(författare)
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Radio frequency interference suppression in DSL
- 2006
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Ingår i: Fundamentals of DSL technology. - Boca Raton, Fl. : Auerbach publ.. - 9780849319136 ; , s. 399-450
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Werner, Karl, et al.
(författare)
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Moving the PAR reduction criterion into the line driver
- 2015
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Ingår i: European Signal Processing Conference. - : European Signal Processing Conference, EUSIPCO. ; , s. 1939-1942, s. 1939-1942
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Konferensbidrag (refereegranskat)abstract
- Traditionally, Peak to Average Ratio (PAR) reduction in digital subscriber line (DSL) transmitters focuses on a digital-domain signal, either at the output of the baseband processing block or at the input of the digital-to-analogue converter (DAC). However, analysis of a DSL transceiver shows that the power dissipation is highly dependent on the PAR at a certain node inside the line driver. Thus, in order to be fully effective, the algorithm design should include the power amplifier dynamics. A typical, actively terminated, line driver is analysed and a model is constructed for PAR reduction purposes. The PAR reduction algorithm is then extended to take advantage of the model. Simulations show that algorithms which are designed to reduce PAR at the new, physically motivated, node obtain about 0.5 dB lower PAR evaluated at this node compared to methods that focus on the PAR of the DAC input.
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| 4. |
- Ödling, Per, et al.
(författare)
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An approach to analog mitigation of RFI
- 2002
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Ingår i: IEEE Journal on Selected Areas in Communications. - 1558-0008. ; 20:5, s. 974-986
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Tidskriftsartikel (refereegranskat)abstract
- Among all noise sources present in wireline transmission systems we focus on one special type: narrowband radio frequency interference generated by radio amateurs (HAM) and broadcast radio stations. This disturbance, characterized by high power and narrow bandwidth, has the potential of overloading the receiver's analog-to-digital converter (ADC). Once the ADC is in saturation, any countermeasure taken in digital domain will fail. A viable way to face this problem is cancellation using the common-mode signal as a reference. This paper describes in detail an adaptive, mixed-signal, narrowband interference canceller employing a modified recursive least-squares algorithm, which is split into an analog and a digital part. The mixed-signal approach enables the circuit to generate an interference-cancelling signal of several MHz while operating the adaptive algorithm at some kilohertz. Simulation as well as measurement results show a steady-state disturbance suppression of about 35 dB. The convergence speed is high enough to protect the ADC from overloading due to time-variant HAM interference.
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| 5. |
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| 6. |
- Magesacher, Thomas, et al.
(författare)
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Longitudinal Signals in DSL
- 2005
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Ingår i: Temporary Document TD 06, 053t06, ETSI STC TM6.
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this contribution is twofold. First, we revisit the longitudinal component (also referred to as common-mode component, asymmetric component or antenna-mode component) occurring at the receive side of a twisted-pair loop. Second, we propose a simple setup for RFI tests that captures reality more accurately than performing differential-mode and common-mode tests separately. In essence, we agree with and support the test environments proposed in [1][2][3]. We stress the fact that differential-mode and common-mode signals should be generated jointly in order to account for their correlation.
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| 7. |
- Magesacher, Thomas, et al.
(författare)
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On the Capacity of the Copper Cable Channel Using the Common Mode
- 2002
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Ingår i: IEEE Global Telecommunications Conference GLOBECOM '02.. - 0780376323 ; 2, s. 1269-1273
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Konferensbidrag (refereegranskat)abstract
- The common-mode (CM) signal in wireline transmission systems has proven to provide valuable information exploited for mitigating narrowband noise at the receive side. We focus on the case of broadband noise. Treating the CM signal as an additional receive signal, we investigate the capacity of the copper cable channel for different levels of coordination among the users. We introduce a channel model which includes the common-mode paths and derive a suitable form of the channel capacity formula. CM crosstalk measurement results, essential for evaluation of the channel capacity, are presented. Using the measurement data, exemplary results of capacity gain achievable by CM-aided data transmission over the copper cable are shown.
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| 8. |
- Magesacher, Thomas, et al.
(författare)
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Splitting the Least-Mean-Square Algorithm
- 2002
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Ingår i: Proceedings of the 5th Nordic Signal Processing Symposium.
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Konferensbidrag (refereegranskat)abstract
- The least-mean-square (LMS) algorithm is an adaptation scheme widely used in practice due to its simplicity. In some applications the involved signals are continuous-time. Then, usually either a fully analog implementation of the LMS algorithm is applied or the input data are sampled by analog-to-digital (AD) converters to be processed digitally. A purely digital realization is most often the preferred choice, however, it becomes costly for high-frequency input signals since fast AD converters are needed. In this paper we propose a hybrid analog/digital approach allowing the AD conversion rate to be as low as the update-rate of the LMS algorithm. We demonstrate the advantage of this approach applying it to an interference cancellation problem occurring in wireline communications: the sampling rate of the AD converters is reduced by a factor of 250.
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