An approach to analog mitigation of RFI

Author

Ödling, Per ; Börjesson, Per Ola ; Magesacher, Thomas ; Nordström, Tomas

Author_Institution

Telecommun. Res. Center, Vienna, Austria

Volume

20

Issue

5

fYear

2002

fDate

6/1/2002 12:00:00 AM

Firstpage

974

Lastpage

986

Abstract

Among all noise sources present in wireline transmission systems we focus on one special type: narrowband radio frequency interference generated by radio amateurs (RAM) 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

Keywords

adaptive signal processing; analogue-digital conversion; convergence of numerical methods; digital subscriber lines; interference suppression; least squares approximations; radio broadcasting; radio stations; radiofrequency interference; ADC; RFI; adaptive algorithm; adaptive interference canceller; analog mitigation; analog-to-digital converter; broadcast radio stations; common-mode signal; convergence speed; digital subscriber line; high power disturbance; interference-cancelling signal; mixed-signal approach; mixed-signal interference canceller; modified recursive least-squares algorithm; narrow bandwidth disturbance; narrowband interference canceller; narrowband radio frequency interference; noise sources; overloading; radio amateurs; simulation results; steady-state disturbance suppression; time-variant HAM interference; wireline transmission systems; xDSL; Analog-digital conversion; Bandwidth; Circuits; Interference cancellation; Narrowband; Noise generators; Radio broadcasting; Radio communication countermeasures; Radiofrequency interference; Signal generators;

fLanguage

English

Journal_Title

Selected Areas in Communications, IEEE Journal on

Publisher

ieee

ISSN

0733-8716

Type

jour

DOI

10.1109/JSAC.2002.1007379

Filename

1007379