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Apparatus for determining a frequency offset error and receiver based thereon

A device and error technology, applied in the field of Bluetooth receivers, which can solve the problems of positioning deterioration, slowing down the calculation of the offset, and wrong initial values.

Inactive Publication Date: 2006-12-13
NXP BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] A low S / N ratio especially deteriorates the positioning of the searched preamble sequence (e.g. "1010") if it is assumed that a low antenna input signal is being received
In this case, the noise at the front end of the receiver degrades the desired signal
[0010] Another disadvantage of known Bluetooth methods based on the MaxMin algorithm is that the compensation may depend on potentially erroneous historical values
For this reason, frequency demodulation of the signal after activating the regular bluetooth receiver but before the signal burst, will produce wrong initial values ​​for the MaxMin algorithm, and even the use of the known leakage concept, either slows down the offset calculations, or drastically reduce the accuracy of

Method used

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  • Apparatus for determining a frequency offset error and receiver based thereon
  • Apparatus for determining a frequency offset error and receiver based thereon
  • Apparatus for determining a frequency offset error and receiver based thereon

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Embodiment Construction

[0035] The Bluetooth radio receiver 10 according to the invention is designed for GFSK demodulation, in combination with figure 1 and 2 to describe. Such as figure 1 The corresponding Bluetooth receiver 10 shown generally includes an analog front-end section 11 having an antenna filter 12 and a low noise amplifier (LNA) 13 . A quadrature mixer 14 directly following the low-noise amplifier 13 converts directly from RF to LIF (Low Intermediate Frequency, where IF=1 MHz). The baseband I and Q signals (I MIX， OUT and Q MIX，OUT ) is fed to a polyphase filter 15 whose outputs I_NZIF and Q_NZIF are connected to a receiver backend block 16 . The receiver 10 is analog from the front end section 11 up to the comparator 17 . Backend block 16 is digital from comparator 17 onwards. Antenna signal V at input 12.1 of antenna filter 12 天线 , for example, may be a 2.5GHz signal. The baseband I and Q signals (I MIX，OUT and Q MIX，OUT ) may have an average frequency of about 1 MHz.

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PUM

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Abstract

The apparatus (20) for determining a frequency offset error comprises an input (24.1) for receiving a digitally coded frequency demodulated signal (demod lp2). The frequency demodulated signal (demod lp2) is processed by digital means (35) for performing a correlation, and by digital means (36) for performing a minimum-maximum evaluation. In order to determine whether a correlation criterion and a minimum-maximum criterion are fulfilled, the apparatus (20) comprises digital processing means (38) to calculate the current offset of the frequency demodulated signal (demod lp2) and to cancel the current offset if both criteria are fulfilled.

Description

technical field [0001] The present invention relates to a device and a receiver based on the device for determining a frequency offset error in a modulated received signal in a communication system using a frequency modulation scheme (eg Gaussian Frequency Shift Keying, ie GFSK). In particular, the invention is applicable to Bluetooth receivers. Background technique [0002] Many receivers require detection means that enable the receiver to detect preambles or certain delimiters. This is especially important in communication systems where the transmitter and receiver operate in an asynchronous manner. Because the receiver does not know when a signal is expected to have a payload (also referred to herein as a signal burst), a preamble or start delimiter that the receiver can detect is typically placed in front of the payload. [0003] In particular the Bluetooth communication system with a very short preamble phase (only 4 bits) requires very fast programming for the receiv...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L25/06H04L27/14H04L27/152H04L27/00
CPCH04L27/1525H04L25/062H04L27/142H04L2027/003H04L2027/0063H04L2027/0095H04L27/10H04L27/12H04L27/14
Inventor R·E·赖特
Owner NXP BV