Method for pulse width modulation of a radar system

• US 20040004567A1
• Filed: 06/16/2003
• Published: 01/08/2004
• Est. Priority Date: 08/16/2000
• Status: Active Grant

• Current Assignee: ADC GmbH (TE Connectivity Ltd. (United Kingdom))
• Original Assignee: ADC GmbH (TE Connectivity Ltd. (United Kingdom))
• Inventors: Mende, Ralph, Kroeger, Jens, Schumann, Karsten
• Granted Patent: US 6,844,842 B2
• Time in Patent Office: Days
• US Class Current: 342/109
• CPC Class Codes: G01S 13/22 using irregular pulse repetition frequency G01S13/12 takes precedence
• CPC Class Codes: G01S 13/522 using transmissions of interrupted pulse modulated waves

Abstract

Radar systems are used for ascertaining the range to at least one reflecting object present in an observation area and/or for ascertaining the speed of the at least one reflecting object. Such a radar system emits into the observation area successive transmitter pulses having a determined pulse duration, with a determined pulse-repetition frequency as a transmitted signal. The system receives transmitted pulses reflected by the at least one reflecting object of the transmitted signal as a received signal. The disadvantage thereby is, that the method has high signal dynamics, which has an unfavorable effect on the price of the circuit components required for the signal processing. The new method for operating a radar system shall be performable with cost effective means.

In the new system the signal dynamics are reduced by ascertaining the mean power of the received signal and limiting it to a predetermined power range by varying the mean power of the transmitted signal preferably by variation of the pulse repetition frequency and/or the pulse duration of the transmitter pulses.

The method is well suited for operating a motor vehicle range warning system.

Claims

1. A method for operating a radar system for ascertaining the range to at least one reflecting object present in an observation area, and/or for ascertaining the speed of the at least one reflecting object, wherein the radar system emits in a timed sequence and with a determined pulse repetition frequency (tP⁻

1) transmitter pulses having a determined pulse duration (tON) as a transmitted signal (s) into the observation area, and which receives transmitted pulses of the transmitted signal (s), which are reflected by the at least one reflecting object, as received signals, characterized in that the mean power of the received signal (r) is ascertained and limited to a predetermined power range by varying the mean power of the transmitted signal (s).

2. The method of claim 1, characterized in that, in case the mean power of the received signal (r) exceeds an upper power value, the mean power of the transmitted signal (s) is reduced by reducing the pulse repetition frequency (tP⁻

1) and/or the pulse duration (tON) of the transmitter pulses until the mean power of the received signal (r) is smaller than or equal to the upper power value.

3. The method of claim 2, characterized in that, in case the mean power of the received signal (r) falls below a lower power value, the mean power of the transmitted signal (s) is increased by increasing the pulse repetition frequency (tP⁻

1) and/or the pulse duration of the transmitter pulses until the mean power of the received signal (r) is larger than or equal to the lower power value.

4. The method of one of the preceding claims, characterized in that the transmitted pulses are respectively transmitted with a determined carrier frequency that is constant during the pulse duration (tON).

5. The method of claim 4, characterized in that in at least one measuring phase the carrier frequency is successively varied from one transmitted pulse to the next transmitted pulse.

6. The method of one of the preceding claims, characterized in that the range and/or the speed of the at least one reflecting object is ascertained by evaluating the frequency difference and/or the phase difference between the transmitted signal (s) and the received signal (r).