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EP-4117243-B1 - AUTOMATIC GAIN CONTROL METHOD, SENSOR, AND RADIO DEVICE

EP4117243B1EP 4117243 B1EP4117243 B1EP 4117243B1EP-4117243-B1

Inventors

  • ZHU, YAN

Dates

Publication Date
20260506
Application Date
20210225

Claims (15)

  1. A method for automatic gain control AGC, applicable in a transmitting and receiving chain (701) of a sensor (700), wherein a radio signal frame transmitted on the transmitting and receiving chain (701) comprises a plurality of continuous unit signals, the plurality of unit signals comprise N test unit signals and at least one scanning unit signal, and the method comprises: step 1) acquiring saturation information of an ith test echo unit signal corresponding to an ith test unit signal, wherein i and N are positive integers, i ≤ N - 1 and 2 ≤ N (S101); step 2) determining an ( i + 1) th preamble gain according to the saturation information of at least one test echo unit signal in first i test echo unit signals (S102); step 3) transmitting, by the transmitting and receiving chain, an ( i + 1) th test unit signal based on the ( i + 1) th preamble gain (S103); step 4) sequentially circulating steps 2) to 3) until i is equal to N - 1; step 5) acquiring saturation information of an Nth test echo unit signal and a power of an output signal of an analog-to-digital converter ADC (702) in the sensor at this moment (S104); step 6) determining a scanning gain based on the saturation information of the Nth test echo unit signal and the power of the output signal of the ADC (S105); and step 7) transmitting the at least one scanning unit signal with the scanning gain and/or receiving a scanning echo unit signal corresponding to the at least one scanning unit signal with the scanning gain (S106).
  2. The method of claim 1, wherein the determining a scanning gain based on the saturation information of the Nth test echo unit signal and the power of the output signal of the ADC (702), comprises: determining whether the transmitting and receiving chain is saturated based on the saturation information of the Nth test echo unit signal; if it is determined that the transmitting and receiving chain is saturated, setting the scanning gain to a default value; and if it is determined that the transmitting and receiving chain is not saturated, determining the scanning gain based on the power of the output signal of the ADC.
  3. The method of claim 2, wherein the default value is a minimum or maximum gain for the transmitting and receiving chain.
  4. The method of claim 3, further comprising: applying left shifting to the output signal of the ADC if an input signal for the ADC is smaller than a pre-defined value when the default value is the maximum gain for the transmitting and receiving chain.
  5. The method of claim 1, wherein the step 3 further comprises receiving, by the transmitting and receiving chain, an ( i + 1) th test echo unit signal based on the ( i + 1) th preamble gain (S103).
  6. The method of claim 2, wherein the determining the scanning gain based on the power of the output signal of the ADC, comprises: determining, based on the power of the output signal of the ADC, the scanning gain by looking up a look-up table and/or by calculation.
  7. The method of claim 1, wherein the acquiring the power of the output signal of the ADC comprises: determining the power of the output signal of the ADC by calculating an average of squared values in the Nth echo unit signal output by the ADC; or designating an absolute value of a preset sequence in a valid period of the Nth echo unit signal output by the ADC as the power of the output signal of the ADC, wherein a largest or a second largest absolute value in the valid period of the Nth echo unit signal output by the ADC is designated as the power of the output signal of the ADC.
  8. The method of claim 1, wherein the sensor comprises at least two transmitting and receiving chains, and the method further comprises: determining a scanning gain for each transmitting and receiving chain; wherein each transmitting and receiving chain transmits and/or receives signals with its own scanning gain; or all transmitting and receiving chains transmit and/or receive signals with a minimum scanning gain.
  9. The method of claim 1, further comprising: dividing the signal frame into the N test unit signals and the at least one scanning unit signal based on the number of unit signals or a frame period of the signal frame; or adding the N test unit signals to an original signal frame to form the signal frame comprising the N test unit signals and the at least one scanning unit signal; wherein the N test unit signals are continuous in the signal frame.
  10. The method of claim 1, wherein for any signal frame, the N test unit signals are at beginning of the signal frame as preamble unit signals; the transmitting and receiving chain, based on the scanning gain, transmits the at least one scanning unit signal in the signal frame and/or receives a scanning echo unit signal corresponding to the at least one scanning unit signal in the signal frame.
  11. The method of claim 1, wherein for any signal frame, the N test unit signals are at end of the signal frame; the transmitting and receiving chain, based on the scanning gain, transmits the at least one scanning unit signal in a next signal frame and/or receives a scanning echo unit signal corresponding to the at least one scanning unit signal in the next signal frame.
  12. The method of claim 1, wherein for any test unit signal, the acquiring the saturation information of the test echo unit signal corresponding to the test unit signal, comprises: counting how many times the transmitting and receiving chain is saturated within a period from start of transmission of the test unit signal to end of receiving of the test unit signal; determining whether the times exceeds a predefined value; if the times exceeds the predefined value, determining the transmitting and receiving chain as saturated; if the times does not exceed the predefined value, determining the transmitting and receiving chain as not saturated.
  13. The method of any one of claims 1 to 12, further comprising: pre-defining a gain setting table; and determining the ( i + 1) th preamble gain and/or the scanning gain by looking up the gain setting table; wherein each echo unit signal is assigned with a gain setting table or all echo unit signals share a same gain setting table.
  14. A sensor (700), comprising: a transmitting and receiving chain (701) for transmitting and receiving radio signals; an ADC (702) for digital processing of received radio signals; and an AGC module (703) for implementing AGC for the transmitting and receiving chain according to any one of claims 1 to 13.
  15. The sensor (700) of claim 14, wherein the transmitting and receiving chain (701) comprises a low noise amplifier LNA, a trans-impedance amplifier TIA, a first variable gain amplifier, and a second variable gain amplifier connected sequentially to process the echo signal; wherein the sensor (700) further comprises a detector, the detector is connected to an output interface of the TIA, an output interface of the first variable gain amplifier and/or an output interface of the second variable gain amplifier, so as to in real time detect the saturation information of the TIA, the first variable gain amplifier and/or the second variable gain amplifier in processing the echo signal; wherein optionally: the detector comprises a first detector, a second detector and a third detector, the first detector is connected to the output interface of the TIA, and the first detector is configured to detect and output first saturation information of the TIA in processing the echo signal; the second detector is connected to the output interface of the first variable gain amplifier to detect and output second saturation information of the first variable gain amplifier in processing the echo signal; and the third detector is connected to the output interface of the second variable gain amplifier to detect and output third saturation information of the second variable gain amplifier in processing the echo signal; wherein the controller is configured to adjust the preamble and scanning gains for the transmitting chain and/or the scanning gain for the receiving chain based on the first saturation information, the second saturation information and the third saturation information, to realize AGC.

Description

This application claims the benefit of and priority to Chinese Patent Application No. 202010136325.8, titled "AUTOMATIC GAIN CONTROL METHOD, SENSOR, AND RADIO DEVICE". TECHNICAL FIELD This disclosure relates to automatic gain control technology, specifically to a method for automatic gain control, a sensor and a radio device. BACKGROUND In sensor (radar for example) applications, due to the changing factors of the shape, size and range of the reflectors (or objects), the signals received by the sensor (echo signals) will change in strength accordingly. However, there is a strength limit for the signals to be received by receiving (RX) chains of a sensor. In other words, there is a maximum received signal strength for the RX chains of a sensor. When the strength of an echo signal exceeds the maximum strength, the signal received by the RX chains will be distorted and therefore the RX chains will be unable to obtain the information of the detected object, which is basically "blind". Similarly, there is a minimum received signal strength for the RX chains of a sensor. When the strength of an echo signal is smaller than the minimum strength, quantization noise is introduced in the signal received by RX chains, which leads to malfunction of the sensor, including missed detection and false detection. US9891311B2 discloses a receiver, including: a tuner receiving an input signal; a signal processor configured to process the input signal; an automatic gain control (AGC) controller configured to: initialize the receiver in a low gain state; determine the presence of a signal; and increase the receiver gain to determine if a weak signal is present prior to a strong signal. US10033367B2 discloses an integrated circuit for saturation detection, which comprises: a plurality of gain components; a plurality of saturation detectors with each saturation detector operably coupled to an output of one of the gain components; a plurality of logic elements with a first input of each logic element associated with an output of one of the saturation detectors; and a controller operably coupled to the plurality of logic elements. The controller is arranged to apply a signal to a second input of individual ones of the plurality of logic elements such that an output of the respective logic element identifies a saturation event of the saturation detector associated with that respective logic element. US20200025874 discloses a method for maximizing surveillance volume in a radar system, which includes determining saturation range probability fsat; determining sensitivity probability fsens; calculating surveillance volume from multiplying the saturation range probability by the sensitivity probability as Vs=fsatfsens; and adjusting the radar system to maximize the surveillance volume. SUMMARY In light of the above-mentioned factors, this disclosure provides a method for automatic gain control (AGC), a sensor and a radio device. By adjusting the gain for transmitting (TX) and receiving (RX) chain based on the saturation information of test echo signals, it is ensured that the power of received signals for object detection is within predefined range. In this way, detection accuracy of the sensor can be improved, and missed detection, false detection and even blinding can be avoided. The invention is defined by the appended claims. BRIFE DESCRIPTION OF THE DRAWINGS For a more complete understanding of the technical solutions in the present disclosure or in prior art, the accompanying drawings to which reference is made to in the following descriptions are briefly described. Obviously, the drawings are only for purpose of illustrating the embodiments described in this disclosure. Those of ordinary skill in the art can acquire other drawings based on the accompanying drawings without creative efforts. Fig. 1 is a flowchart of a method for AGC provided according to an embodiment of this disclosure.Fig. 2 is a block diagram of test echo unit signal processing provided according to an embodiment of this disclosure.Fig. 3 is a schematic of a valid period of a frame provided according to an embodiment of this disclosure.Fig. 4a is a schematic of a signal transmission structure provided according to an embodiment of this disclosure.Fig. 4b is a schematic of another signal transmission structure provided according to an embodiment of this disclosure.Fig. 5a is a block diagram of a radar system provided according to an embodiment of this disclosure.Fig. 5b is schematic of a frequency-modulated continuous wave provided according to an embodiment of this disclosure.Fig. 6 is a flowchart of another method for AGC provided according to an embodiment of this disclosure.Fig. 7 is a schematic structural diagram of a sensor provided according to an embodiment of this disclosure.Fig. 8 is a schematic structural of another sensor provided according to an embodiment of this disclosure.Fig. 9 is a block diagram of a radio device provided according to an embodime