KR20190010402A - Radar device using delay - Google Patents

Abstract

A radar apparatus according to an embodiment of the present invention includes a clock generator, a transmitter, a receiver, and a signal processor. The clock generator outputs a transmission clock, outputs a reception clock at a second time point after a delay from a first time point at which the transmission clock is output, and generates a notification signal when the delay has a minimum value. The transmitting unit emits a transmission signal based on the transmission clock. The receiver receives the echo signal corresponding to the transmission signal and generates the first signal corresponding to the echo signal based on the reception clock. The signal processing unit acquires a third point of time having a minimum delay value based on the notification signal and acquires a fourth point of time at which the echo signal is received by the receiving circuit based on the first signal, To obtain data related to the position of the target. Within a period in which the delay between the first and second time points changes, the delay has one of the different values, and the minimum value is the smallest of the different values.

Description

[0001] RADAR DEVICE USING DELAY [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device, and more particularly, to a configuration and a characteristic of a radar device.

The radar device can transmit radio waves and receive reflected waves. The radar device can measure the time from the time when the radio wave is transmitted to the time when the reflected wave is received. The radar device can sense the direction and the position of the object reflecting the transmitted radio wave based on the measured time. The radio waves used in the radar can be a signal of several MHz to tens of GHz band.

Types of radar apparatus include pulse radar apparatus and continuous wave radar apparatus. The pulse radar device can repeatedly transmit a transmission pulse signal and receive an echo signal reflected by the object.

The radar device can perform signal processing in the process of detecting an object. In the course of processing the signals, the signals may include noise due to various factors. Signals containing noise may exhibit inaccurate information. Therefore, there is a need to reduce the noise included in the signals.

The present invention can provide a configuration and operation of a radar device for reducing noise included in signals processed to obtain information.

A radar apparatus according to an embodiment of the present invention may include a clock generator, a transmitter, a receiver, and a signal processor. The clock generator outputs the transmission clock, outputs the reception clock at the second time after the delay from the first time when the transmission clock is output, and generates the notification signal when the delay has the minimum value. The transmitting unit can emit the transmission signal based on the transmission clock. The receiver may receive an echo signal corresponding to the transmission signal and generate a first signal corresponding to the echo signal based on the reception clock. The signal processing unit acquires a third point of time having a minimum delay value based on the notification signal and acquires a fourth point of time at which the echo signal is received by the receiving circuit based on the first signal, To obtain data related to the position of the target. Within a period in which the delay between the first and second time points changes, the delay has one of the different values, and the minimum value may be the smallest of the different values.

According to an embodiment of the present invention, a radar device can obtain accurate information related to the location of an object.

1 is a block diagram showing a radar apparatus according to an embodiment of the present invention.
2 is a block diagram showing a radar apparatus according to an embodiment of the present invention.
3 is a block diagram showing a radar apparatus according to an embodiment of the present invention.
4 is a block diagram illustrating an exemplary method of adjusting delay by the clock generator of FIG.
FIG. 5 is a timing chart showing signals output by the clock generator of FIG. 1 or FIG. 2. FIG.
FIG. 6 is a graph illustrating an exemplary delay of FIG. 5; FIG.
FIG. 7 is an exemplary graph showing the signal of FIG. 1 and the notification signal of FIG. 5;
Fig. 8 is an exemplary graph showing the signal of Fig. 1 and the notification signal of Fig. 5;
9 is a flow chart showing an exemplary method of calculating the distance between a radar device and a target by the radar device of Fig.

In the following, embodiments of the present invention will be described in detail and in detail so that those skilled in the art can easily carry out the present invention.

Hereinafter, the term " transmitted signal " is used. The transmitted signal may refer to a signal radiated from the radar device to sense an object or the like. Hereinafter, the term " echo signal " is used. The echo signal may be a signal reflected by an object or the like and received by a radar device. Hereinafter, the term " pulse " is used. A pulse can mean a signal (e.g., a quadrature wave) that has a magnitude that varies (e.g., vibrates) over a certain time. For example, when the clock has a logical low value or a logical high value, the " pulse of the clock " indicates the logical value of the clock from the time (rising edge of the clock) at which the logical value of the clock changes from the logical low value to the logical high value Quot; may refer to a signal from a logic high value to a logic low value (falling edge of the clock).

1 is a block diagram showing a radar apparatus according to an embodiment of the present invention.

1, the radar apparatus 100 may include a clock generation unit 110, a transmission unit 120, a reception unit 130, and a signal processing unit 140. The receiving unit 130 may include a sampler 131, and an amplifier 132. The radar apparatus 100 may be connected to the transmission antenna 121 and the reception antenna 133. [

The clock generating unit 110 may receive the reference clock CLK from the reference clock generating unit 50. The clock generating unit 110 can generate a clock (hereinafter referred to as a transmission clock) TCLK used to generate a transmission signal in the transmitting unit 120 based on the reference clock CLK. The clock generating unit 110 may generate a clock (hereinafter referred to as a received clock RCLK) used for processing a signal in the receiving unit 130 based on the reference clock CLK. The clock generator 110 outputs the transmission clock TCLK to the transmitter 120 and outputs the reception clock RCLK to the receiver 130. [

Each of the transmission clock TCLK and the reception clock RCLK may periodically have a logic low value or a logic high value. The transmission clock TCLK and the reception clock RCLK may include pulses of a clock that occurs periodically.

The clock generating unit 110 may include a delay locked loop (DLL). The clock generation unit 110 can adjust the delay by the delay locked loop. The delay may mean a time between a time when the transmission clock TCLK is output from the clock generation unit 110 and a time when the reception clock RCLK is output from the clock generation unit 110. [ The delay locked loop may include a Voltage Controlled Delay Line (VCDL). The voltage-controlled delay element can generate pulses with various delays, using the reference clock (CLK).

The delay locked loop can generate the transmit clock (TCLK) using the pulses generated by the voltage controlled delay element. In addition, the delay locked loop can generate the reception clock RCLK delayed by a predetermined time longer than the transmission clock TCLK. Accordingly, the clock generator 110 can adjust the delay using the pulses generated by the voltage-controlled delay elements.

The clock generation unit 110 may start the operation in response to the signal S2 received from the signal processing unit 140. [ The clock generator 110 can acquire information related to the delay (hereinafter, delay information) from the signal S2. The delay information can be used to determine the delay. By way of example, the delay information may include information related to the minimum value of the delay, the delay period, and the difference value between the delays and the like. The delay information will be described in detail with reference to Figs. 5 and 6. Fig. Alternatively, the clock generating unit 110 may start operation based on the delay information stored in advance by receiving power from the user. Hereinafter, the clock generation unit 110 that starts operation in response to the signal S2 will be described.

The clock generation unit 110 can determine the delay based on the delay information. By way of example, the multiplexer can selectively output a pulse of the transmission clock TCLK and a pulse of the reception clock RCLK based on the specific delay by the signal S2. Referring to Figure 4, the delay locked loop is described in more detail. Hereinafter, an embodiment in which the delay is determined by the clock generating unit 110 will be described.

The delay may be related to the detection distance of the radar device 100. For example, the longer the delay, the longer the detection distance of the radar device 100 may be. The shorter the delay, the shorter the detection distance of the radar device 100 can be. The radar device 100 may change the delay by the clock generator 110 to sense objects located at different detection distances.

As will be described with reference to Fig. 5, the delay may have a value that varies repeatedly in a certain period. Within one period, delays corresponding to different times may each have different values. Herein, the minimum delay may mean a delay having the smallest value among the different values that the delay may have within the period of the delay. The delay information may include information related to the minimum delay.

 The clock generator 110 may output a pulse of the reception clock RCLK to the receiver 130 after a minimum delay from the time when the pulse of the transmission clock TCLK is output to the transmission unit 120. [ When the minimum delay is 0, the clock generator 110 can output the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK at substantially the same time.

Thereafter, the clock generating unit 110 may sequentially output the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK based on the delays longer than the minimum delay. For example, the clock generator 110 may output pulses of a transmission clock TCLK and pulses of a reception clock RCLK based on a periodically changing delay " k * DELTAta " (where k is a natural number) . As an example, k may increase for a particular period. After the delay " k * ?ta " reaches the maximum delay (i.e., after the clock generator 110 outputs the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK based on the maximum delay) The generation unit 110 may again output the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK based on the minimum delay. Herein, the maximum delay may mean a delay having the largest value among the different values that the delay may have within the period of the delay. Referring to Figs. 5 and 6, the periodically varying delay is specifically described.

As an example, the clock generator 110 may determine new delays based on the delay information obtained from the signal S2. The clock generating unit 110 may output pulses of the transmission clock TCLK and pulses of the reception clock RCLK based on the newly determined delays. For example, the clock generating unit 110 may output a pulse of the receiving clock RCLK to the receiving unit 130 after a newly determined delay from the time when the transmitting unit 120 outputs the pulse of the transmitting clock TCLK.

The clock generating unit 110 may output the notification signal DLF related to the delay to the signal output unit 140. For example, when the clock generator 110 outputs the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK based on the minimum delay, the clock generator 110 transmits the time corresponding to the minimum delay to the signal output unit 140 A notification signal DLF may be output. Alternatively, when the delay is changed, the clock generator 110 may output a notification signal DLF indicating n-bit data in order to transmit the data related to the changed delay to the signal output unit 140. Referring to Fig. 5, exemplary notification signals that are output according to a delay are described.

The transmission unit 120 can receive the transmission clock TCLK from the clock generation unit 110. The transmission section 120 can emit the transmission signal 11 and the transmission signal 13 based on the transmission clock TCLK. Transmitter 120 may include an oscillator or the like to emit transmit signals 11 and 13.

In FIG. 1, the transmission signal 11 and the transmission signal 13 are shown as separate signals, but the transmission signal 11 and the transmission signal 13 are signals included in one transmission signal. Therefore, the transmission antenna 123 emits the transmission signal 11 and the transmission signal 13 at substantially the same time. For convenience of explanation, the transmission signal 11 and the transmission signal 13 are described as separate signals.

The oscillator can generate the oscillated signal based on the transmission clock TCLK. As an example, an oscillator may generate a signal having a reference frequency in response to a pulse of an applied transmission clock TCLK. By way of example, the signal generated at the oscillator may comprise a sine wave of the reference frequency. The transmission unit 120 may emit the transmission signals 11 and 13 through the transmission antenna 121 based on a signal generated by the oscillator.

The transmission unit 120 can radiate the transmission signal 11 to the target 10. [ The transmission signal 11 can be reflected by the target 10. [ The echo signal 12 may be received from the transmitted signal 11 reflected by the target 10. [ Thus, the echo signal 12 may represent data associated with the target 10. By way of example, the echo signal 12 may be related to the position and velocity of the target 10, and so on. The echo signal 12 may be received from the target 10 to the receiving unit 130. [ The detection distance corresponding to the echo signal 12 may be the distance between the radar device 100 and the target 10. [ The distance between the radar device 100 and the target 10 may be substantially the same as the distance between the transmitting antenna 121 and the target 10 and the distance between the receiving antenna 133 and the target 10. [

Alternatively, the transmission unit 120 may emit the transmission signal 13. The reception antenna 133 can directly receive the transmission signal 13 from the transmission antenna 121. [ Therefore, the detection distance corresponding to the transmission signal 13 may be zero.

The receiving unit 130 may receive the receiving clock RCLK from the clock generating unit 110. The receiving unit 130 can receive the echo signal 12 corresponding to the transmission signal 11 through the receiving antenna 133. [ Alternatively, the receiving unit 130 may receive the transmission signal 13 through the receiving antenna 133. [ The reception antenna 133 can output the echo signal 12 and the signal RS1 generated from the transmission signal 13 to the amplifier 132. [

Amplifier 132 may receive signal RS1 from receive antenna 133. [ The amplifier 132 may amplify the received signal RS1. By way of example, the amplifier 132 may comprise a Low Noise Amplifier (LNA). The low noise amplifier may be implemented by a parametric amplifier, a field effect transistor amplifier, a tunnel diode amplifier, and a traveling noise wave tube amplifier. The amplifier 132 amplifies the signal RS1 and can output the generated signal RS2 to the sampler 131. [

As described above, the signal RS1 is generated based on the echo signal 12 and the transmission signal 13, and the signal RS2 can be amplified based on the signal RS1. Therefore, the characteristics of the signal RS2 may be related to the characteristics of the echo signal 12 and the transmission signal 13. [

The sampler 131 may receive the reception clock RCLK from the clock generation unit 110. [ The sampler 131 may sample the signal RS2 received from the amplifier 132 based on the receive clock RCLK. As an example, the sampler 131 may sample the signal RS2 in response to a pulse of the receive clock RCLK. The sampler 131 may generate the sampled signal S1 based on the signal RS2 and the receive clock RCLK.

As an example, the sampler 131 may sample the signal RS2 in response to the rising edge of the pulse of the receive clock RCLK. At a particular time, the logic value of the receive clock RCLK received by the sampler 131 may change from a logic low value to a logic high value. At a specific time, the sampler 131 can sample the signal RS2 in response to a logical high value of the receive clock RCLK.

The signal S1 is generated based on the signal RS1 and the signal RS1 is generated based on the echo signal 12 and the transmission signal 13, May be associated with the signal (13). Thus, the signal S1 may represent data associated with the target 10 or data associated with the transmitted signal 13. [ As an example, the signal S1 may represent data related to the distance between the radar device 100 and the target 10. [ Alternatively, the signal S1 may indicate data associated with a point of time when the detection distance is zero. The sampler 131 can output the signal S1 to the signal processing unit 140. [

As described above, the clock generating unit 110 may output the notification signal DLF corresponding to the minimum delay to the signal output unit 140. [ In a specific situation, the signal processing section 140 may output a signal S2 for adjusting the delay in response to the notification signal DLF. As an example, the signal processing unit 140 may output the signal S2 to change an area for detection. The signal S2 may indicate delay information. The clock generation unit 110 can acquire the delay information by the signal S2. The clock generating unit 110 can output the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK based on the delay information. Referring to FIG. 7, the operation of the signal processing unit 140 will be described in more detail.

The clock generation unit 110 may output the notification signal DLF indicating the delay information to the signal processing unit 140 when the delay is changed. As an example, the notification signal DLF may represent n-bit data. The signal processing unit 140 can acquire data on the target 10 based on the signal S1 and the notification signal DLF. As an example, the data about the target 10 may be related to the detection distance. For example, the data relating to the target 10 may be related to the distance from the transmitting antenna 121 to the target 10 and the distance from the target 10 to the receiving antenna 133. [ The signal processing unit 140 can calculate the distance between the radar device 100 and the target 10 based on the data related to the target 10. [ Referring to Fig. 8, the operation of the signal processing unit 140 will be described in more detail.

2 is a block diagram showing a radar apparatus according to an embodiment of the present invention.

2, the radar apparatus 100a may include a clock generation unit 110a, a signal processing unit 140a, a transmission unit 120a, and a reception unit 130a. The radar device 100a may be connected to the first transmission antenna 123_1 through the nth transmission antenna 123_n and the first reception antenna 133_1 through the nth reception antenna 133_n. The transmitter 120a may include n oscillators. The receiving unit 120b may include a first sampler 131a_1 to an nth sampler 131a_n and first amplifiers 132a_1 to 132a_n.

The transmitting unit 120a may transmit the transmission signals through the first transmission antenna 123_1 to the nth transmission antenna 123_n. By way of example, the transmitter may transmit the transmission signals oscillated by the n oscillators.

The first to third reception antennas 133_1 to 133_n may receive echo signals generated by the transmission signals. Alternatively, the first to n < th > reception antennas 133_1 to 133_n may directly receive transmission signals from the transmission antennas 121_1 to 121_n. The first reception antenna 133_1 to the n-th reception antenna 133_n may receive the echo signals or the transmission signals to generate the signals RS1_n to RS1_n, respectively.

The first to n < th > amplifiers 132a_1 to 132a_n may receive the signals RS1_n to RS1_n, respectively. The first sampler 131a_1 to the nth sampler 131a_n can sample the signals RS2_n to RS2_n, respectively, based on the received clock RCLK. The first sampler 131a_1 to the nth sampler 131a_n may output the sampled signals S1_1 to S1_n to the signal processing unit 140a.

2 shows an example in which the first sampler 131a_1 to the nth sampler 131a_n receive the same reception clock RCLK, the first sampler 131a_1 to the nth sampler 131a_n may be provided with different two or more Receive clocks. As an example, different receive clocks may be output based on different delays. Receiver 120a may receive different echo signals from targets located at different distances from radar device 100a, respectively. The first sampler 131a_1 to the nth sampler 131a_n may sample the signals RS2_n through RS2_n generated based on different echo signals.

3 is a block diagram showing a radar apparatus according to an embodiment of the present invention. The radar apparatus 200 of FIG. 3 may include at least one of the radar apparatus 100 of FIG. 1 and the radar apparatus 100a of FIG. The clock generator 210 of FIG. 3 may include at least one of the clock generator 110 of FIG. 1 and the clock generator 110a of FIG. The transmitter 220 of FIG. 3 may include at least one of the transmitter 120 of FIG. 1 and the transmitter 120a of FIG. The receiving unit 230 of FIG. 3 may include at least one of the receiving unit 130 of FIG. 1 and the receiving unit 130a of FIG. The signal processing unit 240 of FIG. 3 may include at least one of the signal processing unit 140 of FIG. 1 and the signal processing unit 140a of FIG.

Referring to FIG. 3, the radar device 200 may include a first substrate SB1 and a second substrate SB2. The clock generation unit 210, the transmission unit 220, and the signal processing unit 240 may be disposed on the first substrate SB1. The receiving unit 230 may be disposed on the second substrate SB2. The connection relationship between the clock generation unit 210, the transmission unit 220, the reception unit 230, and the signal processing unit 240 is similar to that described with reference to FIG. 1 and FIG. The configuration and operation of the clock generating unit 210, the transmitting unit 220, the receiving unit 230, and the signal processing unit 240 are similar to those described with reference to FIG. 1 and FIG.

When all the components of the radar apparatus 200 are disposed on one substrate, the transmitting unit 220 may be arranged close to the receiving unit 230. [ When the transmitting unit 220 and the receiving unit 230 are arranged close to each other, the signals generated by the transmitting unit 220 and the signals generated by the receiving unit 230 may cause coupling. The signals generated by the clock generation unit 210, the reception unit 230, and the signal processing unit 240 may include noise due to coupling. The signal processing unit 240 may perform the calculation based on the signal including the noise. Therefore, the signal processing unit 240 may not accurately calculate the delay, the position of the target, and the like.

If the substrate on which the receiver 230 is disposed is different from the substrate on which the clock generator 210, transmitter 220, and signal processor 240 are disposed, the coupling may be reduced. Accordingly, the signal processing unit 240 can accurately calculate the delay, the position of the target, and the like.

4 is a block diagram illustrating an exemplary method of adjusting the delay by the clock generator of FIG.

As described with reference to FIG. 1, the clock generator 110 may include a delay locked loop. In the example of FIG. 4, the clock generator 110 of FIG. 1 may include a delay locked loop 300. The delay locked loop 300 includes a phase frequency detector (PFD) 310, a charge pump 320, a voltage controlled delay line (VCDL) 330, a multiplexer , 340, and a capacitor (LFC).

The phase frequency detector 310 may receive the clock CLKin and the feedback clock FCLK. For example, the clock CLKin may be the reference clock CLK of FIG. The phase frequency detector 310 can output the signal PD corresponding to the phase difference between the clock CLKin and the feedback clock FCLK. For example, the phase frequency detector 310 may output a signal PD indicating the time between the reception of the pulse included in the clock CLKin and the reception of the pulse included in the feedback clock FCLK.

The charge pump 320 may receive the signal PD from the phase frequency detector 310. The charge pump 320 may output the voltage Vc based on the signal PD. The magnitude of the voltage Vc may correspond to the phase difference between the clock CLKin and the feedback clock FCLK. The voltage controlled delay element 330 may receive the voltage Vc.

The capacitor (LFC) may be connected to the charge pump 320 and the voltage controlled delay element 330. The magnitude of the voltage Vc may correspond to the phase difference between the clock CLKin and the feedback clock FCLK.

The voltage-controlled delay element 330 can output a clock delayed by the reference time based on the voltage Vc. As an example, the voltage controlled delay element 330 may include one or more buffers to output a delayed clock.

According to the method described above, the voltage-controlled delay element 330 can output clocks delayed by various times. The voltage-controlled delay element 330 may output the clocks delayed by various times to the multiplexer 340. The multiplexer 340 may selectively output one of the clocks delayed by various times. As an example, the multiplexer 340 may output the clock CLKout.

By way of example, the clock CLKout may be the transmit clock TCLK or the receive clock RCLK of FIGS. The delay locked loop 300 may generate a pulse of the transmit clock TCLK and generate a pulse of the receive clock RCLK after a specific delay. The clock generator 110 of FIG. 1 and the clock generator 110a of FIG. 2 can output the transmission clock TCLK and the reception clock RCLK generated by the delay locked loop 300.

FIG. 5 is a timing chart showing signals output by the clock generator of FIG. 1 or FIG. 2. FIG.

The clock generator 110 of FIG. 1 or the clock generator 110a of FIG. 2 may output the transmission clock TCLK, the reception clock RCLK, and the notification signal DLF of FIG. The notification signal DLF may include at least one of the first notification signal DLF1 and the second notification signal DLF2. Hereinafter, the transmission clock TCLK, the reception clock RCLK, the first notification signal DLF1, and the second notification signal DLF2 output by the clock generation unit 110 of FIG. 1 will be described.

As described with reference to FIG. 1, the clock generation unit 110 may start operation according to a request of the signal processing unit 140. For example, the clock generator 110 may start the operation in response to the signal S2 indicating the delay information. The clock generating unit 110 may obtain the delay information from the signal S2. The clock generating unit 110 can determine the delays based on the delay information. The clock generating unit 110 may output pulses of the transmission clock TCLK and pulses of the reception clock RCLK based on the determined delays.

As an example, the delay information may include information associated with the minimum delay DELTA tmin. The clock generating unit 110 may obtain information related to the minimum delay DELTA tmin from the signal S2. At time t1, the clock generator 110 can output the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK based on the minimum delay DELTA tmin. In the example of FIG. 5, the minimum delay DELTA tmin may be zero.

By way of example, the delay information may be related to the difference between the delay corresponding to time tk and the delay corresponding to time tk-1, where k is an integer equal to or greater than 1 and equal to or less than m. In the example of Fig. 5, from time t1 to time tm, the delay may increase with time. As an example, the delay DELTA tk corresponding to the time tk may be longer than the delay DELTA tk-1 corresponding to the time tk-1.

By way of example, from time t1 to time tm, the difference values between the delays may be substantially the same. As an example, the difference value between the delay DELTA t2 corresponding to the time t2 and the delay DELTA t1 corresponding to the time t1 may be substantially equal to the difference between DELTA t3 corresponding to the time t3 and DELTA t2 corresponding to the time t2. Referring to Figure 6, an embodiment of a varying delay is described in more detail.

At time t1, the clock generator 110 may output a pulse of the first notification signal DLF1 related to the minimum delay to the signal processor 140. [ The signal processing unit 140 can determine the time at which the detection distance is minimum in response to the pulse of the first notification signal DLF1.

At time t1 to time tm, the clock generator 110 may output the pulses of the second notification signal DLF2 to the signal processor 140. [ Each of the pulses of the second notification signal DLF2 may represent data represented by n bits (n is a natural number). The n-bit data may be related to the delay corresponding to the time at which the pulse of the second notification signal DLF2 is output. As an example, the pulse of the second announcement signal outputted at the time tk may indicate the delay DELTA tk.

A specific delay can correspond to a specific detection distance. As described above, the delay from the time t1 to the time tm can be increased. Therefore, between the time t1 and the time tm, the detection distance of the radar device 100 can increase with the increase of the delay. At time tm + 1, the delay decreases again to the minimum delay, so that the detection distance of the radar device 100 can be reduced again.

6 shows the operation of the radar device 100 for detecting an area from a short detection distance to a long detection distance between time t1 and time tm. However, the present invention is not limited to the radar device 100 for detecting variously varying detection distances, All of the embodiments of the operations of the apparatus 100. [

After time tm + 1, the radar apparatus 100 can detect the same area as the detected area from time t1 to time tm. Therefore, after the time tm + 1, the radar apparatus 100 can perform operations similar to the operations performed at the time t1 to the time tm. That is, the delay may vary with a period of time td (hereinafter referred to as a delay period). The delay period can be determined by the signal S2.

Alternatively, after the time tm + 1, the radar apparatus 100 can detect a region different from the detected region from the time t1 to the time tm. For example, the radar apparatus 100 can detect only a specific area included in the detected area from time t1 to time tm. In order to detect a different area, the signal processing unit 140 responds to the pulse of the first notification signal DLF1 and / or the second notification signal, and outputs a signal S2 indicating the new delay information to the clock generation unit 110 ).

In the example of FIG. 5, the delay DELTA t1 may be the minimum delay DELTA tmin. That is, the minimum delay DELTA tmin may be shorter than other delays in the delay period td. The delay DELTA tm may be the maximum delay DELTA tmax within the delay period td. That is, the delay DELTA tmax may be longer than other delays in the delay period td.

Hereinafter, the transmission clock TCLK, the reception clock RCLK, the first notification signal DLF1, and the second notification signal DLF2 output in accordance with the passage of time will be described.

At time t1, the clock generation unit 110 can start operation in response to the signal S2 received from the signal processing unit 140. [ The clock generating unit 110 can output the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK based on the minimum delay DELTA tmin. As an example, the minimum delay DELTA tmin may be zero. Accordingly, the clock generating unit 110 can substantially simultaneously output the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK.

The time at which the pulse of the transmission clock TCLK is output may correspond to the time at which the pulse of the first notification signal DLF1 and / or the pulse of the second notification signal DLF2 are output. For example, the clock generating unit 110 may output a pulse of the first notification signal DLF1 at time t1 when the pulse of the transmission clock TCLK is output. Alternatively, the clock generating unit 110 may output a pulse of the second notification signal DLF2 at time t1. That is, when the logical value of the transmission clock TCLK changes from a logical low value to a logical high value, the clock generation unit 110 generates a pulse of the first notification signal DLF1 and / or a pulse of the second notification signal DLF2 Can be output. The pulse of the second notification signal DLF2 outputted at the time t1 can represent the delay DELTA t1 by n-bit data.

After time t1, the clock generating unit 110 can output the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK based on the delay DELTA t2 determined based on the delay information obtained from the signal S2 have. At time t2, the clock generation unit 110 can output a pulse of the transmission clock TCLK. After a delay? T2 from time t2, the clock generator 110 can output a pulse of the reception clock RCLK. The clock generating unit 110 may output the second notification signal DLF2 pulse. The pulse of the second notification signal DLF2 outputted at the time t2 can represent the delay DELTA t2 by the n-bit data. The delay DELTA t2 may be longer than the delay DELTA t1.

According to a similar method, the clock generator 110 may output pulses of the second notification signal DLF2 after time t3.

At time tm, the clock generator 110 can output a pulse of the transmission clock TCLK. After the delay DELTA tm, the clock generator 110 can output a pulse of the reception clock RCLK. The delay DELTA tm may be the delay DELTA tmax which is the maximum within the delay period td.

In accordance with the delay information obtained from the signal S2, the clock generator 110 can reduce the delay again at time tm + 1. At time tm + 1, the delay DELTA tm + 1 may be the minimum delay DELTA tmin. Therefore, at time tm + 1, the clock generation unit 110 can substantially simultaneously output the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK. At time tm + 1, the clock generator 110 may output at least one of the pulse of the first notification signal DLF1 and the pulse of the second notification signal DLF2.

The signal processing unit 140 can calculate the distance between the radar device 100 and the target 10 based on the first notification signal DLF1 and / or the second notification signal DLF2. 7, a specific method of calculating the distance between the radar device 100 and the target 10 based on the first notification signal DLF1 will be described. 8, a specific method of calculating the distance between the radar device 100 and the target 10 based on the second notification signal DLF2 will be described.

FIG. 6 is a graph illustrating an exemplary delay of FIG. 5; FIG. In the example of FIG. 6, the x-axis can represent the time in units of [s]. and the y-axis can represent a delay ([Delta] t) in units of [s]. The value on the x-axis corresponding to a specific point on the graph can indicate the time at which the pulse of the transmission clock TCLK is output. By way of example, the value on the x-axis may represent the time at which the logical value of the transmit clock TCLK changes from a logical low value to a logical high value.

Referring to FIG. 5 together with FIG. 6, the time at which the pulse of the transmission clock TCLK is output may correspond to the time at which the pulse of the second notification signal DLF2 is output. The time at which the pulse of the transmission clock TCLK is output may be related to the time at which the transmission signal 11 is radiated. Therefore, the time at which the transmission signal 11 is radiated can correspond to the time at which the pulse of the second notification signal DLF2 is output. The value on the x-axis corresponding to a specific point on the graph may be related to the time at which the pulse of the second notification signal DLF2 is output and the time at which the transmission signal 11 is radiated.

The delay DELTA t corresponding to the time t1 may be DELTA t1. In Fig. 6,? T1 may be? T1 in Fig. 5, i.e., the minimum delay? Tmin. Therefore,? T1 may be zero. Accordingly, the clock generator 110 can substantially simultaneously output the pulse of the transmission clock TCLK and the pulse of the reception clock RCLK. At time t1, the logic values of the transmission clock (TCLK) and the reception clock (RCLK) may change from a logic low value to a logic high value.

The delay DELTA t corresponding to the time t2 may be DELTA t2. Accordingly, the clock generator 110 outputs a pulse of the transmission clock TCLK and outputs a pulse of the reception clock RCLK after? T2. At time t2, the logic value of the transmission clock TCLK may change from a logic low value to a logic high value. After? T2 from time t2, the logic value of the receive clock RCLK may change from a logic low value to a logic high value.

According to a similar method, the delay DELTA t in the area shown in the graph can be increased at regular intervals. Thus, the later the time corresponding to the delay within the delay period td, the greater the delay can have. When the intervals between neighboring times are the same, the difference between delays, each corresponding to neighboring times, may be substantially the same. As an example, the time between the time tk and the time tk + 1 may be substantially the same as the time between the time tk + 1 and the time tk + 2. The value obtained by subtracting DELTA tk from DELTA tk + 1 may be substantially equal to a value obtained by subtracting DELTA tk + 1 from DELTA tk + 2. (In the example of Fig. 6, k is an integer of 1 or more and m-2 or less)

As described with reference to Fig. 5, the delay DELTA t may vary similarly for each delay period td. At time tm + 1, the delay? T can again be reduced to a minimum value, i.e., zero. After the time tm + 1, the delay DELTA t can be changed for each delay period td, similar to that described with reference to the graph between the time t1 and the time tm.

6 shows an embodiment in which the difference between the delay DELTA tk corresponding to the time tk and the delay DELTA tk + 1 corresponding to the time tk + 1 is constant according to k, but the present invention is characterized in that the difference between the delay DELTA tk and DELTA tk + lt; RTI ID = 0.0 > k. < / RTI > For example, the difference between the delay and the delay Δtk Δtk + 1 may be predetermined according to the k ^l. As an example, the difference between delay? Tk and delay? Tk + 1 can be constant according to i ^k (where i is a natural number). By way of example, the delay may change after having a uniform value for a particular time interval (i. E., An increase or a decrease of the stairway format).

Although FIG. 6 shows a delay increasing at regular intervals over time, the present invention can include all embodiments of decreasing delay over time.

FIG. 7 is an exemplary graph showing the signal of FIG. 1 and the notification signal of FIG. 5; The signal processing unit 140 can calculate the distance between the radar apparatus 100 and the target 10 based on the signal S1 and the notification signal DLF as described with reference to Fig. A method of calculating the distance between the radar apparatus 100 and the target 10 based on the signal S1 and the first notification signal DLF1 will be described below.

The signal S1 is generated on the basis of the signal RS1 and therefore the signal processing unit 140 controls the operation of the radar apparatus 100 by referring to the graphs of FIG. 1 and FIG. 7 showing the signal RS1 and the first notification signal DLF1. A method of calculating the distance between the target 100 and the target 10 will be described.

At time ta, the receiving section 130 can receive the transmission signal 13 via the receiving antenna 133. [ The reception antenna 133 can generate the signal RS1 based on the transmission signal 13. [ The receiving unit 130 can output the signal S1 based on the signal RS1.

At the time ta and the time tc, the clock generator 110 can output the transmission clock TCLK and the reception clock RCLK based on the minimum delay. That is, the time ta and the time tc can correspond to the minimum delay. By way of example, the delay corresponding to time ta may be delay t1 of FIG. As described with reference to FIG. 5, when the delay is minimum, the clock generator 110 may output a pulse of the first notification signal DLF1. For example, at time ta, the clock generation unit 110 may output the pulse PS1. The pulse PS1 may be a spherical file.

At time tb, the receiver 130 can receive the echo signal 12 via the receive antenna 133. [ The receive antenna 133 may generate the signal RS1 based on the echo signal 12. The signal processing unit 140 can receive the signal S1 corresponding to the signal RS1.

As described with reference to Fig. 1, the echo signal 12 can be received as the transmitted signal 11 is reflected by the target 10. A process in which the transmission signal 11 is transmitted to the target 10, a process in which the transmission signal 11 is reflected by the target, and a process in which the echo signal 12 is received from the target 10, The size and size of the echo signal 12 can be reduced.

The transmission signal 13 may be radiated from the transmission unit 120 through the transmission antenna 121. [ The transmission signal 13 can be received directly from the transmission antenna 121 through the reception antenna 133. [ The transmission distance of the transmission signal 13 (the distance from the transmission antenna 121 to the reception antenna 133) is determined by the transmission distance of the echo signal 12 (the distance from the transmission antenna 121 to the target 10) The sum of the distances from the antenna 133 to the target 10). The shorter the transmission distance of the signal, the less the magnitude of the signal in the transmission process can be. Thus, the magnitude of the transmitted signal 13 may be greater than the magnitude of the echo signal 12.

Since the signal RS1 is generated based on the echo signal 12, the magnitude of the signal RS1 may be related to the magnitude of the echo signal 12. The magnitude of the signal RS1 outputted after the time tb is related to the magnitude of the transmission signal 13 and the magnitude of the signal RS1 outputted after the time ta may be related to the magnitude of the echo signal 12. Therefore, the magnitude of the signal RS1 output after time tb may be smaller than the magnitude of the signal RS1 output after time ta.

An exemplary method of obtaining the distance between the radar apparatus 100 and the target 10 based on the first notification signal DLF1 and the echo signal 12 will be described below. However, the present invention is not limited thereto, and may include all the embodiments for determining the distance between the radar apparatus 100 and the target 10 based on the first notification signal DLF1 and the echo signal 12 .

At time ta, the signal processing unit 140 can receive the pulse PS1 of the first notification signal DLF1 from the clock generation unit 110. [ The signal processing unit 140 can acquire data regarding the time ta from the pulse PS1.

As described above, after time tb, the receiving unit 130 can receive the echo signal 12 through the receiving antenna 133. [ The receive antenna 133 may generate the signal RS1 generated from the echo signal 12. The signal processing unit 140 can receive the signal S1 corresponding to the signal RS1. The signal processing unit 140 can acquire data regarding the time tb from the signal S1 received after time tb.

As an example, the magnitude of the signal RS1 before time tb may be uniform. After time tb, the magnitude of the signal RS1 may increase. As the magnitude of the signal RS1 increases, the magnitude of the signal S1 may also increase. The signal processing unit 140 can determine the time at which the magnitude of the signal S1 starts to increase as the time tb. Since the time tb is related to the time at which the echo signal 12 is received, the signal processing unit 140 can acquire data concerning the time at which the echo signal 12 is received based on the signal S1.

The signal processing unit 140 can obtain the time tx between the time ta and the time tb based on the data on the time ta and the data on the time tb. The signal processing unit 140 can obtain the delay corresponding to the time tb from the time tx.

The clock generation unit 110 can acquire the delay information based on the signal S2. Referring back to FIG. 6, the delay information may be related to the difference between the delay? Tk and the delay? Tk + 1. Further, the difference value between the delay? Tk and the delay? Tk + 1 can be constant according to k. Thus, the clock generation unit 110 can calculate the difference value between the values of the delay corresponding to each of the two times from the time interval between the two times. In the example of Fig. 7, the clock generating unit 110 can calculate the delay corresponding to the time tb based on the delay information, the time ta, and the time tb.

Hereinafter, the target delay may refer to a delay corresponding to a time at which the signal S1 generated based on the echo signal 12 is received by the signal processing unit 140. [ In the example of FIG. 7, the target delay may be a delay corresponding to time tb.

As described with reference to Fig. 1, the transmission unit 120 can emit the transmission signal 11 based on the pulse of the transmission clock TCLK. Therefore, the pulse of the transmission clock TCLK may be related to the time at which the transmission signal 11 is radiated. When the target 10 is located at a specific distance, the receiving unit 130 can generate the signal S1 based on the pulse of the receiving clock RCLK and the echo signal 12. Thus, the pulse of the receive clock RCLK may be associated with the time when the echo signal 12 is received.

The clock generator 110 outputs a pulse of the transmission clock TCLK at time tb and a pulse of the reception clock RCLK after the target delay from time tb. Therefore, the time between the time at which the transmission signal 11 is radiated and the time at which the echo signal 12 is received can correspond to the target delay.

The time between the time at which the transmission signal 11 is radiated and the time at which the echo signal 12 is received may correspond to the detection distance. The detection distance may be related to the distance from the transmission antenna 121 to the target 10 and the distance from the target 10 to the reception antenna 133. [ Thus, the detection distance may correspond to the distance between the radar device 100 and the target 10. [

The signal processing unit 140 may acquire the distance between the radar apparatus 100 and the target 10 in a manner different from the method described above. As described above, the magnitude of the signal RS1 generated from the transmission signal 13 can be larger than the magnitude of the signal RS1 generated from the echo signal 12. Therefore, when the magnitude of the signal RS1 increases by more than the reference magnitude, the signal processing section 140 calculates the magnitude of the signal S1 corresponding to the signal RS1, , That is, data on the time ta.

The signal processing section 140 can acquire data on the time ta from the signal S1 generated based on the signal RS1 which changes after the time ta. Thereafter, the signal processing unit 140 can calculate the distance between the radar device 100 and the target 10 by a method similar to the method using the data relating to the time ta acquired from the first notification signal DLF1.

In the process of generating the signal S1 based on the signal RS1, the signal S1 may include a noise component due to various causes. As an example, as described with reference to Fig. 3, coupling may occur during the generation of signal S1. Signal S1 may include noise due to coupling. Due to the noise component, the signal S1 may represent inaccurate data. Therefore, the data on the time ta obtained from the signal S1 corresponding to the signal RS1 may not be accurate. As an example, the data on the time ta obtained from the signal S1 may represent a time different from the actual time ta.

The first notification signal DLF1 may be directly received from the clock generation unit 110 to the signal processing unit 140. [ The signal transmission path between the clock generation unit 110 and the signal processing unit 140 may be shorter than the signal transmission path between the reception antenna 133 and the signal processing unit 140. Therefore, the first notification signal DLF1 may include less noise components than the signal S1. The data relating to the time ta indicated by the first notification signal DLF1 can accurately represent the time ta with respect to the data relating to the time ta indicated by the signal S1. The signal processing unit 140 can obtain an accurate time (time ta) corresponding to the minimum delay by the first notification signal DLF1. The signal processing unit 140 can acquire an accurate delay corresponding to the time tb based on the obtained time ta.

Fig. 8 is an exemplary graph showing the signal of Fig. 1 and the notification signal of Fig. 5;

The signal processing unit 140 can calculate the distance between the radar apparatus 100 and the target 10 based on the signal S1 and the notification signal DLF as described with reference to Fig. A method of calculating the distance between the radar apparatus 100 and the target 10 based on the signal S1 and the second notification signal DLF2 will be described. The description related to the signal RS1 in Fig. 8 is similar to that described with reference to Fig. 7, and will not be described below.

The signal S1 is generated on the basis of the signal RS1 and therefore the signal processing unit 140 controls the signal processing unit 140 based on the signal RS1 and the second notification signal DLF2, A method of calculating the distance between the target 100 and the target 10 will be described.

As described with reference to FIG. 5, the clock generation unit 110 may output the second notification signal DLF2 every time the delay is changed. The second notification signal DLF2 may include pulses representing n-bit data. The n bits of data represented by the pulse may be associated with a delay corresponding to a particular time. By way of example, the pulse PS2 may be associated with a delay corresponding to time ta.

The signal processing unit 140 can obtain the delay corresponding to the time ta from the pulse PS2. The delay corresponding to time ta may be the minimum delay. By way of example, the delay corresponding to time ta may be the delay? T1 of FIG.

The signal processing unit 140 can obtain the target delay corresponding to the time tb from the pulse PS3. As described with reference to Fig. 7, the time tb may be related to the time at which the echo signal 12 is received. Therefore, the signal processing unit 140 can obtain the target delay corresponding to the time at which the echo signal 12 is received from the pulse PS3.

The signal processing unit 140 can calculate the distance between the radar apparatus 100 and the target based on the target delay. The specific calculation method is similar to that described with reference to FIG. 7, and the description thereof will be omitted.

9 is a flow chart showing an exemplary method by which the distance between a radar device and a target is calculated by the radar device of Fig.

In operation S100, the signal processing unit 140 may generate a signal S2 indicating the delay information to start the operation. By way of example, the delay information may include information such as a minimum delay, difference values between delays, and so on. 9 shows an embodiment of a clock generating unit 110 that starts an operation in response to a signal S2 received from the signal processing unit 140. In the present invention, the clock generating unit 110 And may include an embodiment of a clock generator 110 configured to start operation in accordance with stored delay information.

In operation S105, the signal processing unit 140 may output the signal S2 generated in operation S100 to the clock generation unit 110. [

In operation S110, the clock generation unit 110 can determine the delay based on the signal S2 output in operation S105. As an example, the clock generator 110 may obtain the delay information from the signal S2. The clock generation unit 110 can determine the delay based on the delay information. As an example, the clock generator 110 may increase the delay based on the delay information.

In operation S115, the clock generation unit 110 may generate a pulse of the transmission clock TCLK and a pulse of the reception clock RCLK based on the delay determined in operation S110. As described with reference to FIGS. 1 and 4, the clock generator 110 may include a delay locked loop 300. The clock generator 110 may generate pulses of the transmission clock TCLK and pulses of the reception clock RCLK based on various delays by the delay locked loop 300. [

In operation S120, the clock generator 110 may output the pulse of the transmission clock TCLK generated in operation S115 to the transmission unit 120. [

In operation S125, the clock generation unit 110 may output a pulse of the reception clock RCLK generated in operation S115 to the reception unit 130. [ The clock generation unit 110 may output the reception clock RCLK based on the delay determined in operation S110. For example, the clock generation unit 110 may output the reception clock RCLK to the reception unit 130 after a delay after outputting the transmission clock TCLK in the operation S110.

In operation S130, the clock generation unit 110 may generate the notification signal DLF based on the delay determined in operation S110. For example, the clock generation unit 110 can generate the notification signal DLF whenever the delay is changed. For example, the notification signal DLF output in operation S130 may be the second notification signal DLF2 in FIGS.

In operation S135, the clock generation unit 110 may output the notification signal DLF generated in operation S130 to the signal processing unit 140. [

It has been described that the operations from S115 to S135 are performed sequentially. However, operations S115 to S135 may be performed substantially simultaneously. 5, at time t1, one of the pulse of the transmission clock TCLK, the pulse of the reception clock RCLK, and the pulse of the first notification signal DLF1 and the second notification signal DLF2 is They can be output substantially simultaneously.

In operation S140, the transmission unit 120 may emit the transmission signal 11 based on the transmission clock TCLK output by the clock generation unit 110 in operation S120. As described with reference to FIG. 1, the transmitter 120 may include an oscillator for emitting a transmission signal.

In operation S145, the receiving unit 130 can receive the echo signal 12 corresponding to the transmission signal 11 radiated in operation S140, through the receiving antenna. The transmission signal 11 can be reflected by the target 10. [ The echo signal 12 can be generated as the transmitted signal 11 is reflected by the target 10. [ Thus, the echo signal 12 may represent data associated with the target 10. [ By way of example, the echo signal 12 may represent data related to the position, velocity, and the like of the target 10.

In operation S150, the receiving unit 130 may generate the signal RS1 based on the echo signal 12 received in operation S135. Since the signal RS1 is generated based on the echo signal 12, the signal RS1 can represent data associated with the target 10. [

In operation S155, the receiving unit 130 can amplify the signal RS1 by the amplifier 132. [ The receiving unit 130 may generate the signal RS2 by amplifying the signal RS1. Since the signal RS2 is generated based on the signal RS1, the signal RS2 can represent data associated with the target 10.

In operation S160, the receiving unit 130 may sample the signal RS2 by the sampler 131. [ The sampler 131 can sample the signal RS2 based on the received clock RCLK output in operation S115. The sampler 131 may generate a signal S1 obtained by sampling the signal RS2.

In operation S165, the receiving unit 130 may output the signal S1 generated in operation S160 to the signal processing unit 140. [

The signal processing unit 140 can calculate the distance between the radar apparatus 100 and the target 10 based on the notification signal DLF output in operation S135 and the signal S1 output in operation S165 in operation S170 . For example, the signal processing unit 140 calculates the distance between the radar apparatus 100 and the target 10 based on the notification signal DLF received before the operation of S100, that is, the notification signal DLF corresponding to the minimum delay . Alternatively, the signal processing unit 140 may calculate the distance between the radar apparatus 100 and the target 10 based on the notification signal received in operation S135.

After operation S170, the radar apparatus 100 may again perform the operation S100.

The above description is specific embodiments for carrying out the present invention. The present invention will also include embodiments that are not only described in the above-described embodiments, but also can be simply modified or changed easily. In addition, the present invention will also include techniques that can be easily modified and implemented using the embodiments. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by the claims equivalent to the claims of the present invention as well as the following claims.

100: Radar device
100a: Radar device
300: Delay locked loop

Claims (14)

A clock generator configured to output a transmission clock, to output a reception clock at a second time point after a delay from a first time point at which the transmission clock is output, and to generate a notification signal when the delay has a minimum value;
A transmission unit configured to radiate a transmission signal based on the transmission clock;
A receiving unit configured to receive an echo signal corresponding to the transmission signal and generate a first signal corresponding to the echo signal based on the reception clock; And
Acquires a third time point at which the delay has the minimum value based on the notification signal and acquires a fourth time point at which the echo signal is received by the receiving circuit based on the first signal, And a signal processing unit configured to acquire data related to the position of the target based on the fourth time point,
Wherein the delay has one of different values, and the minimum value is the smallest of the different values, in a period in which the delay between the first point and the second point of time changes. The method according to claim 1,
And the transmitter includes an oscillator configured to generate an oscillated signal based on the transmission clock. The method according to claim 1,
Wherein the signal processor generates a second signal for adjusting the delay,
And the delay and the period are determined based on the second signal. The method according to claim 1,
Wherein the receiver comprises a sampler configured to sample a third signal generated from the echo signal,
Wherein the first signal is obtained by sampling the third signal. The method according to claim 1,
And the clock generating unit includes a delay locked loop configured to generate the transmission clock at the first time point and generate the reception clock at the second time point. 6. The method of claim 5,
Wherein the clock generator adjusts the delay by the delay locked loop and the delay has one of the different values by the delay locked loop. The method according to claim 1,
The fourth time point arrives after the third time point,
And a value corresponding to the fourth time point among the different values is greater than a value corresponding to the third time point among the different values. The method according to claim 1,
Wherein the signal processing unit is configured to acquire the delay corresponding to the fourth time point based on the third time point and the fourth time point and acquire the data based on the delay corresponding to the fourth time point, . The method according to claim 1,
Wherein the transmission unit is connected to a transmission antenna for radiating the transmission signal, and the reception unit is connected to a reception antenna for receiving the echo signal. The method according to claim 1,
And the clock generator is configured to start operation in response to a second signal received from the signal processor. A transmission unit configured to radiate a transmission signal based on a transmission clock output at a first time;
A receiving unit configured to generate a first signal based on a received clock and an echo signal output at a second time point after a delay from the first time point;
A clock generator configured to output the transmission clock and the reception clock, and generate a notification signal related to the delay; And
And a signal processing unit configured to obtain the delay based on the notification signal, and obtain data related to the position of the target based on the delay. 12. The method of claim 11,
Wherein the delay varies with time and has one of different values during a period in which the delay changes. 13. The method of claim 12,
Wherein the delay corresponds to a larger value as the delay corresponding to the delay within the period is delayed. 12. The method of claim 11,
Wherein the notification signal is configured to indicate the delay by one or more bits.

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