Grove-Doppler-Radar: Speed in m/s

Other Hardware Sensors
1

Hello

Has anyone managed to convert the output of the module into m/s? After reading the documentation I'm not sure how this could be done.

Thanks for the help.

Sample-Code:

#include "BGT24LTR11.h"

#ifdef __AVR__
    #include <SoftwareSerial.h>
    SoftwareSerial SSerial(2, 3); // RX, TX
    #define COMSerial SSerial
    #define ShowSerial Serial

    BGT24LTR11<SoftwareSerial> BGT;
#endif

#if defined(ARDUINO_ARCH_RP2040) || defined(ARDUINO_ARCH_RP2350) || defined(ARDUINO_ARCH_RENESAS)
    #include <SoftwareSerial.h>
    SoftwareSerial SSerial(D7, D6); // RX, TX
    #define COMSerial SSerial
    #define ShowSerial Serial

    BGT24LTR11<SoftwareSerial> BGT;
#endif

#if defined(CONFIG_IDF_TARGET_ESP32C3) || defined(CONFIG_IDF_TARGET_ESP32C6) || defined(CONFIG_IDF_TARGET_ESP32S3)
    #define COMSerial Serial0
    #define ShowSerial Serial

    BGT24LTR11<HardwareSerial> BGT;
#endif

#ifdef SEEED_XIAO_M0
    #define COMSerial Serial1
    #define ShowSerial Serial

    BGT24LTR11<Uart> BGT;
#elif defined(ARDUINO_SAMD_VARIANT_COMPLIANCE)
    #define COMSerial Serial1
    #define ShowSerial SerialUSB

    BGT24LTR11<Uart> BGT;
#endif

#ifdef ARDUINO_ARCH_STM32F4
    #define COMSerial Serial
    #define ShowSerial SerialUSB

    BGT24LTR11<HardwareSerial> BGT;
#endif

#if defined(NRF52840_XXAA)
    #ifdef USE_TINYUSB
    #include <Adafruit_TinyUSB.h>
    #endif
    #define COMSerial Serial1
    #define ShowSerial Serial

    BGT24LTR11<Uart> BGT;
#endif

void setup() {
    // put your setup code here, to run once:
    ShowSerial.begin(9600);
    COMSerial.begin(115200);
    BGT.init(COMSerial);
    while (!ShowSerial);
#ifndef ARDUINO_ARCH_RENESAS
    while (!COMSerial);
#endif
    /*
        MODE 0 -->detection target mode
        MODE 1 -->I/Q ADC mode

    */
    while (!BGT.setMode(0));
}

void loop() {
    // put your main code here, to run repeatedly:
    uint16_t state = 0;
    ShowSerial.print("target speed:");
    ShowSerial.println(BGT.getSpeed());
    state = BGT.getTargetState();
    //2 --> target approach
    //1 --> target leave
    //0 --> Not Found target
    if (state == 2) {
        ShowSerial.println("target approach");
    } else if (state == 1) {
        ShowSerial.println("target leave");
    }
    delay(200);
}

Example output:
tagetspeed: 52

2

You could use the general approach to calibrating any sensor, described in this excellent tutorial.

3

Did you see the following, on the page that you gave the link to?

The minimum speed accuracy that the sensor is capable of detecting is 52cm/s, which equals to 0.52m/s, 3.6km/h and 2.23mph. Additionally, the results returned by function getSpeed() are multiples of 52cm/s and are absolute values accordingly.

So:

Example output:
tagetspeed: 52

Target speed = 52 x 0.52m/s = 27.04m/s

4

Mhh, that cant be possible.

20:27:45.753 -> Target speed: 0
20:27:45.753 -> No target detected.
20:27:45.984 -> Target speed: 0
20:27:45.984 -> No target detected.
20:27:46.249 -> Target speed: 52
20:27:46.249 -> No target detected.
20:27:46.480 -> Target speed: 0
20:27:46.480 -> Target approach detected.
20:27:46.711 -> Target speed: 52
20:27:46.711 -> No target detected.
20:27:46.975 -> Target speed: 0
20:27:46.975 -> No target detected.
20:27:47.206 -> Target speed: 0
20:27:47.206 -> No target detected.
20:27:47.437 -> Target speed: 0
20:27:47.437 -> No target detected.
20:27:47.667 -> Target speed: 0
20:27:47.667 -> No target detected.
20:27:47.931 -> Target speed: 0


20:27:50.110 -> Target leaving detected.
20:27:50.340 -> Target speed: 52
20:27:50.340 -> No target detected.
20:27:50.605 -> Target speed: 0
20:27:50.605 -> No target detected.
20:27:50.836 -> Target speed: 0
20:27:50.836 -> No target detected.
20:27:51.067 -> Target speed: 0
20:27:51.067 -> No target detected.
20:27:51.331 -> Target speed: 0
20:27:51.331 -> Target leaving detected.
20:27:51.562 -> Target speed: 52

52 is like no movement. the values

20:27:51.562 -> Target leaving detected.
20:27:51.793 -> Target speed: 263
20:27:51.793 -> Target leaving detected.
20:27:52.057 -> Target speed: 422
20:27:52.057 -> Target leaving detected.
20:27:52.288 -> Target speed: 422
20:27:52.288 -> No target detected.
20:27:52.552 -> Target speed: 422
20:27:52.552 -> No target detected.
20:27:52.783 -> Target speed: 422
20:27:52.783 -> No target detected.

that is a slow rolling football.

and see Seeed_Arduino_DopplerRadar/src/BGT24LTR11.h at master · Seeed-Studio/Seeed_Arduino_DopplerRadar · GitHub

/****************************************************************
        Function Name: setSpeedScope
        Description: Set the detection speed range.
        Parameters: maxspeed,minspeed 0-65535
        Return: 1:success  0:fail
    ****************************************************************/
    uint8_t setSpeedScope(uint16_t maxspeed, uint16_t minspeed);

and this:

The system is able to detect speeds between 0.1 and 3 m/s for the settings mentioned.

Does this mean?
v= (Output-Value/65535)*3

​

5

Answer from grove:
"Just divide speed by 100.0."

6

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