Beeping sound on brushless motor with Arduino zero when OFF.

Hi,
Would someone out there know an answer to my Arduino/Brushless motor problem.
I have a standard BLDC motor and ESC which is controlled via a Arduino Zero, its programmed for 1 min on and 1min off to drive a fan.
The 1 min works well at the desired speed etc then after the delay (oneMinute); constant, the motor shuts off for 1 min but beeps every 2 secs untill it turns on after the next 1 min.
How can I stop this beep??

Vimeo link to video for what the 'Beep is"
https://vimeo.com/337397830

cheers
jason

My sketch code is:

const long oneSecond = 1000;  // a second is a thousand milliseconds
const long oneMinute = oneSecond * 60;
const long threeMinute = oneMinute * 3;
const long oneHour   = oneMinute * 60;
const long twoHour   = oneHour * 2;
const long threeHour = oneHour * 3;

int sensorPin = A0;   // select the input pin for LDR//
int sensorValue = 0;  // variable to store the value coming from the sensor
int speed;

#include <Servo.h>

Servo myservo;

void arm() {
// arm the speed controller, modify as necessary for your ESC
setSpeed(0);
delay(1000); //delay 1 second,  some speed controllers may need longer
}

void setSpeed(int speed){
// speed is from 0 to 100 where 0 is off and 100 is maximum speed
//the following maps speed values of 0-100 to angles from 0-180,
// some speed controllers may need different values, see the ESC instructions
int angle = map(speed, 0, 100, 0, 180);
myservo.write(angle);
}

void setup()
{
Serial.begin(9600);
myservo.attach(9);
arm();
}


void loop()
{
// read the value from the sensor:
sensorValue = analogRead(sensorPin);
Serial.print("LDR light reading of ");
Serial.println(sensorValue); //prints the values coming from the sensor on the screen
//set speed of the fan from ESC after daylight check
if(sensorValue < 2100)
digitalWrite(9,LOW);

else digitalWrite(9,HIGH);
// sweep up from 0 to to set speed (0 to 100 full speed) in 20 seconds
for(speed = 0; speed <= 40; speed += 5) {

setSpeed(speed);
delay(1000);
}

delay(oneMinute); //run the motor for 1 hr
setSpeed(0);

delay(oneMinute); // stop the motor for 1 hr then loop
}

First, anyone else who comments here will yell at you to put your code in code tags.

Next, I can only assume that the speed 0 will just pull the data pin low.
However, the low should be 1 millisecond frequency signal. High is 2 milliseconds just for reference.
The pin being pulled low makes the ESC assume it is not connected to anything. I would try a different library such as: RCArduinoFastLib