Floating Pin State on pulseIn line

I am currently building an RC star wars droid. The project (obviously) uses an RC receiver, which sends a pwm signal into the arduino, which combines it with gyro data to determine the PWM output to send the motors. The problem is when the droids electronics are powered on, before the receiver is powered on and connected to the transmitter, the motors move for no apparent reason. The receiver is emitting no pwm value into the arduino, and the gyro's role on motor power was removed completely to see if it was a factor in this issue.

I suspect that when there is no signal on the line into the pulseIn() pin that it is floating, and causing the motors to move before any input is received.

What i was wondering, is if it would work to use INPUT_PULLUP on a pin that is using pulseIn() to read pwm values, or something similar to prevent the pin from floating, or if anybody else has an idea as to what is happening.

The issue is not vital, just annoying, and more than anything i was just curious as to what was happening. Any help is appreciated, thanks!

I'd think that you should use a pull-down resistor, to keep the input at Gnd level. A pull-up instead would try to power the receiver, with no reasonable voltage remaining on the pin.