Speed control brushed dc motor with arduino using radio signal

Using Arduino Programming Questions
2

If you're talking about reading the receiver's servo PWM output, you'll be getting pulseIn values between about 1000uS and 2000uS.
You should be able to convert those using map(), to values between 0 and 255, then use PWM with 'analogWrite()' to control the speed of your DC motor, using a suitable (MOSFET?) driver and separate power supply.

pwmVal = map(pulseWidth, 1000, 2000, 0, 255);