You are right, Sir. Thank you.
It is sending data now, but PulseIn() still does not seem to work. I am getting zeros and occasionally random numbers. Pin 7 is connected to one of the channels of Spektrum RC receiver. I can control the interval of the output signal there and set it to any value between 1000 and 2000 uS. When we have interval around 2mS, that should be picked by the Arduino, but it is not happening.