Generating a constant source for Channel gain/fading estimation

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I am using Labview Communication Design suite for programming USRP RIO.

I want to measure channel gain between RX-TX pair for which I plan to send a stream of 1111111 and see the received envelope( without modulating for now).

Since such source for Sin wave was available I thought of generating 1111 stream using 1= sin(m)/sin(m) as per follwing design or 1= sin(m)-sin(m) +1

The issue is though I can see that the waveform entering USRP as data to be streamed is a DC level but at reception side I am getting a sin wave!!

for TX side being:- 

Receiver USRP should actually receive a faded random channel for transmitted sequence of 111111! I cannot explain the behaviour!

Even the frequency of  Sin wave recived varies with the amplitude of the DC multiplier!

Please help explain the situation.