Amplitude is not changing on the receiver side

[josephkirmani]

I am trying to transmit square wave using USRP 2920. If I change the amplitude of square wave in Tx file from 1 to lets say 100. The Tx waveform shows that it is changed but on the receiver side there is no change in the amplitude. Can any body look at my files and guide me why I am not able to see increase in amplitude on Rx file when I increase the amplitude of Square wave on Tx file

Note: I am generating a randon number between 0 to 1. If random no. is greater than 0.5 then the amplitude is 1 or higher but if the random no. is less than 0.5 amplitude will be zero.

Thanks 

JK

[B_Sherm]

Hello,

I have a USRP 2930 at my desk. I noticed the same behavior when running your code as is. When looking at your case structure, you are trying to output a squarewave with an amplitude of approximately 200 Volts. The amplitude to the Square Wave VI is 100 and then you are adding another 100 to the output Square wave. 

When I lowered the amplitude terminal of the of the Square Wave VI, you will see a change in the input ampltude on in the RX.vi. 

The amplitude was not changing on RX because you are reaching the maximum power output of the device.

[josephkirmani]

Thanks for your reply. 

Firstly if I decrease the voltage the receiver amplitude decreases very minute. So when you are decreasing the voltage what value you aare getting at the output. Can you show me the screen shots of Tx and Rx.

Secondly what is the maximum amplitude I can achieve from USRP 2920. I am using LFTX and LFRX daughter boards.

Thanks

JK

[B_Sherm]

Your not going to get a clean squarewave back on the receive side. The USRP uses a local oscillator (LO) so anything it reads will be interpreted as sinusoidal in nature. This is evedent in the screen shots in the attached .zip folder. 

To address your voltage question, assuming your antenna is terminated with a characteristic impedance of 50 Ohms (Zo) and the max power of 100 mW, Power = (approximately) Voltage^2 / Zo

Therefore Voltage = ( Power * Zo ) ^ (1/2) = 2.2 Volts approximately. 

What is your overall application? Why are you concerned about the voltage? What are you testing?