GNU Radio Companion - BPSK Pulse shaping

How to convert a digital data stream to a baseband analog signal using the built-in constellation modulator block.

Prepared by Dr. Aaron Scher
[email protected]
Oregon Institute of Technology

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(Last updated: Oct 2015)

Download file: BPSK_ModulatorA.grc.

Flow Graph:

BPSK

Output:

BPSK

BPSK

Eye Diagram

You can also create an eye diagram by replacing the repeating vector source with a random binary pattern generator and using a WX Gui Scope Sink. To see the eye pattern set the trigger mode of the WX Gui Scope Sink to "free run" and run the simulation. In the scope plot, turn on Persistance and set analog alpha as close to zero as possible. Below is the flow graph. Note that I included the Channel model block. This way I can see how the eye "closes" with with noise.

FM Radio

Eye diagram. NOISE VOLTAGE = 0.0

eye

Eye diagram. NOISE VOLTAGE = 0.2:

eye

Eye diagram. NOISE VOLTAGE = 0.4:

eye