GNU Radio Modulation and Demodulation Demo

1. System Overview

This GNU Radio modulation and demodulation demo combines a HAROGIC T1060 RF transmitter, an R1000 series receiver, a host computer with Gigabit Ethernet, GNU Radio, and the HAROGIC gr-htra module. Using the HTRA: IQ Sink and HTRA: IQ Source blocks, a single GNU Radio flowgraph can generate a baseband signal, modulate and transmit it over RF, receive and demodulate it, and display the results.

The system includes AM, FM, QPSK, and 16QAM examples. The transmitter and receiver form a real RF link through an RF cable and attenuator; the IQ Sink and IQ Source blocks are not connected directly in the flowgraph. For each demo, users can adjust the center frequency, sample rate, decimation factor, symbol rate, output or reference level, and filtering and synchronization parameters.

2. Supported Modulation Schemes

AM FM QPSK 16QAM

3. Demo Screenshots

16QAM transceiver constellation and spectrum view in GNU Radio — Figure 1. 16QAM transceiver, constellation, and spectrum view in GNU Radio.

4. Technical Highlights

A single GNU Radio flowgraph integrates transmission, a real RF link, reception, demodulation, and visualization.
HTRA: IQ Sink sends complex GNU Radio baseband data to the HAROGIC transmitter, while HTRA: IQ Source feeds receiver IQ data into the processing chain.
The demo covers AM and FM analog modulation as well as QPSK and 16QAM digital modulation, illustrating different signal-processing chains.
Users can simultaneously observe the transmit waveform and spectrum, received IQ data, demodulated waveform, and constellation.
The digital demodulation chain includes resampling, RRC matched filtering, AGC, symbol timing recovery, and carrier or phase recovery.
Center frequency, sample rate, decimation factor, symbol rate, and signal levels can be adjusted through variables or QT GUI controls.

Figure 2. 16QAM single-flowgraph transceiver and demodulation chain in GNU Radio.

5. Demo and Development Scenarios

The system is suitable for RF transceiver link integration, GNU Radio modulation and demodulation algorithm prototyping, and gr-htra application development. Developers can use this reference design to quickly build custom signal-generation, demodulation, recognition, and other signal-processing applications.

6. System Requirements

Hardware	Software
HAROGIC T1060 RF transmitter	GNU Radio 3.9 or later
HAROGIC R1000 series receiver (R1090 shown)	HAROGIC `gr-htra` module
Host computer and Gigabit Ethernet interface	Device SDK, drivers, and calibration files
50 Ω RF cable and required attenuators	SGStudio / SAStudio4