Giga Technology Forum

Linear Transponder using a RTL Dongle and HackRF with Gnu Radio. => Linear Transponder using a RTL Dongle and HackRF with Gnu Radio. => Topic started by: Anton Janovsky (ZR6AIC) on May 21, 2018, 08:54:37 pm

Title: How to Create a Linear Transponder using a RTL Dongle and HackRF with Gnu Radio.
Post by: Anton Janovsky (ZR6AIC) on May 21, 2018, 08:54:37 pm
How to Create a Linear Transponder using a RTL Dongle and HackRF with Gnu Radio.
I wanted to test the concept of a linear Transponder and how difficult would it be to build it with conventional components.
(https://4.bp.blogspot.com/-xBzpDAhO55Q/WwLU2u9pcWI/AAAAAAABbq4/M-K38Y6afF4iy5S_hKpn_9TSXV5lVJ8AQCLcBGAs/s400/Lin_transponder_2.png)
Link to Blog with full details here https://www.youtube.com/watch?v=O2FlcrrQaks&t=11s (https://www.youtube.com/watch?v=O2FlcrrQaks&t=11s)
Hardware Configuration
Hardware required to build the Transponder.

    SDR IQ demodulator with rtl dongle (RF In)
    SDR IQ DSP processing system. Gnu Radio (DSP processing)
    SDR IQ Modulator. HackRF (RF Out)
    Background management system. (OBC) for additional telemetry.

Software required for Transponder.

    SDR IQ demodulator. rtl dongle (RF In)
    SDR IQ DSP processing system. Gnu Radio (DSP processing)
    SDR IQ Modulator. HackRF (RF Out)
    Background management system. (OBC)

Video of working Transponder.
https://www.youtube.com/watch?v=O2FlcrrQaks&t=11s (https://www.youtube.com/watch?v=O2FlcrrQaks&t=11s)

Gnu Radio.

Transponder Block Diagram
RTL SDR Block.
RTL-SDR Source
Low Pass Filter Block.
    
Low Pass Filter Block

AGC Block.
AGC Block
Power Squelch.
Power Squelch
Osmocom Sink. (HackRF)
Osmocom Sink (HackRF)
FFT. (Spectrum View of input)
FFT Spectrum View
REF: Power point Slides at AMSAT SA
Ref:Source code is available on Github Version 4
Link to Blog with full details here https://www.youtube.com/watch?v=O2FlcrrQaks&t=11s (https://www.youtube.com/watch?v=O2FlcrrQaks&t=11s)