RTLSDR

RTL SDR

RTL SDRs are one of the cheapest and most generic USB 2.0 Software Defined Radio (SDR) devices on the market while not enough sampling for video has become quite useful for hifi decoding and calibration.

RTL-SDR HiFi-Decode

These 2 GNU Radio Scripts (NTSC/PAL) will automatically connect to the RTL-SDR and use it as an RF input.

Features

• Real-Time Playback

• FLAC 24-bit 48khz

• 8msps 8-bit Unsinged (.u8)

This GNU Radio script is capable of real-time sound playback alongside decoding to a 24-bit 48khz FLAC file and outputting an FM 8msps 8-bit u8 file.

This allows for fine adjusting of HiFi FM tracking before doing a full capture with a CX Card or DdD for example.

Example FLAC File Output

RTL SDR Driver Windows Install

The RTL SDR (and clones) will show up as "Bulk-In, Interface (Interface 0)

Simply select the device, then click install WinUSB.

Zadig Tool Download

Usage

Install GNU Radio Linux / Windows

Connect an RTLSDR to the HiFi Test Point on your VCR.

Simply run GNU radio companion then file --> Open --> Select the NTSC/PAL Script

F6 Will Export the script to a python .py file.

F6 Will run the script.

F7 Will stop the script.

The FM RF output is defined by the File Sink

The FLAC audio output is defined by the Wav File Sink

You need to set the output location, to do this double click on a module and set the location you wish to save your files to, be sure to name them differently each time or the script will overwrite the previous file.

The Scripts

The two .grc GNU radio scripts are provided below.

RTLSDR HiFi NTSC Download

RTLSDR HiFi PAL Download

RTL SDR Sample Rates

The max sample rate of the RTLSDR is 3.2MSPS or 1.6Mhz of bandwidth.

You can change this with the sample_rate module. (Bottom Left)

RTL-SDR Rates In GNU Radio

250000.000000, 1024000.000000, 1536000.000000, 1792000.000000, 1920000.000000, 2048000.000000, 2160000.000000, 2560000.000000, 2880000.000000, 3200000.000000.

Working sample rates for Real-Time HiFi-Decode PAL (GNU Radio)

3 sample rates work with the script before it starts skipping (Tested on Ryzen 5800x)

1 MSPS = 1024000.000000

1.5 MSPS = 1536000.000000

1.9 MSPS = 1920000.000000

Credit

Adam R for creating these scripts and Tony Andersan for R&D.