Advanced RF Analysis

Advanced RF Analysis

Studys & Writeup's

• Rene Wolf - VHS-decode vs Signal degradation - Nov 2023

Reading RF Waveforms

The cool thing you can do with full RF captures is taking advantage of any SDR or Audio Processing tools on the market for inspecting the waveform.

Import Data

Import -> RAW Data

Byte Order -> Little Eiden

Sample Rate ->

4000000 DdD/MISRC 40MHz/16-bit (10-bits padded to 16-bits)

4000000 Clockgen 40MHz/8-bit

2860000 CXADC 28.6 MHz/8-bit

Legacy CXADC Modes:

3580000 cxadc3 35.8 MHz/8-bit

1430000 10cxadc 14.3 MHz/16-bit

1790000 10cxadc3 17.9 MHz/16-bit

Example of a frame of VHS

Ocenaudio

Download

Cross Platform & Free replacement for similar viewing to adobe audition.

Adobe Audition

View -> Show Spectral Frequency Display (Shift+D)

Inspect Data

Then you can use normal visual inspection to determine if it's signal is too low or too high.

It's recommended to use 8/16bit FLAC compressed or uncompressed 8/16bit captures for this task and set your cache directory to a location with enough space or you will possibly zero-fill a drive.

Audacity

Download

Right-click on the left-hand side to change settings and enable the spectrograph.

You can change the settings according to the sample rate used for the capture.

ld-analyse

ld-analyse allows you to view the values of your .json metadata file with visually assisted graphing.

Black SNR (Signal To Noise Ratio) is your basic quality indicator.

40-50 dB - Great Signal

30-40 dB - Good Signal

20-30 dB - Weak Signal

10-20 dB - Poor Signal

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