# The NSA Selector Eurorack Module Cheat Sheet
**Manual PDF:** *No direct PDF provided, content referenced from [NSA Selector GitHub Manual/Readme](https://github.com/wenzellabs/the_NSA_selector)*
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## Quick Overview
- The NSA Selector is a unique Eurorack module that acts as a Fast Ethernet (100 Mbps) switch with two front-panel RJ45 Ethernet jacks and a single audio output.
- It does **not** function as a standard audio interface; it does not decode conventional protocols or audio formats. **All Ethernet traffic** passing between the two ports is tapped and converted into audio.
- The audio output reflects the raw binary data (bits) present on the network, not the decoded analog signal.
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## Connections & Controls Reference
| Jack / Control | Type | Function | Voltage Range / Notes |
|----------------------|-----------------|--------------------------------------------------------------------------------------------|--------------------------------------------------------|
| **LAN A (RJ45)** | Input/Output | Ethernet network connection; port 1 (switched with LAN B) | Standard Ethernet; not voltage controlled |
| **LAN B (RJ45)** | Input/Output | Ethernet network connection; port 2 (switched with LAN A) | Standard Ethernet; not voltage controlled |
| **AUDIO OUT** | Output (TS/Mono)| Analog audio output derived from all bits on the network | Line level, 4-bit, 25MS/s (MII), filtered through LPF |
- **No panel controls**: No knobs, buttons, sliders, or toggles are present.
- **No CV inputs or outputs**.
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## Basic Usage Instructions
1. **Patch Network**: Connect two Ethernet devices (computers, hubs, etc.) to LAN A and LAN B ports.
2. **Patch Audio**: Connect AUDIO OUT to desired Eurorack audio input, mixer, or recording interface.
3. **Send/Receive Data**: Any network traffic passing between LAN A and LAN B is mirrored & converted to audio in real time.
- Use ping, file transfers, or any unencrypted/unencrypted data to manipulate the resulting audio.
4. **Creative Patching Tips**:
- Use tools/scripts (included in the GitHub repo) to sequence or generate traffic (e.g., ping different IPs for rhythmic clicks).
- Streaming uncompressed BMP image files" through the network creates audio patterns corresponding to image pixel data.
- You can encode a .wav to raw 4-bit/25MHz (`.nsa` format, delta-sigma modulator needed) for maximum control.
5. **Network Echo/Delay Trick**:
- Use tcpdump or similar commands (see manual) on a computer connected to the network to generate echo-like effects by forwarding/dumping packets.
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## Reference Summary
- **Ethernet Ports (LAN A, LAN B)**: Bi-directional, 100 Mbps Fast Ethernet.
- **Audio Output**: Analog, mono, 4-bit digital interpreted through a DAC and low-pass filter. Output is *not voltage controlled* — purely data driven.
- **No direct voltage or CV integration.**
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### Example tcpdump Commands (for Network Echo):
```sh
tcpdump -ni eth0
tcpdump -nvi eth0
tcpdump -nvi eth0 icmp
tcpdump -nvxi eth0
tcpdump -nxi eth0 not port ssh
Use these on a connected computer to maximize/modify traffic for creative results.
For more documentation/tools:
- NSA Selector GitHub Repository