# Communication System README

This repository contains a Python-based transmitter/receiver system for sending 40-character text messages over a simulated noisy channel (local or remote server).

---

## Prerequisites

* Python 3.7+
* NumPy

Install dependencies:

```bash
pip install numpy
```

---

## Files

* `encoder.py` — builds codebook and encodes messages.
* `decoder.py` — decodes received samples back into text.
* `channel.py` — local channel simulator.
* `client.py` — client stub to send samples to the remote server.
* `main.py` — main driver: wraps encode → channel → decode, plus performance testing.

---

## Usage

All commands assume you are in the project root directory.

### 1. Test locally for 1 trial

```bash
python3 main.py \
  --message "This is a 40-character test message...." \
  --trials 1 \
  --mode local
```

### 2. Test locally for 500 trials

```bash
python3 main.py \
  --message "This is a 40-character test message...." \
  --trials 500 \
  --mode local
```

### 3. Test on the remote server (1 trial)

This will write `input.txt` and `output.txt` in your working directory.

```bash
python3 main.py \
  --message "This is a 40-character test message...." \
  --trials 1 \
  --mode server \
  --input_file input.txt \
  --output_file output.txt \
  --hostname iscsrv72.epfl.ch \
  --port 80
```

> After running, `input.txt` contains your transmitted samples, and `output.txt` contains the noisy output from the server.

---

## Manual decoding of server output

If you want to decode `output.txt` yourself:

```bash
python3 - << 'EOF'
import numpy as np
import encoder, decoder

# Load noisy samples
Y = np.loadtxt("output.txt")

# Rebuild codebook
C = encoder.make_codebook(r=5, num_blocks=40)

# Decode
msg = decoder.decode_blocks(Y, C)
print("Decoded message:", msg)
EOF
```

---

Feel free to adjust `--trials` or swap between `local` and `server` modes as needed.