Hackrf tcp server

demos/hackrf_tcp_server/Makefile

@@ -0,0 +1,15 @@
+# Simple Makefile for hackrf_tcp_server
+CXX = g++
+CXXFLAGS = -std=c++17 -Wall -O2
+LDFLAGS = -lhackrf
+TARGET = hackrf_tcp_server
+SRC = main.cpp
+
+all: $(TARGET)
+
+$(TARGET): $(SRC)
+	$(CXX) $(CXXFLAGS) -o $(TARGET) $(SRC) $(LDFLAGS)
+
+clean:
+	rm -f $(TARGET)
+

demos/hackrf_tcp_server/README.md

@@ -0,0 +1,259 @@
+# HackRF TCP Server for FLEX Paging
+
+A TCP server that receives paging messages and transmits them using HackRF One with FLEX protocol encoding.
+
+## Features
+
+- **FLEX Protocol Support**: Encodes messages using TinyFlex library
+- **EMR Support**: Automatically sends Emergency Message Resynchronization messages
+- **Flexible Configuration**: Supports both config files and environment variables
+- **Multiple Output Modes**: Debug, verbose, and normal operation modes
+- **Network Binding**: Configurable bind address for network interfaces
+
+## Configuration
+
+The server supports two configuration methods:
+
+### 1. Configuration File (Recommended)
+
+Create a `config.ini` file:
+
+```ini
+# HackRF TCP Server Configuration
+BIND_ADDRESS=127.0.0.1
+PORT=16175
+SAMPLE_RATE=2000000
+BITRATE=1600
+AMPLITUDE=127
+FREQ_DEV=2400
+TX_GAIN=0
+```
+
+### 2. Environment Variables
+
+If `config.ini` doesn't exist, the server will use environment variables:
+
+```bash
+export BIND_ADDRESS="127.0.0.1"
+export PORT="16175"
+export SAMPLE_RATE="2000000"
+export BITRATE="1600"
+export AMPLITUDE="127"
+export FREQ_DEV="2400"
+export TX_GAIN="0"
+```
+
+### Configuration Parameters
+
+| Parameter | Description | Default | Range/Notes |
+|-----------|-------------|---------|-------------|
+| `BIND_ADDRESS` | IP address to bind TCP server to | `127.0.0.1` | Use `0.0.0.0` for all interfaces |
+| `PORT` | TCP port to listen on | `16175` | "page" in phone keypad |
+| `SAMPLE_RATE` | HackRF sample rate (Hz) | `2000000` | Minimum 2MHz for HackRF |
+| `BITRATE` | FSK bitrate (bps) | `1600` | Minimum 1600 for 2FSK FLEX |
+| `AMPLITUDE` | Software amplitude scaling | `127` | Range: -127 to 127 |
+| `FREQ_DEV` | Frequency deviation (Hz) | `2400` | FLEX 2FSK uses ±2400Hz = 4800Hz total |
+| `TX_GAIN` | HackRF hardware gain (dB) | `0` | Range: 0-47 dB |
+
+## Building
+
+```bash
+make clean && make
+```
+
+## Usage
+
+```bash
+./hackrf_tcp_server [OPTIONS]
+```
+
+### Command Line Options
+
+| Option | Description |
+|--------|-------------|
+| `--help`, `-h` | Show detailed help message and configuration info |
+| `--debug`, `-d` | Debug mode: prints raw bytes, creates IQ file, skips transmission |
+| `--verbose`, `-v` | Verbose mode: detailed output with actual transmission |
+
+### Examples
+
+```bash
+# Show help and configuration options
+./hackrf_tcp_server --help
+
+# Run with verbose output
+./hackrf_tcp_server --verbose
+
+# Run in debug mode (no RF transmission)
+./hackrf_tcp_server --debug
+
+# Run with environment variables
+source vars.sh && ./hackrf_tcp_server --verbose
+```
+
+## Message Protocol
+
+Send messages via TCP connection in the format:
+```
+{CAPCODE}|{MESSAGE}|{FREQUENCY_IN_HZ}
+```
+
+### Examples
+
+Using netcat:
+```bash
+# Send a simple message
+echo '001122334|Hello World|925516000' | nc localhost 16175
+
+# Send to different frequency
+echo '123456789|Emergency Alert|929500000' | nc localhost 16175
+
+# Send long message
+echo '555123456|This is a longer message for testing purposes|925516000' | nc localhost 16175
+```
+
+Using telnet:
+```bash
+telnet localhost 16175
+# Then type: 001122334|Test Message|925516000
+```
+
+## EMR (Emergency Message Resynchronization)
+
+The server automatically handles EMR protocol requirements:
+
+- **First Message**: Always sends an EMR message before the first transmission
+- **Idle Timeout**: Sends EMR message if more than 10 minutes have passed since last transmission
+- **Purpose**: Ensures pager receivers maintain proper synchronization
+
+EMR behavior:
+- Debug mode: Shows "Would send EMR messages here" without transmission
+- Verbose mode: Shows detailed EMR transmission progress
+- Normal mode: Sends EMR silently in background
+
+## Debug Features
+
+### Debug Mode (`--debug`)
+- Prints encoded FLEX data in hexadecimal
+- Generates `flexserver_output.iq` file for signal analysis
+- Shows EMR message notifications
+- **Does not transmit RF signals** (safe for development)
+
+### Verbose Mode (`--verbose`)
+- Shows configuration on startup
+- Displays client connection details
+- Reports EMR transmission status
+- Shows sample generation and transmission progress
+- **Performs actual RF transmission**
+
+### IQ File Analysis
+In debug mode, the server creates `flexserver_output.iq` containing the generated I/Q samples. This file can be analyzed with tools like:
+- GNU Radio
+- SDR#
+- GQRX
+- Custom analysis scripts
+
+## Error Handling
+
+The server validates all inputs and provides detailed error messages:
+
+### Capcode Validation
+- Must be valid FLEX capcode format
+- Range checking performed
+- Invalid format returns error to client
+
+### Frequency Validation  
+- Range: 1 MHz to 6 GHz
+- Invalid frequencies rejected with error message
+
+### Message Encoding
+- Uses TinyFlex library for FLEX encoding
+- Encoding errors reported with error codes
+- Buffer overflow protection
+
+## Network Configuration
+
+### Local Access Only (Default)
+```ini
+BIND_ADDRESS=127.0.0.1
+```
+
+### All Network Interfaces
+```ini
+BIND_ADDRESS=0.0.0.0
+```
+
+### Specific Interface
+```ini
+BIND_ADDRESS=192.168.1.100
+```
+
+## Development
+
+### File Structure
+```
+├── main.cpp                 # Main server application
+├── include/
+│   ├── config.hpp          # Configuration management
+│   ├── tcp_util.hpp        # TCP server utilities
+│   ├── hackrf_util.hpp     # HackRF device management
+│   ├── fsk.hpp             # FSK signal generation
+│   ├── flex_util.hpp       # FLEX encoding wrapper
+│   └── iq_util.hpp         # I/Q file utilities
+├── config.ini              # Configuration file
+├── vars.sh                 # Environment variables example
+└── README.md               # This file
+```
+
+### Dependencies
+- libhackrf
+- TinyFlex library
+- Standard C++ libraries
+- POSIX networking
+
+## Troubleshooting
+
+### Common Issues
+
+**Server won't start:**
+- Check if port is already in use: `netstat -ln | grep 16175`
+- Verify bind address is valid
+- Ensure HackRF permissions are correct
+
+**No RF output:**
+- Verify HackRF is connected and detected
+- Check TX_GAIN setting (try increasing from 0)
+- Ensure frequency is within HackRF range
+- Verify antenna is connected
+
+**Connection refused:**
+- Check if server is running
+- Verify port and bind address
+- Test with: `telnet localhost 16175`
+
+**EMR not working:**
+- EMR is automatic - no manual intervention needed
+- Check verbose output for EMR transmission status
+- Verify 10-minute timeout behavior
+
+### Debugging Steps
+
+1. **Test with debug mode:**
+   ```bash
+   ./hackrf_tcp_server --debug
+   ```
+
+2. **Check IQ file generation:**
+   ```bash
+   ls -la flexserver_output.iq
+   ```
+
+3. **Test message format:**
+   ```bash
+   echo '123456789|Test|925516000' | nc localhost 16175
+   ```
+
+4. **Verify configuration:**
+   ```bash
+   ./hackrf_tcp_server --verbose
+   ```

demos/hackrf_tcp_server/config.ini

@@ -0,0 +1,16 @@
+# HackRF TCP Server Configuration
+# This file should be named config.ini
+
+# Network Configuration
+BIND_ADDRESS=127.0.0.1
+PORT=16175
+
+# HackRF Configuration
+SAMPLE_RATE=2000000
+BITRATE=1600
+AMPLITUDE=127
+FREQ_DEV=2400
+TX_GAIN=0
+
+# Comments are supported using # at the beginning of lines
+# Trailing commas in values are automatically removed