ka9q-python 3.7.0

Python interface for ka9q-radio control and monitoring

ka9q-python

General-purpose Python library for controlling ka9q-radio

Control radiod channels for any application: AM/FM/SSB radio, WSPR monitoring, SuperDARN radar, CODAR oceanography, HF fax, satellite downlinks, and more.

Note: Package name is ka9q-python out of respect for KA9Q (Phil Karn's callsign). Import as import ka9q.

Table of Contents

• Features
• Installation
• Getting Started
• Quick Start
• ka9q-radio Compatibility
• Documentation
• Examples
• Use Cases
• License

Features

✅ Zero assumptions - Works for any SDR application
✅ Complete API - All 85+ radiod parameters exposed
✅ Channel control - Create, configure, discover channels
✅ RTP recording - Generic recorder with timing support and state machine
✅ Precise timing - GPS_TIME/RTP_TIMESNAP for accurate timestamps
✅ Multi-homed support - Works on systems with multiple network interfaces
✅ Pure Python - No compiled dependencies
✅ Well tested - Comprehensive test coverage
✅ Documented - Comprehensive examples and API reference included

Installation

pip install ka9q-python

Or install from source:

git clone https://github.com/mijahauan/ka9q-python.git
cd ka9q-python
pip install -e .

Quick Start

Host selection: All examples reference bee1-hf-status.local, which is the default integration test radiod in this repo. Replace it with your own radiod host or set RADIOD_HOST, RADIOD_ADDRESS, or the --radiod-host pytest option when running in other environments.

Listen to AM Broadcast

from ka9q import RadiodControl

# Connect to radiod (default test host: bee1-hf-status.local)
control = RadiodControl("bee1-hf-status.local")

# Create AM channel on 10 MHz WWV
control.create_channel(
    ssrc=10000000,
    frequency_hz=10.0e6,
    preset="am",
    sample_rate=12000
)

# RTP stream now available with SSRC 10000000

Request Specific Output Encoding

from ka9q import RadiodControl, Encoding

control = RadiodControl("bee1-hf-status.local")

# Create a channel with 32-bit float output (highest quality)
control.ensure_channel(
    frequency_hz=14.074e6,
    preset="usb",
    sample_rate=12000,
    encoding=Encoding.F32
)

Monitor WSPR Bands

from ka9q import RadiodControl

control = RadiodControl("bee1-hf-status.local")

wspr_bands = [
    (1.8366e6, "160m"),
    (3.5686e6, "80m"),
    (7.0386e6, "40m"),
    (10.1387e6, "30m"),
    (14.0956e6, "20m"),
]

for freq, band in wspr_bands:
    control.create_channel(
        ssrc=int(freq),
        frequency_hz=freq,
        preset="usb",
        sample_rate=12000
    )
    print(f"{band} WSPR channel created")

Discover Existing Channels

from ka9q import discover_channels

channels = discover_channels("bee1-hf-status.local")
for ssrc, info in channels.items():
    print(f"{ssrc}: {info.frequency/1e6:.3f} MHz, {info.preset}, {info.sample_rate} Hz")

Record RTP Stream with Precise Timing

from ka9q import discover_channels, RTPRecorder
import time

# Get channel with timing info
channels = discover_channels("bee1-hf-status.local")
channel = channels[14074000]

# Define packet handler
def handle_packet(header, payload, wallclock):
    print(f"Packet at {wallclock}: {len(payload)} bytes")

# Create and start recorder
recorder = RTPRecorder(channel=channel, on_packet=handle_packet)
recorder.start()
recorder.start_recording()
time.sleep(60)  # Record for 60 seconds
recorder.stop_recording()
recorder.stop()

Multi-Homed Systems

For systems with multiple network interfaces, specify which interface to use:

from ka9q import RadiodControl, discover_channels

# Specify your interface IP address
my_interface = "192.168.1.100"

# Create control with specific interface
control = RadiodControl("bee1-hf-status.local", interface=my_interface)

# Discovery on specific interface
channels = discover_channels("bee1-hf-status.local", interface=my_interface)

Automatic Channel Recovery

ensure your channels survive radiod restarts:

from ka9q import RadiodControl, ChannelMonitor

control = RadiodControl("bee1-hf-status.local")
monitor = ChannelMonitor(control)
monitor.start()

# This channel will be automatically re-created if it disappears
monitor.monitor_channel(
    frequency_hz=14.074e6,
    preset="usb",
    sample_rate=12000
)

### Channel Cleanup (frequency = 0)

`radiod` removes channels by polling for streams whose frequency is set to `0 Hz`. Always call `remove_channel(ssrc)` (or explicitly set `set_frequency(ssrc, 0.0)` if you build TLVs yourself) when tearing down a stream so the background poller can reclaim it:

```python
with RadiodControl("bee1-hf-status.local") as control:
    info = control.ensure_channel(
        frequency_hz=10e6,
        preset="iq",
        sample_rate=16000
    )

    # ... use channel ...

    control.remove_channel(info.ssrc)  # marks frequency=0

Note: remove_channel() finishes instantly on the client; radiod’s poller typically purges the channel within the next second.

ka9q-radio Compatibility

ka9q-python tracks a specific git commit of ka9q-radio to ensure its protocol definitions (StatusType, Encoding) match the C headers exactly. This prevents subtle bugs from protocol drift between the two projects.

How It Works

File	Role
ka9q_radio_compat	Plain-text pin recording the validated ka9q-radio commit hash
ka9q/compat.py	Importable KA9Q_RADIO_COMMIT constant for deployment tooling
ka9q/types.py	Auto-generated from ka9q-radio's status.h and rtp.h
scripts/sync_types.py	The tool that parses C headers and regenerates types.py
tests/test_protocol_compat.py	Drift test (runs automatically if ../ka9q-radio exists)

Checking for Drift

If you have the ka9q-radio source tree at ../ka9q-radio:

python scripts/sync_types.py --check    # CI mode: exits non-zero on drift
python scripts/sync_types.py --diff     # Preview changes without modifying anything

Syncing After ka9q-radio Updates

python scripts/sync_types.py --apply    # Regenerates types.py, updates pins
git diff ka9q/types.py                  # Review the changes
python -m pytest tests/                 # Verify nothing broke

The --apply mode updates three files atomically:

1. ka9q/types.py — regenerated from the C headers
2. ka9q_radio_compat — updated with the new commit hash
3. ka9q/compat.py — updated with the new commit hash (importable)

For Deployment Tooling

ka9q-update (or any deployment tool) can read the pinned commit to ensure the correct radiod version is running:

from ka9q.compat import KA9Q_RADIO_COMMIT

print(f"This ka9q-python requires ka9q-radio at {KA9Q_RADIO_COMMIT[:12]}")

Running the Drift Test

The pytest drift test runs automatically as part of the test suite:

python -m pytest tests/test_protocol_compat.py -v

It auto-skips if ../ka9q-radio is not present, so CI environments without the C source tree are unaffected.

Documentation

For detailed information, please refer to the documentation in the docs/ directory:

• API Reference: Full details on all classes, methods, and functions.
• RTP Timing Support: Guide to RTP timing and synchronization.
• Architecture: Overview of the library's design and structure.
• Installation Guide: Detailed installation instructions.
• Testing Guide: Information on how to run the test suite.
• Security Considerations: Important security information regarding the ka9q-radio protocol.
• Changelog: A log of all changes for each version.
• Release Notes: Release-specific notes and instructions.

Examples

See the examples/ directory for complete applications:

• High-Level API: ensure_channel() handles the complexity of checking existing channels, creating new ones only when necessary, and verifying configurations.
• Destination-Aware Channels: Support for unique per-application multicast destinations and deterministic IP generation.
• Stream Sharing: Deterministic SSRC allocation allows multiple independent applications to share radiod streams efficiently.
• discover_example.py - Channel discovery methods (native Python and control utility)
• tune.py - Interactive channel tuning utility (Python implementation of ka9q-radio's tune)
• tune_example.py - Programmatic examples of using the tune() method
• rtp_recorder_example.py - Complete RTP recorder with timing and state machine
• test_timing_fields.py - Verify GPS_TIME/RTP_TIMESNAP timing fields
• simple_am_radio.py - Minimal AM broadcast listener
• superdarn_recorder.py - Ionospheric radar monitoring
• codar_oceanography.py - Ocean current radar
• hf_band_scanner.py - Dynamic frequency scanner
• wspr_monitor.py - Weak signal propagation reporter

Use Cases

AM/FM/SSB Radio

• Broadcast monitoring
• Ham radio operation
• Shortwave listening

Scientific Research

• WSPR propagation studies
• SuperDARN ionospheric radar
• CODAR ocean current mapping
• Meteor scatter
• EME (moonbounce)

Digital Modes

• FT8/FT4 monitoring
• RTTY/PSK decoding
• DRM digital radio
• HF fax reception

Satellite Operations

• Downlink reception
• Doppler tracking
• Multi-frequency monitoring

Custom Applications

No assumptions! Use for anything SDR-related.

License

This project is licensed under the MIT License - see the LICENSE file for details.