Signal Monitor

Signal Monitor for WaveCap-SDR

This skill provides real-time signal quality metrics from SDR channels, including RSSI, SNR, signal power, and S-meter readings.

When to Use This Skill

Use this skill when:

• Checking signal strength of a tuned station
• Monitoring reception quality over time
• Debugging weak or noisy signals
• Comparing signal quality between antennas
• Verifying that a channel is receiving properly
• Getting S-meter readings (ham radio style)

Available Metrics

Usage Instructions

Step 1: Get Channel Metrics

Use the helper script to get signal metrics:

PYTHONPATH=backend backend/.venv/bin/python .claude/skills/signal-monitor/get_signal_stats.py \
  --channel ch1 \
  --port 8087

Or use curl directly:

# Get extended metrics for a channel
curl http://127.0.0.1:8087/api/v1/channels/ch1/metrics/extended | jq

# Example output:
{
  "channelId": "ch1",
  "rssiDb": -45.2,
  "snrDb": 28.5,
  "signalPowerDb": -22.1,
  "sUnits": "S8",
  "squelchOpen": true,
  "streamSubscribers": 1,
  "streamDropsPerSec": 0.0,
  "captureState": "running",
  "timestamp": 1700000000.0
}

Step 2: Monitor Signal Over Time

Monitor signal quality continuously:

PYTHONPATH=backend backend/.venv/bin/python .claude/skills/signal-monitor/get_signal_stats.py \
  --channel ch1 \
  --monitor \
  --interval 1.0 \
  --duration 60

Step 3: Get Spectrum Snapshot

Get a single FFT spectrum snapshot (without WebSocket):

curl http://127.0.0.1:8087/api/v1/captures/c1/spectrum/snapshot | jq '.centerHz, .sampleRate'

Interpreting S-Meter Readings

API Reference

GET /channels/{chan_id}/metrics/extended

Returns extended signal metrics including S-meter reading.

Response:

{
  "channelId": "ch1",
  "rssiDb": -45.2,
  "snrDb": 28.5,
  "signalPowerDb": -22.1,
  "sUnits": "S8",
  "squelchOpen": true,
  "streamSubscribers": 1,
  "streamDropsPerSec": 0.0,
  "captureState": "running",
  "timestamp": 1700000000.0
}

GET /captures/{cid}/spectrum/snapshot

Returns single FFT spectrum snapshot.

Response:

{
  "power": [-80.1, -78.5, ...],
  "freqs": [90000000, 90000122, ...],
  "centerHz": 90300000,
  "sampleRate": 250000,
  "timestamp": 1700000000.0
}

GET /channels/{chan_id}/metrics/history?seconds=60

Returns time-series of metrics (currently single point).

Common Issues

Issue: No Signal / Low RSSI

Symptoms: RSSI below -90 dB, S0-S1 readings Solutions:

• Check antenna connection
• Verify frequency is correct
• Increase gain in capture settings
• Check for interference

Issue: Low SNR Despite Good RSSI

Symptoms: RSSI is good but SNR is poor (<10 dB) Solutions:

• Reduce gain (may be overloading)
• Check for nearby interference
• Try different antenna
• Enable noise blanker

Issue: Squelch Always Closed

Symptoms: squelchOpen is always false Solutions:

• Lower squelch threshold (more negative dB)
• Check if signal is actually present
• Verify channel offset is correct

Files in This Skill

• SKILL.md: This file - instructions for using the skill
• get_signal_stats.py: Helper script for fetching and displaying signal metrics