RFI Hunting Workflow: Operator Runbook

Radio Frequency Interference hunting is a disciplined operational activity, not an improvised troubleshooting exercise. In complex ground station environments, interference events can originate from internal equipment, nearby terrestrial emitters, distant facilities, or space-based sources, and they often present under time pressure during active passes. An effective RFI hunting workflow provides operators with a repeatable path from detection to isolation without relying on intuition or guesswork. A runbook approach ensures that early actions preserve evidence rather than destroying it through uncontrolled changes. It also creates consistency across shifts, experience levels, and sites. Without a structured workflow, teams often jump ahead to spectrum coordination or hardware replacement before validating basic assumptions. This page presents an operator-focused RFI hunting runbook that prioritizes methodical progression, evidence capture, and safe escalation, enabling faster resolution and stronger coordination across technical and organizational boundaries.

Why an RFI Runbook Is Essential
Trigger Conditions and Initial Detection
Step 1: Stabilize and Preserve Evidence
Step 2: Confirm Impact and Scope
Step 3: Rule Out Internal Causes
Step 4: Characterize the Interference
Step 5: Correlate with Geometry and Time
Step 6: Apply Controlled Isolation Tests
Step 7: Determine Escalation Path
Step 8: Document and Hand Off
When to Stop and Avoid Over-Testing
Common Operator Errors During RFI Events
RFI Hunting Workflow FAQ
Glossary

Why an RFI Runbook Is Essential

RFI events are disruptive precisely because they introduce uncertainty into otherwise deterministic systems. Operators may see symptoms that resemble RF chain faults, modem issues, or backhaul instability, leading to misdirected effort. A runbook provides cognitive offloading under pressure, ensuring that critical steps are not skipped. It also enforces a sequence that preserves observability before changes are made. Consistent workflows make interference events comparable across time and sites, enabling pattern recognition. From a governance perspective, a runbook protects operators by demonstrating due process. Effective RFI hunting is less about brilliance and more about discipline.

Trigger Conditions and Initial Detection

The RFI hunting workflow begins when predefined trigger conditions are met rather than subjective suspicion. These triggers may include unexpected drops in Eb/N0, repeated modem unlocks, unexplained packet loss, or sudden noise floor changes. Automated alarms often provide the first indication, but operator observation remains critical. Initial detection should prompt awareness rather than immediate action. The goal at this stage is recognition, not resolution. Premature intervention risks altering the signal environment. Clear trigger definitions prevent both overreaction and delayed response.

Step 1: Stabilize and Preserve Evidence

The first operational priority during an RFI event is to preserve evidence. Operators should avoid making changes that alter RF conditions unless safety or mission integrity requires it. Spectrum analyzer snapshots, modem statistics, timestamps, and antenna state should be captured immediately. Logging tools should be verified as running correctly. Stabilization may include holding current configurations steady even if performance is degraded. This step ensures that subsequent analysis is based on facts rather than memory. Evidence preservation is the single most valuable early action in interference hunting.

Step 2: Confirm Impact and Scope

Once evidence is preserved, operators should assess the scope of the impact. This includes determining whether the interference affects a single carrier, multiple services, or multiple antennas. Comparing affected and unaffected paths provides critical clues. Operators should check whether the issue is isolated to one frequency band or spans wider spectrum. Understanding scope prevents misclassification and unnecessary escalation. It also informs priority and response urgency. Scope definition turns symptoms into an actionable problem statement.

Step 3: Rule Out Internal Causes

Before assuming external interference, internal sources must be systematically excluded. Operators should review recent configuration changes, maintenance activity, and alarms across the RF chain. Controlled actions such as temporarily disabling local transmitters or switching to reference loads can be highly revealing. Power levels should be checked against known compression margins. Grounding and waveguide integrity should be considered if symptoms correlate with transmission activity. Internal causes account for a significant percentage of suspected RFI cases. Ruling them out early saves time and credibility.

Step 4: Characterize the Interference

Characterization focuses on what the interference looks like rather than where it comes from. Operators should note whether the signal is continuous, intermittent, narrowband, or wideband. Frequency stability, bandwidth, polarization, and amplitude behavior provide strong classification cues. Comparing current spectra to historical baselines is particularly valuable. Characterization should be descriptive, not speculative. This step creates a technical fingerprint that guides next actions. Good characterization narrows the universe of possible causes significantly.

Step 5: Correlate with Geometry and Time

Interference often correlates with antenna pointing, elevation, azimuth, or time of day. Operators should analyze whether symptoms change with satellite motion or antenna slewing. Elevation-dependent behavior may suggest terrestrial emitters or horizon effects. Time-based repetition may indicate scheduled systems such as radars or shared transmitters. Correlation transforms raw observation into hypothesis testing. Logs and visual overlays are especially useful here. Geometry-aware analysis is a hallmark of advanced RFI hunting.

Step 6: Apply Controlled Isolation Tests

Only after characterization should controlled isolation tests be applied. These tests change one variable at a time to observe response, such as polarization rotation or antenna null steering where permitted. Any change must be logged with timestamp and rationale. The goal is confirmation, not elimination, of suspected sources. Operators should avoid stacking multiple changes that obscure cause and effect. Controlled testing provides confidence in conclusions. This step bridges observation and escalation.

Step 7: Determine Escalation Path

Once sufficient evidence is collected, operators must decide whether escalation is required. Internal engineering teams, spectrum management, satellite operators, or regulatory bodies may be involved depending on classification. Escalation without evidence weakens credibility and slows resolution. Operators should summarize findings clearly and objectively. Knowing when to escalate is as important as knowing how. Escalation decisions should be guided by impact, persistence, and confidence level. A disciplined handoff accelerates collaborative resolution.

Step 8: Document and Hand Off

Final documentation ensures that the RFI event contributes to organizational learning. Records should include timeline, symptoms, tests performed, conclusions, and remaining uncertainties. This documentation supports follow-up analysis, coordination, and future pattern recognition. Even unresolved cases benefit from structured records. Hand-off to engineering or coordination teams should be explicit rather than implied. Documentation closes the operational loop. Good records turn one event into future preparedness.

When to Stop and Avoid Over-Testing

One of the most subtle skills in RFI hunting is knowing when to stop testing. Excessive probing can destabilize systems and erase evidence. If isolation tests are no longer producing new insight, escalation is preferable to further experimentation. Operators should resist pressure to “fix something” without clear justification. Over-testing often creates secondary issues that complicate analysis. The runbook exists to prevent this drift. Discipline includes knowing when to pause.

Common Operator Errors During RFI Events

Common errors include changing configurations before capturing data, assuming external interference too early, and failing to log actions precisely. Operators may also chase spectrum visuals without correlating operational impact. Another frequent mistake is escalating too late or too early without sufficient context. These errors are procedural, not technical. Awareness and adherence to a runbook reduce their occurrence. Consistency matters more than speed. RFI hunting rewards patience and structure.