How to Monitor VHF and UHF Radio Networks

VHF and UHF Bands

The VHF (Very High Frequency, 30-300 MHz) and UHF (Ultra High Frequency, 300-3000 MHz) bands form the backbone of professional radio communications infrastructure. These frequencies support critical services ranging from aeronautical communications to maritime safety, from emergency services to industrial operations.

The VHF band is particularly valued for its excellent long-distance propagation and ability to overcome natural obstacles.

The aeronautical VHF band operates between 118-137 MHz, while marine VHF uses the 156-174 MHz band to ensure safety at sea. Public and commercial services occupy various portions of the VHF spectrum.

The UHF band, with its superior building penetration and lower susceptibility to atmospheric interference, is ideal for communications in urban and industrial environments. Professional radio systems, public safety networks, and military communications rely on the unique characteristics of UHF propagation.

The Need for VHF and UHF Monitoring

VHF and UHF monitoring is no longer an option but an operational necessity in an increasingly congested radio environment. The explosion of wireless devices, IoT systems, and new radio technologies has created a complex RF environment where interference can emerge without warning.

The main challenges in monitoring these bands include:

• Interference: Malfunctioning devices, unauthorized transmissions, or spurious harmonics can appear randomly, making manual identification nearly impossible without continuous monitoring.
• Degradation: Aging components, oxidized connectors, or damaged cables cause gradual performance losses that go unnoticed until total failure.
• Violations: Out-of-band transmissions or excessive power levels can result in severe penalties and loss of operating licenses.

TP-RFX: The Professional RF Spectrum Analyzer for VHF and UHF

The TP-RFX system represents the evolution of the classic RF spectrum analyzer, with complete coverage from 15 MHz to 2700 MHz, the device simultaneously monitors the entire VHF and UHF spectrum.

Technical Specifications

The -130 dBm sensitivity allows the TP-RFX to detect even the weakest signals, essential for identifying low-level interference that could degrade communications. The 1 kHz frequency resolution ensures precise separation between adjacent channels, particularly critical in marine and aeronautical VHF bands where channel spacing is tight.

The ±10 ppm frequency accuracy is essential for services like aviation, where minor deviations can compromise communication safety.

The automatic resolution bandwidth (3 kHz - 600 kHz) dynamically adapts to the type of signal being analyzed.

Real-Time VHF UHF Scanner

Spectral waterfall: Graphical visualization of RF activity over time, enabling immediate identification of anomalous patterns or interference.

Smart notifications: Automatic alarms based on configurable thresholds for signal level, channel occupancy, or presence of unauthorized signals.

Data Analysis and Reports

When it comes to radio monitoring, finding the problem is only the first step. You also need to understand what caused it and have proof of what happened.

The TP-RFX stores all data for up to 30 days. This means that if someone reports that "the radio wasn't working well last Friday," you can go back and verify what happened at that exact moment. You can check if there was interference, how strong it was, and how long it lasted.

The system's automatic reports are very useful for two reasons. First, when authorities require proof of compliance with radio frequency regulations, there are charts showing signal levels, transmission frequency, and any anomalies. Second, when you need to justify investments to improve the radio system, there's concrete data showing where and when problems occur.

Airport Implementation: Case Study in VHF Monitoring

An international airport implemented a network of 8 TP-RFX units to monitor the entire aeronautical communications VHF spectrum (118-137 MHz).

System Configuration

The units were strategically positioned:

• Two units at the control tower to monitor tower and ground frequencies
• Two units at runway ends to verify approach and departure coverage
• Dedicated units for emergency frequencies (121.5 MHz) and ATIS
• Monitoring of airport service and maintenance frequencies

Operational Results

In the first month of operation, the system identified:

• Interference from illegal taxi radios operating on adjacent frequencies causing occasional disruptions to ground communications. Precise identification enabled authorities to intervene and eliminate the problem.
• VOR antenna degradation detected through variations in the radiation pattern, allowing preventive maintenance before it impacted ILS operations.
• Faulty backup transmitter generating spurious emissions when in standby. The problem, invisible during daily tests, was corrected avoiding potential emergencies.

Alarm Threshold Configuration

The RF spectrum analyzer TP-RFX allows setting different types of alarms:

• Primary alarms: for operational channels: Immediate notification if the signal drops below acceptable minimum.
• Interference alarms: Warning when signals appear where they shouldn't be.
• Maintenance alarms: Alert when something is degrading but still working, so you can intervene before failure

Integration with Existing Systems

The TP-RFX integrates seamlessly into existing infrastructure through:

• Standard protocols: SNMP for NMS integration, REST API for custom applications, Modbus for industrial SCADA systems.
• Power supply: PoE eliminates the need for local power supplies, simplifying deployment in remote locations.
• Centralized management: Unified dashboard to manage multiple units across distributed sites, with user hierarchy and permissions.