AVQA Advanced voice quality assurance system

Non-intrusive voice quality assurance system

Key facts

Non-intrusive quality assurance system
Monitors both IP and RF communications
Automatic recognition of the impairment root cause
Compatible with any ED-137 VCS and radio system
ATC-specific reporting and visualization

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Insightful analytics and detailed monitoring of ATC voice networks

Designed for efficient operation with modern IP-based architecture

AVQA is a non-intrusive voice assurance system that provides many integrated monitoring functions for ATC communications systems. These functions include:

Quality assurance reports to CAA
Type acceptance for new IP systems
Live disturbance information to ACC admin
Voice quality report on ANSP interconnection (e.g. NewPENS)
Network quality reporting

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Features & benefits

Ground-ground voice assurance

Reachability and voice quality monitoring between centers and towers

The AVQA ground-ground assurance monitors and stores quality details about each ground-ground call. In the event of problems, automatic impairment recognition immediately alarms the maintenance team with background information about the root cause. Long-term statistics for MOS, reachability and other parameters also form the basis for annual reports to civil aviation authorities.

**Ground-ground call details** - Detailed information about ground-ground streams with low packet intervals of 10 ms and tolerable jitter.

Air-ground voice assurance

End-to-end voice and radio system monitoring to ensure safe flights

Monitors both functions and the quality of entire air-ground communications systems as well as ATC radios. The statistical analysis reports on VoIP KPIs in line with ED-136 requirements. In the event of an impairment, automated notifications and alarms provide important information for further investigations along with an analysis of the root cause. The system is compatible with any ED-137-compatible radios and VCS systems.

**Air-ground call details** - Clearly structured call details on air-ground calls with indicators and detailed information for every five seconds of each call.

Frequency monitor

Keep track of overall frequency utilization for efficient management

Air navigation service providers must be aware of frequency spectrum availability. The AVQA frequency monitoring function gives the most efficient overview. In addition, impairments such as long-pressed PTT and SQL drops cause immediate alerts, which helps remedy issues faster.

**Frequency utilization monitor** - Real-time utilization monitoring for each channel provides valuable insights when adjusting to a particular load.

Radio channel statistics

Squelch and noise power level monitoring

The AVQA RSSI monitor is a prime example of efficient self-diagnostics. The monitor lets network managers track the RSSI value at every receiver with no additional RF monitoring equipment. This is useful for quickly localizing a faulty receiver or a related issue, such as a misaligned antenna.

**RSSI statistics** - The AVQA RSSI monitor extracts vital RF performance analytics and summarizes them centrally for a clear overview.

Loopback monitor

Insightful closed-loop monitoring of the entire communications chain

The AVQA loopback monitor uses patented techniques for end-to-end checks of voice systems. The AVQA covers the RF in a network and can provide a very broad system overview for the network administrator. As the name suggests, the loopback monitor compares different receiver responses to signals transmitted from ground-based radios.

Non-intrusive monitoring

AVQA probes are connected via TAPs or mirroring ports to the monitored environment. This one-way connection ensures that the monitored environment cannot be influenced. Traffic is analyzed locally on the probes and only summary data (QDRs) are sent back to the AVQA manager.

Available options

Related videos

AVQA – Avertning a crisis on the emergency frequency

02:44

AVQA – Avoiding a crisis on the emergency frequency

A "resolved" radio issue turned out to be far bigger. AVQA revealed severe jitter affecting eleven radios across two sites, including both the main and spare emergency frequency radios. Had a real emergency occurred, controllers might not have been able to respond. AVQA isolated the full scope within hours, safety issue caught in time.

27-Jul-2026

03:10

AVQA – Identifying an ATC hazard

After swapping an old analog radio for a new VoIP one, an ANSP could finally monitor RSSI remotely, and AVQA immediately flagged a high noise floor on multiple frequencies. Engineers traced it to a faulty electric fence around a nearby horse pasture. Turning the fence off confirmed it instantly in AVQA. Case closed.

27-Jul-2026

01:38

AVQA – Quickly pinpointing an interference source

A controller complained about constant squelch on the emergency frequency, 121.500 MHz, with no actual transmissions. AVQA isolated the issue to a single receiver, showing the noise floor rising above the squelch threshold day after day. An on-site investigation found the cause: a defective power supply near the receiver. Case closed.

27-Jul-2026

01:59

AVQA – Uncovering a codec mismatch

A controller calling an airport tower heard nothing but silence, even though every audio packet arrived. The culprit: a codec mismatch. The airport's device sent G.711 A-law while the ANSP device expected µ-law, the very codec the airport itself had proposed. A stark reminder that safety-critical comms can fail silently.

27-Jul-2026

02:22

AVQA – Tracing phantom calls to a defective cable

A customer's DVR kept crashing, and the vendor got the blame. AVQA traced it to "ghost calls," recordings under 100 ms with no audio, amplified by frequency coupling. Searching for short squelch events pinpointed the source: a defective radar cable near the RX antennas causing EMI interference. Mystery solved, DVR saved.

27-Jul-2026

01:29

AVQA – Detecting an interreference with ATC frequencies

During a trial, AVQA picked up unusually high squelch power every morning, a strange pattern the ANSP already knew about. A public radio station's transmitter was interfering with ATC frequencies nearby. The customer had it under control, but was glad to see AVQA could detect and alarm on it too.

27-Jul-2026

01:59

AVQA – Revealing an ED-136 violation

A real deployment showed MOS repeatedly dropping below the ED-136 required threshold of 4.0. AVQA helped drill down to the cause: packet loss and severe jitter. At the call level, 1 in 11 packets was lost, not enough to be obvious to controllers, but enough to flag for the network provider before it became a real problem.

27-Jul-2026

02:22

AVQA – Catching a gateway violating RTP standards

AVQA flagged a strange pattern: perfect voice quality during calls, but a MOS of 1.0 during idle times. Drilling down revealed the gateway sent non-standard keep-alive packets, breaking the sequence numbering RFC 3550 and ED-137 require. Radios saw this as massive packet loss. A clear compliance violation, caught before it caused real harm.

27-Jul-2026

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AVQA Advanced voice quality assurance system

Non-intrusive voice quality assurance system

Insightful analytics and detailed monitoring of ATC voice networks

Features & benefits

Ground-ground voice assurance

Air-ground voice assurance

Frequency monitor

Radio channel statistics

Loopback monitor

Non-intrusive monitoring

Available options

Related downloads

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