Solutions · Aeronautical band systems
VHF aeronautical band systems for control towers, airports, and airfields: transmission, reception, and recording.
We design, install, and maintain VHF aeronautical band communication systems for airports and airfields: transceivers, antennas, transmitter and receiver sites, operator positions in the control tower, and recording of every communication. With the Respondr platform we bring the aeronautical band channels and the ground staff radio networks together at the same operator position.
Communication between the control tower and the aircraft travels in the VHF aeronautical band, by voice and on one channel at a time: if that channel degrades, there is no second one. The faults almost always start in the equipment and the lines of the radio system: a corroded connector that reduces radiated power, a transmitter too close to the receiver that lowers its sensitivity, an antenna shadowed by a building that leaves a dead zone in the area to be served.
That is why we treat an aeronautical band system as a complete radio installation: coverage study, antenna positions, separation between the receiver site and the transmitter site where the design calls for it, sizing of filters and lines, operator positions in the control tower, and instrumented measurements before the system enters service. We also handle the authorization paperwork and the frequency assignment.
The typical difficulties of an aeronautical band system.
The three problems we meet most often on an aeronautical VHF system: channel quality, the coexistence of transmission and reception, and traceability of the communications.
One channel, by voice
In the VHF aeronautical band the voice travels in analog form, on one channel at a time: there is no second path to fall back on. Attenuation on the antenna line, or a loss of receive sensitivity, does not stop the system that same day, but it shortens the usable range and loses the more distant communications.
Transmission and reception on the same site
When the transmitter and the receiver work close together, the transmitted signal reduces the receiver’s sensitivity and the receive range shortens. That takes filters sized on the design, antennas spaced apart, and, where the required performance demands it, a receiver site separate from the transmitter site.
Traceability of the communications
After an event you have to listen back to the communications and know which channel they took place on and at what time. We record every channel in service, those in the aeronautical band with the ED-137 protocol, and store the recordings so they stay searchable by time, channel, and message content.
How the aeronautical band radio chain is built.
From the operator position in the control tower to the aircraft: the transmitter and receiver sites, the voice link, and the recording of every communication.
- Control tower
- The operator positions in the tower select the aeronautical band channel and control transmission. The link to the radio equipment at the two sites runs over an IP network.
- Transmitter and receiver sites
- The VHF equipment, the filters, and the antennas are installed at the sites. Separating the receiver site from the transmitter site, where the design calls for it, keeps the transmitter from reducing the receivers’ sensitivity.
- Recording of the communications
- Every channel in service is recorded together. Aeronautical band communications are recorded with the ED-137 protocol and stay searchable by time, channel, and message content.
- Links
- The dashed lines show the voice link with the aircraft and the links between the control tower, the two radio sites, and the recording system.
What an aeronautical band system includes.
The systems we build and the checks we carry out on each one, from the VHF equipment to the as-built documentation.
VHF aeronautical band equipment
- Aeronautical band transceivers installed in the site’s technical room or technical shelter
- A standby unit on every channel, with automatic switchover on failure
- Filters, duplexers, and combiners to put several channels on the same site without interference
- Channel programming and verification of the firmware version of every unit
- Measurement of output power, modulation, and receive sensitivity
Antennas, transmitter and receiver sites
- Transmit and receive antennas on a mast, on a tower, or on the structure of the control tower
- Separation of the receiver site from the transmitter site, where the design calls for it, so the receivers do not lose sensitivity
- Downlead cables, connectors, terminating loads, and surge arresters on the RF lines
- Verification of the installation height and of the obstacles that shadow the area to be served
- Measurement of the standing wave ratio (VSWR) and location of line faults through the distance-to-fault measurement
Operator positions in the control tower
- Positions connected to the radio equipment, with channel selection and transmit control
- Headsets, microphones, loudspeakers, and transmit foot pedals
- Audio management between adjacent positions, with echo and feedback cancellation
- Operator profiles, access control, and integration with the corporate authentication system (SSO)
- Call tests on every channel in service, together with the staff working in the tower
Recording of the communications
- Simultaneous recording of every radio channel in service
- Aeronautical band communications recorded with the ED-137 protocol
- Search of the recordings by time, channel, group, radio ID, and message content
- Configurable data retention and automatic backup of the recordings
- A check that every active channel appears in the recordings, before the system is handed over
Integration with the other radio networks
- Aeronautical band channels and the ground staff’s DMR, TETRA, and VHF/UHF networks brought together at the same operator position with Respondr
- Gateways and interfaces to the radio equipment already installed, which stays in service
- A dispatch console in web and desktop versions for Windows, Linux, and macOS
- A link between the control tower and the control room over an IP network, with TLS 1.3 and AES-256 encryption
- A unified directory of radio and telephone contacts, with direct call and online status
Power supply, continuity, and earthing
- Distribution boards, protection devices, and lines dedicated to the radio equipment at every site
- Uninterruptible power supplies and buffer batteries, sized for the required autonomy
- Bonding of equipment, racks, and antenna supports to the earthing system
- Surge arresters on the RF lines and on the power lines
- A functional test of the installation running without mains power
Maintenance and periodic measurements
- Scheduled visits with measurement of the parameters of equipment, antennas, and lines
- Check of connectors, seals, mechanical fixings, and antenna alignment
- Check of the buffer batteries and the uninterruptible power supplies, with an autonomy test
- Continuous monitoring of the site’s radio carriers with TP-RFX and collection of the alarms in Track-TP
- Call-out on failure within 24 h of the request, with technicians on call around the clock and a written report
Authorizations, acceptance testing, and documentation
- Authorization paperwork and frequency assignment with the competent authorities
- An acceptance report with the acceptance measurements, signed by the technicians who carried them out
- Layout drawings, wiring diagrams, and RF diagrams updated to the system as actually installed
- An equipment register with serial number, installation position, and firmware version
- Training for the operators who use the positions and for the technicians who look after the system
Frequently asked questions.
The questions we are asked most often about this type of system.
Do you need an authorization to transmit in the aeronautical band?
Yes. Aeronautical band frequencies are reserved for the aeronautical service and are assigned by the competent authorities: the equipment enters service only after the assignment. The application covers the radio station as a whole, meaning the equipment, the antennas, the installation site, and the channels requested. We prepare the technical documentation with the equipment and antenna data and handle the application on the customer’s behalf, alongside the design of the system.
How do you notice that an aeronautical band system is losing range?
The fault usually does not show up as a sudden failure. The first sign is that communications with the more distant aircraft come through noisy or are lost, while at short range everything seems fine. The most frequent causes are on the antenna line, for example a corroded connector or moisture ingress, or a loss of receiver sensitivity. Telling them apart takes instrumented measurements: output power, modulation, receive sensitivity, and the standing wave ratio of the line, followed by a distance-to-fault measurement when the value comes out wrong.
Who can listen back to the recordings of the radio communications?
Only the profiles the customer grants that permission to. Access to the recordings is configured by role, together with the other permissions on the platform, and every consultation stays traced: it shows who listened to which communication and when. The retention period is also set by the customer, according to its own procedures: we configure the system accordingly and enable automatic backup of the recordings.
How long does it take to build an aeronautical band system?
There is no single duration that fits every job: it depends on the number of channels, on the work to be carried out at the sites, and on the lead times of the authorities that assign the frequencies, which are not under our control. The authorization paperwork and the equipment supply are the stages with the least predictable timing, while installation, measurements, and acceptance testing are scheduled on fixed dates. After the site survey we hand the customer a works programme with the stages and the dates, and we update it if the authorizations take longer than expected.
Request a proposal for aeronautical band systems.
For every project we provide a tailored technical and commercial proposal based on your requirements — feasibility analysis, RF coverage study, and intervention planning.