The technical advantages of the high resolution 2030 DF include extensive BITE facilities, remote control and indication of fault parameters, remote fault diagnosis, remote system testing and a modular, versatile design which allows for expandability as requirements change.

Fernau DF systems provide accurate navigation information including positional data without the need for special airborne or shipborne equipment other than standard VHF or UHF Radio systems.

With nearly 30 years experience and over 500 systems installed world-wide, Fernau now offers the high resolution 2030 DF to meet increasing demands for greater reliability, performance, flexibility, monitoring and control.

The Doppler method for bearing resolution of the 2030 DF is a cost effective method of traffic control and an enhancement to Radar installations, assisting positive identification of contacts in otherwise cluttered air and sea areas. The prime users of the system are therefore the world’s Civil/Military Air Traffic Control authorities; Port/Harbour authorities; Coastguards and The Royal Navy for ship operations.

Fernau has paid particular attention during the development of the 2030 DF to equipment reliability and maintenance aspects. The use of latest technology and more reliable components has set new standards in reliability, with a MTBF in excess of 11,000 hours. The modern design will see the 2030 DF operational well into the 21st Century.

The 2030 DF system is capable of receiving signals in the VHF and/or UHF frequency range and determining the bearings of these signals to a resolution of 0.1 degrees.

A typical 2030 DF system comprises an antenna, receiving and resolving equipment, numerical vector display and frequency control equipment, front-end processor and signal distribution facility option.

The basic resolving equipment comprises a combined RF resolver rack with a capacity for eight resolving channels, one resolver module per channel as required. Expansion beyond the 8-channel system requires the simple addition of RF resolver racks. The receiving and resolving equipment, which is configured for installation into a 19” rack mounting is co-located with the aerial. All information is processed at the aerial site before transmission in digital format to the display site. At the display site, the received information is processed by the front-end processor and passed to the display equipment. The number of operators is unlimited, due to the multi-drop bus structure. Additional operators can be accommodated by connecting a numerical vector display and control unit to the bus and adjusting the bus address range. Test transmissions can be applied to a selected channel. This facility can be locally activated at the aerial site or remotely activated via the communication link.

All modules are plug-in and accessed from the front of the DF cabinet. The BITE system continually monitors the DF and gives alarm indication in the event of a module failure or change in state of the system performance.

By using the RMM system for fault indication, a typical repair would take less than 15 minutes.

All LRU’s are keyed to prevent a module being inserted in the incorrect position.

 Position Fixing Systems (Autotriangulation)

The Fernau 18 element wide aperture DF systems are the optimum solution and highly accurate. They provide a more cost effective solution than antenna with a great number of elements, without loss of performance. They also minimise site errors caused by reflections from surrounding objects and in addition employ a unique phase comparison technique which helps to cancel errors due to frequency drift, aircraft/vessel movement or rotor blade modulation. The system is based on an electronically scanned ring of dipoles producing a Doppler modulated output which is combined with that of a reference antenna. This signal is fed to a standard communications receiver and the resulting audio processed by a hybrid analogue/digital computer. Frequency shift techniques isolate the directional information from interfering frequency modulated signals and ensure that bearings are not affected by transmitter frequency drift. This design approach also permits the use of standard communications receivers using AM modulation, although CW, AM and FM signals may be resolved for DF processing.

The Fernau 9 element medium aperture DF system has most of the electrical characteristics of the wide aperture system. They are used in applications where the site improvement factor is not so critical and/or where a simpler and smaller light weight antenna would be an advantage.

Various options exist for having a combined VHF and UHF DF system. The most comprehensive of these configurations is the UHF unipole counterpoise system with a VHF wide aperture antenna mounted coaxially.
The UHF counterpoise system manufactured by Upfield Engineering, a division of Fernau, comprises an array of 18 unipole elements mounted on a ground plane to sample the incoming signal at eighteen equally spaced points. The counterpoise comprises a 7.6m diameter framework covered by wire mesh typically 3.7m above the ground. The purpose of the counterpoise is to provide a psuedo earth screen directly below the unipoles. This prevents any distortion of the polar field of the main antenna array due to the mechanisms below it (e.g. metal objects, power cables, buildings etc). It also acts as a shield to ground reflected signals. The standard VHF antenna is mounted above the centre of the array.

Where site conditions allow, the counterpoise can be discarded and it is then possible to mount the Medium aperture VHF system on a common mast above a wide aperture UHF antenna and offset the UHF auxiliary antenna. This reduces the overall capital costs without detriment to performance.

The Fernau 2030 DF provides an accurate bearing of any aircraft transmitting on monitored frequencies within the VHF or UHF airbands and permits the Air Traffic Controller to track flight progress, landing approach and ground traffic movements.

At many smaller airfields a DF system may be the only economical navigational aid available to the Controller. It does not require any form of transponder or other device fitted to the aircraft apart from the standard Radio Transceiver. At larger airports and FIR centres the Fernau DF provides invaluable supplementary information in the form of target identification on Radar displays and is used as a back up system in the case of Radar failure. It is also used as a primary aid in the event of Distress / Diversion operations.

Another application of the Fernau 2030 DF is its vital role in Marine safety and its assistance to Vessel Traffic Management. This facility is essential especially in areas of high shipping density and adverse conditions where small vessels can be lost in the clutter of a Radar display. Radio Direction Finding is often the only means of locating vessels in distress, especially when they have little or no radar reflection capability either due to size, sea state, hull construction, or simply that they are too low in the water. Port authorities from the UK to Korea have found the Fernau solution the best solution, whilst the UK Coastguard service utilises the 2030 DF throughout the British Isles.