SERVOFlight Series 2100 Direction Finder Systems


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System Operation and Equipment

In the 1940's Servo pioneered the concept of quasi-doppler DF systems. SERVOFLIGHT systems are the result of over 50 years of continuous engineering development, production and field service experience, bringing DF technology to a new level of accuracy, dependability and simplicity of operation.

The SERVOFLIGHT 2100 Series DF Systems are reliable and cost-effective systems for the accurate detection and display of bearing and heading information derived from a radio signal transmitted by aircraft equipped with standard voice radio. No other special equipment is required. In the ground station where it is installed, existing VHF and UHF communication equipment is employed in conjunction with the DF system. Solid state technology utilizing high efficiency integrated circuits assures maximum reliability, compact packaging and low power consumption.

Sequential sampling of the antenna array is accomplished by electronic commutation with no moving parts. The result: improved reliability, less maintenance, and greater resistance to extreme weather conditions, particularly cold temperatures.

If required, the display and control units can be located remotely (any distance away) from the antenna site, with transmission accomplished via telephone line or telemetry link.

The various antenna configurations employ a Servo-patented design which reduces error effects from extraneous objects such as hangers, buildings, fences, and power lines. It is an essential factor in providing non-ambiguous information for accurate performance of the system on all forms of radio transmissions encountered during ATC procedures. High speed scanning of antenna elements is performed at the rate of 216 Hz, providing a typical system response time as fast as one-quarter second. In addition to applications requiring directional information, 2100 Series Systems can be employed for a broad variety of applications where position information is also required. Such information is readily developed by combining a multi-location arrangement of DF systems with conventional triangulation techniques.

The installation cost of a typical airport application system is only a small fraction of the cost involved for a surveillance radar system. The 2100 Series System will out-perform radar in many instances, offering greater range and better "pickup" of small planes flying without transponders at low altitudes or near thunderstorms.


 Model        Freq.       Aperture        Dipoles       Local       Remote     Slave Display     

2105             VHF        MEDIUM          8               x                                         x

2110             VHF        WIDE                16             x                                         x

2115             VHF        MEDIUM           8              x               x                        x

2120             VHF        WIDE                16             x               x                        x

2130             UHF        WIDE                16             x                                         x

2140             UHF        WIDE                16             x               x                        x

2150         UHF/VHF    WIDE               16             x                                         x

2160         UHF/VHF    WIDE               16             x               x                        x


Principle of Operation:                Quasi Doppler

Bearing Accuracy:                      +/-1 (Instrumental)   3 (Site)

Vertical Angle Coverage:             0     (Horizontal) to 60 elevation

Frequency Range:                       115.975 to 150.025 MHz VHF, 225 to 400 MHz UHF

Operating Channels:                    1363 VHF, 7000 UHF

Channel Spacing:                         25 kHz

Channel Selection                        Keypad;  10 preset channels  

DF Sensitivity :                            5 uV/m field strength for indicated bearing within 2 deg.

Operational Control:                    Local or Remote

Receiver Characteristics

  • Sensitivity (AM)   1.5 uV for l0dB (S + N) IN with 30% AM at 1000 Hz
  • Selectivity (IF)      VHF: 6dB Passband t 10 kHz; 60 dB Rejection 18 KHz, UHF 6db Passband +/- 13kHz; 70 dB Rejection +/- 23 kHz
  • Image, Spurious, EF Rejection 80 dB to within 100 kHz of Channel Frequency
  • Demodulation Audio Out VHF: AM 11 5.975 to 143.975  FM 144.000 to 174.025
  • Frequency Accuracy - +/- 20 ppm

Bearing Display:         Ring- of -Lights: 72 LEDs every 5 deg. on surrounding compass                                                  rose

                                     Digital: 3 Digits:   (000 to 359deg.) with 7-Segment LED Indicators

Audio Output:      Speaker or Headphone Jack adjustable to maximum output of at least + 10 dBm to 600 ohms

Local/Remote Interface:     FSK Data, frequency multiplexed with audio, over 4 -wire voicegrade 600 ohm telecom circuit or other transmission mode.


RS232, 300 baud data link for connection to a modem


Receiver/Bearing Processor 150 watts

Bearing Display/Control 100 watts

Antenna Arrays 200 watts (for obstruction lamps on wide-aperture type only)


Receiver/Bearing Processor :   - 40 to + 60 C; Humidity up to 90%

Bearing Display/ Control :        -40 to + 60 C; Humidity up to 90%

Antenna Arrays:                       Withstand wind velocity 0 to 100 mph with 0.50 -inch ice loading;  -50C to

                                                 + 70 C; Humidity up to 100%


Receiver/Bearing Processor                                                Bearing Display/Control

Height 17.8 cm (7 in.)                                                         Height 17.8 cm (7 in.)

Width 48.3 cm (19 in.)                                                       Width @.3 cm (19 in.)

Depth 50.8 cm (20 in.)                                                       Depth 50.8 cm (20 in.)

Weight 17.6 Kg (39 lbs.)                                                   Weight 16.7 Kg (37 lbs.)

more information

For further information please call 516 938 9700 ext.16 or email us.

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