direction finding sar

  • Multi-beacon DF
  • Single compact antenna unit
  • High sensitivity receiver
  • Fully COSPAS-SARSAT compatible

The Techtest DF system is designed to reduce the time to locate emergency locator beacons. It is compatible with both 121.5MHz swept tone distress beacons and 406MHz COSPAS-SARSAT transmissions on current and future frequencies.

The user is able to monitor four frequencies and detect emergency transmissions. Each transmission is allocated a unique identification which can then be selected for more detailed information.

For 121.5MHz the system can display relative bearing details.

For 406MHz the system will give all the same information as 121.5MHz but in addition will record and decode the COSPAS-SARSAT message, giving details of the distress beacon and if available the GPS beacon location.

The system comprises of three modules

  • 1. Antenna (10-246-1) The Antenna is a single compact module comprising a circular array of elements with integral high sensitivity receivers. The array is designed todf control panel give optimal angular resolution of the emitters.
  • 2. Control Unit (406-28) The Control Unit takes the array output and, using a digital processing and advanced beam forming technique, is able to discriminate multiple emitters and direction find on the signals. All the data is processed using intelligent algorithms to reduce system noise and spurious responses.
  • 3. Display (407-3) Different display options are available and are platform specific. The basic display module is based on the Techtest 407-2 unit. This unit is designed for ease of use featuring mode and scroll controls and a dual function uncluttered graphic LCD display. A secondary display option is available.

In normal operating mode the DF receiver frequency is switched cyclically between 121.5, 156.8 and 243 MHz. If a signal above the threshhold is detected, a 0.3 second snapshot is recorded before continuing. A separate receiver is used to continuously monitor the 406 SARSAT frequency. If a signal is detected then the DF receiver will immediately switch to 406MHz frequency and record a snapshot. In the event of transmitting beacons incorporating a GPS position, the system will display the applicable lat/long co-ordinates.

Direction Finding / Homing
A 360˚ direction finding facility is provided giving a direction for the aircraft to fly to the transmitting beacon. No other navigation aids are required. If however on board GPS navigation systems are installed in the aircraft, system integration will provide aircrew with both an absolute bearing and distance information to the transmitting beacon.
In the Homing mode the system sequentially scans the distress frequencies and provides a visual display of left/right steer information.

Cockpit Controller / Indicator
The controller / indicator is mounted in the cockpit. There are just two controls : a push button mode selector (switching between Decode and DF modes), a rotary click / push selector providing control of menu options. The unit is designed to operate mainly without user input.
The user can select any of three modes:

  • i)    Left-Right Indicator: To show bearing relative to aircraft heading.
  • ii)   Map display: Showing relative positions, (or bearings), of all detected emitters, both from DF receiver and 406 Decoder.
  • iii)  Text Display: Ideal for 406 decoder information. Can also be used to display range and bearing data.pdf icon
Dimensions Short 3/8 ATR (90x198x322mm)
SAR frequencies 121.5, 243, 156.8, 406 MHz
Training frequencies 4 selectable: 110 to 410 MHz
Sensitivity 2.5μV
DF Accuracy Better than 5˚
Decoder Frequency 406.025 - 406.050 MHz
Message Format COSPAS-SARSAT C/S T.001
Supply Volts 18-36V DC MIL-STD 704D
Antenna 10-246-1
Diameter 250mm
Height Standard 250mm
Reduced 180mm
Polarisation Vertical
Cockpit Controller / Indicator 406-3
Dimensions 146 x 67 x 152mm
LCD Display 56 x 42mm (320 x 420 pixels)
Backlighting NVIS Green B (MIL-STD 3009)
Environmental MIL-STD 810F

12-602-8 cable antenna analyzerAs manufacturers of antennas and SAR equipment, the company has always believed it of great importance to provide supporting equipment to these products. Over the years, this has resulted in a range of Test Sets being manufactured by Techtest.

Our range of VSWR Test Sets is known throughout the aviation community as the industry standard products for testing aircraft antennas. They are all available with ruggedized cases and models are available to cover all the frequencies commonly found in avionic equipment. These VSWR Test Sets allow antennas to be checked for correct operation and can be used whilst the antenna is still on the airframe thus saving costly removal of the antenna when it is not necessary.

It is vital that an Emergency Locator Transmitter works correctly, if it is used, so Techtest supply a range of test equipment to check correct operation of this type of equipment. These Test Sets can be used with all types and makes of ELTs and EPIRBs.

Brochure downloads

pdf12-602-8 Antenna and Cable Analyzer (PDF)  
pdf12-406 Homing Test Set (PDF, 436Kb)
pdf12-503-5 Programming Test Set (PDF, 84Kb)

The need for Search and Rescue (SAR) services to accurately detect and locate the distress signals from emergency beacons resulted in Techtest developing its range of Homing Systems.

These use a phase comparison method to provide left-right steering information, to the SAR pilot enabling him to locate emergency beacons operating on all the standard distress frequencies (121.5 MHz, 156.8 MHz, 243 MHz and 406 MHz). This type of system requires only two antennas and offers a more compact, lower cost solution to the more complex DF systems available.

 Techtest now manufactures a range of Homer/Decoder systems which decode the unique data included in the COSPAS-SARSAT 406 MHz distress signal. This includes the position infor406-2-053 homing systemsmation from Location Protocol Beacons and gives the user real time information to help minimise rescue times. A number of integrated airborne systems are available as well as the unique Portable 406 SAR Decoder which is a fully self contained unit which can be carried on to any aircraft, boat or land vehicle. This unit is ideal for a SAR force which already has Homing/DF systems fitted but wishes to extend its capability to include 406 MHz decoding in a cost effective way.

Brochure downloads

pdf12-406-7 Portable 406 SAR Decoder (PDF, 160Kb)
pdf12-406 Homing Test Set (PDF, 436Kb)
pdf406-2-053 Full NVIS Compatibility SAR Homing System (PDF, 284Kb)
pdf406-407 Delivering real-time SAR 406 decode and position (PDF, 520Kb)


The 500 series of Personal Locator Beacons or Survival Emergency Locator Transmitters offers a wide range of options to suit any requirement. The 500 series of Personal Locator Beacons has been chosen by a wide customer base, including armed forces, commercial airlines, off-shore helicopter operators, life raft manufacturers and ejection seat manufacturers.

For all the 500 series Personal Locator Beacons, Techtest has obtained full certification to aircraft standards so these products should not be confused with inferior quality beacons intended for hobby use.

The 500-1 Personal Locator Beacon is a compact light-weight unit operating on 121.5 MHz and 243 MHz and has been favoured by customers requiring a small beacon for many years.

The 500-12 Personal Locator Beacon is designed to work with the COSPAS-SARSAT search and rescue satellite system and features 406 MHz as well as 121.5 MHz and 243 MHz distress signals. It also incorporates a speech function which allows survivors to have two way voice communication with a rescue craft. In addition to the normal aircraft approvals the 500-12 also has full Boeing and Airbus approvals making it the natural choice for commercial airline operators due to its compact size and low weight. The 500-27 shares all the functionality of the 500-12 but also incorporates embedded GPS to minimize location time in the event of an emergency.

The latest 500-27-07 PLB (above right) utilizes all the proven electronics of its predecessors but updates the casing design to give a modern stylish appearance without losing the rugged and durable qualities associated with Techtest SAR products.

The new 500-32 PLB (above left) offers similar features to the 500-27-07 but in a significantly smaller package (35% reduction in volume). This has been achieved by using state-of-the-art battery technology and optimised electronics.

After rigorous testing the 500-32 series of ELT(s) or PLB has recently been awarded a COSPAS SARSAT type approval (Certificate No. 223).

500-30, 406 MHz Ejection Seat Compatible PLB

The 500-30 is the latest member of the highly successful Techtest PLB range offering 406MHZ transmission and Guard frequency transmission combined with embedded GPS to
500-30 provide positional accuracy of 100m.

With both manual and automatic activation capability the beacon offers maximum flexibility across a fleet of aircraft. Providing interface solutions for inclusion in PSPs within ejection seats such as ACES II/III and in combination with parachute activation mechanisms such as the BA22. Once activated upon ejection the PLB will transmit SAR frequency signals via remote antennas allowing rapid recovery.

Once on the ground aircrew can continue to transit using remote or integrated dual frequency antennas including GPS providing portable functionality and the ability to control beacon transmission according to circumstance. With 5 year battery life, 48 hours transmission on 121.5MHz and 24hours on 406MHz at -20 °C the 500-30 meets COSPAS SARSAT, ED-62A, STANAG 7007 and MIL-STD 810F specifications.


Brochure downloads

pdf500-12 Multi Function Personal Locator Beacon
pdf500-27 Multi Function Personal Locator Beacon + Embedded GPS
pdf500-27-07 Multi Function Personal Locator Beacon + Embedded GPS
pdf500-30 Multi Function Personal Locator Beacon
pdf500-32 406MHz Multi Function Personal Locator Beacon
pdf12-503-5 Programming Test Set

Cookies make it easier for us to provide you with our services. With the usage of our services you permit us to use cookies.
More information Ok Decline