1. DF-517 DIRECTION FINDING SYSTEM
CLASSROOM TRAINING
BASIC OPERATION
of the
DF-517 DIRECTION FINDING SYSTEM
The purpose of this presentation is to present the basic operational characteristics of the DF-517

2. SAR Direction Finder DF 517
Search and
SAR Direction Finder DF 517
Rescue System BY

3. DIRECTIONS FOR USING THIS PROGRAM
“Click-On” the to see new information within each slide. (Try it!)
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Each slide may contain several topics of information. You will need to click on the yellow oval several times to see all of the information in each slide.
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4. Purpose of the direction finder
The SAR DF 517 is a precision direction finder was developed for professional SAR (search and rescue) purposes. It has the ability to bear and analyse traditional MHz and MHz emergency frequencies in the VHF and UHF bands, maritime radio channel 16, and the new digitally encoded MHz COSPAS/SARSAT emergency signal. Because of its very short pulse length, the bearing of the COSPAS/SARSAT signal cannot be determined accurately using conventional direction finders.
The traditional MHz ELT signal that is currently required in U.S. aircraft is a low power signal that operates continuously once activated.
The COSPAS/SARSAT signal on MHz is a high power signal that is transmitted only once every 50 seconds. The pulse length of this signal is only 400ms, making it impossible to locate using traditional direction finder equipment.
This system incorporates a newly developed and patented antenna (small, rugged and wideband), as well as sophisticated bearing analysis algorithms, allowing delivery of a quick and steady indication for both the and MHz signals. It also has the ability to track a wide range of training frequencies for training exercises. The direction finder was developed for working under stressful mission conditions such as in an aircraft, helicopter or vehicle.

5. SAR–DF 517 Direction Finder Principles of Operation

6. Two Modes of Operation EMERGENCY MODE (For Use on Actual SAR Missions)
Unit will search for MHz, MHz, Marine Channel 16 and COSPAS/SARSAT Emergency Signal Transmissions
Depending on selection, the unit will either SCAN all of these frequencies or search on a single selected frequency.
TRAINING MODE (For Use on Practice Exercises)
Unit will search for specific training frequencies entered by the operator
Unit can also SCAN a group of training frequencies
EMERGENCY frequencies are ignored when in the training mode.
Two Pre-Flight checklist have been developed for use with the DF-517.
EMERGENCY MODE CHECKLIST (for actual SAR missions)
TRAINING MODE CHECKLIST (for training missions)
USE YOUR CHECKLIST!

7. Selecting Operation Mode
1) Turn ON by pressing ON/OFF
2) Select EMERGENCY or TRAINING mode by rotating PAGE knob.
3) Verify desired mode is selected.
Note: Unit will automatically timeout and go to PAGE 1. You must select the operational mode before this timeout occurs. It will be necessary to turn the unit OFF and then ON again if the timeout occurs before you select the desired mode..
Indicates unit software version
Serial number of control-display

8. SAR–DF 517 Direction Finder Power-On and Operation Mode
Basic operation of the DF-517 is the same in either the EMERGENCY MODE or TRAINING MODE. Pre-Flight settings however are different!
Emergency-mode with fixed preselected emergency frequencies
MHz (Ch16/seaband)
MHz (VHF)
MHz (UHF)
MHz (CP/Sarsat)
Training-mode with freely adjustable training frequencies
(1) [ ] MHz
(2) [ ] MHz
(3) [ ] MHz
(4) [ ] MHz

9. Operations Common To Both Emergency Mode & Training Mode
The following slides will discuss basic operations that are common to both EMERGENCY mode and TRAINING mode operations.
There are 6 viewing PAGES that may be selected by turning the PAGE control in the upper right corner of the control-display unit.
PAGES 1-3 display the RELATIVE BEARING of the ELT signal. The method used to display the bearing on the DF-517 is similar to (but not exactly the same) as how a relative bearing is displayed on an ADF indicator. It is very important to realize that this is a RELATIVE BEARING that is relative to the nose of the aircraft, NOT the heading to be flown.
PAGES 4-6 display the COSPAS/SARSAT signal decoding information and allow the flight crew to make changes to units operational settings.

10. SAR–DF 517 Direction Finder Page Selection and Dimming
Turn the PAGE knob to select the desired page.
Page [ ]: Relative Bearing Pages
Page 4: Cospas/Sarsat Message decoding
Page 5: Edit menu
Page 6: Adjustable Training Frequencies
Dimming
Is executed in an exponential curve, allowing very accurate adjusting of display brightness under night and/or NVG conditions. Adjustments are made by pressing down the REP button while turning the PAGE knob.

11. SAR–DF 517 Direction Finder (Pages 1, 2, 3)
Pages 1, 2 and 3 are used during flight to locate the ELT.
The function knobs on the face of the control-display work identically for each page.
Notice this display is set to PAGE 1 as shown in the upper right corner of the control-display

12. SAR–DF 517 Direction Finder Bearing (Pages 1, 2, 3)
360-degree view
Page 2:
90 degrees view
Page 3:
Digital reading

13. Display Readings Page 1: 360°bearing Page 2: expanded 45°
Page 3: bearing text
(1) Relative Bearing value
(2) Spread Maximum deviation of unaveraged bearing. Good bearing results even with a spread of 45°as a result of the averaging procedure. Note: as you approach near the ELT and the signal becomes very strong, the spread will narrow.
(3) Receive level Field strength. Page 1 shows approx. 50%, Page 2 shows approx. 75%
(4) Squelch level Squelch level must be above the noise level without a received signal.
(5) Offset Corrects for antenna alignment (adjusted in the edit-menu).
(6) Mounting Page 1 shows a BOTTOM mounted antenna. Page 3 shows TOP mounted.
(7) LS: ---:--- Internal timer (LS meaning last signal) indicating the time since the last signal was received, displayed in min /sec

14. SAR–DF 517 Direction Finder SQUELCH ADJUSTMENT
Proper SQUELCH adjustment is very important.
The squelch is adjusted using the SQL knob.
The squelch setting MUST be set slightly above the noise level. It should be set while performing the pre-flight checklist after engine start while the aircraft is still on the ground.
The level of the squelch adjustment is indicated by the small arrow next to the vertical signal level bar.
The DF-517 in the above example is receiving an active ELT signal level that is approximately 50% and is above the original squelch level

15. “Locate Target = Fly the Ball”
Bearing +002° RIGHT
Bearing -002° LEFT or
+358° RIGHT.
Bearing +006° RIGHT
PAGE 1 Observer tells pilot to turn 2 degrees right to center ball at top of display.
PAGE 2 Observer tells pilot to turn 2 degrees left to center ball at top of display
PAGE 3 Observer tells pilot to turn 6 degrees right (no ball is displayed on Page 3).
Note: How do you know when you are over your target?
The “ball” will swing to the 180 degree position on PAGE 1 just after you pass over the target.
When you are exactly over the target you may notice a “cone of influence” similar to passing over a VOR during which the signal may be lost momentarily before it swings to 180 degrees.

16. SAR–DF 517 Direction Finder FREQUENCY SELECTION
The frequency is selected using the (+/-) knob in the lower right corner of the control-display.
The FRENQUENCY selected is shown in the bottom right corner of the control-display.
You can select individual frequencies in either the EMERGENCY or TRAINING modes. If an individual frequency is selected the unit will search only for the selected frequency.
You can also select to sequentially SCAN all of the frequencies.
Note: If the unit is in TRAINING mode and SCAN is selected, it will NOT search for EMERGENCY frequencies. If the unit is in EMERGENCY mode and SCAN is selected it will NOT search for TRAINING frequencies.

17. SAR–DF 517 Direction Finder VOLUME ADJUSTMENT
The VOLUME is adjusted using the volume adjustment (+/-) knob in the lower left corner of the control-display.
This will adjust the audio volume of the received signal.
It is highly recommended that you also monitor the search frequency on one of your aircraft COMM radios.
Note: On some aircraft the audio signal may not be available from the DF-517 control-display. In this case the volume adjustment will have no function.

18. SAR–DF 517 Direction Finder FUNCTION KEYS
Pressing CLR will clear the last stored bearing from the units memory. It is usually not necessary to use this feature during searches.
Pressing STORE will save the current bearing in the units memory.
Pressing REP will recall the last bearing stored in the computers memory.

19. SAR–DF 517 Direction Finder COSPAS-SARSAT (Page 4)
Cospas/Sarsat Signal
This slide shows the details of an acutal COSPAS/SARSAT signal.
Transmitted once every 50 sec (pulse is only 400 msec long)
Contains a digital message (112/144 bit)
Includes a country code, a specific trasmitter Hex ID code and LAT/LONG coordinates of the ELT.

20. Using the SCAN mode while bearing COSPAS/SARSAT signals
It is recommended that you use the SCAN mode when searching for a COSPAS/SARSAT MHz signal. This will allow the unit to also search for other emergency signals during the delay time between the MHz signal transmissions.
The COSPAS/SARSAT signal is transmitted only once every 50 sec (Pulse length of 400ms).
The scanning mode is possible with frequencies MHz, MHz and MHz or the matching training frequencies.
The LS: ---:--- timer (LS meaning last signal) will display the time since last COSPAS/SARSAT signal.
This unit is set to SCAN mode.

21. SAR–DF 517 Direction Finder Edit Menu (Page 5)
TimeHold: Duration [sec] of internal storage of the averaged bearing value. This is normally set to 10 sec.
Offset: Electronic correction (rotation) of the antenna orientation. This is normally set to Do NOT make changes to the Offset value unless you have received training on how to set this value.
Mounting: Type of Antenna Mounting (Top/Bottom) Very Important!
Ext. Dimm: Range of voltage to control the dimming of the display
VERY IMPORTANT. The antenna Mounting MUST be correct. Top means the antenna is mounted on the TOP of the aircraft facing up. Bottom means it is mounted on the BOTTOM of the aircraft facing down. Improper setting will cause bearing to 180 degrees out.

22. SAR–DF 517 Direction Finder Edit Menu (Page 6)
Adjustable Training Frequency Ranges
Adjustable Training Frequency Ranges:
Seaband: [ ] MHz (Chnl sea)
Freq.1: [ ] MHz (VHF-band)
Freq.2: [ ] MHz (UHF-band)
Freq.3: [ ] MHz
Select the frequency to be changed using the knob on the bottom left corner
Change the frequency using the knob on the bottom right corner. Then press STORE to save changes.
Typical training frequency is MHz.

23. ! USE THE PREFLIGHT CHECKLIST !

24. EMERGENCY MODE CHECKLIST
(7)
(3)
(2)
(4)
(6)
(1)
(5)
Turn ON
Select EMERGENCY
Select PAGE 1
Verify Correct Antenna Mounting
Turn Volume ON
Select EMERGENCY Frequency or SCAN mode.
SET SQUELCH LEVEL ! (Set just above noise level. This example is a little too high.)

25. TRAINING MODE CHECKLIST
(6)
(3)
(11)
(7)
(2)
(8)
(4)
(5)
(10)
(1)
(9)
Turn ON
Select TRAINING
Select PAGE 6
Select Training Frequency Band
Set/Verify Training Frequency. Change only if needed.
Press STORE button to save any changes made to training frequency. Not necessary if no changes made.
Select PAGE 1
Verify Antenna Mounting
Turn Volume ON
Select Training Frequency or SCAN mode.
11) SET SQUELCH LEVEL ! (Set just above noise level. This example is a little too high.)

26. SOME FINAL NOTES
SQUELCH Adjustment. It takes some practice to learn the correct setting of the squelch control. If the squelch is set to high, you may not be able to receive the ELT signal. If the squelch is set to low (in the noise level) you will receive erroneous ELT signals that may tend to “bounce” around the screen.
Don’t be afraid to play with the squelch adjustment while in flight. You will quickly learn how to tell the difference between a valid ELT signal and an erroneous signal cause by noise.
Be sure to monitor your COMM radio also. Listen for the characteristic ELT “whooping” signal on the correct frequency (usually MHz for EMERGENCIES or for TRAINING). If you can hear the ELT on your COMM radio, but it is not being indicated on the DF-517, your squelch setting is probably too high.
The PILOT should not be watching the DF-517 display. The OBSERVER should be watching the display and giving bearing directions to the pilot. The pilot’s job is to provide the crew a safe flight environment. FLY SAFE!
Proper training and practice using the DF-517 will SAVE LIVES!

27. SAR–DF 517 Direction Finder Error Messages
Error, location
Reason
Error 10 E10:VOLT/D
Main voltage supply
Voltage input too low (10.0V)
Error 9 E9:NO DATA
Connecting cable:antenna  display or Display-Unit
No or damaged connection between antenna and display, or damaged display-unit
Error 8 E8:BAD/ANT
Connecting cable: antenna  display
Incompatibility of antenna and display resp. bad connection of display and antenna.
Error 7 E7:BAD/DIS
Display
Incompatibility of antenna and display
Error 6 E6:VOLT/A
antenna
Voltage supply at antenna unit too low (9.0 V). Main voltage supply too low or considerable drop of voltage between display and antenna.
Error 5 E5:OSCILAT
error in synthesizer-oscillator of receiver in antenna-unit.
Error 4 E4:F/+OFS+
received transmitter
Received frequency too high (more than 6 KHz / error of transmitter
Error 3 E3:F/-OFS-
received frequency too low (more than 6KHZ / error of transmitter)
Error 2 E2:CS/SYNC
radio distance: transmitter  DF
Synchronising bits of Cospas/Sarsat signal (bit 1 to 24) defective
Error 1 E1:CS/BCH1
Error of data bits in 1st Cospas/Sarsat data block PDF1/BCH1
Error 0 E0:CS/BCH2
Error of data bits in 2nd Cospas/Sarsat data block PDF2/BCH2
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