Link/SADL

Question 1

List/describe the differences between dedicated and contention access for Link 16.

Answer 1

Dedicated Access - Participants are assigned exclusive transmit time slots.

• All other participants are programmed to receive-only during these time slots.
• One unit per time slot.
• Unique transmission assignments.
• Guarantees conflict-free access to all JU within LOS

Contention Access - Common time slots are shared amongst all terminals within a group.

• Multiple transmitters, same time slot, same crypto.
• User selects slots at random based on their assigned rate.
• If two terminals pick the same slot, other terminals will only hear the closest transmitter to them.

Question 2

List Link-16 J-series messages commonly used by the U-28.

SLIDE 38

Answer 2

J3.5 (land point/track) - pass information on land points and tracks

J12.6 (target sorting) - pass targets and targeting information among non-C2 JU, pass sensor data, pass non-C2 JU engagement-status information

J28.2(0) (text) - send text messages

Question 3

Describe stacked nets function of Link 16.

Answer 3

Same time slot, same NPG, same function, different hopping patterns. Up to 127 nets theoretically may be stacked, but in practice more than 20 to 30 may cause interference.

Question 4

Describe Link 16 messages.

Answer 4

TADIL-J messages (J-series). 32 categories. 8 subcategories. 256 total possible message types.

Question 5

Define NPG and what goes into it.

Answer 5

Network participation groups. The “building blocks” of the Link 16 network.

• Supports specific functions and exchange of specific J-series messages.
• Time slots are allocated to different NPG
• Defined by participants, functions and access modes

BL: not everyone participates in the same NPG
-NPGA determines what info can be tx’d or rx’d by different JU.

Question 6

Describe the function of NPG 19/20.

Answer 6

Function- exchange of fighter-derived target and engagement info.
Participants- non C2 JU
Access- Contention
Ex- 12.0, 12.6, 12.7

Question 7

List J-series messages commonly used by the U-28.

SLIDE 38

Answer 7

J3.5 (land point/track) - pass information on land points and tracks

J12.6 (target sorting) - pass targets and targeting information among non-C2 JU, pass sensor data, pass non-C2 JU engagement-status information

J28.2(0) (text) - send text messages

Question 8

List Link-16 hopping characteristics.

SLIDE 15

Answer 8

Link-16 hops among 51 frequencies spaced 3 MHz apart.

Transmission frequency changes after each 6.4 usec pulse.

Hope rate in excess of 70,000 hops per second.

Pseudorandom hop pattern is based on net number (0-126).

Hopping provides protection against jammers.

Question 9

List OPTASKLINK items specific to U-28s (JU number, track block).
SLIDE 41

Answer 9

JUDATA/UNIT:318TH/319TH/34TH/CS:U-28/-/PRI:34000-34034/16/BLOCK:UU001-UU227/-/U28/-/MORN/0200/PRI/Y//ANPW:AIRCRAFT SIM AND TRACK BLOCK ASSIGNED BY UNIT SCHEDULER.

LOOK AT SLIDE 41.

Question 10

List time qualities.

SLIDE 30

Answer 10

Time quality values range from 1 (worst) to 15 (best), and describe how long the time terminal remains in fine sync.

Ex: 7 = 5 hours
6 = 4 hours

Question 11

List and describe terminal Sync States.

SLIDE 22-24

Answer 11

No Sync: terminal has not received any initial entry messages (IEM)

Coarse sync: terminal has received 2 IEM and is capable of RX only

Fine sync: terminal has exchanged 3 round trip timing (RTT) and can RX and TX

Question 12

Given a sample SADL OPTASKLINK, be able to identify frequency channel, air key, etc.
SLIDE 25-26

Answer 12

SADLSQD/319th/34th/-/TNBLOCK:34000-34023/GW/ACTIVE/4-4/12/33/8/LONG/20//AMPN/Track Block UU001-UU277//

LOOK AT SLIDE 25-26

Question 13

Given a sample SADL OPTASKLINK, be able to identify frequency channel, air key, etc.
SLIDE 25-26

Answer 13

SADLSQD/319TH/34TH/-/TNBLOCK:3400-34023/GW/ACTIVE/4-4/12/33/8/LONG/20//AMPN/TRACK BLOCK UU001-UU277//

LOOK AT SLIDE 25-26

Question 14

Describe what net shape and net position mean in SADL

Answer 14

Net Shape (slide 19)
2 digit code defining the networks flight makeup
Digit 1 = Number of flights    
Digit 2 = Number of Aircraft per flight

Network position (slide 20)
Digit 1 = Flight that ownship belongs to   
Digit 2 = Ownship position with the flight

Question 15

List what SADL network position is the timing master

Answer 15

1/1 (first position in first flight) (slide 20)

Question 16

What are the extended network capabilities of SADL?

Answer 16

Allows up to 80 aircraft (16x5=80) by connecting air-key number 90-94, by using these air keys it directs the system to connect all five networks (90, 91, 92….) into an extended one (slide 22)

Question 17

What is the guard channel and secondary channel for SADL?

Answer 17

Guard Channel – (first digit): Defines the frequency the radio tunes to for receiving network-entry messages

Secondary channel (second digit): Defines radio’s hopping range (slide15)

These are written as a two digit number example 37, 3 is guard channel, 7 is secondary channel

Question 18

What are the SADL to SADL J-series messages and what information do they send?

Answer 18

J2.X: PPLI
J12.0: Mission Assignment
J12.6 Target sorting
J13.2 Platform status
J28.2: Text message
(these are all on slide 24)

Question 19

What is the normal operating power of the SADL (EPLRS) radio?

Answer 19

20 W (medium-high) is the normal operating power

Question 20

What are the 3 different channel maps for SADL?

Answer 20

5 channel map
Six channel map
Eight channel map
(slide 14)

Question 21

What are the requirements for SADL network participation?

Answer 21

Track number (five-digit JU number)
Correct RF channel (frequency map)
Determine network type
Determine network shape
Correct air key, GAT key, ground key
Correct crypto

Question 22

What is required for to participate in a SADL Gateway?

Answer 22

Specific GAT key required for a specific gateway