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APPENDIX F

ANTI-JAM AND ANTI-INTERFERENCE TECHNIQUES

TABLE OF CONTENTS

PARAGRAPH PAGE

F.1 GENERAL 507F.1.1 Scope. 507F.1.2 Applicability. 507F.2 APPLICABLE DOCUMENTS 507F.2.1 General. 507F.2.2 Government documents. 507F.2.2.1 Specifications, standards, and handbooks. 507F.2.2.2 Other Government documents, drawings, and publications. 508F.3 DEFINITIONS 508F.3.1 Standard definitions and acronyms. 508F.3.2 Abbreviations and acronyms. 508F.3.3 Operating parameters. 508F.4 GENERAL REQUIREMENTS 509F.4.1 Overview. 509F.4.2 Hop sets. 509F.4.3 System performance requirements. 510F.4.3.1 Linking probability: link before hopping. 510F.4.3.2 Linking probability: link while hopping. 510F.4.3.3 Occupancy detection: link before hopping. 510F.4.3.3 Occupancy detection: link while hopping. 511F.5 DETAILED REQUIREMENTS 511F.5.1 Linking before hopping. 511F.5.2 Linking while hopping. 511F.5.2.1 Hopping synchronous slot duration. 512F.5.2.2 Hopping synchronous dwell structure. 512F.5.2.3 Hopping PDU transmission. 512F.5.2.3.1 Hopping PDU transmit level control sequence. 512F.5.2.3.2 Hopping 3G-ALE PDU transmission during data time. 512F.5.2.3.3 Hopping transmission of other PDUs during data time. 513F.6 NOTES 513

TABLES

TABLE F-I. Modes of operation. 509TABLE F-II. Linking probability requirements for linking while hopping (3 kHz SNR dB). 510TABLE F-III. Occupancy detection requirements for linking while hopping (3 kHz SNR dB). 511

FIGURES

FIGURE F-1. Hopping PDU transmission. 512


F.1 GENERAL

F.1.1 Scope.

This appendix contains the requirements for implementation of third generation (3G) HF link automation when frequency hopping is used in anti-jam and anti-interference applications.

F.1.2 Applicability.

Frequency hopping operation with 3G HF link automation may not be required for some users of HF radio systems. However, if the user has a requirement for the features and functions described herein, they shall be implemented in accordance with the technical parameters specified in this appendix.

F.2 APPLICABLE DOCUMENTS

F.2.1 General.

The documents listed in this section are specified in F.3, F.4 and F.5 of this appendix. This section does not include documents cited in other sections of this standard or recommended for additional information or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements documents cited in F.3, F.4 and F.5 of this appendix, whether or not they are listed here.

F.2.2 Government documents.

F.2.2.1 Specifications, standards, and handbooks.

The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those listed in the issue of the Department of Defense Index of Specifications and Standards (DODISS) and supplement thereto, cited in the solicitation.
STANDARDS
FEDERAL
FED-STD-1037 Telecommunications: Glossary of

Telecommunications Terms

MILITARY
MIL-STD-188-148 (S) Interoperability Standard for Anti-Jam (AJ) Communications in the High Frequency Band 2 - 30 megahertz (MHz) (U)

(Unless otherwise indicated, copies of the above specifications, standards, and handbooks are available from the Standardization Document Order Desk, 700 Robbins Ave. Building 4D, Philadelphia, PA 19111-5094.)

F.2.2.2 Other Government documents, drawings, and publications.

The following other Government documents, drawings, and publications form a part of this document to the extent specified herein. Unless otherwise specified, the issues are those cited in the solicitation.
NTIA Report 98-348Software Implementation of a Wideband HF Channel Transfer Function

(Applications for copies should be addressed to the U.S. Department of Commerce, NTIA, Room 4890, 14th and Constitution Ave. N.W., Washington, DC 20230.)

F.3 DEFINITIONS

F.3.1 Standard definitions and acronyms.

None.

F.3.2 Abbreviations and acronyms.

The abbreviations and acronyms used in this document are defined below. Those listed in the current edition of FED-STD-1037 have been included for the convenience of the reader.
3Gthird generation
AJAnti-Jam
ALEAutomatic Link Establishment
ALMAutomatic Link Maintenance
AWGNadditive white Gaussian noise
DODISSDepartment of Defense Index of Specifications and Standards
HFhigh frequency
kHzkiloHertz
MHzmegahertz
PDUProtocol Data Unit

F.3.3 Operating parameters.

The operating parameters used in this appendix are collected here for the convenience of the reader.
SymbolParameter Name Default Value
TsymPSK symbol time 1/2400 s _ 417 µs
Tbit32 Tsym; quantum of 3G PSK signaling ~13.333 ms
TpropMaximum propagation delay among network members 70 ms
ThopDuration of hopping dwell *
TguardGuard time at hop boundary for radio tuning *
TdataPortion of hopping dwell used for data transmission (Thop - Tguard) *

TdiscMaximum discrepancy among synchronized, hopping radios *
TslotDuration of slot in synchronous mode 3G ALE *
NbphNumber of data bits sent per hop *
Hbw0Number of hops necessary to send a 3G ALE PDU while hopping *
CNumber of calling hop sets scanned by radio that links while hopping
* depends on specific hopping scheme in use

F.4 GENERAL REQUIREMENTS

F.4.1 Overview.

Systems employing both 3G HF link automation (see Appendix C) and frequency hopping may operate in any of the following five modes listed in table F-I.

TABLE F-I. Modes of operation.
Mode Hopping Mode Linking Mode Scanning Mode
1A MIL-STD-188-148 Link before hopping Async
1B MIL-STD-188-148 Link before hopping Sync
2 MIL-STD-188-148 Link while hopping Sync
3A Army enhanced Link before hopping Async
3B Army enhanced Link before hopping Sync

F.4.2 Hop sets.

An ordered list of frequencies, along with timing specifications that determine when each frequency is used, is termed a hop set. When 3G protocols are used in a frequency-hopping network, hop sets take the place of channels. Thus, in 3G systems that support frequency hopping, the channel table specified in C.4.11.3 Channel table shall be extended to store a hop set specification in each entry, and channel numbers in 3G automatic link establishment (ALE) and 3G automatic link maintenance (ALM) protocol data units (PDUs) shall refer to hop sets.

F.4.3 System performance requirements.

F.4.3.1 Linking probability: link before hopping.

When linking before hopping (Mode 1A, 1B, 3A, or 3B), 3G ALE systems shall meet or exceed the linking probability requirements of C.4.6.1.1 Linking probability and the appropriate sub-paragraph for linking in synchronous or asynchronous mode.

F.4.3.2 Linking probability: link while hopping.

When linking while hopping (Mode 2), 3G ALE systems shall meet or exceed the linking probability requirements of table F-II. The test procedure of A.4.2.3 shall be employed, with the following modifications:

TABLE F-II. Linking probability requirements for linking while hopping
(3 kiloHertz (kHz) SNR dB)
.
Prob Link Success
Gaussian
CCIR Good
CCIR Poor
25%
-7
-5
-3
50%
-6
-3
0
85%
-5
0
3
95%
-4
4
6

F.4.3.3 Occupancy detection: link before hopping.

When linking before hopping (Mode 1A, 1B, 3A, or 3B), 3G ALE systems shall meet or exceed the occupancy detection requirements of C.4.6.1.2 Occupancy detection and the appropriate sub-paragraph for synchronous or asynchronous operation.

F.4.3.3 Occupancy detection: link while hopping.

3G ALE systems operating in link-while-hopping mode (Mode 2) shall correctly recognize that a traffic hop set is occupied at least as reliably as indicated in table C-II during the Listen portion of Slot 0 (see F.5.2.2, Hopping synchronous dwell structure). The test procedure of A.4.2.2 shall be used. Systems shall also meet or exceed the requirements of
table F-III for detecting calling hop sets in use while listening before calling during Slots 1 through 3. The probability of declaring a hop set occupied when each hop dwell contains only additive white Gaussian noise (AWGN) shall be less than 1percent.

TABLE F-III. Occupancy detection requirements for linking while hopping
(3 kHz SNR dB)
.
Waveform AWGN 3 kHz SNR (dB) Minimum Required Detection Probability
2G-ALE
1
50%
3G-ALE (BW0)
-8
50%
3G-HDL (BW2)
1
30%
SSB Voice
7
50%
MIL-STD-188-110 or
1
30%
FED-STD-1052 PSK modem
7
70%
STANAG 4285 PSK modem
1
30%

F.5 DETAILED REQUIREMENTS

F.5.1 Linking before hopping.

When 3G ALE systems link before hopping, the ALE protocols of Appendix C shall be employed with the following modification: hopping synchronization and startup shall occur at the point in the respective protocol at which traffic startup would occur in non-hopping operation. Traffic startup shall commence upon completion of hopping startup.

F.5.2 Linking while hopping.

When linking while hopping, a 3G ALE system shall operate in the modified synchronous mode specified below. The following timing parameters are used:

F.5.2.1 Hopping synchronous slot duration.

When the network hopping rate is such that an entire 3G-ALE PDU can be sent during Tdata, the slot time Tslot shall be equal to Thop. Otherwise, the 3G-ALE Tslot shall be extended to the smallest integral multiple of Thop greater than or equal to Tprop plus the time to send an entire 3G-ALE PDU using the procedure specified in F.5.2.3 Hopping PDU transmission.

F.5.2.2 Hopping synchronous dwell structure.

The dwell structure for 3G ALE while hopping shall comprise five slots, each of duration Tslot:

F.5.2.3 Hopping PDU transmission.

When any 3G PDU cannot be sent during a single hop, it shall be spread over multiple hops as described below.

F.5.2.3.1 Hopping PDU transmit level control sequence.

The transmit level control portion of a PDU shall be sent by the controller to the transmitter during Tguard and the first portion of Tdata, with symbols dropped from the beginning of the sequence if necessary so that the end of the Ttlc sequence shall occur at time Tdisc after the end of the guard time (see figure F-1). Some of the symbols may be dropped by the transmitter while it is changing frequency.



FIGURE F-1. Hopping PDU transmission.

F.5.2.3.2 Hopping 3G-ALE PDU transmission during data time.

When Tdata > TBW0 pre + TBW0 data + 2 Tdisc, the 3G-ALE PDU shall be sent during a single hop, with the preamble beginning immediately after the end of the Ttlc sequence.

Otherwise, the preamble and data portions of the 3G ALE PDU shall be split over multiple hops. The transmissions during each Thop shall be (a portion of) the Ttlc sequence as described above, followed immediately by a 40 ms (96 symbol) segment of the preamble, followed immediately by up to Nbph PDU data bits:


Transmissions should cease during the period from the final symbol of the PDU data bits until the first symbol of the next Ttlc sequence. This will reduce interference levels. The number of hops required to send the 26 data bits that compose a 3G ALE PDU is HBW0:


Preamble segments shall be sent in order in successive hops, with the specified symbol sequence cycling back to the beginning if necessary in the later hops. If the unused PDU data bit positions in the final hop do not exceed Tprop, an extra hop must be included in Tslot to allow for propagation to all network stations.

F.5.2.3.3 Hopping transmission of other PDUs during data time.

The other 3G PDUs shall be sent similarly to the 3G ALE PDUs.

F.6 NOTES

None.