.... _ 

TRAFFIC ANALYSIS RESEARCH 

1. Analysis of Discriminants 

As new discriminants were observed at SSA, this group 

studie• them to determine their function, use, relative 

importance, and echelon from external characteristics. Through 

close liaison with the c-ryptographic intelligence unit, 

information from that source waa constantly being related 

to the purely external. At regular interirals, studies were 

conducted on already established systems so that current 

records of all known J/A cryptographic systems were maintained 

at all times. Especially complete records were maintained 

on one time pads as these were found to be particularly 

valuable from the standpoint of direct T/A intelligence. 

This group also conducted studies on dummy traffic 

other miscellaneous traffic types when necessary. 

8F.ISftE! 

and 4t 

oq; 

eclassifi ed and a roved for release b NSA on 07-25-2013 ursuantto E .0. 1352 
~:A58826 

TRAFFIC ANALYSIS RESEARCH 

2. DD Research 

The function of this group was primarily the identification of DD numbers and the establishment of the validity of 

identifications. All methods of identi'ying DD1 a, including 

T/A cribs, short time lapses, etc. were used, but special emphasis was placed on methods which exploited available 

ultra material, notably Ate and Dendai Order of Battle 

cribs. 

The secondary function was the cryptanalytic solution 

of the DD systems themselves as an aid to further identifications. 

8H6HE'l' 
REF ~~6826 

TRAFFIC ANALYSIS RESEARCH 

3. NR Studies 

Studies were made of the NR patterns used by Japanese 

Army Headquarters. When more than one pattern was ·round 

at a location, these patterns were related to specific 

originators through a study of Dendais. These studies 

were used for drawing inference by the T/A area organization and for cribbing originators by the military cryptanalytic branch. 
REF :M~~8826 

TRAFFIC ANALYSIS RESEARCH 

4. Call Sign Analysis 

This group was responsible for the isolation and 

cryptanalytic solution of the various systems used by 

tbe Japanese for the allocation of call signs. The 

reconstructed allocation charts were used by the net reconstruction unit for the identification of nets and circuits • 

• 
.-? _b 71- - -

-;.:;CL.. --?'~ ...: 

t ' 

j ' l j ~ v ~..__) I • 
...... 

-~:A58826 

STATION PERFORMANCE AND CONTROL 

1. Intercept Facilities 

MS-2 Petaluma, Cal. (SSA) 

MS-5 Honolulu, T. H. {SSA) 

MS-6 Amchitka, Alaska '(SSA) 

MS-8 New Delhi, India (SSA) 

MS-11 Guam (SSA) 

l MS-15 Ft. Lewis, Wash. (WDC) 

MS-19 Anchorage, Alaska 

(Alaskan Dept) 

MS-20 Guam (POA) 

MS-21 Honolulu (POA) 

Daily station activity reports were received from the 

above stations and from these coverage results were determined; 

assignment changes were alao made on the basis of these daily - reports. Intercept missions were assigned directly by SSA 

to these stations. 

·. 
A/REf !D:A58826 . Le."'-1 

/I 

.- . ~ 

..___' 

• 

' 
~8826 

STATION PERFORMANCE AND COUTROL 

2. Liaison with Allied Centers 

WEC New Delhi, India - Station 94 

CB San Miguel, Luzon - Stations 25, 26] 30, 40 and 95 

I - Circuit coverage was coordinated by SSAj certain nets 

located in the particular area of interest to the center 

w·ere covered exclusively. by that center. Othor circuits 

monitored were those which met their individual needs. 

Coverage statistics were supplied to SSA and these were incorporated into the weekly coverage summa~y which included totals 

of all intercep~ sources devoted to J~p Army. 

PL 86-36/50 USC 3605 

EO 3.3(h)(2) 
.. Jd%i?tft) : A5 8 8 2 6 

STATION PERFORMANCE AND CONTROL 

~ Liaison with Theatre Commands 

POA 

IBT 

\"IDC 

AFPAC 

Alaskan 

Dept 

Honolulu, T. H. - Stations 20, 21, 2? 

Kunming, China - Stations 37, 38, 39 

Presidio, San Francisco - Station 15 

San Miguel, Luzon (See Central Bureau) 

Anchorage, Alaska, Station 19 

In all cases except IBT, assignments were made directly 

by SSA. In the case of IBT, a block assignment was made and 

individual circuits assigned by theatre headquarters to. the 

intercept stations. 
STATIOU PERFORMANCE AND CONTROL 

. J -C. Directives to Stations 

Included all stations listed under section l. Allied 

centers and theatre commands were contacted when specific 

requests were made of any particular station under their 

control. 

8B6HE! 
REF~S.826 

STATION PERFORMANCE AND CON~ 

~ Information to Stations 

Sent to all units listed under sections 1, 2 and 3. 

Circuit information was radioed daily to each unit so that 

station records were completely current. 
.. . . RE~B26 

STATION PERFORMANCE· AND CONTROL 

1S Circuit priorities 

Needs of cryptanalysis, traffic analysis and intelligence 

were weighed and individual circuit priority then determined. 

Circuit.was then assigned for coverage based on its priority 

classification. 

S!iGRE'i' 
.. 

. .. ~A58826 

STATION PERFORMANCE AND CONTROL 

+ ..... ~ Gase book f'ile 

A master file was maintained on all known Jap Army 

circuits including latest information on locations and 

validity, tau range, frequencies, call signs and validity. 
~Clfft'":A58826 

STATION PERFORMANCE AND CONTROL 

-a Other f1 le s 

a. Station assignments - current 

b. Station assignments - historical 

c. Circuit histories 

d. Gommon transmitters 

e. Geographical case book listing 

f. Predominant discriminant over each circuit 

g. Schedules 

h. WEC and CB assignments 
.. REF fi39:~B132 6 

STATION PERFORMANCE AND CONTROL 

9' Coverage re~!~ 

These reports were based on tau sheets prepared by net 

personnel. Each circuit was listed and messages intercepted 

compared with messages sent to arrive at an efficiency of 

coverage percentage figure. 

8l!l8M'f 
0 REF ~D : ~,,8 82,6 /\~ ~-~- { I! -+--

• .!!., - I ; .;,-J ~ ~ o 

' --''• v""""""" _, -7~ "--'-- •: I I ' \ 

:t I (; . 
. - - ,, 

NET RECONSTRUCTION AND INTELLIGENCE 

NETS 

-

l. Circuit Analysis 

Analysis of traffic available at this center, together 

with daily reports from intercept stations and foreign 

centers made possible daily changes in circuit listings. 

Since nets are established for communication within specific 

army units, correlation with order of battle was constantly 

checked. 

- SPJ8ft'.!Y" 
NET RECONSTRUCTION AND INTELLIGENCE 

~ 

~ Reading Operator Cha~ 

All chatter copied on Japanese circuits was submitted 

on continuous teletype rolls, containing also all traffic sent 

in proper order. Many security breaks were noted in plaintext, giving clues as to unit dispositions and other valuable 

intelligence. 
NET RECONSTRUCTION AND INTELLIGENCE 

~ 

().. W. Field Traffic Analysis Liaison 

rn' addition to disseminating reports from intercept 

stations, this section prepared daily coJ1llllents on field 

analysis reports, which were relayed by teletype and radio 

to the stations concerned. · 

SB8Hiff 
NETS 

R~'iln : AS a a2 6 

KET RECONSTRUCTION_AND INTELL~~ 

Maintaining Schedule and Gover~Records 

Analysts maintained weekly records showing activity on 

each circuit by amount of traffic sent and schedules. 

SECRE'f 
.... 

- REF~8826 

NET RECONSTRUCTION AND INTELLIGENCE 

NETS 

- .3 • Ci. Deriving of Net Inte lli_genc,,! 

Daily reports wore prepared giving possible interpretations of net changes in terms of Order of Battle. 

Net analysts assisted in work by maintaining records of 

contacts on circuits. 
~A58826 

NET RECONSTRUCTION AND INTELLIGENCE 

D/F 

.4 =&.. Direction Finding Up,!! 

Many bearings were taken on frequencies unlocated by 

traffic analysis, the results being correlated by this unit. 

Confirmation pf other analysis was also made possible. 
• ~pef!mt: A58 82 6 

NET RECONSTRUCTION AND INTELLIGENCE 

.,. "!11!-!" 

During the course of this section's activity, 26 

Japanese radio operators were identified and cataloged 

according to individual characteristics as recorded on 

tape. This technique was particularly applicable to low 

echelon traffic analysis. 

8l!l8HH'!'