From:      Commanding Officer
To  :      Chief of Naval Operations.
           (Communication Security Section)
Via:       The Commandant, 13th Naval District.
Subject:   Radio Intelligence Report for the month ending
           30 November 1941.

      1.   There is being forwarded herewith the report of Radio Intelligence Activities of this station for the month ending 30 November 1941, consisting of the following sections:

     During the month of November a sharp increase has been noticed in the amount of message traffic sent on the Kana General Information Broadcasts. Where before we seldom averaged more than one or two such messages monthly, it is now not unusual for two or three such messages to appear daily. These messages are sent in both number code and Kana.

     On the JJC/JYD 2330 Kana Press schedule on 24 November (see our sheet #4342) a message was sent addressed to "MRD" (YO NA HO). This seems to be a newly assigned call, and is assumed to include both Naval and commercial ships. It was sent at a very slow speed, and repeated, which leads to the assumption that all ships, including the very small ones, quite probably having poor operators, were included in the address.

     This would seem to indicate that the Japanese ships at sea, both Naval and commercial, are operating more or less under a radio silence.

     Possibly because of seasonal changes in effecting frequencies, or possibly for other reasons, there have been changes in times and frequencies of the continental General Information Broadcasts. On the 2330 schedule on 19 November (see sheet #4103) the following schedule of broadcasts was sent:

     On the 2330 schedule on 22 November (see our sheet #4217) another new schedule of broadcasts was sent as follows:

     This schedule differs from the first, only by the addition of the JUD (15880) listing to the 0930 broadcast. These broadcasts were covered on the first day they were effective, and copy was sent in with the regular traffic consignment. They appear to be the usual press broadcasts.

     Among the apparent reason for these changes is the possibility that the Japanese are trying to arrange a more satisfactory intercept system to their ships operating in the South Pacific.

     On 28 November, a directive was received by TWX from OP-20-GX which called for coverage of the following stations at times specified, with priority transmission of intercepted material by TWX. Times listed were given as PST. Because the use of PST time designation is unusual, we asked for a verification, but were told that time zone was uncertain and verification was not possible.

     Since the time zone indicated was not certain we were faced with the possibility that the time could be either GCT, PST, zone -9, or even a combination of these. As soon as the directive was received we started copying all broadcasts of this same type which were readable at "S". We found that in some cases other stations were tied in with the stations listed in the original directive, and that although we could not copy the station listed we could copy the cornetted channel carrying the same broadcast. The stations and times that we can copy are listed below. Times used is GCT:

     At the present rate the telephone charges will be about sixty dollars ($60.00) per day to send in this material. This is not including our regular traffic that we send in via TWX. In view of the expense involved, and the large amount of this material available at "S", it is requested that this assignment be re-qualified, and further instructions be issued to cover specific transmissions which carry material of such priority as to warrant transmission to OP-20-GX via TWX.

     On 27 November, directions were received from OP-20-GX to cover both ends of the San Francisco-Tokyo radio telephone circuit, and to mail all records made via air mail to OP-20-GX.

     Watch was set immediately, and almost immediately thereafter the San Francisco end of the circuit was located, but it was a few hours before the Tokyo end was located definately. Since these circuits use scrambles speech except when calling, it was difficult to follow them, as they give directions for shifting frequencies while using scrambled speech. If this circuit is to be covered successfully, we need a device for unscrambling this inverted speech. Sometimes coverage is lost due to our being able to pick up the new frequency in time. A detailed memorandum on this subject was mailed in on 27 November.

     Channels used by both ends, and their frequencies, are listed below:

     There may be other calls and frequencies assigned to this service, but as yet they have not been used. This circuit is apparently not continuous, but may secure for as long as five or six hours during light traffic periods. If traffic comes up during this time, a service message is sent over regular radio telegraph circuits.

     76 records have been made and sent via air mail, up to and including 30 November.

     The West Coast Strategical High Frequency Direction Finder Net carried on the assignment of tracking all Orange Merchant vessels in the Eastern Pacific Ocean during the month of November, 1941.

     During the period 1 to 14 November, 1941, inclusive a searching watch was maintained at the Net Control and Plotting Center at Bainbridge Island on the calling and working frequencies used by Orange Merchant Vessels. When an Orange Merchant Vessel was heard transmitting a control signal was transmitted by the searching operator at the Control Center by radio F method, consisting of a call and frequency designator, designating the call sign of the Orange Merchant zessel and the frequency on which transmitting.
     Stations of the Net obtained bearing simultaneously in response to the Net Control Station's signal and during intervals between control signals search for targets independently and obtained bearings when possible. Bearings were reported to the Net Control and Plotting Center twice daily at 0000 and 1400 GCT by despatch.

     At 0000 hours 15 November, 1941, the Net was plasced in CONDITION TWO which differs from the previous method in that no control signals are transmitted by the Net Control Center. Each station of the net conducting it's own searching and taking bearings on Orange Merchant Vessels, when possible, when such transmissions occur on prescribed frequencies. The present searching schedule is:

     All bearings reported by stations of the net were logged and fixes plotted of ship's positions, when possible, from bearings obtained from two or more stations when taken at or approximately the same time.

     Good fixes on Orange Merchant vessels obtained by plotting reliable bearings from three or more stations of the Net were reported in confidential code despatches to the Chief of Naval Operations and the Commandants of the Twelfth, Thirteenth, and Fourteenth Naval Districts. Included in this report were any intercepted position reports from Orange Merchant Vessels received since last report of previous day.

     In accordance with instructions received from the Chief of Naval Operations (OP-20-G) a weekly summary of high frequency direction finder bearings obtained on Orange Merchant Vessels by the West Coast Strategical High Frequency Direction Finder Net is forwarded to the Chief of Naval Operations (OP-20-G) and the Commandants of the Twelfth, Thirteenth, and Fourteenth Naval Districts.

     The weekly summary of bearings tabulated daily consists of the names of the Orange Merchant vessels, radio call sign, stations of the Net obtaining bearings, bearing obtained, the estimated D/F position, and remarks.

     The following list shows the Orange Merchant vessels and dates on which two or more stations of the net obtained bearings at or approximately the same time. These bearings were plotted by the Net Control and Plotting Station to determine a D/F fix for tracking. Further information is shown by listing the frequencies used by each Orange Merchant vessel and the ship or station communicated with.

     All direction finder position fixes of Orange Merchant vessels are plotted on separate charts. A total of 21 Orange Merchant vessels were tracked during the month of November, 1941.

     Movement reports of Orange Merchant vessels received from the Office of Naval Intelligence and the District Intelligence Officer of the Thirteenth Naval District as well as intercepted position reports are entered in a card index file, arranged alphabetically by call sign, for comparison and reference with direction finder tracking.

     High frequency direction finder bearings recevied via the Commandant Thirteenth Naval District from the Canadian High Frequency Direction Finder Stations at GORDON HEAD and UCLUELET on Orange Merchant vessels were used for separate plotting with the bearings obtained by the West Coast net and for separate records.

     A daily average of Orange Merchant vessels positions plotted by the Net Control and Plotting Center at Bainbridge Island was five while a daily average of eight bearings were taken by Bainbridge Island Direction Finder Station on five different Orange Merchant vessels during the month of November, 1941.

     As the general trend of movements of Orange Merchant vessels is toward the Western Pacific and seven of the vessels which were in the Eastern Pacific during the first few days of November had arrived in Japanese ports the number of positions plotted during the period 16 to 30 November was less than one third the total number plotted during the month. So far as can be determined only three Orange Merchant vessels are now in the Pacific, east of the 180th Meridian, TERUKAWA MARU, proceeding northwest from the West Coast of South America; NARUTO MARU, prodeeding northward along the coast of South America and the TOA MARU in the South Pacific and due at a Japanese Port in early December, 1941.

     No other special assignments were conducted by the Net during November, 1941.