Radio system notes

MSoltysiakB781032-170622-14.pdf

Title

Radio system notes

Description

Notes on signals, system of wireless signalling, R/T radio telephony, aerials, wireless equipment in bomber aircraft (including Marconi set (1155-54), G.P.set (1083-1082), Bendix, beam approach installation, TR-9, TR 1196, amplifier A1134, IFF, Gee, proposed VHF, DF system and other equipment. Continues with description of other radio equipment, techniques and procedures.

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Multi-page handwritten document

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This content is available under a CC BY-NC 4.0 International license (Creative Commons Attribution-NonCommercial 4.0). It has been published ‘as is’ and may contain inaccuracies or culturally inappropriate references that do not necessarily reflect the official policy or position of the University of Lincoln or the International Bomber Command Centre. For more information, visit https://creativecommons.org/licenses/by-nc/4.0/ and https://ibccdigitalarchive.lincoln.ac.uk/omeka/legal.

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Identifier

MSoltysiakB781032-170622-14

Transcription

Transcription:

[underlined] Signals [/underlined]

[underlined] Wave length & Frequency [/underlined]
Speed of wireless is 300,000,000 meters [sic] per second. The wave length is the distance covered by one complete cycle of the wave and is measured in meters [sic]. The number of complete cycles occurring in a second is called the [underlined] Frequency [/underlined], and this is equal to the total disturbance covered by wave motion in one second divided by distance covered by one cycle.

[calculations]

The frequencies of wireless are of the order of millions of cycles per second so larger units of frequency are used.

L.F. is less than 300 K/cs and greater than 1000 meters.
M.F. is 300 to 3,000 K/cs which is 100 to 1000 meters
H.F. is 3,000 to 30,000 K/cs which is 10 to 100 meters
V.H.F. is 30 m/cs to 300 m/cs which is 1 to 10 meters
Aim is to get higher and higher frequencies. On long waves there is no space on band for many frequencies and H.F. is better because there is more space on band for frequencies.

[diagram]

[page break]

[underlined] System of Wireless signalling [/underlined]

[underlined] W/T. Wireless telegraphy [/underlined] is signalling in morse. Advantages is that it has greater range than R/T. and lends itself easily to cyphering. Disadvantage ist [sic] that trained operators are needed to use it. A/C are difficult to control using W/T and also that the enemy can hear it.

[underlined] R/T. Radio Telephony [/underlined] is signalling by means of speech and therefore any one can use it. Disadvantage is, it has smaller range and is no good for cypher to set phrases have to be used.

[diagram]

H/F.
[underlined] Advantages. [/underlined]
Greater Signal range for equal power. More frequencies available in H/F. Band.

[underlined] Disadvantages. [/underlined]
Short ground wave. No good for accurate D/F. beyond 100 miles with RAF. H.F./DF.

M/F.
Advantages.
Longer ground waves. O.K. for accurate D/F. up to 300 miles with RAF. D/F. M/F.

Disadvantages.
Greater [deleted] signal [/deleted] power required for same signals. Fewer frequencies available in M/F. D/F band.

[page break]

[underlined] Loop Aerials [/underlined]
The loop aerial has peculiar directional properties which are used in D/F. When the plane of the loop is in direction of the transmitting station a maximum signal will be heard. When the plane of the loop is at right angles to the transmitting station a minimum signal will be heard and as minimum is more clear and defined than maximum, we use minimum to find the direction of the transmitting station.

Two positions of minimum signals will be received 180° apart, and to determine which position is correct we use a method known as [underlined] sense [/underlined] finding. Bearing is in respect to fore and aft of the a/c.

[underlined] Quadrantal Error [/underlined]
Is caused by the Electro-magnetic field round the a/c. (Like compass deviation). Which gives us an error of a few degrees, which either added or subtracted on to the bearing.

[underlined] Advantages. [/underlined]
1). [underlined] D/F. assistance obtained without breaking W/T. silence. [/underlined]
2). [underlined] No limit to number of A/c that can take bearings on one M/F. Beacon. [/underlined]

[underlined] Wireless Equipment in Bomber Aircraft. [/underlined]

[underlined] Marconi Set. [/underlined] (1155-54)
Receiver calibrated in kilocycles [inserted] 24 pre set freq. work on [/inserted] M.F. & H.F.
Easy tuning.
W/T. Transmiter [sic] and receiver, Range approximately

[page break]

350 to 400 miles.
R/T. good but too powerful but can be cut down. Visual Indicator can be used in conjuction [sic] with receiver, hence home keeping needles crossed on the centre line. When A/C passes over beacon needles will collapse momentarily. Used in conjuction [sic] with the Loop aerial.

[underlined] G.P. Set. (1083-1082) [/underlined]
Used for W/T. transmission and reception on M/F or H/F. Loop aerials and [indecipherable word] fixed can be used. Range 250 miles (depending on weather conditions)
Disadvantages:- difficulty in frequency changing. 15 sets of coils for receiver and 4 sets for transmiter [sic]. Superceded by the Marconi.

[underlined] Bendix. [/underlined]
W/T. and R.T. set fitted in Venture and Boston a/c. in No 2. Group. On 4 frequency press button tuning control. (Usually Group Ops. Wave, 1 M/F. D/F section 1 H/F, D/F station and 1 other frequency, usually a diversion station) W/T. Range approx. 400 miles. R/T. range approx. 50 miles.

[underlined] Beam Approach Installation. [/underlined]
Two receiver, one for Main Beam and one for markers. Both receivers connected to Pilots control panel.

[underlined] TR.9. [/underlined]
Pilot operated H/F. R/T. transmitter and receiver. Crystal controlled frequency on [underlined] 6440 K/cs Bomber) [/underlined] and [underlined] 2410 (Costal [sic]). [/underlined] Range Air to ground 10 mls. Range air to air 3 miles. Battery operated 2 volt. Low Tension and 120 volt H.T. Receiver Tuning

[page break]

very critical and should be set up by a W.O./M. using a low powered monitor. Tuning can be locked to avoid mistuning by accidental knocking of dials.

Points to meter with [underlined] TR.9.[?] [/underlined] in F.C. office.
1). Battery L.T. changed [indecipherable word].
2). Battery H.T. changed when down to 100 volts.
3). Volume control always full on.
4). Reaction just half turn from on position.

[underlined] TR.1196 [/underlined]
Will be shortly fitted in lieu of TR.9.
R/T. set with 4 frequencies selected by press buttons.
Good speed. Range approx. 20 miles. Power will probably be cut down for Darky.

[underlined] Amplifier A.1134. [/underlined]
Used for inter-communication only. Is connected through G.P. or Marconi set, also through TR.9. to enable crew if necessary to hear all messages received from the ground by TR.9.

[underlined] I.F.F. (Identification Friend or Foe) [/underlined]

[underlined] Loop Aerial [/underlined]
Most a/c are fitted with Loop Aerial.

[underlined] Proposed fitting of V.H.F. [/underlined]
Some of 2 Group a/c are fitted with V.H.F enabling them to use Fighter services and it is proposed to fit all bomber a/c with it.

[underlined] Gee Set. [/underlined]

[page break]

[underlined] D./F. Systems in use on the Ground
Bellini-Tosi system. [/underlined]

[diagram]

In the Bellini-Tosi system which was the first to be used on the ground and is the basis of the Marconi-Adcock system at present in general use. Two large loops (fixed) are mounted outside the cabin. One North to South the other East to West. Each loop is connected to a similar oriented coil inside the cabin. A search coil is rotated until the minimum signals are heard. It will then be at right angles to the right direction of the transmitting station. This arrangement of coils is known as a [underlined] Goniometer [/underlined]. If an indication be mounted on it and read off against a scale, the direction of the transmitting station may be read off. Two positions of minimum signals will be heard as with a simple loop.

[page break]

[underlined] Night Effect. [/underlined]
All loops and combinations of loops suffer from an error known as Night effect.

Bellini-Tosi systems are therefore not reliable at night beyond a range of approx. 50 miles. Night effect has been eliminated by introduction of the Marconi Adcock system.

[underlined] Marconi-Adcock System. [/underlined]
This system cuts off the top horizontal arms and screens the bottoms by enclosing them in earthed metal tubes. Otherwise the system is similar to the Bellini-Tosi. Used for H.F. and M.F.

[underlined] Cathode Ray Indicator [/underlined]
A visual Indicator in lieu of switching search coil for position of minimum signals. A [indecipherable word] screen on which a signal appears as an elipse [sic] of light. This elipse [sic] can be transformed into a line of light which will indicate the direction of transmition againts [sic] a scale. A possible 180° error still exists. This may be eliminated by switching to sense which has two effects of either.
1). eliminating the wrong end of the line.
2). Defocussing or blurring the wrong end of the line.

[underlined] Advantages. [/underlined] 1). Quicker than aural method.
2). More accurate than aural method.

[underlined] P.3. H.F./D.F. Set [/underlined]
Range 50 miles. Used in the past to

[page break]

to relieve congestion on H.F./D.F. station in Bomber Command. Maybe encountered again. Suffers from night effect.

[diagram]

[underlined] V.H.F./D.F. [/underlined]
Range 100 miles (approx). For use with Fighters. Fitted at Fighter Station and all Type 1 stations.

[underlined] Capabilities of D./F. Station. [/underlined]
M.F./D.F. Station give approx. 12 fixes per hour to 12 a/c.
H.F./D.F. can give approx. 120 QDM's per hour to 15 a/c.
H.F./D.F. and Cathode Ray can give approx. 240 QDM's to 40 a/c per hour.
VHF. Passes 240 Vectors per hour.

[underlined] Classifications of Bearings and Fixes. [/underlined]
A Bearing is classified by the width of minimum signals. A number of degrees between signal disappearing and reappearing.

1st. Class
Bearings – 0° to 2°
Fixes – 2 or more 1st class bearings making good cut.

2nd Class
Bearings – 2° – 5°
Fixes – One 1st Class Bearings and one or more 2nd Class making good cut.

3rd Class
Bearings – 5° and over
Fixes –
All other than 1st. class bearings making good cut.

[underlined] Procedure for obtaining Fixes, Bearings & QDMs [/underlined]
V.E. D/F. v A/C x696 IMI (QDM IMI)
VE A/C. v D/F x687 or K
VED/F. v A/C A/C [underlined] 15 sec. [/underlined] A/C [underlined] 15 sec. [/underlined]
VE A/C. v D/F x 638 097 2030 (QDM, 097, 2030)

[page break]

VE D/F. v A/C x 702 (QTE IMI)
VE A/C. v D.F x 687 or K
VE D/F. v A/C A.C [underlined] 15 sec [/underlined]
VE A/C v D/F. Q
Control collects bearings
VE A/C v D/F x 714 [calculations]

On transmission from a/c the other 2 D/F's pass bearings to the Control Station. Control Station make a fix. If he [deleted] can [/deleted] is satisfied that a/c is friendly He will pass it. If not he verifies a/c by [two indecipherable words] from S.D.0182.

[underlined] Verification. SD.0182 [/underlined]
Is a W/T system of challenge & answer between D/F station and A/C by using a card from S.D.0182. Only one card covering one day is held by A/C and cards are changed at 1200 hrs (local time). D/F station should only challenge when definite suspicion exists A/C may also challenge D/F station’s.

[chart]

[page break]

[underlined] Recognition. [/underlined]
Purely visual. By flashing letters and colours Pyrotechnics, etc.

[underlined] Identification [/underlined]
Means of proving self friendly when 100 miles from English coast on return, normally done by switching IFF. to stud 1, or by sending ops. Call sign by W/T. to the appropriate M.F/DF station.

If suspected A/C could not give correct answer to challenge MF/DF control would not pass the fix but would pass it to the MLO. at appropriate Fighter Group to be plotted as on X raider.

[underlined] Wireless Services available to Bomber A/C. [/underlined]
[underlined] M.F/DF. Organisation. [/underlined]
This organisation will give immediate fixes up to a range of about 300 miles. Aim is to provide a 24 hrs S.O.S. and safety service for a/c and to assist in identification of A/C. MF/DF. Station are grouped in section’s arranged to give good fixing facilities over the area served by each section. All stations in one section work on the same frequency. A/C are allotted section on which they should normally make distress calls and request for fixes or for identification purposes. In emergency A/C can ask any section they wish. Group H.Q. informs the MLO. to whom they are connected of the M/F. section their A/C will be working. They also pass the ops. call sign of the A/C which are passed by the MLO. to the MF/DF. control station who in turn passes fixes

[page break]

or distress and identification messages to the MLO. who in turn passes it to the A.C.H.Q. who inform A.S.R.S. for search action and the parent station also for information.

[diagram]

MF/DF. control station also passes fixes or identification messages from A/C to the MLO. who plots these fixes as friendly raiders. Fighter Command has overiding [sic] control of transmissions by MF./DF. stations (if enemy attempts to use) Permission to transmit may be withheld if enemy air activity makes such action necessary. MF/DF control station send out tuning & timing transmission at 15 to 18 and 45 to 48 minutes past the hour, from 11.15 to 1348 hrs daily. (16 MF/DF sections)

[underlined] HF/DF. Organisation [/underlined]
All Bomber stations are fitted with HF/DF. for homing their own A/C. Accurate range approx. 100 miles. Only QDM.'s are passed. All HF/DF stations transmit tuning and timing signals at 15 and 45 minutes past the hour.

[underlined] Group Operational Wave (Blower) (H.F./D.F.) [/underlined]
This consists of a high powered transmitter and receiver at Group HQ and is used for passing Operational Instructions to A/C in flight, and when necessary for receiving operational reports

[page break]

from A/C. This wave is not used for DF. But Group often arranges for HF/DF stations not being used to open watch during operations on this frequency, so that DF bearing may be obtained on any transmission from A/C. Group usually pass diversions on this wave using appropriate groups from C.D.0250 (Bomber Code) A/C maintain listening watch during operation on this wave, especially at hour and half hour when Group transmits tuning and timing signal. Any messages on hand are also transmitted at these times. Range 2 way communication 800 miles with a/c fitted with Marconi Set, 500 miles [indecipherable words] G.P. set.

[underlined] VHF/DF. [/underlined]
Fitted at all Fighter Stations and some Type I stations in other Commands for use of Fighter A/C R/T only. Range approx 150 miles. It is proposed to fit Bombers with VHF. sets to enable them to use the VHF/DF Service. Certain A/C in No 2 Group have VHF. Sets fitted for cooperation with Fighters.

[underlined] Emergency R/T Organisation. [/underlined]
[underlined] Darky Procedure [/underlined] (see on the front).
[underlined] Organisation [/underlined]
All FC. stations in Bomber Command and Type I stations in other Commands have Darky Sets on 6440 k/cs. All FC. Station in Coastal Command and Type I station in other Commands have Darky Sets on 2410 K/cs. All Aerial Lighthouses and some

[page break]

ROC. posts, some M/F. Beacons Sites and certain other stations in Fighter Command and Flying Training Commands have Darky Sets on 6440 K/cs or 2410 K/cs or both. Hours of watch are from Dusk to dawn unless otherwise ordered (bad visibility etc). A/C of Bomber and Coastal Command maintain Darky watch on Tr.9. or 6440 K/cs (B) or 2410 K/cs (C) respectively. Stations in Bomber and Coastal Commands maintain R/T watch on their respective frequencies. If an a/c is a) not in W/T communications b) is lost and cannot obtain position by any other means, C) is short of fuel, the pilot may call Darky on TR.9.

Any of the above mentioned stations hearing a call loud and clear will assume that the a/c is within 10 miles and will answer giving the name of their aerodrome or position in clear.

A/C requiring special assistance will ask for it. A/C in distress will include "May day" in their Darky call, and will receive same service except they will be given absolute priority. Group or ROC. may inform you that a friendly bomber is flying in your vicinity obviously lost or in difficulties. You may be able to assist the A/C by calling "Nemo" from Darky.

[underlined] Squeakers. [/underlined]
Low powered transmitters situated on outer ring of Balloon Barrages. Working on 6440 K/cs and or 2410 K/cs as ppropriate [sic]. Range 8 to 12 miles. Heard on TR.9. in A/C as a wakling [sic] note and constitutes a warning of proximity of Balloon Barrage to Bomber and Costal [sic] A/C.

[page break]

[underlined] Frequencies. [/underlined]
Red: 6410 to 6470. 60 K/cs sweep } Bomber
Blue: 6415 to 6450. 35 K/cs [indecipherable letters] } Bomber
Yellow: 2405 to 2420. 15 K/cs [indecipherable letters] Coastal.

[underlined] S.B.A. Organisation. [/underlined]
Each Group H.Q. details the 6 frequencies to be pre-set in the A/C main beam receiver.
These are selected by the pilot by use of the frequency selector switch. Approx. 20 to 30 Beams will thus be available to a/c.

[underlined] Radio Track Guides (T. Beams) [/underlined]
Lorenz beams directed down safety lanes on to target after attack to enable A/C to home using S.B.A. system.

These are located at Cravenscar, Cransford, Haine [indecipherable name] and Fulston. Morse characteristic [inserted] letter [/inserted] every 2 1/2 minutes for identification purposes.

[underlined] M/F. Beacon Organisation [/underlined]
This organisation consists of several groups of beacons geographically distributed over the British Isles. Each group comprising of 3 Beacons [indecipherable word]. A continous [sic] 24 hrs. service is maintained by Groups A, B, C, D, F.J [deletedword] but transmissions are made from only one Beacon at a time in each group, using different call sings[sic] and frequencies. Schedules are issued setting out the programme which is operated by the various groups and showing the beacon site call signs and frequencies which are used in each group.

[page break]

1030 – 1115 A3 BB7 350K/cs
1115 – 1200 A1 CC7 345 K/cs
1200 – 1300 A2 ZZ7 320 K/cs
1300 – 1415 A1 PP7 360 K/cs.

Group "G" operates on 236 K/cs. Call sign GG7 1 beacon at a time as per schedule or on request from H.Q. North Ireland via F.C.O. Nutts Corner.

[underlined] Enemy M/F Beacons. [/underlined]
The enemy has an extensive organisation. He also changes call signs, frequency and locations but is methodical and Bomber Command's special staff forecast the schedule accurately about 24 hrs in advance. A signal is despatched to all Stations giving the following details of enemy Beacons available and reliability, location, call sign, frequency and colour-code. To prevent enemy using their Beacons to assist navigation to targets in this country, certain Beacons are jammed by us. The limitations so imposed on the use of Enemy Beacons by our A/C is indicated by a color[sic]-code e.g. Red = No good anywhere, White = O.K. anywhere, Green = O.K. when 70 miles from British Coast or over enemy territory.

[underlined] IFF. Installation [/underlined]
[underlined] G. set [/underlined]
[underlined] Telephone Organisation and Procedure [/underlined]
The G.P.O. is responsible for all fitting, removal, recovery, and maintenance of telephone lines and instruments. They act on the advice of the Station Signal Officer, who also advises as to Local Organisation. Stations have P.B.X. with

[page break]

extensions to all important officers on the station and one or two lines to the Local GPO. Exchange. Station PBX. has also a tie line conecting [sic] it to the PBX at Group.

[diagram]

[underlined] A Tie-line [/underlined]
A Tie line is a private wire connecting 2 P.B.X.'s. Tie lines are not secret because they are linked up with G.P.O. System by the P.B.X. at either end The PBX. operators cannot be regarded as responsible persons.

[underlined] RAF. Tie-line Organisation. [/underlined]
A control or Central P.B.X. has tie-lines linking it with all Group PBX's. Group PBX. have tie lines connecting them to all station P.B.X. within their Group.

[diagram]

[page break]

[a] Operational Area. [b] W/T Control Stns. [c] W/T Periods. [d] Control Frequencies
[a] Gibraltar [b] A.C.H.Q. Gibraltar [c] 20 & 50 mint pass hour [d] 6666 Kc/s by night
3925 Kc/s by day
[a] Plymouth [b] A.C.H.Q. Plymouth [c] 15 & 45 mint pass hour [d] 6666 kc/s by night 3925 Kc/s by day
[a] Western Approach [b] A.C.H.Q. Liverpool [c] 0 & 30 mint pass hour [d] 6666 Kc/s by night 3925 Kc/s by day
[a] Iceland [b] ACHQ Iceland [c] 20 & 50 mint pass hour [d] 6666 Kc/s by night 3925 Kc/s by day
[a] S.N.O.C.E. SENIOR NAVAL OFFICER CONVOY ESCORT [c] 10 & 40 mint pass hour [d] 6666 Kc/s by night 3925 Kc/s by day

Continuous W/T watch should be maintained by A/C on the control frequency except when interference from A.S.V. prevents it. Watch must be kept at the periods indicated when A.C.H.Q. will make transmissions and pass any messages on hand at these times.

[underlined] W/T silence [/underlined] is to be maintained by A/C except for the following:
1) To make an enemy report
2) When called by W/T control
3) When called by S.N.O.C.E. or W/T Guardship
4) as directed by A.C.H.Q. control
5) To obtain navigastional [sic] assistance.

[underlined] Continuous R/T watch [/underlined] should be kept [inserted] by A/C [/inserted] except when interference from A.S.V. prevents it.
R/T watch must be opened:
1) To make an enemy report to S.N.O.C.E.
2) In an emergency
3) When ordered by visual signalling by S.N.O.C.E.
4) When visibility renders visual signalling unreliable at 10 to 15 and 40 to 45 minutes past the hour.
[5] For identification purposes in emergency (e.g. when firing opened on A/C from friendly vessels).

All enemy sighting reports to S.N.O.C.E. first by R/T and then immediately afterwards to control by W/T.

[page break]

Urgent operational messages for A/C not maintaining continuous watch at times other than routine transmission are to be passed by W/T Station to Naval W/T Station for transmission to S.N.O.C.E. who will pass to A/C by visual signalling or R/T.

[underlined] Fighter Command. [/underlined]
[underlined] Signals Organisation and Procedure. [/underlined]
[underlined] SECTOR CONTROL ROOM AT GROUP [/underlined]

[diagrams]

[a] [underlined] Channell [sic] [b] Day [c] Night [/underlined]
A [a] Ops. 1. [b]Aerodrome Control [c] Aerodrome Control
Each Station has DF on this channell [sic]
B [a] Ops. 2. [b] Aerodrome Control. [c] Ground Control interception.
C [b] Group Com. Frequency. [c] Com. Guard
All Stations in Group maintains listening on Group

[page break]

[underlined] Tied Tie-lines. [/underlined]
A Tied tie line is a private wire which connects 2 telephones but does not pass through any exchange. It can therefore be regarded as secret.

[underlined] Group Operations Room. [/underlined]
Group Operations Room have tied tie lines to:
1) All [deleted] Group [/deleted] Stations in the Group (to ops. room).
2) All other Groups in the Command.
3) Command HQ.
4) M.L.S. at appropriate Fighter Groups.
5) R.O.C. Centre
6) F.C. Office at Type 1 stations within the Group.

[underlined] F. Control Room at Type I station have tied tie line [/underlined]
[underlined] to: [/underlined] 1) H.F/DF Station
2) VHF/DF station
3) Beam approach Main Beam
4) Stations ops. Room
5) Group ops. Room
6) Met. Office.

[underlined] Telephone Instruments connecting to G.P.O. [/underlined]
1) A black instrument with black base (this is an ordinary instrument connected to an ordinary switchboard and gives no security what so ever)
2) A green instrument with a green base (this is connected to separate switch board manned by operators specially selected and gives a certain amount of security. Only fitted in selected offices.
3) A green instrument with a black base (on the base, a button marked seecret [sic]. These instrument are only fitted in specially selected Offices. When they are connected to ordinary telephones and

[page break]

used in the ordinary way they offer no security. When they are conected [sic] to a similar instrument and the button marked secret is pressed, speech will be scrambled. If the button on the far instrument is pressed the speech is unscrambled. This system is regarded as quite secure)

[underlined] Telephone Procedure. [/underlined]
When called say who you are e.g. “Control Valley". Make sure to whom you are speaking before discussing service matters. Remember that when a telephone receiver is lifted the instrument is alive, so be careful what you say, (especially when one receiver is lifted and you are speaking into another instrument on Service matters) Never discus [sic] secret matters except on Tied tie lines. (or secrecy equipment) If you have to pass a message by phone always get the receiver to repeat back and make a note of his initials and time of passing. Difficult and unusual words should be spelt out phonetically and in speaking figures “refer" to 5 as “five and 9 as "niner" and 0 as zero. Ask for telephone connection by number and not name.

[underlined] Telephone Priorities [/underlined]
[underlined] G.P.O. Lines. [/underlined]
[underlined] Priority No. 1 [/underlined] = Rescue A/C, F. Control, and other urgent operational matters
[underlined] Priority No. 2. [/underlined] = All other vital urgent calls.
Officer originating call will ask for priority required

[page break]

giving his name and rank to operator.

[underlined] RAF. Tie Lines [/underlined]
On RAF. Tie lines some conditions will apply except that priorities are a) Rescue A/C. b) Flying Control. Officer originating call will [deleted] give [/deleted] ask for Rescue A/C or F. Control and give name and rank to operator.

[underlined] Code Words. [/underlined]
Pine-tree = Bomber Command = 8th Air Force (U.S.)
Ajax = Fighter Command = 8th Air Force (U.S.)
Gangway = Air Support = 8th Air Force (U.S.)
Wide wing = H.Q. 8th Air Force 8th Air Force (U.S.)

Southdown = H.Q. Bomber Command RAF.
Bentley Priory = H.Q. Fighter Command RAF.
Northwood = H.Q. Coastal Command RAF.

[underlined] Signals Organisation and Procedure during Bomber Operations. [/underlined]
[underlined] The following Signals Publications are carried. [/underlined]
1) AP. 1927 (Air Force Code)
2) CD. 0250 (Bomber Code)
3) AP. 982 (X Signals)
4) SD. 0182 (Verification tables)
5) F. 398 (W/T Log Book)

[underlined] The following information is carried on destructible paper (Rice paper). [/underlined]
1) The call signs and frequencies of selected Continental wireless stations.
2) Location of British M/F Beacons.
3) Location of Continental wireless Stations.

[page break]

[underlined] The following information need not be carried on destructible paper. [/underlined]
1) [deleted] Call signal Group H.Q. the collective call-signs of [/deleted] Call signs and frequencies of H.F/D.F. stations in Bomber Command and other stations to which a/c may be diverted.
2) The call-signs of group H.Q. The collective call-sign of all Group a/c in Flight, and appropriate Group Operational Frequency.
3) The call signs and frequencies of F.C. and Type 1 stations.
4) The call-signs and frequencies of the various M.F/D.F. sections.
5) The schedule of operations of the British M/F. Beacons for the period covered by the flight.
6) The outline map showing pictorially the details of the B.A. instatations [sic] which are available on each stud setting on the receiver.
7) The Operational call-sign alotted [sic] to the a/c for that particular operation. The A/C letter and the MF/DF. Section allotted for that particular flight.
8) Location call signs, and frequencies and colour code of enemy M/F beacons.

[underlined] Procedure. [/underlined]
W/T. Silence must be maintained during whole of operation, except in emergency, when any wireless aid may be used. On taking-off I.F.F. and Detonator Circuit are connected and I.F.F. switched on to Stud I. When airborne

[page break]

Wireless operator tests his receiver only on the Group ops. Wave and if not satisfied with the reception before reaching a point 40 miles from base he must inform pilot who should return to base. The wireless operat. must listen out on the Group ops. Wave at the hour and 1/2 hour periods when Group will be transmitting tuning and timing signals and transmission serial no. and any messages on hand will be send [sic] at these times. During remaining time W/O should be obtaining Loop bearings on M/F Beacons. While over sea transmitter only must be tuned to the MF/DF. section and trailing aerial must be reeled out. (Ready in case of emergency) Except when listening on Group ops. Wave (Blower) the W/O. will be obtaining Loop Bearings on British or Enemy M/F Beacons. IFF. must be switched off when 50 miles from the British Coast, if North of 54° N and 10 miles from the British coast, South of 54° N.

On return flight a pilot may be use on R.T.G. to assist him to navigate back to base, across the sea to a safe landfall. A/C must identify itself when approx. 100 miles from the British coast or on crossing the enemy coast if this is nearer.

[underlined] Identification. [/underlined]
Normally done by switching IFF on Stud I. if however the IFF. is u/s or not fitted or the a/c is below 2000 feet or if a/c is returning from direction not expected an identification signal must be sent by W/O to appropriate MF/DF section. (May use GCN. or GGB) with identify signal if occasion arises to necessitate their use.

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Image 24
GCN 3 – mean I am being followed by 3 the enemy A/C } [underlined] AP 1927. [/underlined]
GGB 2 – mean I am being followed by two identified A/C. } [underlined] AP 1927. [/underlined]
MF/DF will make a D.F. fix on the transmission and will look up the list of curent [sic] operational call-sign. If O.K will pass the fix to MLO. as a friendly plot together with appropriate group from [underlined] CD.0250 [/underlined] /Bomber Code dealing with enemy or unidentified a/c flying with bomber if received. When within 100 miles of base W/T gear should be tuned to the station HF/DF freque. [sic] in case QDMs are required. When within R/T range of base pilot will call F.C.O. on TR.9. for control in landing. Before landing W/O must not indicate by W/T signal that A/C is about to land. Before landing the W/O switches off I.F.F. making sure that it was not on stud 3 and disconnect interogation [sic]. Used paper are removed from they [sic] book and filed by signal officer.

[underlined] Procedure during Distress Bomber operation. [/underlined]
[underlined] PART. A. [/underlined] If A/C is unlikely to regain British teritory [sic] but ditching is not imenent [sic] the wireless operator should send an MF/DF. the appropriate call group from [underlined] CD.0250 [/underlined] or [underlined] AP.1927 [/underlined] prefixed emergency [indecipherable word] riquest [sic] for D.F. fix. The A/C sent ops. call sign and 15 second dash repited [sic] every 10 minuts [sic] and Gee fix if fitted.

[underlined] PART B. [/underlined] If switching is imennent [sic] the following signal should be sent on MF./D.F. SOS. 3 times 15 second dash and its "G" fix (if time permits a message giving track G/S, endurance [sic] and number of crew) prior to switching the W/O should clamp the W/T key down.

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If within 100 miles of British coast IFF should be switch on to stud [underlined] 3 [/underlined]. If pidgens [sic] are caried [sic] one should be rileased [sic] before switching and the other from the dinghy provided they have a chance of reaching base during the hour of day light. When on the water in the dinghy, the dinghy W/T set if fitted should be operated, 15-18 and 45-48 minutes pass the hour or continuously when vessel are in sight. Automatic or hand key on [underlined] 500 Kc/s sending SOS. and 4 A" [/underlined] on the [underlined] internationall [sic] distress wave. [/underlined] Aerial held aloft by a kite which is fired into the air by a rocket or if in sufferient [sic] wind a telegraph aerial is used or hydrogen ballon. [sic]

[underlined] Action taken on Distress call’s. [/underlined]
On receiving a distress call MF/DF. make a fix on the transmission. They pass the fix to a/c and to the MLO. to whom they are connected. The M.L.O. passes the information to the F.C.L.O. who passes it to the appropriate ACHQ for ASR action and to the parent station for information. If an A/C make a distress call on HF/DF the FCO. at the station receiving the call must tell his DF. operator to maintain contact with the distress A/C and pass as many QDM's as possible. The F.C.O. should immediately ring own group and pass the following information
1) time and text of distress message.
2) last QDM. passed out and time of position.
3) call sign and frequency A/C is using.
4) time of last hearing distressed A/C.
Group can swing other D.F. station not being used to that frequency and so obtained a fix.

[underlined] Diversion [/underlined]
Group in colaboration [sic] with F.C.O. decide necessary diversion.

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Having decided on a diversion, Group must inform A/C to be diverted by sending W/T message on the group ops. wave (blower) during the next transmission period using appropriate code from [underlined] CD.0250. [/underlined] If the chosen diversion aerodrome is one whoes [sic] particular are not carried, group may transmitt [sic] the call sign and frequency of the HF/D.F. station and if necessary the latitude and longitude of aerodrome in bomber code. Group must also inform the chosen diversion aerodrome giving the following details.
1) Number (of plane A/C) Type and squadron.
2) ETA and remaining endurance.
3) Ops. call sign and R/T call sign of A/C.
4) Details of instruction passed to A/C of last wireless communication and position if available.

[underlined] Trans Atlantic Control. [/underlined]
1) Control Station – New Foundland until 30°W – Prestwick T.A.C. until approximately 10°W usually on 6500 Kc/s. Prestwick flying control after approximatly [sic] 10°W until landing on 3105 Kc/s Primary alternative. 1) Squires Gate – Valley and Silloth. [two deleted words] Sq.V. maintain HF/DF watch on 3105 from 0600 hrs until all A/C are landed. Silloth opens HF/DF watch on 3105 Kc/s on request from Prestwick.

If all terminal stations are U/S, Type I F.C. Station may be used.

[diagram]

2) [underlined] R/T [/underlined] on 6440 Kc/s for local Control.

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3) [underlined] HF/DF [/underlined] St. Eval } L.D.3 on 6500 Kc/s
Westbrough } L.D.3 on 6500 Kc/s
Butser } L.D.3 on 6500 Kc/s

also HF/DF at Prestwick, Squires Gate, Valley, Silloth, Lough Erne, and Stormaway.

[diagram]

4) [underlined] MF/DF [/underlined] Section B for North route.
Section E for South route

5) [underlined] MF/Beacons. [/underlined]
Lough Erne (Leader Beacon)
High power (800) screned [sic] on East side
Lymington (homing beacon) nr. Prestwick

[diagram]

Tory Island } Fixing Purposes
Barra Head } Fixing Purposes
Butt of Lewis } Fixing Purposes

6) Radio Track Guides at –
Direction on to leader Beacon at Lough Erne – Prestwick } Switch on as requested from Prestwick.
Direction on to leader Beacon at Lough Erne – Silloth } Switch on as requested from Prestwick.
Direction on to leader Beacon at Lough Erne – Squires Gate } Switch on as requested from Prestwick.
Slightly to East to avoid Eire [symbol] Valley } Switch on as requested from Prestwick.

7) Radio Ranges Being introduced by U.S.A.

[diagram]

Range approx.. 100 miles.

Stornaway and Prestwick
Main Beacon transmits a morse letter characteristick [sic] for identification purposes.

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8) [underlined] IF.F. [/underlined] Fitted to most A/C must be left on all the time.

9) [underlined] Any F.C. centre [/underlined] using its own frequency and call sign.

[underlined] Procedure. [/underlined]
All times G.M.T. W/T Silence is maintained as far as possible. A/C keep listening watch on Controled [sic] Freque. [sic] say with Newfoundland until approx. 30° W. then handed over to T.A.C. Prestwick if communication O.K. Any messages to A/C Met etc. are send [sic] in civilian Syko at 10 and 40 minutes past the hour. (or [deleted letters] in clear when speed is required. If in doubt as to Syko card in use signal QTK IMI (what Syko card are you using) answer "QTK" (No. of card). IFF. left all the way. If I.F.F. u/s or not fitted, identification by W/T. 60 to 90 miles from the coast to Section "B" if north about or Section E if south about. Control headed over Prestwick F.C. on HF/DF 3105 Kc/s at approx. 10° W and [indecipherable word] on R/T on 6440 Kc/s. If Prestwick unfit, control handed over to Squires gate, Valley or Silloth on 3105 Kc/s or any F.C. Station on their own frequency.

[underlined] Distress. [/underlined]
When West of 10° W, the A/C is to send its D/R position on Control frequency and then go over to 500 Kc/s. When East of 10° W the A/C is to send its call sign and D/R position on the Control frequency and then call Renfrew 0363 Kc/s (MF/DF for Sector) to enable a fix to be made. If A/C in distress near coast of Eire ring A.O.C. 15 or 19 group and request him to imitate S.O.S. from G.P.O. W/T station Mallin [sic] Head

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or from G.P.O. Station Lands End to Valentia Island. Another alternative is for A.O.C. 15 or 19 group to ring United Kingdom Reps in Dublin (Tel: 60196)

[underlined] Publications Carried. TAC [/underlined]
A.P. 1927 (Air Force code) Sykomachine (civilian 2 cards). "Q" Code,
S.D. 0182 (verification chart).

[underlined] Coastal Command Signal Organisation. [/underlined]
Norman operations are:
1) Patrols
2) Anti Submarine activities
3) Convoy duties
4) Reconnaisance [sic]
5) Anti shipping

[underlined] Wireless Services Available. [/underlined]
1) Type I F.C. Stations
2) Coastal Command HF/DF.
3) Long Distance Cathode Ray HF/DF (Section LD.2) [inserted] ST. EVAL, [indecipherable word], DYCE [/inserted]
4) Fixed M/F. Beacons (with addition of 2 Naval stations Scapa Flow & Rosyth) Lough Erne, Leader Beacon for coastal a/c as well as for Atlantic Ferry Service. All M/F transmissions come under overriding control of H.Q. Fighter Command.
5) "Darky" organisation on 2410 Kc/s also "Squeakers" on this frequency.
6) MF/DF Organisation (as in Bomber C.)
7) Responder Beacons. Normal range 80 miles. Morse letter characteristic for identification purposes also works in conjunction with A.S.V.
8) [underlined] B.A. Organisation. [/underlined] Not all need B.A. because of A.S.V.

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[underlined] Equipment in Coastal A/C. [/underlined]
Same as for Bomber A/C with addition of A.S.V. TR.9. is on 2410 Kc/s. Some a/c fitted with S.B.A. Bendix fitted to some Coastall [sic] a/c which has only 8 crystal controlled channels (2 sets).

[underlined] Organisation I. Procedure. [/underlined]
The Control Station is at A.C.H.Q. the Group Base D/F Stations and the A/C operate on the Group frequency under the Control of A.C.H.Q. A/c must listen on Group frequency at 0 to 5 and 30 to 35 minutes past the hour. (HF/DF.) A/c engaged on recconnaisance [sic] duties should maintain W/T silence expect [except] for the following.
1) To make an enemy report
2) When called by W/T coastal
3) In special circumstances when directed by A.C.H.Q.
4) To obtain navigational assistance on any frequency (HF or D/F.)
R/T silence is maintained [deleted] exp [/deleted] except when called by H.M. Ships or as directed by A.C.H.Q. All Base station maintain HF/DF. listening watch on Control Frequency and pass message intercepted from A/C together with D/F bearings to Group control A/C are to repeat all enemy reports on the appropiate [sic] MF./D.F. wave immediately they have completed transmission to H/F on control.

[underlined] Action Taken. [/underlined]
Striking forces are sent out by A.C.H.Q. While A/C shadowing enemy sea forces against whom striking action is ordered will change to appropiate [sic]

[page break]

MF/DF wave to enable continious [sic] D/F check of position to be made, and to provide navigational assistance to striking Force to reach target.

Control will order shadowing A/C to change to MF/DF and will pass call sign of Leader of striking Force. Control will also open watch on M/F wave. When requested by Leader of Striking Force, the shadowing A/C will transmit call sign & dashes Of 15 seconds duration to enable strike Force to obtain loop bearings and close in on convoy. MF/DF. Section will continiously [sic] check position of shadowing A/c and pass these direct to A.C.H.Q. A/c on patrols may average 12 hrs closing convoy duties. W/T silence is maintained but listening watch is kept with A.C.H.Q.

[underlined] Enemy Air Attacks on convoys. [/underlined]
If a convoy or unit is being attacked within 40 miles of the coast the escorting A/c will broadcast on 385 Kc/s MF/DF if beyond 40 miles message is sent on Operational Frequency to Control.

[underlined] Action taken by A.C.H.Q. [/underlined]
If help message is received on 385/Kc/s it is immediately rebroadcasted on the same wave so that message may be picked up by Fighter Stations keeping watch on this frequency. Appropiate [sic] Fighter Group H.Q. is immediately informed direct. If help message is received on Operational Frequency message is passed to the Control at A.C.H.Q. who takes necessary action.
D/F. A/C
VE v C/S v C/S 0-A HELP. "PILOT" 10 A.P (Position) – 2030

[page break]

[underlined] Aircraft in Distress [/underlined] should broadcast on S.O.S. call first on the wave they are working and by R/T on 2410 Kc/s if within range of convoy or shore stations and then if time and circumstances permit changes to appropiate [sic] MF/DF. wave and broadcast S.O.S. with 15 second slashes and call sign to enable a fix to be made. A/C requiring navigational assistance to reach their base they are to make a signal to their control station requesting control. On receipt of this message at A.C.H.Q. the Control officer will in collaboration with Duty Signals Officer decide whether A/C be controled [sic] by A.C.H.Q. or Control handed over to any particular station. Alternatively A/C may be instructed to change to appropiate F.C. [inserted] wave [/inserted] range in which case the F.C.O. concerned will take over and [indecipherable word] complete control.

A flying-[indecipherable word] which may be forced – land on the sea is to be prepared on instruction from A.C.H.Q. control to change to 385 Kc/s in order that searching A/c or rescue ships may [deleted word] obtain homing bearings or fix to be made. Identification has to be effected in Coastal Command exactly or in Bomber Command also within visual range of convoys (NORTH of Duncansby Head and in the atlantic area I.F.F. on all the times).

[underlined] Organisation III [/underlined]
Signals Organisation of A/C engaged on convoy Escort duty on the Atlantic.

[page break]

guard frequency by day if necessary. All stations maintain watch on Command Guard frequency by night. DF watch opened up if necessary.

D. Fixer – Sector Control – Sector Control
Each sector has own D/F fixing service on this channell [sic] comprising of two to four D/F stations.

Fighter are fitted with VHF. R/T set range approx. 150 mls. Press button tuning. Usually 4 channells, [sic] also fitted with AI. Aerodrome FCO is responsible for keeping sector controler [sic] informed of serviceability and readiness of A/C at this station. He is also responsible for landing and diverting this A/C when necessary. He is responsible for geting [sic] fighter airborne when ordered by sector controller.

[underlined] Procedure for day interception. [/underlined]
Enemy usually attack in large formation. Fighter formation take off under control of FCO on channell [sic] A. When clear of aerodrome A/C change to channell D and contact sector Controler [sic] (sometimes a/c controlled on A-B.) but fixing stil [sic] on channell D.

Fighter a/c are fitted with a contactor switch which automatically sends signal on Channel D for 14 seconds of each minute for DF fixing purposes. The signal transmitted is known as the [underlined] "Pip Squeak" [/underlined] and is a high pitched note. Sector Controler tells each formation when to switch contactor in and the A/C in the formation who has been detailed, switches in his contactor, from then on this A/C is automatically transmitting a "pip squeak" signal for 14 seconds every minute which enable a D/F plot to be kept on this formation. Sector Controller "pips" in each formation in turn on his master clock, allotting 15 sec. of each

[page break]

minute to each four formations. Sector Controller is also receiving plots on enemy A/C from R/DF and BOC. He is therefore able to vector his formation and make an interception. After interception he vectors formation towards base and hands them back to aerodrome FCO on Channell A for homing and landing.

[underlined] Procedure for Night Interception [/underlined]
Enemy usually attacks single and are therefore intercepted by single fighter. Fighter take off on Channel A, under control of aerodrome FCO. When clear of the aerodrome, are handed over to sector controller on Channel D. Sector Controller obtains fixes on voice transmission from fighter. He is therefore able to vector A/C on to a patrol line and keep him on it. He feeds G.C.I. controller on Channel [underlined] B [/underlined] with one A/C at a time as required from patrol line. GCI controller has radio location gear which enables him to see both the enemy A/C and the fighter A/C on the screen. He is therefore able to vector fighter A/C towards interception. Radius of action approx. 50 miles. Degree of accuracy about 5 miles. When GCI controller has got fighter as near enemy A/C as possible, he will tell him to switch on AI. (Punch). Radius of action accurate to approx. 200 yds. Fighter should be able to get within visual range of enemy A/C.

Enemy A/C may be flying below 2000 feet in which case he will not be picked up by GCI. He will however be picked up by CHL. and will be plotted by CHL station. Fighter A/C may, if fitted with CHL. Channel

[page break]

be handed over to CHL. Controller, who by watching plots of enemy a/c and fighters vectors a/c towards interception. After intercepting fighter report to sector controller on Channel D. Sector Controller having regard to remaining endurance of fighter(s) either put him on a patrol line again or gives him a vector towards base & hands him back to the aerodrome FCO on channel A for homing and landing.

[underlined] A1. Responder Beacons [/underlined]
All night fighter aerodromes are fitted with Responder Beacons, on which fighters fitted with A.1 may home from an approx. of 50 miles. Each aerodrome has a 2 letter morse characteristic. When near aerodrome beacons at either end of runway will be picked up. (Uncle or Father)

[diagram]

and pilot may fly out from outer marker on reciprocal of QDM of the runway. He will then return and line up his blimps from outer and inner marker. When over Outer Marker, O.M. blimps will have merged with ground blimp which indicates O.K. to land ahead. If A/C wished to use "Mother" they must ask for it on channel A approx. 20 miles away. FCO. will then give A/C a height to fly at. Whe[missing letter] over base a/c must report to F.C.O. and will then be giving turn for landing. On receiving instruction to pancake A/C will go over to uncle if required.

[page break]

[underlined] V.H.F. Beam Approach (Tramlines) [/underlined]
For use with Fighters. At present installed at Hunsdon, Bradwell, Manston, Wittering, West Malling and Ford. The system has similar characteristics to S.B.A. but works on higher frequencies of the order 100 m/cs for the Main Beacon and 300 m/cs for markers. Range of Main Beacon 20 miles. This system is made available on either channel A, or channel C,on request from F.C.O. in conditions of low cloud or poor visibility. It may be then switched on remotly [sic] by F.C.O. by means of a remote control panel. The signal from the Main Beacon are received on the normal fighter V.H.F. R/T receiver. From the markers are received on a separate VHF receiver using a the pole aerial.

[underlined] Use of Channel "C". [/underlined]
Is used as Group Guard by day, each group using a different frequency. Stations keep watch on this channel in order to provide a safety service for A/C needing special assistance.

The channel is used as Command Guard by night. All stations in Fighter Command and some Type 1 stations in other Commands maintain watch during the hours of darkness for a similar purpose.

Where stations have not an additional V.H.F. D/F. station to maintain a continuous watch, VHF. D/F on Channel A will be switched over if necessary to channel C to keep a listening watch.

[page break]

[underlined] Day Sweeps.[/underlined]
A/C take off on Channel A or B and remain on this channel keeping R/T silence until landing. Sector Controler passes plots on enemy A/C on this channel if necessary. These signals are not answered. A/C in distress over the sea will go over to channel [underlined] D [/underlined] and transmit "May Day" call. When fighter A/C operating from their own forward sectors, call "May day" on Channel [underlined] D [/underlined], a fix will be made on the transmision [sic] by the normal sector fixing service. Certain forward sector have special AS/RS fixer layouts comprising 3 or 4 VHF/DF station which make fixes on fighter in distress over the sea, who come from Groups or sectors, other than the forward sectors. Before a sweep, Group HQ's instructs forward sectors to open watch on the AS/RS fixer layouts on Channel D frequency of the a/c operating from other Groups or sectors.

Fixes made on "May Day" calls, are passed from sector to FCLO at groups, who may inform ACHQ or the Naval Officer in charge search area direct for AS/RS action and to the parent Group for information.

[underlined] Diversions. [/underlined]
If A/C is under Sector Control when diversion becomes necessary, Sector Controller will obtain a D/F fix on A/C and will give pilot one vector towards Diversion Station telling him to change to channel [underlined] "C" [/underlined] and call (call sign of diversion station). Sector Controller will inform F.C.O of diversion station who will home and land A/C on Channel [underlined] "C" [/underlined]. If A/C is under aerodrome control F.C.O. when diversion becomes necessary, aerodrome F.C.O. will first home A/C over aerodrome and will then give pilot one vector towards Diversion station telling

[page break]

him to change to Channel [underlined] "C" [/underlined] and call – (call sign diversion station). F.C.O. will inform F.C.O. of Diversion station who will home and land the a/c on channel [underlined] "C" [/underlined]. The Diversion Station [inserted] is [/inserted] chosen in conference with sector Controller. Sometimes A/C are handed over to Channel D en route for D/F check of position and further vectors from sector.

[underlined] Ground Point to Pos’n Organisation message. Writing and Priorities. [/underlined]
Signals Officers are responsible for maintaining communication from [inserted] his [/inserted] station and other Station and other formations. The following system of communications are at their disposal.

[underlined] Teleprinter. [/underlined]
Messages are sent in plain language. Secret messages are also sent in clear (DTN. system)

[underlined] Standby, W/T System. [/underlined]
Station and Group link up messages must be sent in cypher. Type X or high grade RAF. cypher.

[underlined] Telephone [/underlined]
Secret or confidential matter must not be passed unless using tied-tie lines or scramblers.

[underlined] D.R.L.S. [/underlined]
RAF. postal system which is served by M.T. over regular routes to a set time table. Times are held in SHQ. D.R.L.S. office where packages are accepted for delivery to addresses.

[underlined] D.R. (motor cycle) [/underlined]
For urgent signals or packages when D.R.L.S. cannot be used owing to set route and time schedule. Over long distances Signals Officer on Station will

[page break]

co-operate to have a chain system from on [sic] Station to another.

[underlined] Message Writing. [/underlined]

Citation

“Radio system notes,” IBCC Digital Archive, accessed March 29, 2024, https://ibccdigitalarchive.lincoln.ac.uk/omeka/collections/document/35275.

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