Radio Finger Printing (RFP) and TINA
Edited by Jerry Proc VE3FAB

During WWII, the most common method of locating enemy radio transmissions was through the use of radio direction finding whereby two or more monitoring stations would obtain bearings on enemy transmitters then triangulate the results to obtain a fix.  There were at least two other techniques which could provide data or intelligence  about the characteristics of the transmitter making the transmission and the Morse code sending style  of the operator. These techniques were known as Radio Finger Printing (RFP) and TINA  and were used by the Allies. When used jointly, TINA and RFP were known as 'Z' intelligence or 'Z' service in the Commonwealth countries. As with many other WWII activities, RFP and TINA were shrouded in a cloak of secrecy.


Radio Finger Printing (RFP) was the process used to catalogue a specific transmitter through its distinct characteristics with the aim of locating it at a future date.  The idea was to identify individual transmitters by their emitted waveform. The rectified signals were applied to a cathode ray tube, (without a time base), and photographed onto moving film.

The German naval transmitters were remarkably uniform and showed little more than an initial damped oscillation produced, perhaps, by a carbon-pile voltage regulator. The Italian mobile naval transmitters were remarkably erratic, and never looked the same twice; while their shore stations could often be identified by the ripple frequency of anything but 50 Hz.

This is an example of a  radioteletype signal whose transmitter is slightly faulty. The keying envelope is perfectly formed except for the 100 Hz ripple riding on the signal. To see more transmitter faults detected via the RFP equipment, please select this link, (Courtesy Collingwood Heritage collection) 
RFP was very useful technique in checking Allied transmitters when used for deception purposes to ensure that they really did correspond to the transmitters that they were impersonating. It also needs to be emphasized that radio fingerprinting was never meant to be used standalone, but rather, to be used in conjunction with other identification tools such as TINA.
TINA in the UK

TINA was the method used to recognize specific radio operators by their Morse code "fist" and habits.  One definition has the code name of TINA as being derived from the Latin word "tinea" which meant "worm".  TINA was the process that involved studying the distinctive characteristics of particular Morse code operators to identify and tracing the locations of those operators, for which might show that a  particular operator has changed ships which may indicate damage or destruction to the previous ship or even a re-assignment. Each operator had a distinctive touch, or 'fist'. Some were slower while others were jerky; some held down the key or paused  between dots and dashes for different  lengths of time and so on.

Extracts from a TINA article written by John Roscoe G4QK provide a more detailed picture of TINA.

"The early TINA recordings of Morse were made with a siphon-pen recording on paper tape using  a device known as an undulator.  At a later date, Morse transmissions were recorded on 35 mm film with a slow running RFP machine. This allowed measurements to be made through considerable noise conditions (QRN).  This permitted the desired waveform to be distinguishable from the ambient noise.

Above and below: Two undulator variants. The lower device has its dust cover raised to expose the mechanics. (Photos courtesy of the Collingwood Heritage Collection) 
This is a bridge unit that interconnects the receiver audio output to the input of the undulator. By arranging one or more valves (tubes)  to alter the balance of a resistance bridge network across which is connected the recorder, equal mark and space currents can be passed in opposite directions through a single coil. The device , in all of its forms became known as a "bridge." (Courtesy Collingwood Heritage Collection) 
In the UK, the standard method of measuring Morse involved several WRENS. Two WRENS at a time would start the process. One would read off the measurements from the film using an enlarger and the other transferred them to graph paper. The dashes and dots were then marked with red and blue circles. Attempts at identification with previously captured records were made by direct comparison.  This procedure inevitably relied on the acuteness of observation  and perhaps the memory of the operator on duty. This was not a fast method so two ideas were pursued to help automate the process.

(1) A method of recording that would permit simple and more rapid measurement.
(2) A machine-compatible system for classifying the records.

To summarize:

On the issue of measurement, the TINA device would make a vertical deflection on  the 35 mm film instead of a horizontal one.  The vertical deflection would correspond to each dot or dash in the Morse character.

The idea behind the mechanical classification scheme was to extract parameters from the Morse that could be coded  numerically and searched mechanically. In those pre­computer days, the best machine that was available was the Hollerith 80-column punched card sorter with a built-in 8-column group selector which worked at the astonishing rate of 400 cards per minute!  However, there were issues with the generation of Morse code before a solution could be implemented.

In the WWII era, Morse was sent mostly by straight key.  Semi automatic keys did exist in 1942 but they sent relatively clean code so it would be challenging to make an identification to a specific operator using  TINA.  So TINA was limited to the analysis of Morse generated by straight keys.  In addition, sidetone oscillators were uncommon, so practically all the operators wouId have been sending by "feel" alone.

At the top is the output tape of the undulator with the equivalent Morse characters shown below. This is how TINA started but later on the system used photographic film, From this hard copy, the TINA operator could study the length of the dots and dashes in the character stream. (Courtesy of High Speed Recording of Radiotelegraph Signals)
The most consistent characteristic in Morse code was the ratio between an adjacent dot and dash in the longer symbols. For example, the dash might be markedly longer than the following dot in D, B, and 6. This would almost certainly be matched by a similar disparity in U, V, and 4. Invariably, A and N did not fit into this pattern. The fate of the other dots, in 4 and 6 for example, 'was a matter of individual taste. This simplified measurements, as there was no need to establish a notional average length for the dot. The ratio between adjacent elements could be immediately coded on a scale of 1 to 10, with adequate provision for the spread of results.

The most interesting application of this technique was to the U-boats in the North Atlantic. Although they carried more than one radio operator, only one appeared to do the transmitting, thus reducing the number of our records that had to be maintained by TINA personnel.  Mass training for the German U-boat radio operators  was so standardized that their style of sending made TINA analysis impractical.

The U-boats were at sea, generally, for a maximum of 6 weeks, so a preliminary scrutiny could be made,  and had to be made, in a few minutes of all records obtained within this period. More leisurely checks could then be made for long term files. Of course this was only part of the picture, as direction-finding, RFP, decoding. etc., would also have contributed their intelligence to the records base. Of course,  the "victims" were well aware that they were being monitored but since the U-boats invariably sent short messages (quite unlike the Italian submarines in the South Atlantic). they presumably felt the risk was small ".

TINA and RFP in New Zealand

In the early 1940s, at least seven New Zealand signals intelligence stations were constructed and operated as part of the British-American
intelligence system. Three of these stations were set up in Awarua (ZLB) ,  Auckland (ZLF) and Waipapakauri (WPP)  which became part of the US  Navy's Pacific-wide DF net.  The purpose of the net was to locate Japanese ships and other sources of enemy radio transmissions.

In 1942, a new station  (RNW) joined the net. RNW, was the Post Office call-sign for Renwicktown, near Blenheim NZ. In the direction finding stations,  little was told about RNW's function except that it was a naval W/T station and that all personnel were to fully co-operate with it. The new station would be staffed by the Womens Royal New Zealand Naval Service (WRENS). These WRENS were all competent operators, and  fluent in the Japanese Katakana code. Many years after the war, it was revealed that RNW was set up as a Radio Finger Printing station.

The job of the New Zealand D/F net, was to take radio bearings on enemy signals that were radioed from the US Pacific Fleet’s Headquarters (NIT) in Hawaii, and later Guam. RNW tracked around with these frequencies and call-signs received from NIT.

At RNW, the identification process was started by photographing signals which were displayed on an oscilloscope and examining the developed print in minute detail for any peculiarities in the received waveform. These would then be compared with previously recorded photographic strips to see if there were any similarities which would enable the identity of the station or vessel to be made.

The RNW station itself was a two-storey farmhouse taken over for the duration of the war by the  New Zealand Ministry of Defence. It was at the end of a long no-exit road at Rapaura, terminating on the banks of the Wairau River.

The house was altered to allow an operations room downstairs but the radio equipment and sleeping quarters for the eight Wrens who would be staffing the station were on the second floor. The area surrounding the house was enclosed with a six-foot high, barbed wire fence, with a locked gate, and security was provided by a detachment from the Guards-Vital Points which camped on the site.

It was an ideal radio receiving situation, away from all interference. There was a clump of tall poplar trees close to the house and these were used to provide masts for the inconspicuous aerial, which was erected by using a bow and arrow! The equipment was based around a special receiver incorporating an oscilloscope and movie camera, known as REB 2, which had been sent out by the  British Admiralty from London. Also provided were two Collier and Beale HRO type receivers, fitted with oscilloscopes.

This equipment was installed by an ex-Post Office telegraphist who was a Leading Telegraphist in the RNZVR. He remained at the station to instruct the staff in the Japanese Katakana code and left when they were proficient.

The operating procedure was to tune into the frequency and identify the callsign which had been signalled from Awarua on the landline. The signals were checked on the oscilloscope attached to the standard receiver for photographic suitability. If suitable, a button was pressed which brought into operation the REB 2 equipment which then started photographing the waveform on the oscilloscope.

Later, when the film was developed, the Classifier examined the films in detail looking for imperfections such as harmonics, damped waves, key-relay effects and anything else peculiar to that transmitter. In many cases the operator’s style of sending could be recognized and this would be a further clue to the station’s identity.

The photographic strip details were recorded, given a file classification and stored for future reference. Once a file had been built up the station could be identified by the signal it emitted and the style of sending. This meant that no matter how often the callsigns were changed – and the Japanese changed theirs daily for a while – the station or vessel could be identified irrespective of call-sign.

The operators worked during the night, 6 pm to 6 am, on four-hour watches, and the classifiers during the day, examining the photographic strips that had been received overnight. If there was incoming traffic of importance during the night or if it was busy, the operators would thump on the ceiling with a broom handle to wake up the sleeping classifiers to bring them down to attend to the urgent traffic and clear the filled cassettes. The results of the classifiers’ analysis would be suitably coded up and telephoned to the Navy Office in Wellington over a Scrambler (inverted speech) telephone.

There were other Radio Finger Printing stations set up by the Admiralty, The one in the UK was responsible for identifying the German pocket battleship Bismark when it broke out into the North Sea and was ultimately sunk by the Royal Navy. There was another RFP station at Sri Lanka (formerly Ceylon) and possibly other locations.

The Japanese advance southwards was blocked by the Battle of the Coral Sea in May 1942, and their offensive power effectively broken four weeks later at the Battle of Midway. Japan was on the defensive and their large, ocean-going submarines were no longer able to roam at will. A considerable number were used to re-supply their isolated garrisons under Allied blockade in the Pacific.

Enemy radio activity steadily dwindled and in May 1944 the Rapaura Naval W/T station (RNW)  was closed, with the staff being transferred to the New Zealand Navy Office in Wellington, to work in the Intelligence and Communications sections.

During its operation, the Naval W/T station Rapaura (RNW) provided a valuable insight into the characteristics of enemy signals from Japanese forces that were menacing the islands of the Pacific. It is to the credit of the Wrens that this particular specialized service was performed with discipline, diligence and in total secrecy.  All the personnel involved at RNW were held under an Oath of Silence from the NZ  Ministry of Defence until 1982.

(The above are extracts from an article titled " NZ Navy Wrens In Secret Ops During WW2" written by Frank Barlow ZL2NB with contributing WRENS Bunty Longuet and Philippa Corkill, both Leading WRENS at the Rapaura Station.  The article was originally published in Break-In, December 1996.)

During the war in the Pacific, a Canadian military unit called the "1 Canadian Special Wireless Group" was deployed to the Pacific Theater and conducted tactical SIGINT activities against the Japanese along with the Australian military in New Guinea. It was active from 1944 to 1945.

TINA and RFP in Canada

TINA/RFP equipment was given to the RCN by the British Admiralty in December 1941 and by January 1942, operations on an experimental basis had begun at a Department of Transport station near Ottawa. In May 1943, "Z" operations moved to the RCN station at Gloucester Ontario but due to the drop in U-boat W/T traffic, the RCN chose to install RFP/TINA at Harbour Grace, Newfoundland.

During a visit to England by Lt. Low (Royal Canadian Navy) , he observed that all "Z" operations and classification work was performed by British WRENS who were most capable for this job.  The RCN based their decision on this observation and decided that Canadian "Z" operations should be operated by WRCNS personnel, wherever this could be done considering the locations and amenities of the isolated Canadian stations. Two RN WRENS were requested and ultimately sent to Canada to train Canadian WREN personnel for these duties. They arrived November 1943 and spent three months between  Gloucester and the Harbour Grace, stations.

By 1943, using TINA, RFP, HFDF, and “Y” intercepts, the Allies,  with a network of 40 stations all over the world, were able  to track enemy units at sea.

TINA and RFP Operations in the USA

USN work on Japanese and German fingerprinting was carried out by  the USN  group OP-20-G.

The acronym OP-20-G stands for "Office of Chief Of Naval Operations (OPNAV), 20th Division of the Office of Naval Communications, G Section / Communications Security". It was the U.S. Navy's signals intelligence and crypto analysis group during World War II. Its mission was to intercept, decrypt, and analyze naval communications from Japanese, German, and Italian navies. OP-20-G was responsible for TINA and RFP operations in both theaters of war.  In addition, this group also copied diplomatic messages of many foreign governments. The majority of the sections effort was directed towards Japan and included breaking the early Japanese “Blue” book fleet code. This was made possible by intercept and High Frequency Direction Finder (HFDF) sites in the Pacific, Atlantic, and continental U.S., as well as a Japanese telegraphic code school for radio operators in Washington, D.C.

Although British RFP could distinguish between U-boat and surface vessel transmissions, British and American RFP gave poor results when a TINA analysis was performed. The likely cause of this was the consistency in transmitter hardware (ie emission)  and good Morse operator training.

The US Army Signal Intelligence Service (SIS) was another source of radio intelligence, but their group and OP-20-G were badly hobbled by bureaucracy. The groups had become rivals, competing with each other to provide their intelligence data, code named "MAGIC", to high officials. Eventually in 1940, SIS and OP-20-G came to agreement to provide MAGIC on alternating days, and try to draw up guidelines for which team handled what traffic. Complicating matters was that the Coast Guard, the FBI, and even the FCC also had radio intercept operations. The result was that much of the MAGIC was unused. There was no efficient process for assessing and organizing the intelligence, or getting it to proper end users.

Domestic US radio intelligence was administered by the Radio Intelligence Division (RID) but their focus was to track down illegal domestic transmitters using a network of 58 monitoring stations in the continental US.

Fleet Radio Units (FRU) were the major centers for Allied cryptological and signals intelligence during the Pacific Campaign of World War II. Initially two FRUs were established in the Pacific, one at Pearl Harbor, Hawaii, called Station HYPO or FRUPAC (Fleet Radio Unit, Pacific), and the other, called Station CAST or Belconnen, at Cavite Naval Yard, then Corregidor, Philippines. With the fall of the Philippines to Imperial Japanese forces in April and May 1942, CAST personnel were evacuated to a newly established FRU at Melbourne, Australia, called FRUMEL (Fleet Radio Unit, Melbourne).

Captain Eric Nave of the Australian Navy,  commanded operators who had been monitoring Japanese preparations for war. He  said that the Japanese Navy had mounted a massive deception exercise to prevent anyone from realizing that Pearl Harbor was a target. One step which undoubtedly deceived the US Navy was the transfer of the wireless operators from aircraft carriers which were to take part in the Pear1 Harbor attack to other ships in Japan's Inland Sea. Since the Allied intercept operators were using the fists of their Japanese counterparts to identify the various enemy radio transmissions, this move completely threw them off guard and leading them to place the carrier force that was to attack Pearl Harbor in Japanese home waters.

In 1958, the terms listed below were used to describe various aspects of radio intelligence. It is not evident at this time as to which other  techniques were applicable to the WWII era other than TINA or RFP.

* Special Identification Technique (SIT) - A collective term including Morse operator analysis, radio fInger printing. and direction finding.
* Advanced Identification Technique (AIT) - A technique of emitter identifIcation involving analysis of unintentional variations in amplitude modulation and frequency modulation which occur in target emissions. This is the preferred term  for ""radio fingerprinting" or "waveform analysis."
* Emitter location/Identification (ELT) - The process of locating or identifying an emitter through the use of one or a combination of the following techniques: direction finding, advanced identification techniques, unintentional frequency deviation. In British usage, the preferred term is
"technical aids."
* Radio Fingerprinting (RFP) -, identify. and classify the unique characteristics the unique characteristics of individual radio transmitters by the study of oscillograms of their signals. Also called transmitter identification.
* Morse operator analysis (MOA) - The cataloging and identification of manual Morse operators by their individual sending characteristics. Formerly referred to as TINA.
* Morse characteristics analysis (MOCA) - The study and cataloging of recorded manual Morse transmissions in order to identify individual Morse operators by their sending operator characteristics.
* TINA - Former term for Morse operator analysis. Derived from the last four letters of the word "Serpentina", one name for undulator tape used in early methods of recording hand-send Morse transmissions.
*  Direction Finding (DF) - The process determining the apparent azimuth of an emitter by the use of  a direction finder.
*  Hull-to-Emitter Correlation (HULTEC) The association of ELINT intercepts to a specific ship, through analysis of all available parameters of the intercept and consideration of the elapsed time and possible distance traveled by the target ship since the signal was last intercepted.
* Unintentional Frequency Deviation (UFD) A technique of emitter identification involving analysis of unintentional phase variance of on-off keyed Morse code.

Does anyone have a photos of TINA or RFP operations in OP-20-G? If so please contact :

Intelligence Operations in Australia.

Fleet Radio Unit, Melbourne (FRUMEL) was one of two US-Australian-British signals intelligence units in the Pacific, the other being FRUPAC, feeding information to US headquarters in Washington.

Nowhere near the size of Britain's famed Bletchley Park intelligence headquarters, a few hundred people, many from the Women's Royal Australian Naval Service or female civilians, worked at Monterey, Australia. America had the biggest units which received intercepts from Mornington in Victoria, Harmen in Canberra, and Townsville in Queensland. FRUMEL’s biggest receiving station was Adelaide River in the Northern Territory, staffed by the US Navy.

Captain Eric Nave commanded a small Royal Australian Navy cryptographic unit which worked at Victoria Barracks in Melbourne  starting in 1940.

Members of the Women's Royal Australian Naval Service (WRANS) working at FRUMEL on Queens Rd, Melbourne in 1942. (Royal Australian Navy photo)

The data in the following  table was derived from manual M651, Nomenclature for Radio Equipment Part XXVI dated 1946  This equipment was used by the British Admiralty and some of it was also  issued to Canada and New Zealand.  Minor updates from other sources have also been applied to this table.

REA Shore stations for range estimating purposes  Motor operated camera and receiving panel
REB 1 Shore recording stations Camera, receiver, film viewer, loudspeaker, monitor unit oscilloscope , power unit. Initially saw service in 1938
REB 2 Shore recording stations  Camera, receiver, film viewer, loudspeaker, monitor, unit, oscilloscope, power unit. Released in 1940
REB 3  Shore receiving stations  Film viewer, oscilloscope, camera unit, dual beam oscilloscope, B28 receiver, G64 oscillator. REB 3 could be used with different types  of receivers and variable film speeds. Designed primarily for "noise" investigation. See explanation below table.
REB 4 Shore recording stations.
Specially approved ships
This was a modified/improved version of REB 3. Produced near the end of WWII.  Select this link to view the REB4 Handbook(Courtesy Collingwood Heritage Collection). 
REB 5  Under development in 1946  
REB 6    No info available at this time. 
REC 1 Shore recording stations  Recording unit, M61 amplifier, SE2 rectifier unit, 12 VDC power unit
REC 2 Shore recording stations Recording unit, M62 amplifier, rectifier unit. 

This extract, from the British Admiralty document titled "Radio Warfare 1949" provides some details about the technique of noise investigation.

"At the beginning of the war, intercept watch was centered entirely on radio communications, but with the advent of radar and radio navigational aids it soon became necessary to organize intercept watches  for these noises in order to ascertain progress made by the enemy in using these new features of radio, and to turn such use, where practicable, to the advantage of the Allies.

The first naval noise investigation was carried out towards the end of 1940 to determine the characteristics of enemy radar in the Pas de Calais area of France so that suitable countermeasures could be initiated for the protection of Allied convoys. At much the same time, assistance was given to the R.A.F. in elucidating and countering the radio aids used by enemy bombers over the U.K.

The R.A.F. organization expanded continuously from 1940 onwards, since, once they had effectively countered the enemy aids over U.K. they were called on to assist in the Allied bomber offensive over Europe by upsetting the German radio warning and control systems there.

Naval effort, however, marked time till about 1942, as there were few important German naval noises to work on. The commencement of large scale amphibious operations was the next objective . It was soon clear that, if assaults were to achieve any tactical surprise and avoid crippling damage from radar controlled coastal batteries, careful pre-investigation of enemy coastal radar and initiation of suitable counter-measures was essential. Obviously the problem would become more acute as the Allies got closer to the heart of enemy resistance, where the German  coastal defences would be  stronger.

The problem was not only one of obtaining intelligence to enable jammers to be designed , but also to provide noise investigation personnel and equipment to specific ships so that any jammers fitted could he used to the best advantage .  In most amphibious operations noise investigation equipment and personnel were always in short supply. Towards the end of the war, a measure of standardization was achieved in the equipment and personnel supplied to ships,

Meanwhile, the Americans in the Pacific had been faced with a rather different noise investigation problem. There, distances were great and, besides amphibious operations, there was more chance of surface engagement and attacks by enemy naval aircraft. Information was sorely needed about enemy coastal radar, both for long-range amphibious assaults and for air strikes on shore targets - particularly to discover 'blind' radar areas in which forces (both sea and air) could approach undetected. Information was also needed about enemy ship and airborne radar so that appropriate countermeasures' equipment could be produced. To obtain this information,  much use was made of specially fitted 'Ferret' aircraft and by including noise investigation equipment in ships, and especially in submarines operating in enemy coastal waters, or subject to attack by enemy surface and air forces. For these reasons, noise investigation developed rapidly in the U.S. Navy.  Their results were communicated freely to the Brits and steps were in hand at the end of  the war to bring the British Pacific Fleet up to the same standard.

A further use of noise investigation under development at the end of the war was the tactical possibility of locating enemy radar transmissions and using this knowledge to evade or to take up an advantageous position; the value of this depended on the fact that radar transmissions can be intercepted well outside radar detection range, Naval noise investigation started ashore but its future would  lie mainly afloat and in the air, since radar ranges are comparatively short and shore stations can only intercept them when the enemy 'is close at hand.

The Results of Noise Investigation

Practically all successful radar countermeasures were initially due to noise investigation. The main successes were:-

(i) The countering of the enemy coastal radar chain in the Straits of Dover; successful jamming of enemy coastal radar in amphibious operations thus permitting a measure of tactical surprise and subsequent protection against coastal batteries.
(ii) Masking of feint operations by deliberately inadequate jamming, so that the enemy should 'see' something but be unable to determine details.
(iii) The general success of the US Navy in the Pacific in countering enemy radar.
(iv) The countering of enemy radio controlled missiles. "

This is a Royal Navy  REB 6 device  fitted into a 1950s era COMAL (Communications Analysis) bay . The camera and oscilloscope are at the top left corner of the photo.  (Via Collingwood Heritage Collection). 
There are no known photographs of early REB or REC equipment however Clive Kidd of the Collingwood Heritage collection provides some elementary descriptions.

"The B40 receiver (a 1950's design), also known as outfit CDW (from handbook BR222)  has  two sockets -  SK202 and SK203.  These are for REB and REC equipment . REC ( SK202) is the output from the detector and is an audio output  (described as DC) . It was designed to record audio to a disc, i.e a shellac disc as per the old 78 records on a piece of kit known as REC. No further info was found on this equipment.  It could also be connected to an audio tape recorder, wire or tape.

SK 203 is connected to REB and is the IF output  for "photographic analysis of transmitter characteristics using equipment with the designation REB. Manual BR1433 dated 1945 describes REB as being used to "...investigate the faults and characteristics of any radio transmitter..." The signals were fed from any  receiver (with an IF frequency between "...100 kc/s and 1 Mc/s..." ) into the apparatus and examined visually and also the signal could be photographed. The apparatus had two CRTs - one for the operator to sight on and the other covered by a camera. The Y axis of the CRT was fed with the signal from the receiver, via an adjustable gain amplifier and the X axis of the operators CRT was fed with a time base - as per a normal oscilloscope. The only difference between REB and a scope was REB had two CRTs. The camera could be set to drive the film past the second CRT at "...1.5/3.8/9.6/24/60/150 cm [yes cm in 1945 in the Royal Navy ] per sec…] . Time markers could be produced internally to aid analysis.

The BR on REB does not contain any photos of the kit, only some line drawings of the chassis and a drawing of an amplitude modulated carrier signal, in the time domain, to show what a signal might look like - standard picture as per any text book. There is no description in the BR to aid in the determination of faults or special characteristics.

I have also found out that there were a number of different marks of REB equipment -  mainly changes to recording speeds and the way the CRTs were fitted into the case along with other mods to the operator interface".


This was developed by the British during the war as an ancillary to H/F D/F fixing. It consisted of taking measurements of the path differences between various incoming rays appertaining to the same signal, and, by correlating these differences with current ionospheric data, estimating the distance of the transmitter.

In 1944, after a great deal of experimental work, a method of analyzing results was evolved which enabled some 80 per cent of experimental intercepts to be assessed for range with a 10 per cent accuracy. The scheme never became a practical success as it was complicated and suffered from many difficulties.

It is hoped that this  research has been helpful in providing an overview of TINA/RFP operations.

Contributors and Credits:

1) "A Few Measurements" by John Roscoe,  G4QK. Published in Morsum Magnifact, Autumn 1987 issue
2)  Aryeh. Ben-Ami  <dufs44(at)>
3) Frank Barlow ZL2NB Break-In, publication, December 1996.)
4) Clive Kidd <cjckidd(at)>  Collingwood Collection
7) High Speed Recording of Radiotelegraph Signals by  R. B. Armstrong B.Sc.  and J. A. Smale, B.Sc,
8) Radio Warfare document 1949. Ref: SD 1080/47   British Admiralty publication.
9) Manual M651, British Admiralty
10)  FOIA cases 18871A and 40738B dated June 7, 2006
11) Combined Glossary of Traffic Analytic Terminology, January 1958
12) Google Books
15) Captain Nave quote from the book "The Emperors Codes".
16) Daily Telegraph article on Codebreaking
17) Brian Harrison <briankn4r(at)>
18) Nick England <>

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Sept 9/17