Unless otherwise noted, the equipment listed in the table below for the -1, -2 and -3 Trackers was derived from the following sources:

1) The Royal Canadian Navy Aircraft General Information Manual whose pages are dated May 1, 1963.
2) Manual MICN 3-35-01 (1K) dated July 30, 1970.
3) Stencilling on an aircraft found at the Tracker boneyard in Abbotsford BC.

The electronics suite of the Maritime Reconnaissance version is shown in a separate document elsewhere in the Tracker web page. If anyone can help to refine this listing, please contact : jerry.proc@sympatico.ca

Table Legend
 X= fitted   n/u = not used  ? = Don't know

Tracker: Locations of the obvious antennas. The MAD boom in the extended position. On the -3 variant modified for the Maritime Reconnaissance role, there were eighteen antennas in total with three of them being flush mounted on the aft belly .   (Canadian Forces photo)

This underbelly view of a USN Tracker provides a much clearer view of the APS-38 radome in the extended position. (Photo courtesy US Navy)

The UPD horn antennas are very evident in this Tracker lineup. The AN/UPD-501 was the only operational ESM ever carried by the Tracker. (Photo source unknown)  The AN/ALR-76 ES system was fitted and tested aboard a Tracker in the late '80s, (circa 1988-90) by DASP and HOTEF which operated out of CFB Shearwater. WO Jack Carter (AESOP) was the lead operator. Robert Langille was tasked to analyze the intercepts and compare them against other systems that collected the same data. The system was also installed on HMCS ATHABASKAN for OP FRICTION. While the ALR-76 was being groomed for the Seaking replacement, then came the political cancellation of the replacment helos by the Canadian Government in 1993.

As mentioend above the AN/ALR-76 was only eveluatyed on one Tracker. This system detects and processes electromagnetic signals in the microwave frequency region, with a particular emphasis on radar transmissions of short duration. This includes tracking, classification, location and identification of emitters in dense environments. The system combines ES and radar warning functions in a single system and consists of two sets of spiral antennas, two multi-bandwidth receivers and a signal comparator. Audio alerts are provided, as are outputs for a countermeasures dispenser. Emitter identification, location and parametric data from the system are made available over a digital interface for sensor integration and display. ALR-76 makes use of an array of fixed antennas that drive 'high-sensitivity' receivers to provide a 'high-accuracy' amplitude direction-finding capability. The broadband spiral antennas installed provide five-octave coverage in a single unit, with each antenna being a planar cavity-backed device with an integral broadband balun (a passive electronic device that converts between balanced and unbalanced electrical signals and which can also frequently change impedance) feed and a protective radome.

This diagram shows the 3rd and 4th Positions for the CS2F-2 only. The layout is different for the -1 and -3 variants. Click to enlarge. (From the collection of Leo Pettipas)

Leo Pettipas provides an insight into ASWTNS (later designated AN/ASN-501).

" It was with a CS2F-1 aircraft, that experimental squadron VX 10 developed and tested what would prove to be a triumph in engineering – the Anti-Submarine Warfare Tactical Navigation system, or ASWTNS.  The Canadians acquired the prototype technology from the USN, who had been seeking to optimize the tactical advantages provided by the Explosive Echo Ranging (EER)  technique but were pleased to hand its development over to the RCN.  The American prototype was called “JASAP” – Julie Attack Search and Plotter.

The ASWTNS was an electro-mechanical navigational and tactical computer and display system designed to solve ASW plotting, display and tactical co-ordination problems.  It incorporated an analogue computer, and utilized both automatic and manual inputs to compute and display solutions to both navigation and tactical ASW requirements.  All data, including basic navigational and tactical inputs from ASW search, localization and tracking equipment involved in EER, MAD, radar and ESM, were resolved electro-mechanically into X and Y co-ordinates.  Lighted symbols were indicated on the main display unit that featured a 12-inch screen.  This unit was mounted in the instrument panel between the pilot and co-pilot, with the control unit positioned to the right of it and in front of the co-pilot who acted as the ASWTNS operator.  Driven by the above-mentioned co-ordinate outputs, the moving symbols presented a pictorial display of the navigational and tactical situation.  It was all made possible by a pair of RCN technicians who took a “breadboard” piece of hardware and developed it into an effective, working, operational system.

By mid-1959 the ASWTNS was in the final stages of evaluation to determine if it could markedly improve the navigational and tactical capability and overall ASW effectiveness of the CS2F.  It was decided that the trials aircraft should participate in a major fleet exercise so that VX 10 could evaluate the effectiveness and maintainability of the ASWTNS equipped Tracker for operating in a naval task force environment under operational conditions at sea."

To read the historic account on the effectiveness of ASWTNS and how it detected the USS Skipjack during an exercise, please select this link.

Canadian Trackers carried *no* ESM equipment except for the AN/UPD-501 SHF D/F set . The United States Navy Trackers had embedded ESM antennas in the wingtips but these were not used for anything in Canadian service. Also, the radome above the cockpit was used for ESM in the USN.

Bob Langille clarifies the usage of the acronyms ESM and ES versus (the now incorrect) ECM. "As most early systems were designed as countermeasures against specific German radars during WW2, all systems were categorized as either RCM (Radio CounterMeasures) (British) or ECM (Electronic Countermeasures) (US).  Although these systems had a receiver type ability to detect the desired signal,  ECM/RCM systems were treated as a jammers and were designed to confuse or jam a certain radar (threat specific). These systems covered a very small RF range or just enough to counter it.  It was not uncommon for Allied bombing sorties to be supported by a multitude of ECM fitted aircraft that carried a wide range of ECM systems so that it could provide jamming against a frequency range of 120-600 MHz (unheard of today). It wasn't until later in WW2 that systems were designed with a wider search capability with no jammer ability and became part of a suite that provided tip-offs to jamming equipment if available. These receivers were still categorized as ECM - kind of homeless in a sense.

WW2 Allied Airmen relied very much on ECM/RCM, as it provided them a safety or survival net. They would turn them on before they took off and would only shut them off after they had landed. The ECM or RCM terminology was used during WW2 and up until the late 50's were it was split up into ESM (Electronic Support Measures), ECM  (Electronic CounterMeasures) and ECCM (Electronic Counter-Counter Measures). With this newer name change, ESM, ECM and ECCM were placed under the EW (Electronic Warfare) umbrella - the military effort to understand the electromagnetic spectrum.  In short - ESM category covered those systems that only intercepted, ECM for those that provided jamming and ECCM was for chaff or using radar anti-jam features.

Over the course of these two naming conventions and these three new names, ECM was the most confusing, as it had served two purposes -  initially as both a receiver and/or jammer, then only as a jammer. Depending on one's timeline, this could prove additionally confusing to both researchers and even EW operators.

In the late 90s the EW terminology was further refined to read ES (Electronic Support) for intercept,  EA (Electronic Attack) for Jamming and EP (Electronic Protection) for Chaff/Flares/Anti-Jam. In a simpler form, the "Black-Box" category served all and was very understood, at least by those who used it."

S/N 1600- Two different Tracker cutaway drawings show the radome above the cockpit to be an ESM antenna. That's only true for USN versions. In Canadian service, this was the TACAN D/F antenna for the AN/ARN504. (Photo by Jerry Proc)

S/N 1600 - The forward blade antenna in the photograph is the VHF-FM antenna. On the -1 and -2 Trackers, the aft blade antenna was the sonobuoy antenna for the Julie and Jezebel receivers/recorders. On the -3, Maritime Reconnaissance version, it  appears that it has been removed and replaced by the ARA-25 directional homing antenna (out of view) .  (Photo by Jerry Proc)

Leo Pettipas provides some background information which explains why a data relay system for Jezebel was installed in the Tracker.

"In July of 1959, a change in command structure put the operational control of all maritime forces in the hands of the Navy’s Flag Officer Atlantic (FOAC).  One consequence of this was that the Navy’s Trackers and ASW helicopters could now be assigned to shore-based maritime patrol, a duty that had long been the sole responsibility of the RCAF.  This included routine “Checker” patrols (so-called because of their criss-crossing, checkerboard pattern) to follow up on SOSUS contacts.   Differences in technology use between the Air Force and the Navy can be illustrated in the different ways they worked with SOSUS.  On the Canadian side of the border, the RCAF had taken the lead in developing Jezebel, and by 1959 the Argus patrol aircraft was already using it in its SOSUS operations.  The CS2F-1s and -2s in service at that time were not equipped with it, so if one of them was sent to investigate a SOSUS contact, the crew could only report whether or not there was indeed a contact in the probability area.  If there was, they could not verify if the one they encountered was the same as that reported by the SOSUS station.  They were given a geographic probability area and then sent to investigate visually or with radar to determine if there was a contact within the probability area.  Because the Tracker initially did not have the Jezebel system, and recognizing the chance that there could be two or more contacts in the area of interest, the crew could only report whether or not there was a contact in the probability area.  If there was, it could not verify if the contact it made was the same one as that reported by SOSUS.

Although the RCN did not go operational with the AN/AQA-3 Jezebel system until 1963, a VX 10 (Experimental Squadron) Tracker was fitted with the prototype model as far back as 1956.  In November of 1960, trials began on a Jezebel relay system designed and built by a squadron officer.  The detection, identification and tracking of a submarine was a time-consuming process: when the operating aircraft had to leave station, the relieving aircraft had to start all over again.  The relay system enabled the departing aircraft to transfer its information to the relieving aircraft, thereby eliminating the period when contact would otherwise have been lost.

In addition, the relay system allowed the operating aircraft to pick up the underwater signal detected by a normal sonobuoy receiver, amplify it and forward it to a ship such as the Bonaventure.  On receipt, the signal could be fed into analyzing equipment installed in the carrier where the frequency of submarine vibrations could be analyzed.  In the subsequent analysis, the submarine could be identified by type, since each class of vessel had a distinctive signature.  The relay system was eventually adopted for Service use by the Navy".

FOOTNOTES:

[1] From "The Naval Institute Guide to World Naval Weapons Systems, 1991/92"  by Norman Friedman.

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Credits and References:

1) Leo Pettipas <lpettip(at)mts.net> Associate Air Force Historian. Air Force Heritage and History 1 Canadian Air Division.
Winnipeg, Manitoba.
2) Bruce MacMillan <bruce_macmillan(at)telus.net>
3) Robert Stitt
4) ARC-1 photo.  Surplus Conversion Handbook #122 by Tom Kneitel. 1964
5) Ernest Cable Associate Air Force Historian,  Shearwater Aviation Museum <erncar(at)ns.sympatico.ca>
6) Tom Brent  <tgb@telus.net>
7) http://www.aviation.technomuses.ca/assets/pdf/e_GrummanCS2F-CP121Tracker.pdf
8) Robert Langille <ewcs(at)ewcs.ca>
9) AN/ALR-76  http://articles.janes.com/articles/Janes-Electronic-Mission-Aircraft/AN-ALR-76-United-States.html
 

Aug 31/13