Kelvin Hughes

            This UK-based radar manufacturer is a division of Smiths Industries, and has a long and illustrious history in maritime affairs which dates back to around 1750. At that time, Hughes Company, a small London-based clock-making industry, was beginning to make a reputation for quality marine chronometers; and within a century, its owner had become Master of the Guild of Clockmakers, a considerable accolade. Perhaps it was the attendant publicity that brought him together with one William Thomson, one of Britain's pre-eminent mathematical physicists of the 19th Century, who was also a man fascinated by matters maritime. Science aside, Thomson was a very successful lobbyist, who managed to persuade the British Admiralty to accept many of his "inventions", such as binnacle compasses suited to iron-clad warships. In need of a marketing partnership, he allied his own Scottish company with the Hughes Company in London, around 1870. Only later would he be recognized for his work in physics, and ennobled as Baron Kelvin1 of Largs, the name deriving from a river running through the grounds of Glasgow University, where he had been Professor of Natural Philosophy in his early twenties.

            Kelvin Hughes continued as an independent entity manufacturing marine instruments until 1961, when the consortium was acquired by yet another clock-making company, Smiths Industries (with a similarly-notable history: in 1787, when Captain William Bligh RN took his vessel, HMS Bounty, on its most famous voyage, the vessel was fitted out with chronometers manufactured by the then Samuel Smiths Company). By the time of its acquisition in 1961, Kelvin Hughes was already well-established in the manufacture of marine navigation radars, and has continued in that industry ever since. 

            As well as selling its own radar systems, Kelvin Hughes has at times provided badging facilities to other manufacturers, specifically to the Japanese company Anritsu: in the late 1960s, Anritsu found it more effective to market products in the USA under the Kelvin Hughes label, rather than under its own.  These sales were undertaken by another wholly-owned subsidiary of Smiths Industries, which was subsequently sold off to a different Japanese corporation, Koden Electric, in 1988; this subsidiary is known today as SI-Tex (the SI-Tex brand is described in detail in the Koden section, along with other Koden-family systems.) The company has also, it appears, sold its radars to other companies to be retailed with their own logo. Norcontrol (now Kongsberg) is one such example; there may be others.

      Today's "conventional" Kelvin Hughes product line is based primarily around two X-band transceivers with two antenna options, two S-band transceivers, also with two antenna options, and two turning motors. These components are used in a variety of radar configurations, with names such as Manta 2300; and in its Nucleus-series installations, none of which bears any obvious relation to the transceiver names: the Mark-IV through Mark-VII, all but the first of which may be installed as either up-mast or down-mast configurations. In addition to these, there is a "Black Box" version that is parametrically identical to the Kelvin Hughes Mark-V transceiver, lacking only the latter's display units. Thus, the observer may note a wide range of apparent product names, and yet the number of underlying configurations is small.

        In addition to these conventional, magnetron-based designs, Kelvin Hughes has recently introduced an architecture based on a coherent RF source, rather than being magnetron-based. This architecture, about which there is only scant information available, underpins its SharpEye family of MNR products for both civil and naval applications. There is insufficient information in the public domain for any detailed discussion of the SharpEye system in this  edition.

            The published characteristics of the Kelvin Hughes transceivers are documented in Appendix 1, which follows. Appendix 2 awaits opportunities for observation and characterization of cooperative Kelvin Hughes systems.

Copyright @2011 EMForensics

Kelvin Hughes

Appendix 1

Published Radar Characteristics

            Kelvin Hughes' magnetron-based radars use four basic transceivers, four antennas and various turning motors. The characteristics of these are tabulated as follows:

    • Table 1 cross-indexes transceivers' pulse durations with pulse rates. In order to simplify documentation, this table includes a column for the peak power output of the various transmitters
         
    • Table 2 cross-indexes the same transceivers' scan rates with the appropriate antenna systems.

The following points should be borne in mind when interpreting these tables:

  • Magnetron-triggering mechanisms for this product line are somewhat rare in the MNR market, comprising pulse-forming networks rather than the more common field-effect transistors (FETs) favored by many of its competitors.           
  • Pulse timing processes are also distinctive: the modulator board bears a PRF oscillator that may be set to any value within a range of 2400 to 3400 Hz, and individual pulse-rates are derived from this via a simple divider circuit. Beyond this, the user may opt to use another facility that is inherent to the design: a noise source capable of modulating, on a pulse-by-pulse basis, the inter-pulse intervals. According to manufacturer documentation, this facility introduces up to 15 μS variability in pulse timing.
  • In type-approval documentation, Kelvin Hughes is credited with providing transceivers to Kongsberg AB for its DataBridge10 radars, to which the documentation ascribes different pulse rates from those given by Kelvin Hughes, even though the Kelvin Hughes transceiver design incorporates the pulse-rate generator on its modulator board.
  • Where multiple scan rates are given, they are exclusive, as they are determined by the turning motor included in the configuration. Very fast rates are intended to comply with IMO regulations regarding high speed craft, rather than large ocean-going merchant vessels.
    Radiated beam characteristics provided in Table 2 are estimated from antenna sizes. Lengths given in the table have been rounded to integer values, whereas the documented radiator-lengths2 were used for beamwidth approximations, which are rounded to 0.1°.    

[1] Remembered for determining absolute zero temperature, and development of the Kelvin Scale.

[2]   Excluding the double-curvature end-feed; all Kelvin Hughes open-array antenna designs are end-fed.