Furuno

Appendix 2
Published Radar Parameters

            The nominal parameters of present-day Furuno-manufactured radars are advertised and thus readily available in the public domain. For radio frequency, no tabulation here is necessary; all Furuno S-band systems are specified as using a nominal RF of 3050 MHz, while X-band systems are specified as using a nominal RF of 9410 or 9415 MHz. Tables 2.1 through 2.3C below, show the parameters for the present generation of systems being manufactured by the company:

♦    Table 2.1 lists the systems either in the product catalog or for which maintenance support appears to be available, with a grid showing which average pulsing rates (commonly known as Pulse Repetition Frequency, or PRF) may used by the system,  and what PD or PDs may be used with that tabulated pulse rate. It should be borne in mind, when viewing this table, that:

o  The system names are not exhaustive; where several variants exist (e.g. the FR-2135S/2135S-BB/2135SW/2135SW-BB), and they are documented with similar characteristics, only the basic version is listed. An exception has been made for FR- and FAR- versions, even where their characteristics are similar, since they are designed for entirely different classes of vessel.          

o    Where multiple PDs are shown for a given PRF, these may represent factory-determined settings for individual systems, rather than operator-selectable alternatives. Ordinarily, individual systems will have no more than four PDs available, in the range 0.07 to 1.2 μS.         

o    There are more PRFs listed than are available to any one system. Often, manufacturer literature will specify 'any two of three values' for any given radar range-setting; selection of these is typically beyond user control.           

o Handbooks for a small number of systems specify that radar range scales may be switched from nautical miles to statute miles by replacing the PRF source crystal for one with a different value.

♦    Table 2.2 lists the same systems as in Table 2.1, grouping these systems by a combination of peak power and antenna physical specifications. These characteristics should be treated with caution, as they are derived from comparison of a diverse range of materials, some of which is contradictory in nature: a brochure may differ slightly from an operator's handbook, and this in turn may differ from the installation manual. When viewing these groupings, the following should be borne in mind:       

o    The same magnetrons (MG5241 and 9M602) are rated variously by Furuno at 10kW and 12kW peak power output. Although the systems have been separated in these tables, this is solely to reflect the Furuno ratings; in reality, magnetron manufacturers will rate their products at a nominal peak power and specify an output range deviation of as much as ± 50%.                  

o   Open arrays less than 4' in length are disappearing from the Furuno inventory; only the Model 1932 Mk2 (updated in April 2005 from a 1998 design) now uses such an antenna. The largest radome (2' externally) is thus likely to become around half the diameter of the shortest open array antenna.       

o    However, some care must be taken in expressing antenna sizes. Where radomes are concerned, it is often but not always the external diameter that is quoted. With open arrays, it may be either the radiating element of the antenna or the turning circle; the latter is slightly greater, since it makes allowance for the curved end-section of the waveguide that connects the array to its pedestal, which is not always visible.     

♦  Tables 2.3A through 2.3C summarize the scan rates of the various antenna systems, with separate tables describing radomes (Table 2.3A), X-band open arrays (Table 2.3B) and S-band open arrays (Table 2.3C). Where individual systems are capable of more than one turning-speed, this is indicated in the tables with a plus sign between the relevant rates; in all other instances where multiple rates are given, these are exclusive - an individual system may exhibit only one of the alternative values provided. In this latter case, multiple alternative rates arise because a vessel's power supply frequency may be either 50 Hz or 60 Hz; or, in the case of radars designed for IMO-defined high-speed craft, because a different motor is provided to satisfy mandated performance. In the special case of radomes, some Furuno models provide the user with the option of selecting a default turning-speed; and a high turn-speed may be adopted automatically when either a very short range-scale (less than 3 nautical miles) is selected, or the vessel's speed through the water exceeds some threshold value.  With modern systems, which have extensive interaction between data-processor, control logic and low-mass low-inertia antenna, further adaptability of scan should be anticipated.