Radar Reference Materials
Many sources were consulted and extensive research was undertaken in the development of the Handbook. For preservation of editorial sanity, considerable use was made of Microsoft® Excel 2003, both as a catalog of resources and to tabulate key facts as they were gleaned. The result is an Excel workbook called MNR Characteristics, representing what might be considered a snapshot-in-time of the MNR manufacturing base, as it appeared in March 2007 and May 2009. This Excel workbook is included with the CD version of the MNR Handbook, and our purpose here is to describe the Excel workbook contents.
The Excel workbook MNR Characteristics comprises two worksheets:
♦ Documented Parameters:
This worksheet lists the characteristics of a substantial range of radar systems as listed in some combination of product catalogs, user handbooks, installation manuals, type-approval documents and brochures - around 650 radars, with around 2900 documented modes of behavior. An entry (a row, in Excel parlance) usually describes a single system, except where there are multiple instances of a system, each with a variation of the basic model name. There will be more than one entry for each radar system when that system has some combination of multiple antenna options, multiple peak power outputs and multiple distinctive sets of pulse rates. Each record comprises a number of cells, as follows:
This cell describes the physical attributes of the antenna - dimension and type. Associated with this cell, a "comments" field provides horizontal and vertical beamwidth information and documented scan rates. In the latter context, manufacturers usually specify rate in revolutions per minute; additionally, some will specify slightly different rates depending on power supply frequency (50/60 Hz); finally, some models may have multiple scan rates associated with them.
This cell describes the peak power in kW of the magnetron used by the system; it is substantially greater than the peak power radiated in the radar's main beam. Some cells have associated comments in which information about the magnetron or other power-related issues may be found.
This cell describes the power source used to drive the antenna, wherever possible. Again, associated comments may be used to amplify the bare facts reflected in the cell.
This is usually the manufacturer model name, as listed in brochures or handbooks. Sometimes, it has been necessary to adjust the cell entry so as to achieve readability. In almost all instances, a hyperlink is associated with the cell entry; this hyperlink associates the record with the internet source from where the information provided in the worksheet was obtained. In a very small number of instances, only printed materials could be traced; these are not hyperlinked. As well as the hyperlinks, cells may have associated remarks within which may be found "model history" information, e.g. when first publicized, when last upgraded.
In most cases, this cell contains a numeric value representing the nominal RF as documented by the manufacturer; in a small number of cases, only a band or wavelength was documented, reflecting the manufacturer data. In a very small number of cases, RF values include an asterisk; this signifies that alternative RFs are documented as an available, usually either 9375 or 9410 MHz; or either 3025 or 3075 MHz.
o PD1 through PD11:
Each PD cell has an associated PRF cell; the PD value entered in any cell represents the pulse duration in microseconds, for the PRF value that is present in the adjacent cell to the right. Each PD's resolution is the same as that published by the manufacturer, with neither rounding nor artificial improvement.
o PRF1 through PRF11:
Wherever a PRF value is present, it is expressed in Hz, to the same resolution provided by the manufacturer. Some manufacturers choose to provide PD values without associated PRF values; because of this, there are inevitably PD values with empty associated-PRF cells.
Finally, as noted above, systems are grouped by manufacturer. Preceding each group, there is at least one record containing the name of the manufacturer; in almost all instances, this record includes a hyperlink to a manufacturer/distributor website; and, in some instance, there are associated comments providing amplifying information about the manufacturer or its products.
♦ Observed Paras:
The purpose of this sheet is to tabulate the physical, electrical and parametric characteristics of the specific radar systems subjected to detailed characterization during the preparation of the Handbook. Because of this specificity, the structure is somewhat different and the linkages are entirely different. In all instances, the tabulated data represents the findings from physical examination and parametric study, and the information presented may be unique to individual systems. Also, individual records describe only one mode of operation. The makeup of the worksheet is as follows:
This cell refers to the specific antenna used by the radar system under test. Scan rates listed in comments for this cell refer explicitly to the system, rather than to manufacturer documentation; in other respects, the comments are the same as in Documented Paras. In some records, the Antenna cell is hyperlinked to a locally-stored photographic image in JPEG format;
This data is copied directly from the Documented Paras worksheet;
This data, too, is copied directly from the Documented Paras worksheet;
This cell contains the name of the specific system examined during testing phases, because of which there are minor differences between the two worksheets. There is also a more substantial difference; in the Observed Paras worksheet, the cell is hyperlinked to the characterization report used in describing the system within the handbook. This characterization report represents the complete description of observed parameters from which the other elements of the worksheet are synthesized.
o RF Band:
This cell indicates whether the radar system under test was an X band system or an S band system. This was preferred over RF, because of the wide variabilities noted during characterization activities;
The content of this cell denotes the inter-pulse interval modulation used by the radar system. Three categories are used: Stagger and Discrete Jitter are as described in Annex B; to this was added a third modulation, Stutter, signifying an inter-pulse interval modulation comprising a Stagger with an undetermined type of jitter superimposed on it. Stutter as used in this context is a term coined for the purpose, rather than a commonly used term.
This cell amplifies the modulation term, describing the number of individual elements (distinct inter-pulse intervals) in the modulation, and -where relevant - the total number of pulse intervals that occur in a complete sequence; the terms "elements" and "positions" are explained in detail in Appendix B. Where it is appropriate, comments provide additional information about stagger sequences; and when reference material is available to describe the pattern-generation mechanisms of more complex waveforms, hyperlinks provide connectivity to the relevant document.
o Clock (MHz):
Where a VHF oscillator could be identified from physical examination as the source from which pulse timings are derived, the oscillator frequency is shown in this cell. In some instances, the cell is hyperlinked to a photographic image in JPEG format, of the radar system's processing board; some of these JPEG images also show other oscillator frequencies.
It is normal practice in MNR designs to "count down" (i.e. subdivide) the frequency generated by the VHF oscillator, resulting in a much lower frequency that represents the minimum increment of time within the system. The value, if any, contained in this cell represents either the periodicity of the Clock; or an estimation of the most likely sub-clock periodicity, in μS, calculated rather than measured. Associated comments indicate the countdown used; in their absence, the cell value denotes the periodicity of the Clock.
o Sub-clock Multiplier:
This value, when present, is a mode-dependent scalar value providing a second stage of count-down processing from which is derived a PRI Range-base value, as described below.
o PRI Range-base:
This value is the measured PRI Range-base derived from inter-pulse timing characterization and the derivation of the greatest common denominator for all derived timings. In conjunction with the Clock value derived from physical inspection, the PRI Range-base provides the basis of estimation for the Sub-clock Multiplier and the Sub-clock values tabulated in the Observed Paras worksheet. PRI Range-base values were derivable for all but the Stutter modes of operation, even when no intermediate values were found.
o Count Min:
In most instances, this cell tabulates the minimum inter-pulse interval in the pulse modulation, as a multiple of the PRI Range-base. In a very small number of instances, where the interval modulation is Stutter, this cell contains an integer value showing the relationship of the minimum inter-pulse interval to the maximum. In these special cases, comments are used to further amplify the relationship;
o Count Max:
Ordinarily, this cell tabulates the maximum inter-pulse interval in the pulse modulation, again as a multiple of the PRI Range-base; where no PRI Range-base was found, it contains an integer value representing the relationship of the longest interval to the shortest.
o PRI Min:
This cell tabulates the shortest interval in the inter-pulse modulation, in μS. Additional comments are used to describe the mean PRI and mean PRF.
o PRI Max:
This cell tabulates the longest interval in the inter-pulse modulation, again in μS.
o PD Min:
In general, this cell tabulates the minimum pulse duration observed, in μS, during characterization studies. In a small number of cases, there may have been too little data, or perhaps the overall range was deemed to restrictive; in these cases a very small reduction of the tabulated value was made.
o PD Max:
This cell tabulates the maximum pulse duration observed, again in μS, and with the same qualifiers described above;
This label defines the operating mode of the radar at the time that the inter-pulse modulation was recorded. It should be noted that the terms used are either those contained in manufacturer documentation or as applied by the Handbook editors to attain consistency. The labels are not those used on the radar itself; a user selects a range-scale by reference to the radius of the display, rather than the pulse mode.