US3822038A - Multicoupler percent frequency separation calculator - Google Patents

Abstract

A circular slide rule device for quickly and accurately determining percent frequency separation necessary between frequencies for acceptable operation in high frequency multicoupler environments. A circular base member is circumferentially graduated clockwise in three concentric, overlapping logarithmic scales which represent frequencies from 2,000 kHz to 30,000 kHz. A transparent cursor member is concentrically and rotatably mounted on the base and has marked thereon percent frequency separation indicia with respect to a centerline zero percent reference. The device is easily operated and provides direct readouts of percent frequency separation at any frequency for multicoupler/transmitter/receiver combinations.

Description

Olson [451- I July 2,1974

MULTICOUPLER PERCENT FREQUENCY SEPARATION CALCULATOR [75] Inventor: Irving C. Olson, San Diego, Calif.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

[22] Filed: June 15, 1972 [211 App]. No.: 263,067

[52] US. Cl 235/88, 235/78, 116/133 [51] Int. Cl G06c 3/00, 6060 27/00 [58] Field of Search 235/78, 88, 116, 84, 70 R; l16/l15,l26, 133

[56] References Cited UNITED STATES PATENTS 3,050,249 8/1962 Awramik, Jr. et al. 235/78 3,206,] 15 9/1965 Norman 235/88 3,259,31l 7/1966 Sama et al. 235/78 3,604,622 9/1971 Yamada 235/78 3,643,859 2/1972 Kreisel, Jr 235/88 Primary Examiner-Stephen J. Tomsky Attorney, Agent, or Firm-R. S. Sciascia; G. J. Rubens; J W. McLaren 5 7] ABSTRACT A circular slide rule device for quickly and accurately determining percent frequency separation necessary between frequencies for acceptable operation in high frequency multicoupler environments. A circular base member iscircumferentially graduated clockwise in three concentric, overlapping logarithmic scales which represent frequencies from 2,000 kl-Iz to 30,000 kl-lz. A transparent cursor member is concentrically and rotatably mountedon the base and has marked thereon percent frequency separation indicia with respect to a centerline zero percent reference. The device is easily operated and provides direct readouts of percent frequency separation at any frequency for multicoupler/- transmitter/receiver combinations.

2 Claims, 1 Drawing Figure FREQUENCY k HZ MULTICOUPLER PERCENT FREQUENCY SEPARATION CALCULATOR BACKGROUND OF THE INVENTION Thecircular slide rule shown in the FIGURE essen- As high frequency communication system require- 5 tially comprises a circular base member (disk) havments for use aboard naval ships continue to increase, topside antenna mounting space is becoming limited. As a result of limited space, the use of multicouplers has become mandatory since a multicoupler allows sev-' eral transmitters or receivers to be connected to one antenna. Shipboard couplers are normally passive and comprise tunable bandpass filters with a combining network. Practical design considerations dictate the minimum channel separation requirement. The minimum separation requirement for a multicoupler is normally determined by the manufacturer through a consideration of maximum allowable impedance interaction and/or maximum power transfer between channels. The minimum channel separation is normally expressed as percent frequency separation. Violations of the minimum separation requirement can cause adjacent channel detuning and equipment damage.

A calculation of percent frequency separation is not difficult for one who understands percentages, but it may require more time than is available in an operational situation when a rapid decision is required. The percent frequency separation calculator to be disclosed herein has been designed to enable communication personnel to rapidly and accurately determine the separation required between channels in the 2,000 to 32,000 kHz frequency bands.

SUMMARY OF THE INVENTION A small, inexpensive, circular slide rule device for rapidly determining percent frequency separation necessary for acceptable operation in high frequency multicoupler environments is disclosed. The device comprises a circular base member having a transparent circular cursor, of the same radius, rotatably mounted thereon, The base member is circumferentially graduated clockwise in three concentric, overlapping logarithmic scales representing the frequency band of 2,000 kHz to 30,000 kHz. The cursor has marked on a portion of its circumference linear indicia representing percent frequency separation with respect to a zero percent reference centerline. By means of simple manipulation, the device can provide direct readouts of percent frequency separation at any frequency for multicoupler/transmitter/receiver combinations.

OBJECTS oF THE lNVENTlON BRIEF DESCRIPTION OF THE DRAWING The FIGURE is a top view of a circular slide rule device embodying the present inventive concept.

ing rotatably and concentrically mounted thereon a transparent, circular cursor member (disk) 12. The cursor member 12 is mounted on 10 by means of a conventional pivot means 14 and its radius is equal to the of the base member 10.

The indicia bearing base member 10. has marked thereon three concentric scales I6, 18, and 20 which are graduated in a curved logarithmic scale clockwise along the circumference thereof. The logarithmic scales 16, 18, and 20 overlap along the circumference of the base member 10 and represent the three fre- I quency bands 2,000 to 6,000 kHz, 4,000 to 12,000 kHz, and 10,000 to 30,000 kHz, respectively. It can be appreciated that by using logarithmic scales. percent frequency separation can be read in a linear manner so that only one cursor is needed for the device.

The pivot 14 is centrally located and allows the transparent cursor 12 to rotate freely with respect to the base member 10 while holding the base and cursor in a contiguous relationship. The cursor 12 has linear markings along a portion or are of the circumference graduated to indicate percent frequency separation. The markings 22 extend from 0 to 15 percent (or more if desired) in equal divisions to either side of the zero reference mark.

The base member 10 can be constructed from any convenient semi-rigid material such as plastic, rigid paper, etc. Likewise, the cursor or transparent overlay 12 can be constructed from transparent, semi-rigid plastic material of the type commonly used on circular slide rules. By way of illustration the preferred embodiment has a radius of approximately 4 inches although this is in no way intended to limit the size of the device.

The cursor indicia 22 indicate percent frequency separation from the centerline reference and provide direct readouts of percent frequency separation at any frequency for multicoupler/transmitter/receiver combinations. Multicoupler minimum frequency separation requirements are usually provided and are available in equipment manuals and in multicoupler specification tables. They can also be tabulated from operational experience with a particular equipment and antenna suit.

The device embodies the principle that percent separation between any two adjacent frequencies on a logarithmic scale is a constant physical length and in determining percent separation, the higher of the two frequencies under consideration is always used as the reference frequency.

Referring to the FIGURE, assume an operational situation in which a multicoupler frequency separation requirement is 10 percent and circuits are called for at 4,500 kHz, 5,000 kHz, and 5,500 kHz with 5,000 kHz being the priority frequency. Setting the cursor l2 zero centerline on 5,000 kHz on the base 10 quickly reveals that 4,500 kHz is at the required 10 percent separation.

On the right side of the cursor centerline, however, 5,500 kHz is clearly separated by less than 10 percent and cannot be accommodated by the multicoupler. Consequently a higher frequency must be selected somewhere above 5,600 kHz. In actual shipboard operation situations are very much more complicated, and

priority frequencies is then checked to ensure that adjacent frequencies are adequately separated. Next, the remaining frequencies are checked for proper separation. Violations of manufacturers specified separation require frequency change, different multicouplers, or separately tuned antennas. For a new multicoupler frequency, zero on the percent separation scale 22 is set over the new frequency. Percent frequency separation is checked between adjacent frequencies, and violations are treated as above.

It should be noted that the calibration of the percent separation scale 22 ensures that the two frequencies are separated by at least the amount indicated regardless of which of the two frequencies is under Zero.

Thus it can be appreciated that a simple, inexpensive, and effective percent frequency separation calculator tool for advance frequency planning, and for on the spot checking of frequency assignment with specific multicouplers has been disclosed. The calculator can be used by relatively inexperienced personnel to provide percent frequency separation data for at least the following communication equipment configurations:

two or more transmitters used in a common multicoupler and a common antenna system; two or more transmitters using a common multicoupler but separate antenna systems; a transmitter and receiver on a common antenna system; and two or more receivers on a common multicoupler.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is: 1. Apparatus for calculating percent frequency separation required between frequencies in multicoupler environments of high frequency communication systems comprising:

a circular, disk-like base member; said base member having a plurality of concentric logarithmic scales marked and graduated in a clockwise manner substantially about the circumference thereof and overlapping with respect to each other to represent continuous high frequency band; a circular and transparent cursor member having a radius equal to the radius of said base member.

said cursor member having linear percent frequency separation indicia along an arc of said cursor member; and,

center pivot means connected to said base member and said cursor member for supporting said cursor member in a rotatable manner with respect to said base member.

2. The apparatus of claim 1 wherein said plurality of logarithmic scales comprises three frequency scales representing the high frequency band from 2,000 kHz to 30,000 kHz.

Claims (2)

1. Apparatus for calculating percent frequency separation required between frequencies in multicoupler environments of high frequency communication systems comprising: a circular, disk-like base member; said base member having a plurality of concentric logarithmic scales marked and graduated in a clockwise manner substantially about the circumference thereof and overlapping with respect to each other to represent continuous high frequency band; a circular and transparent cursor member having a radius equal to the radius of said base member, said cursor member having linear percent frequency separation indicia along an arc of said cursor member; and, center pivot means connected to said base member and said cursor member for supporting said cursor member in a rotatable manner with respect to said base member.

2. The apparatus of claim 1 wherein said plurality of logarithmic scales comprises three frequency scales representing the high frequency band from 2,000 kHz to 30,000 kHz.

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