scope:

This specification covers the requirements for all types of analog shaft angle input to digital output encoders. It is not complete in itself, but should be used in conjunction with MIL-S-81963 which will form an integral part of this specification.

The nomenclature consists of the item name, followed by a type designation which includes a modification letter and a part identifying number. All encoders having the same design nomenclature are physically, mechanically and electrically interchangeable for all military applications. The type designation is indicated by digits and letters which indicate in code form the principal physical and electrical characteristics affecting interchangeability (see Table I). Throughout the designation, a "W" will indicate a special case to be defined by the applicable specification sheet.

In all cases, the item name will be "Encoder, Shaft Angle to Digital". Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to Commanding Officer, Naval Air Warfare Center Aircraft Division, Code SR3, Lakehurst, NJ 08733-5100 by using the self-addressed Standardization Document Improvement Proposal (DD FORM 1426) appearing at the end of this document or by letter.

The first two digits of the type designation will indicate the maximum diameter of the encoder in tenths of an inch. If the maximum diameter is not a whole number of tenths, the next higher tenth will be used.

The type, or operating principle employed, will be designated by a single letter according to the following schedule:

Capacitive - C Optical (Lamp) - L Contact - K Optical (LED) - S Eddy Current - E Other - W Magnetic - M

The output code and scanning method will be designated by a single letter according to the following schedule:

Natural Binary, Line-Scan - A Natural Binary, U-Scan - B Natural Binary, V-Scan - C Natural Binary, M-Scan - N Reflected (Cyclic) Binary (Gray Code) Line-Scan - D Reflected (Cyclic) Binary (Gray Code) Lead-Lag - P Binary Coded Decimal, Line-Scan - E Binary Coded Decimal, U-Scan - F Binary Coded Decimal, V-Scan - G Binary Coded Decimal, M-Scan - M Decimal, Line-Scan - H Incremental (With Zero Reference) - J Incremental (Without Zero Reference) - K Altitude reporting (ICAO) - U Other - W

Whether the sensor selection is accomplished internally or externally, and whether the readout is parallel or serial will be designated by a letter according to the following schedule:

External Logic, Parallel - J External Logic, Serial - K Internal Logic, Parallel - L Internal Logic, Serial - M

The capacity of the encoder, with reference to the code, will be designated by a two-digit number equal to the highest power of two or ten, contained in the total count. If the number is less than 10, it should be preceded by a zero. Incremental will be listed as the closest power of two. The resolution will occasionally be listed directly instead of exponentially. Consult the applicable specification sheet to avoid confusion.

The digital output of the encoder is a mathematical function of the shaft position. This function will be designated by a letter according to the following:

Linear - R Sine-Cosine - S Tangent - T Exponential - X Logarithmic - Z Other - W

The resolution of the encoder will be designated by a number equal to the highest power of two or ten, with reference to the code, counted by one revolution of the input shaft. If the number is less than 10, it should be preceded by a zero. Incremental units will be listed as the nearest power of two. The resolution will occasionally be listed directly instead of exponentially. Consult the applicable specification sheet to avoid confusion.

The upper case letter "A" following the resolution designation indicates the original or basic issue of an encoder type. Subsequent modifications which affect interchangeability are designated by succeeding letters in the alphabet, with the exception of "I", "L", "O", and "Q", which are prohibited.

The input voltage required for proper operation will be specified on the applicable specification sheet.

An encoder bearing the type designation 18KCJ13R07B, illustrated in Table I, has the following characteristics:

Size - Diameter greater than 1.7 but (18) not more than 1.8 inches Type - Contact (K) Code and Scan - Natural Binary; V-Scan (C) Readout - External Logic; Parallel (J) Capacity - 2¹³ counts (13) Function - Linear (R) Resolution - 7 Bit (07) Modification - First Modification (B)

The part identifying number consists of the letter "M", the basic number of the specification sheet (not including the revision letter), an assigned dash number and a suffix letter designating the latest modification letter in the type designation, as shown in Table II.

intended Use:

The intended use for encoders covered by this specification must be in accordance with MIL-S-81963.