EDO's IRIG A/B Decoder Instrumentation

IRIG General Description IRIG Features IRIG Characteristics IRIG Block Diagram Main Instrumentation Page

IRIG A/B Decoder General Description

EDO's InterRange Instrumentation Group (IRIG) Decoder is a full VME MIL-SPEC IRIG 200-89 board. The IRIG board incorporates a microprocessor that controls all timing operations and a unique automatic threshold adjustment circuit.

The automatic threshold adjustment circuit compensates for a wide range of IRIG input signal amplitudes.

When the threshold adjustment circuit completes a threshold adjustment, the microprocessor automatically determines the format (IRIG A or B) of the input signal.

If no input signal is present, the board provides the capability of setting time manually.

If the IRIG input signal falters, the board will automatically switch all timing to the back-up timer with no loss in time.

A phase-locked loop frequency divider is utilized to synchronize internal time registers to the IRIG B input signal.

The board accepts IRIG A or B format, modulated or demodulated differential. The following Binary Coded Decimal (BCD) time parameters are accessible via the VME interface:

Month/Day
Hour/Minute
Seconds.

All time registers are latched by reading milliseconds (Hex) and are held indefinitely until milliseconds are read again, thus preventing clock rollover during a read cycle.

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IRIG A/B Decoder Instrumentation Features

Embedded microcontroller

Automatic detection of IRIG format (A/B)

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Software-selectable leap year provision

Modulated or demodulated IRIG input

±1 (One) millisecond accuracy

Computer-controlled input threshold adjustment

VME accessible time

Manual time set capability

On-board programmable back-up timer for uninterrupted timing

Extensive Built-In-Test (BIT) capability. BIT may be executed anytime via software

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IRIG A/B Decoder Instrumentation Characteristics

FUNCTIONAL:

Processor	87C528
Clock Rate	12 MHz
Memory
Static EPROM	512 Bytes 32 Kilobytes
Interfaces	VME bus IEEE 1014 compatible
Interrupts	3 local
Counter/Timer	One Real-Time Clock
Reliability	320,000 hours ground benign, 72,000 hours airborne inhabited transport
Power Requirements	10 W (typical), 20W (max)

PHYSICAL:

Parts & Materials
MIL-SPEC	ICs are MIL-STD-833 Class B. All other parts are QPL.
Construction	All components are soldered to the board and conformally coated on standard product. Modules containing microprocessors and/or EPROMS are available in a socketed version for development of "Flyable Prototypes."
Cooling
MIL-SPEC	Conduction via integral heat-sink to the sidewalls of the chassis.
Size	9.18" wide by 6.29" high
Mounting Pitch, Module	0.8"
Approximate Weight
MIL-SPEC	1.4 lbs

ENVIRONMENTAL:

Operating Temperature
MIL-SPEC	-55 to +85 degrees Celsius
Temperature / Altitude (System)
MIL-SPEC	MIL-STD-810D, method 504.1, 50,000 feet
Storage Temperature
MIL-SPEC	-62 to +125 degrees Celsius
Relative Humidity
MIL-SPEC	0 to 100% with condensation, MIL-STD-810D, method 507.1
Vibration (Module) Sinusoidal
MIL-SPEC	5 Gs, 5-2000 Hz, MIL-STD-514.2
Random
MIL-SPEC	12 Gs RMS 20-2000 Hz
Shock (Operating)
MIL-SPEC	40 Gs 11 msec, MIL-STD-810D, method 516.2

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IRIG A/B Decoder Instrumentation Block Diagram

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Updated: January 23, 2008

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