Ordnance – Fuse setters – Combined with projecting – launching or releasing devices
Reexamination Certificate
2002-10-24
2004-11-30
Johnson, Stephen M. (Department: 3641)
Ordnance
Fuse setters
Combined with projecting, launching or releasing devices
Reexamination Certificate
active
06823767
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method for fuze-timing an ammunition unit and a fuze-timable ammunition unit.
For identifying the ammunition of an ammunition unit, ammunition-specific data, such as the type of ammunition, batch number, date of manufacture, etc., may be stored directly on a data memory (ammunition-data chip) located in the ammunition unit. These data are read out automatically when the ammunition unit is brought into a chamber of a weapons system. Often, a fire-control computer of the weapons system reads out the data. The computer then generates directional signals for the aiming system of the weapon, based on ammunition- and target-specific data, and control signals for activating an electrically programmable projectile fuze located in the respective cartridge or ammunition unit.
DE 40 08 253 C2 discloses an apparatus for fuze-timing a projectile fuze, which comprises a coil arrangement.
DE 197 16 227 C2 describes a weapons system having an ammunition unit that contains a microcontroller; this system has no fire-control computer as such. The computer is replaced by the system interaction within the ammunition- and device-controlled weapons system.
DE 198 27 378 A1 describes a weapons system having a fire-control system and a generic ammunition unit that can be fired from a weapon. For continuous monitoring of the electrical connection between the fire-control computer and the actuatable assemblies in the respective ammunition unit, a bi-directional data transmission takes place over the two lines required for the supply of voltage and current to the electronic circuits of the ammunition unit. The data transmission from the fire-control system to the electronic switching device in the ammunition unit is effected through the modulation of the voltage signals of the supply voltage. The feedback to the fire-control system is effected through the modulation of the current signals of the operating current. For this purpose, a converter is connected between the fire-control system and the electronic switching device. The fuze-timing data for setting the fuze are transmitted in analog fashion. The completed fuze timing is then acknowledged through a brief increase in the operating current. A drawback of this analog fuze timing is the required additional fuze-timing signals, which must be generated by separate hardware and software. Another disadvantage is that the hardware dictates the fuze-timing precision.
SUMMARY OF THE INVENTION
It is the object of the present invention to avoid the disadvantages known to be associated with analog fuze timing.
The object is accomplished by a method for fuze-timing an ammunition unit, including the steps of: digitizing the fuze-timing time through modulation; inserting a stop byte and a start byte in a system disposed upstream of the ammunition unit; and, transmitting the encoded fuze-timing data into the ammunition unit, demodulating the fuze-timing data in a demodulation stage and transmitting the data to a microprocessor for internal further processing, in an interaction with an oscillator.
The invention is based on the concept of providing a digital data transmission of the fuze-timing data into a fuze-timable ammunition unit, for example with an HDB-3. (High-Density Bipolar) transmission code, and voltage modulation. As is known from asynchronous data transmission, a start byte and a stop byte are respectively positioned in front of and behind the HDB-3 code, and are therefore components of the fuze-timing data. The fuze-timing time is transmitted numerically as a data byte between the start and stop bytes.
The start and stop bytes are distinguished from all other bit patterns in the weapons system in order to assure a unique identification of the start and stop signal. Preferably, the start byte begins, and the stop byte ends, with positive modulation pulses. This prevents a data transmission from being initiated or halted erroneously due to a temporary line disconnection or interruptions in the supply voltage.
For this purpose, the ammunition unit includes fuze-timing electronics, which comprise a (voltage) demodulator, a (current) modulator and a microprocessor having an RC-oscillator cycle counter, an RC oscillator, a fuze-timing counter and an actuator end stage. A firing sensor serves as the triggering element of the fuze-timing counter at the start of the flight phase. The fuze-timing data are digitized in an ammunition communications system that is integrated between the ammunition unit and a weapon that can fire the ammunition unit.
Further advantages ensue from the description claims.
The encoding of the binary data into bipolar data (HDB code) results in a DC-free voltage and current modulation, as well as a continuous synchronization of the data-transmission interface. In a modification of the invention, thief DC-free modulation also allows for the simultaneous transmission of the fuze-timing data and the voltage and current data on a connecting line provided for supplying the voltage to the fuze-timing electronics; the average values of the supply voltage and the output current of the ammunition communication system (ACS), for example, remain constant.
A time-synchronous recognition of the start and stop bytes can be effected by an interrupt-controlled evaluation of the signals from a voltage demodulator by the microprocessor and software in the fuze-timing electronics (generation of a countergate).
In a modification of the invention, the digital transmission of the fuze-timing data permits the properties of a clock oscillator (time base) that is required for fuze timing to be taken into consideration in the fuze-timing electronics. Frequency instability and aging phenomena may be temporarily compensated through the determination of the oscillator clock rate and the calculation of a time-corrected desired fuze-timing value, so a current-saving, firing-proof RC oscillator can be used. The time base in the fuze-timing electronics is calibrated with the aid of the data-transmission speed (baud rate); the transmission from a quartz oscillator in the ACS to the RC oscillator in the fuze-timing electronics is effected with quartz precision.
The feedback via the current, corrected programmed fuze-timing data is provided with the aid of a digital supply-current modulation of the fuze-timing data that have been programmed in.
The data transmission is bi-directional.
The feedback of the programmed, time-corrected desired fuze-timing value and the number of the RC oscillator clock rate can also be used for a system check. This allows the ACS to determine whether the fuze timing and time corrections have been executed properly.
A further check of the data transmission involves checking the number of transmitted bits, and performing a check sum.
The advantage of digital fuze timing is that the fuze-timing precision can be varied with software, because it is not subjected to hardware-related constraints. The fuze-timing precision can be set, for example, through the selection of the data transmission time.
Of course, the use of a definable ammunition data chip (ADC) inside the ammunition unit further ensures that the same data and voltage transfer can be used for the ADC as for the fuze timing. In other words, the structural and software costs remain low. The advantage of a definable ADC is that, for example, aging phenomena in the ammunition can be compensated with experimental values. In a special embodiment, electrical assemblies of the fuze-timing electronics can form the ADC.
The result is highly flexible fuze-timing electronics that additionally offer greater protection of the electronic assemblies through the use of only positive or only negative (unipolar) voltages.
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Vornfett Karl-Ulrich
Voss Jürgen
Johnson Stephen M.
Rheinmetall Landsysteme GmbH
Smith Stuart I.
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