The Military Communication System Information Technology Essay

This chapter will reexamine some of the proficient cognition and extra information about current available solution to line replacing unit that necessary to place the major constituents and system failure of the selected specimen. In this chapter besides some of of import hardware devices and package accomplishments which have been used in the undertaking are traveling to be discussed.

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2.2 Military Communication System

From couriers on pes to bearer pigeons to orbiters and blackberries, methods of military communicating have evolved side-by-side with engineering discoveries. Indeed, military necessity has frequently been the motivation factors behind communicating progresss ( such as Internet ) that were subsequently adapted for civilian intent.

Presents, the modern military relies to a great extent on electronics and computing machines. Although the telegraph and telephone communications have revolutionized the armed forces, World War II began the revolution of electronic applications for the military. From the 1940s to modern-war, the utilizations of electronic devices have become compulsory in the war.

2.3 Radio Communication

In the history of the wireless creative activity, it originally invented as a radio telegraph. wireless created from thoughts of some mastermind along with two other cardinal creative activity, the telegraph and telephone and an.during of used radio engineering, no 1 can claim recognition for this find.

Radio is the transmittal of signals that is frequences below the seeable visible radiation, by transition of electromagnetic moving ridges. The electromagnetic radiation travels in the air and vacuity infinite. The information carried by consistently altering ( modulating ) some belongings of the moving ridge radiation, such as amplitude, frequence, stage, or pulse breadth. When wireless waves pass an electrical music director, magnetic field induces an jumping current oscillation in the music director. This can be read and converted by specific devices into sound or other signals that conveying information.

2.4 PRM 4700

Figure 2.4: PRM 4700

2.4.1 Descriptions

The wireless set is a VHF sender and operate in the frequence scope 30-88 MHz. It use manual frequence entree and nine programmable channels, utilizing individual switch to carried out the channel choice. The channels can be programmed utilizing the front panel keyboard to run in simplex or half semidetached house. The channel can accept 16bit/sec and can be plan for sing frequence operation, two operations or mixture. A Built In Test Equipment ( BITE ) is provided to look into the truth of programmed channels, the control system and the receiving system map of the transceiver. In transmit, power end product confirmed by the presence of the side tone in the French telephone. Normally, the PRM 4700 is powered by an IDV Ni Cd rechargeable battery attached to the base of the unit. As alternate the non rechargeable battery utilizing primary cell, is available. The transceiver is design to supply automatic rebroadcast installation utilizing the MA 4009B Rebroadcast Unit ( voice signal ) or the MA4709A Rebroadcast Unit ( Voice or 16k bit signal ) . Assorted broad set aerials such as discones or periodic can be used.

PRM 4700 VHF Transmitter Receiver consists of 10 faculties. The illustrations of the faculties are transceiver, receiver board, audio board, power amplifier board and show and driver faculty.

2.4.2 Receiver Module

2.4.3 Audio Board

2.4.4 Power Amplifier Board

2.4.5 Front Panel

2.4.6 Display and Driver Module

2.4.7 Principle of Operation

The PRM 4700 VHF transceiver is modular equipment shown in Figure 2.4.7. When the transceiver is first switch on, a BITE sequence is initiated. During BITE operation, the microprocessor controls a self trial process, a channel memory cheque and two receiving system trials. When the PTT switch is opened, the BITE checks the sender and doing the presence of side tone.

2.4.7.1 Reception

Frequency or channel informations is fed from the panel frequence keys or the channel switch in parallel signifier to the microprocessor. The parallel informations input to the microprocessor is used to bring forth consecutive informations which is sent to the Synthesizer Board to find the frequence of the Receiver Voltage Controlled Oscillator ( VCO ) .

The incoming frequence modulate the RF signal from the aerial is fed trough the AMU Board and switched via a PIN rectifying tube on the PA Board and applied to the RF amplifier on the Receiver Board.

Figure 2.4.7: Block diagram of PRM 4700

2.5 Receiver Module

2.5.1 Background

The receiving system faculty is mounted on the lower half of the human body assembly. Connections to the board are made by a 16 manner border connection and three coaxal connection. The receiving system faculty provides the undermentioned circuit:

Receiver electromotive force controlled oscillator ( VCO )

Receiver RF Amplifier

Squelch Circuit

Figure 2.4.1: Block diagram of Receiver faculty

2.5.2 Principle of Operation

2.5.2.1 Receiver VCO

Figure 2.5.2.1: Block diagram of Receiver VCO Board and Synthesizer Board

The receiving system VCO forms parts of an electronic servo-control system or stage locked cringle ( PPL ) . In a PPL, the frequence of the VCO is related to a crystal mention frequence. Typically the VCO frequence, F, is divided by ratio, N, which is controlled by the frequence choice switches to give a frequence F/N which is fed together with a sub-multiple of the mention frequence to a stage comparator. The comparator compares the comparative stage of the two inputs and gives an end product electromotive force which controls the frequence of the VCO in such mode as to cut down the frequence mistake to zero.

Merely the receiving system VCO itself and its associated constituents are on the Receiver board, the balance of the stage locked loop signifiers portion of the Synthesizer Board. The DC varactor control electromotive force from the Synthesizer Board is fed down the same coax as the VCO end product to the Synthesizer Board.

The receiving system VCO covers a frequence scope of 51.4MHz to 109.4MHz. Because of the broad frequence coverage of the receiving system, the receiving system VCO frequence scope is split into the undermentioned two sets:

Low Band: 51.4MHz to 59.4MHz

High Band: 59.5MHz to 109.4MHz

2.5.2.2 Receiver

Figure 2.5.2.2: Block diagram of Receiver

The standard signal, after go throughing through the AMU and the PIN rectifying tube switch on the PA PCB, is applied to the tuned RF amplifier. Tuning constituents for the RF amplifier are switched to cover the broad input frequence scope in two sets, 30MHz to 37.975MHz and 38MHz to 88MHz. The RF amplifier is varactor tuned, the tuning electromotive force being derived from the Synthesizer Board. A individual tuned circuit is used before the RF amplifier and dual tuned circuit following.

The end product of the dual tuned circuit is applied to a double-balanced quad FET mixer together with the receiving system VCO. The ensuing different frequence of 21.4MHz ( intermediate frequence ) is filtered ( in order to take unwanted commixture merchandises ) by an 8 pole crystal filter, amplified and filtered once more, this clip in 2 pole crystal filters to cut down IF noise. After high addition IF elaboration, the signal is demodulated in a crystal quadrature circuit, and applied to the Audio Board.

2.5.2.3 Squelch Operation

Under no signal conditions a DC proportional to the noise end product from the IF/demodulator phase is applied to the bearer put-down planimeter and sensor circuits to muffle the audio phase. When a signal is present the noise end product is reduced and the put-down is opened to enable the audio phases.

The modulated sound is applied to a 150Hz filter and sensor circuit, the DC end product of which is taken to a pin on the front panel, channel in usage ( CIU ) , and used when the wireless signifiers portion of a rebroadcast station.

In the sender mode the 150Hz tone from the synthesist is passed through the same 150Hz filter ( to take harmonics ) and forms the 150Hz pilot tone, which is added to the sender audio signal in the synthesist.

2.5.3 Circuit Description

The description is divided into three subdivisions, the Receiver VCO, receiving system and squelch circuits.

2.4.3.1 Receiver VCO

Figure 2.5.3.1: Receiver VCO Description

The frequence scope of the receiving system VCO is 51MHz to 109.4MHZ covered in two sets. The extra tuning constituents required for the lower set are selected by the control board.

The oscillator transistor is TR2. The tuned circuit for the high set comprises L4, C8, C10 and D3 is a varactor rectifying tube whose electrical capacity varies harmonizing to the DC electromotive force applied when the device is rearward biased. As the electromotive force at the cathode of D3 varies from the Synthesizer Board via R5, L6 and PL2, the rectifying tube electrical capacity is varies and therefore the frequence of oscillation of the VCO varies. D4 clams the degree of oscillation at the gate of TR2.

The extra tuning constituents required for the low frequence set are L1, C2, C3, C4 and C5. These are brought into circuit when D1 and D2 are frontward biased b the set exchanging circuit TR1, controlled by the Voltage on pin 14, determined by the Control Board.

The end product Receiver VCO is applied to an end product buffer amplifier dwelling of TR3 and its associated constituents. The balance end product buffer amplifier dwelling of TR3 from the secondary twist of T1 is fed to the two-base hit balanced mixer phase.

2.5.3.2 Receiver Circuit

Figure 2.5.3.2 Receiver Circuit Description

The RF input to the Receiver board enters on coaxal socket PL3. The signal is applied to a tuned RF amplifier TR5 and its associated constituents. The input turned circuit of TR5 on the high set comprises L8, C25, C26 and D8. When the frequence in the low set is selected, D9 will be frontward biased and extra tuning constituents C28 and C29 are brought into dependent on the electromotive force applied by the Synthesizer Board to the cathode of varactor rectifying tube D8.

The end product of the tuned circuit is applied to gate 1 of TR5 via pat on L8 and C30. R34, R35, R36, R37 and R39 provide prejudice for the FET. D11 protects TR5 agains really high degree input signals. The end product from the drain of TR5 is applied via C41 and C43 to a dual tuned circuit. D12 and R38 cut down overload consequence caused by high degree input signals. On the high set, L14 is tuned by C40, D14, and C42 in the primary circuit, and L15 is tuned by D15 and C44, C45 in the secondary circuit. When the frequence in the low set is selected D13 and D16 will be Forward Biased and extra tuning constituents C37, C38 on the primary side and C46 and C47 on the secondary side are brought into circuitry. Table 2.4.3.2 shows the tuning constituents for each set for all of the tuned circuits in the receiving system VCO and the RF receiving system. The end product of the dual tuned circuit is applied to the input transformer of the sociable, via a pat on L15.

The same varactor tuning electromotive force which tunes the VCO is used to tune the RF receiving system. In order that, receiver aa‚¬E?tracksaa‚¬a„? the VCO accurately over the whole of the frequence scope it is necessary that the 4 varactor rectifying tube D3, D8, D14 and D15 are closely matched to each other.

Circuit

High BAND

Low BAND ( ADDITIONAL COMPONENTS )

Receiver VCO

L4, C8, C10, D3

L1, C2, C3, C4, C5

RF Receiver

Input tuned circuit

L8, C25, C26, D8

C28, C29

RF Receiver

Input tuned circuit primary

L14, C40, C42, D14, C42, R43

C37, C38

RF Receiver

Input tuned circuit secondary

L15, C44, C45, D15

C46, C47

Table 2.5.3.2: Effective Components in Tuned Circuits

2.5.3.3 Squelch Circuit

Figure 2.5.3.3: Squelch Circuit Description

The end product of the ML4 put-down circuit ( pin 12 ) , which is a series of pulsations reciprocally relative to receiver input signal degree, is applied to integrator circuit R14, R15 and R19 to bring forth an mean DC degree from the pulsations. The planimeter end product is inverted by ML1a operational amplifier. The addition of ML1a is set by R16 and R19. The upside-down end product of ML1a is applied to the non-inverting input of ML1b. R20 and C21 form a 2nd integration circuit to further smooth the squelch signal. The threshold at which ML1b will give an end product is determined by splitter concatenation R21, R22 and R23. R22 sets the degree at which a received RF signal will open put-down. Hysteresis is provided by R26, R27 linking the non-inverting input of ML1b to its end product. The sum of Hysteresis is set by R26.

Under no signal status the end product from the squelch thrust circuit of ML4 will hold a high pulsation content above a DC degree of about 1V. After integrating the inverting input of ML1a will be high and so the end product of ML1a will be low. This electromotive force will be below the threshold set by R22 so the end product of ML1b will be low, therefore there will be no bearer detects end product to the control board.

When RF signal is present the end product from the put-down circuit of ML4, pin 12, will cut down. This will do the end product of ML1a to lift. If the RF signal is big plenty, so the electromotive force degree at the non-inverting input of ML1b will be sufficient to get the better of the threshold set by R22 and a bearer detect end product will be present.

R22 sets the receiving system end product degree at which the bearer detect end product goes high and so allows the receiving system input signal to be heard at the sound end product. R26 sets the hysteresis and the receiving system input degree that closes the put-down.

2.6 Line Replacement Unit ( LRU )

Line Replacement Unit ( LRU ) is a modular system that design to get the better of the care job such as broken constituent or equipment and deficiency of trim portion supply. The LRU besides increase the system efficiency by cut downing the faculty care clip and minimal the procedure overall cost. The LRU can rapidly reconstruct and keep the of import system service while the originally broken faculty is undergoing mending procedure or replace by other trim portion because this faculty can be stored in the on-site storage.

2.7 National Instrument LabVIEW

2.7.1 Background

Since being introduced to the populace in 1986, LabVIEW becomes a popular graphical scheduling environment in the concern of making ocular instrument. LabVIEW helps the research workers particularly applied scientists and scientists to make their research in developing complicated system, trial processs, and practical measuring by generate graphical icons and processs, which replaces a batch of hardware devices and cut downing trial processs clip. LabVIEW besides has really ain built-in library utilizing practical instrumentality for informations visual image and other advanced analysis including signal processing.

2.7.2 History of LabVIEW Real-Time Module

“ For more than 20 old ages, NI LabVIEW graphical development has revolutionised the development of scalable trial, measuring, and control applications. Regardless of experience, applied scientists and scientists can quickly and cost-effectively interface with measuring and control hardware, analyze informations, shared consequences, and distribute systems. ” ( Gary W. Johnson, 2006 )

In 1976, National Instruments developed by CEO, and Cofounder, Dr. James Truchard and grown into a transnational company with 1000s of employees 30 old ages subsequently. In 1986, the first version of LabVIEW was produce for the Apple Macintosh. The chief propose at that clip was to better the manner applied scientists and scientists work, design, paradigm, and use the system with their package such as NI LabVIEW for measuring and mechanization industry, and making a new engineering about the practical instrument in order to overhaul our life style.

LabVIEW Versions

1986: LabVIEW 1.0 ( for Macintosh )

1990: LabVIEW 2.0

1992: LabVIEW ( for Sun & A ; Windows )

1993: LabVIEW ( Multiplatform )

1997: LabVIEW 4.0

1998: LabVIEW 5.0

1999: LabVIEW Real-time

2000: LabVIEW 6i

2003: LabVIEW 7 Express

2005: LabVIEW 8

2006: LabVIEW 8.20 twentieth Anniversary Edition

2007: LabVIEW 8.2.1

2008: LabVIEW 8.5 & A ; 8.6

2009: LabVIEW 2009 ( 32 and 64-bit )

2010: LabVIEW 2010 ( 32 and 64-bit )

2.8 Data Acquisition ( DAQ )

DAQ hardware is what normally interfaces between the signal and a Personal computer. It could be in the signifier of faculties that can be connected to the computing machine ‘s ports or cards connected to slots in the female parent board. Data acquisition applications are controlled by package plans developed utilizing a batch of general intent programming linguistic communications such as MATLAB and LabVIEW. The devices used to supply the I/O capablenesss, measuring truth, and package flexibleness that requires by the user.

2.8.1 DI-158 Starter Kit

DI-158 Starter Kit is a low-priced, compact, USB data acquisition starting motor kit. It has a capableness to enter information with 12 spots of measuring truth up to 14400 samples/second. WinDaq High Speed Acquisition package required for entering rates over 240Hz. It can bring forth four AA±10V or optional AA±64V fixed differential inputs and four digital spots for general intent I/O. It besides has two 0V to 1.25V digital to analogue end product ports.

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Figure 2.8.1: DI-158 Starter Kit

2.8.2 The USB-4303

The USB-4303 is a 10-channel version, based on two 9513 series french friess. The merchandises emulate Measurement Computing PCI-CTR05 and PCI-CTR10 counter/timer classics. These units with input frequences of up to 20MHz are suited to event numeration, PWM, frequence measuring and division, responsibility rhythm coevals and more. The 9513 bit has five independent 16-bit counters.

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Figure 2.8.2: The USB-4303

2.8.3 NI USB-6009

The National Instruments USB-6009 provides a DAQ with 8 parallel inputs ( 14-bit, 48kS/s ) . It besides has 2 parallel end products ( 12-bit, 150 S/s ) , 12 digital I/O and 32-bit count. This merchandise besides compatible with LabVIEW, LabWindows/CVI, and Measurement Studio for Visual Studio. It is truly low-cost for pupil usage and powerful plenty for more sophisticated measuring applications.

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Figure 2.8.3: NI USB-6009