142-548: The M577 command post carrier , also known as the M577 command post vehicle or armored command post vehicle, is a variant of the M113 armored personnel carrier that was developed and produced by the FMC Corporation to function on the battlefield as a mobile command post i.e. a tactical operations centre, usually at the battalion level. In U.S. military service its official designation
284-440: A digital-to-analog converter , typically at a frequency less than the desired RF-output frequency. The analog signal must then be shifted in frequency and linearly amplified to the desired frequency and power level (linear amplification must be used to prevent modulation distortion). This low-level method for AM is used in many Amateur Radio transceivers. AM may also be generated at a low level, using analog methods described in
426-535: A tactical response vehicle . The M577 is easily distinguished from the M113 upon which it is based by its raised upper hull and roof-mounted auxiliary power unit (APU). Vehicles are generally unarmed. The experience gained by the U.S. Army in the Second World War showed that close co-operation between infantry and armored forces is a necessity for combined-arms mechanized mobile warfare. Mobile warfare increases both
568-400: A video signal which represents images. In this sense, the carrier wave, which has a much higher frequency than the message signal, carries the information. At the receiving station, the message signal is extracted from the modulated carrier by demodulation . In general form, a modulation process of a sinusoidal carrier wave may be described by the following equation: A(t) represents
710-418: A circular turret for the .50-caliber M2 machine gun in the track commander (TC) position, two M60 machine guns with shields for the left and right rear positions, and "belly armor"—steel armor bolted from the front bottom extending 1/2 to 2/3 of the way towards the bottom rear of the M113. The two rear machine gunners could fire their weapons while standing inside the rectangular open cargo hatch. This transformed
852-581: A common work area. With the introduction of the M1068 SICPS Carrier, the M577-specific tent was replaced with a Modular Command Post System (MCPS) tent, which attaches to the rear of the vehicle by a "bootwall" that covers the rear of the vehicle but still has an entrance to the vehicle's interior. The MCPS tent has the advantage of being quicker and easier to erect and dismantle, provides overhead lighting and power sockets for electrical equipment, and
994-436: A compromise in terms of bandwidth) in order to reduce the required channel spacing. Another improvement over standard AM is obtained through reduction or suppression of the carrier component of the modulated spectrum. In figure 2 this is the spike in between the sidebands; even with full (100%) sine wave modulation, the power in the carrier component is twice that in the sidebands, yet it carries no unique information. Thus there
1136-975: A detonation of the explosives carried on the exterior of their M113. On 24 June 2024, Al-Qassam Brigades published footage of its forces attacking an M113 using a Chinese HJ-8 ATGM, hitting the vehicle, caused an external fire on the carry-on CARPET demining system. Several disabled Zelda APCs in Nabatieh , Lebanon and Gaza have revealed VBIED use by the IDF, where the vehicles are filled with explosives, towed to their target, and detonated. An unknown number of M113s were converted into Unmanned Ground Vehicles and were observed to be acting as VBIEDs in Rafah. In November 2024 IAI showed videos of unmanned M113 units working with unmanned D9 bulldozers in what appeared to be Gaza as an example of its new teaming system for robotic units. The Israel Defense Forces still operates large numbers of
1278-460: A digital signal, in which case the technique is generally called amplitude-shift keying . For example, in AM radio communication, a continuous wave radio-frequency signal has its amplitude modulated by an audio waveform before transmission. The message signal determines the envelope of the transmitted waveform. In the frequency domain , amplitude modulation produces a signal with power concentrated at
1420-603: A dismounted infantry unit. The remaining SPATS platoon was reequipped with M113s in late 1966 and the mortar platoon was deactivated in early 1967. From early 1967, D/16th had three line platoons equipped with M113s and eventually, its diesel version, the M113A1. It was also standardized in late 1968 with three machine guns per track, one M2 .50 caliber and two M60 machine guns mounted on each side. The M113s were instrumental in conducting reconnaissance in force (RIFs), search and destroy missions, and large invasions (incursions) such as
1562-408: A folded aluminum plate installed under each sponson for the first three road wheels on each side of the vehicle. In 1970, a further 38 mm of aluminum armor was fitted along the entire bottom of the hull, which greatly reduced crew and passenger casualties even from large mines. This armor upgrade package was subsequently fitted to all M577s (and other M113 vehicles) purchased to replace those lost during
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#17330848889771704-400: A frequency and phase reference to extract the modulation from the sidebands. In some modulation systems based on AM, a lower transmitter power is required through partial or total elimination of the carrier component, however receivers for these signals are more complex because they must provide a precise carrier frequency reference signal (usually as shifted to the intermediate frequency ) from
1846-459: A front-mounted trim vane; they are propelled in the water by their tracks. The Vietnam War was the first combat opportunity for mechanized infantry , a technically new type of infantry with its roots in the armored infantry of World War II , now using the M113 armored personnel carrier. In addition, armored cavalry squadrons in Vietnam consisted largely of M113s, after replacing the intended M114 in
1988-455: A great increase in the number of radio stations experimenting with AM transmission of news or music. The vacuum tube was responsible for the rise of AM broadcasting around 1920, the first electronic mass communication medium. Amplitude modulation was virtually the only type used for radio broadcasting until FM broadcasting began after World War II. At the same time as AM radio began, telephone companies such as AT&T were developing
2130-468: A greater operating range, as well as the reducing the fire hazard of gasoline fuel. Specifications and performance are as follows: In 1979, further upgrades were introduced based on the M113A2. Engine cooling was improved by switching the locations of the fan and radiator. Higher-strength torsion bars increased ground clearance, and shock absorbers reduced the effects of ground strikes. Increased weight affected
2272-466: A greatly reduced "pilot" carrier (in reduced-carrier transmission or DSB-RC) to use in the demodulation process. Even with the carrier eliminated in double-sideband suppressed-carrier transmission , carrier regeneration is possible using a Costas phase-locked loop . This does not work for single-sideband suppressed-carrier transmission (SSB-SC), leading to the characteristic "Donald Duck" sound from such receivers when slightly detuned. Single-sideband AM
2414-408: A human voice for instance, the frequency content (horizontal axis) may be plotted as a function of time (vertical axis), as in figure 3. It can again be seen that as the modulation frequency content varies, an upper sideband is generated according to those frequencies shifted above the carrier frequency, and the same content mirror-imaged in the lower sideband below the carrier frequency. At all times,
2556-503: A maximum headroom in the rear compartment of 74.75 in (190 cm), allowing operators to perform duties standing up. On the roof, the commander's cupola of the M113 APC has been replaced with circular hatch similar to the driver's hatch, and the large rectangular hatch over the troop compartment was removed. There is no external weapons stations fitted to the M577, although most vehicles were fitted with an internal rifle rack. Mounted to
2698-702: A modernized version known as an "MRV" (medium reconnaissance vehicle). The MRV featured a Scorpion turret with 76 mm gun, improved fire control, and passive night vision equipment. Regiments using the M113 included former Citizens' Military Forces (CMF) units like the 4/19th Prince of Wales Light Horse Regiment (armoured reconnaissance) and Regular units such as 2ns Cavalry Regiment (armoured reconnaissance) and 3/4th Cavalry Regiment (APC Regiment). An Armoured Reconnaissance Troop consisted of Alpha Track – Charlie Track (M113 LRV) Bravo – Delta Track (M113 MRV) Echo Track (M113 APC) with Assault Section (armoured infantry) later known as Scouts... The Israel Defense Forces are
2840-498: A more powerful turbocharged engine with a larger alternator increasing output from 100A to 200A, and internal spall liners for improved fragmentation protection for occupants. Weight increased again, and some vehicles were fitted with the larger trimvane from the M113A3 to offset the freeboard issues first encountered with the M577A2. Specifications and performance are as follows: The A4 is
2982-584: A rather small (or zero) remaining carrier amplitude. Modulation circuit designs may be classified as low- or high-level (depending on whether they modulate in a low-power domain—followed by amplification for transmission—or in the high-power domain of the transmitted signal). In modern radio systems, modulated signals are generated via digital signal processing (DSP). With DSP many types of AM are possible with software control (including DSB with carrier, SSB suppressed-carrier and independent sideband, or ISB). Calculated digital samples are converted to voltages with
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#17330848889773124-535: A second or more following such peaks, in between syllables or short pauses in the program. This is very acceptable for communications radios, where compression of the audio aids intelligibility. However it is absolutely undesired for music or normal broadcast programming, where a faithful reproduction of the original program, including its varying modulation levels, is expected. In 1982, the International Telecommunication Union (ITU) designated
3266-603: A similar AS3 standard as the ACV and redesignated as the M113AS3 armored ambulance. Based on the M577A3 command post vehicle, 23 vehicles were in service with the Canadian Army. Nicknamed the 'Queen Mary', the vehicle is equipped with an upgraded communications suite. Externally, additional stowages are mounted on the vehicle's roof, along with removable antenna masts. At the front of the vehicle
3408-499: A single sine wave, as treated above. However, by the principle of Fourier decomposition , m(t) can be expressed as the sum of a set of sine waves of various frequencies, amplitudes, and phases. Carrying out the multiplication of 1 + m(t) with c(t) as above, the result consists of a sum of sine waves. Again, the carrier c(t) is present unchanged, but each frequency component of m at f i has two sidebands at frequencies f c + f i and f c – f i . The collection of
3550-421: A spark gap transmitter with a specially designed high frequency 10 kHz interrupter , over a distance of one mile (1.6 km) at Cobb Island, Maryland, US. His first transmitted words were, "Hello. One, two, three, four. Is it snowing where you are, Mr. Thiessen?". The words were barely intelligible above the background buzz of the spark. Fessenden was a significant figure in the development of AM radio. He
3692-403: A special modulator produces such a waveform at a low level followed by a linear amplifier . What's more, a standard AM receiver using an envelope detector is incapable of properly demodulating such a signal. Rather, synchronous detection is required. Thus double-sideband transmission is generally not referred to as "AM" even though it generates an identical RF waveform as standard AM as long as
3834-514: A stowage basket is attached to the engine cover in place of the trim vane, and cable cutters were mounted at each side. A transparent perspex shield was often fitted in front of the driver's hatch for Arctic operations. Snow hawsers and spiked "ice cleats" were carried on external mountings. From 2001, the Diehl 213G steel tracks were replaced by Soucy rubber band tracks for quieter operation on roads and better operation on snow and ice. In German service,
3976-624: A true infantry fighting vehicle rather than an armored personnel carrier. Pacific Car and Foundry entered the steel-armored XM701, but this proved to be too slow and too heavy to be airmobile, even in the C-141. FMC entered the XM734, which was largely the ACAV M113, but whereas the M113 seated the troops facing inward on benches along the walls, the XM734 sat them facing outwards on a central bench. Four gun ports and vision blocks were added on each side to allow
4118-673: A variety of roles, and armor battalions contained M113s within their headquarters companies, such as the maintenance section, medical section, vehicle recovery section, mortar section, and the scout (reconnaissance) section. United States Army mechanized infantry units in Vietnam were fully equipped with the M113 APC/ACAV, which consisted of one headquarters company and three line companies, normally with an authorized strength of approximately 900 men. Ten U.S. mechanized infantry battalions were deployed to Vietnam from 1965 until their departure in 1972. Company D, 16th Armor, 173rd Airborne Brigade ,
4260-407: A very strong resemblance to both of these earlier vehicles. The M75 was too heavy and expensive to be useful, as its weight precluded amphibious use and transport by air. The lightened M59 addressed both of these problems, but ended up with too little armor, and was unreliable as a result of efforts to reduce its cost. The Army was looking for a vehicle that combined the best features of both designs,
4402-491: Is Carrier, Command Post, Light Tracked M577 . Introduced to the U.S. Army in 1962 it soon saw operational service in the Vietnam War and more recently in the 2003 invasion of Iraq . It is used by many armies around the world and has been adapted for further uses such as an armored ambulance, emergency medical treatment vehicle and fire control vehicle. It is also used by various police forces and law enforcement agencies as
M577 command post carrier - Misplaced Pages Continue
4544-475: Is on–off keying , the simplest form of amplitude-shift keying, in which ones and zeros are represented by the presence or absence of a carrier. On–off keying is likewise used by radio amateurs to transmit Morse code where it is known as continuous wave (CW) operation, even though the transmission is not strictly "continuous". A more complex form of AM, quadrature amplitude modulation is now more commonly used with digital data, while making more efficient use of
4686-464: Is Spanish for Armored Tracked Carrier. In the Ukrainian Army it is called "Emka" (M). The basic M113 armored personnel carrier can be fitted with a number of weapon systems. The most common weapon fit is a single .50 caliber M2 machine gun. However, the mount can also be fitted with a 40 mm Mk 19 automatic grenade launcher. A number of anti-tank weapons could be fitted to the standard variant:
4828-448: Is a great advantage in efficiency in reducing or totally suppressing the carrier, either in conjunction with elimination of one sideband ( single-sideband suppressed-carrier transmission ) or with both sidebands remaining ( double sideband suppressed carrier ). While these suppressed carrier transmissions are efficient in terms of transmitter power, they require more sophisticated receivers employing synchronous detection and regeneration of
4970-410: Is a varying amplitude direct current, whose AC-component is the speech signal extracted at the central office for transmission to another subscriber. An additional function provided by the carrier in standard AM, but which is lost in either single or double-sideband suppressed-carrier transmission, is that it provides an amplitude reference. In the receiver, the automatic gain control (AGC) responds to
5112-451: Is always positive for undermodulation. If m > 1 then overmodulation occurs and reconstruction of message signal from the transmitted signal would lead in loss of original signal. Amplitude modulation results when the carrier c(t) is multiplied by the positive quantity (1 + m(t)/A) : In this simple case m is identical to the modulation index , discussed below. With m = 0.5 the amplitude modulated signal y ( t ) thus corresponds to
5254-450: Is distinguished from U.S. and other NATO M577s stationed in Germany by the following external features: Israeli designation of the M577 command post carrier. Vehicles are equipped with external stowages and storage racks along the hull sides, similar to those seen on IDF M579 Fitter's vehicles. The NM196 Hjelpeplasspanservogn was the medical treatment version of M577A2. This vehicle saw
5396-492: Is estimated that over 80,000 vehicles in the M113 family have been produced and used by over 50 countries worldwide, making it one of the most widely used armored fighting vehicles of all time. M113 production was terminated in 2007. The Army initiated the Armored Multi-Purpose Vehicle (AMPV) program to search for a replacement. In 2014, the U.S. Army selected BAE Systems ' proposal of a turretless variant of
5538-691: Is impractical and less vibration and rolling resistance. Most of the 13,000 M113s that are still in U.S. Army service have been upgraded to the A3 variant. The current U.S. Army M113 fleet includes a mix of M113A2 and A3 variants and other derivatives equipped with the most recent RISE (reliability improvements for selected equipment) package. The standard RISE package includes an upgraded propulsion system (turbocharged engine and new transmission), greatly improved driver controls (new power brakes and conventional steering controls), external fuel tanks, and 200-amp alternator with four batteries. Additional A3 improvements include
5680-529: Is installed, along with an improved '4B' version of the TX-400 automatic transmission. The new vehicle has a maximum capacity of seven personnel: driver, vehicle commander and up to five staff officers or system operators, and can be configured as a Fire Direction Centre Vehicle. Limited in numbers and used as the basis for the M577A4 armored treatment vehicle. Like the M113 upon which it is based, there are many variants of
5822-560: Is nevertheless used widely in amateur radio and other voice communications because it has power and bandwidth efficiency (cutting the RF bandwidth in half compared to standard AM). On the other hand, in medium wave and short wave broadcasting, standard AM with the full carrier allows for reception using inexpensive receivers. The broadcaster absorbs the extra power cost to greatly increase potential audience. A simple form of digital amplitude modulation which can be used for transmitting binary data
M577 command post carrier - Misplaced Pages Continue
5964-464: Is not favored for music and high fidelity broadcasting, but rather for voice communications and broadcasts (sports, news, talk radio etc.). AM is also inefficient in power usage; at least two-thirds of the power is concentrated in the carrier signal. The carrier signal contains none of the original information being transmitted (voice, video, data, etc.). However its presence provides a simple means of demodulation using envelope detection , providing
6106-505: Is prototyping the Eitan (Hebrew for steadfast), an eight-wheeled armored fighting vehicle to replace their M113s. Designed to serve alongside the tracked Namer, the Eitan is planned to be cheaper and lighter, at 35 tons, incorporating an active protection system and a turret. They are expected to begin replacing the M113 starting in 2020. However, due to the slow rate of production of replacement APCs,
6248-404: Is shown in the first waveform, below. For m = 1.0 {\displaystyle m=1.0} , it varies by 100% as shown in the illustration below it. With 100% modulation the wave amplitude sometimes reaches zero, and this represents full modulation using standard AM and is often a target (in order to obtain the highest possible signal-to-noise ratio ) but mustn't be exceeded. Increasing
6390-527: Is similar to the Allison TX-200-1 fitted to the M113A1/M577A1 and features four forward and one reverse gears. The vehicle is also fitted with night vision driving aids, NBC protection, improved communications suite and other minor changes. The M577 has been adopted by various police forces and law enforcement agencies (mostly in the U.S.) as a tactical response or hostage rescue vehicle. Agencies that use
6532-447: Is sometimes called double-sideband amplitude modulation ( DSBAM ), because the standard method produces sidebands on either side of the carrier frequency. Single-sideband modulation uses bandpass filters to eliminate one of the sidebands and possibly the carrier signal, which improves the ratio of message power to total transmission power , reduces power handling requirements of line repeaters, and permits better bandwidth utilization of
6674-446: The 2010 raid on Complexo do Alemão . Amplitude modulation Amplitude modulation ( AM ) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave . In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal . This technique contrasts with angle modulation , in which either
6816-541: The Fleming valve (1904) and the crystal detector (1906) also proved able to rectify AM signals, so the technological hurdle was generating AM waves; receiving them was not a problem. Early experiments in AM radio transmission, conducted by Fessenden, Valdemar Poulsen , Ernst Ruhmer , Quirino Majorana , Charles Herrold , and Lee de Forest , were hampered by the lack of a technology for amplification . The first practical continuous wave AM transmitters were based on either
6958-759: The U.S. invasion of Cambodia on 1 May 1970 and later Laos ( Operation Lam Son 719 ) in 1971; all of which used the M113 as the primary workhorse for moving the ground armies. While operating with cavalry and armor units, the M113s often worked in conjunction with U.S. M48 Patton and M551 Sheridan tanks. During the Vietnam War, U.S. Army gun trucks , along with V-100 armored cars, conducted convoy escorts for military traffic. The USAF used M113 and M113A1 ACAV vehicles in USAF security police squadrons, which provided air base ground defense support in Vietnam. Also, M113s were supplied to
7100-434: The carrier frequency and two adjacent sidebands . Each sideband is equal in bandwidth to that of the modulating signal, and is a mirror image of the other. Standard AM is thus sometimes called "double-sideband amplitude modulation" (DSBAM). A disadvantage of all amplitude modulation techniques, not only standard AM, is that the receiver amplifies and detects noise and electromagnetic interference in equal proportion to
7242-404: The frequency of the carrier wave is varied, as in frequency modulation , or its phase , as in phase modulation . AM was the earliest modulation method used for transmitting audio in radio broadcasting. It was developed during the first quarter of the 20th century beginning with Roberto Landell de Moura and Reginald Fessenden 's radiotelephone experiments in 1900. This original form of AM
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#17330848889777384-682: The "APC disaster". The vulnerability of the M113 armored personnel carrier to IEDs and RPGs led the IDF to later begin to develop the Namer APC. M113s were used again in the 2006 Lebanon War and Operation Cast Lead . In 2014, during the first wave of the IDF's ground incursion into Gaza in Operation Protective Edge , a Hamas RPG-29 destroyed a fully loaded M113 in Gaza during the Battle of Shuja'iyya , killing all seven Golani Brigade soldiers inside
7526-428: The "Zelda" and "Zelda 2", which are fitted with ERA -suites. The Australian Army refers to its M113A1s as "buckets", "bush taxis" and modified M113A1s fitted with 76 mm turrets as "beasts". The German Army has various nicknames, depending on location and branch of service, including "elephant shoe", "Tank Wedge" and "bathtub". In Spain's Army it is known as "TOA", the acronym of Transporte Oruga Acorazado, which
7668-520: The "airborne armored multi-purpose vehicle family" (AAM-PVF) of all-purpose, all-terrain armored fighting vehicles. FMC had been working with Kaiser Aluminum and Chemical Co. in the late 1950s to develop suitable aluminum armor. It was known that use of this armor could produce a vehicle that provided the protection of the M75 and the low weight and mobility of the M59. FMC responded with two proposals; two versions of
7810-763: The ARVN. One notable ARVN unit equipped with the M113 APC, the 3d Armored Cavalry Squadron , earned the Presidential Unit Citation . Additional M113s were supplied to the Cambodian Khmer National Armed Forces , equipped with a turret for the machine gun and a M40 recoilless rifle mounted on the roof. The Army of the Republic of Vietnam also used M113 armored personnel carriers. In 1975, 1381 ARVN M113s were destroyed and captured. Losses in other years are unknown. The Australian Army also used
7952-654: The Bradley Fighting Vehicle to replace over 2,800 M113s in service. Thousands of M113s continue to see combat service in the Israel Defense Forces , although by 2014 the IDF was seeking to gradually replace many of its 6,000 M113s with the Namers , and with the Eitan AFV in 2020. The M113 was developed by FMC Corporation , which had produced the earlier M59 and M75 armored personnel carriers. The M113 bears
8094-487: The IDF in the 1978 South Lebanon conflict . In the 1982 Lebanon War , they saw heavy action. PLO ambushes with RPGs caused extensive casualties because of the tendency of the M113's aluminum armor to catch on fire after being hit by anti-tank weapons. Israeli infantrymen being ferried by M113s learned to quickly dismount and fight on foot when engaged. By the time of the Siege of Beirut , M113s were only used to carry supplies to
8236-707: The IDF is expected to be dependent on the M113 well into the 2020s. The IDF has also increased production of Namer APCs to replace the M113. In the United States, M113s have been adopted by numerous law enforcement agencies. An M113 belonging to the Midland County Sheriff's Department was used in the 2008 raid of the Fundamentalist Church of Jesus Christ of Latter Day Saints compound. The Brazilian Marine Corps 's M113s were used in joint operations with Batalhão de Operações Policiais Especiais during
8378-516: The M113 in Vietnam. After initial experiences showed that the crew commander was too vulnerable to fire, the Australians tried a number of different gun shields and turrets, eventually standardizing with the Cadillac-Gage T-50 turret fitted with two .30 cal Browning machine guns, or a single .30-single .50 combination. Other turrets were tried as were various gun shields, the main design of which
8520-476: The M113 are capable of mounting anti-landmine applique armor. The M113A3 was upgraded with internal spall liners and additional applique armor which provided 14.5 mm ballistic protection. In comparison, a modern APC such as the Stryker has all-around 7.62 mm armor-piercing protection, plus 14.5 mm protection on the front, sides, and rear, and a protection against antipersonnel mines. Its weight allows
8662-478: The M113 family after the APC. The M577 has followed a similar upgrade path to the M113 upon which it is based, resulting in the following basic versions: The original version based upon the M113 chassis. Specifications and performance are as follows: The initial upgraded version based upon the M113A1, introduced in 1964. The gasoline engine was replaced with a more powerful diesel engine, providing better fuel economy and
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#17330848889778804-586: The M113 into a fighting vehicle, but the vehicle still suffered from its lightly armored configuration, having never been designed for such a role. Canada also adopted the ACAV kits when employing the M113A2 during peacekeeping operations in the Balkans in the 1990s. In order to improve the fighting ability of the mounted troops, a number of experiments were carried out in the 1960s under the MICV-65 project, which aimed to develop
8946-473: The M113 series, making them function as assault guns and fire support; while in many cases still having room inside to carry dismounted infantry or cavalry scouts. The M113 is built of 5083 aircraft-quality aluminum alloy . Aluminum alloy is lighter than steel but requires around three times the thickness for an equivalent level of ballistic protection, meaning the armor of the M113 was only designed for 7.62 mm and shell splinter protection. All variants of
9088-459: The M113, maintaining a fleet of 6,000 of the vehicles. On numerous occasions since their introduction in the late 1960s, the IDF's M113s have proven vulnerable to modern anti-tank missiles, IEDs, and RPGs, resulting in the deaths of many Israeli soldiers riding inside the vehicles. The IDF has nonetheless been unable to replace the use of them in combat operations, due to budget constraints in equipping its large mechanized infantry regiments. Israel
9230-470: The M113, under the Military Assistance Command, Vietnam (MACV) program. Eventually, the M113 was the most widely used armored vehicle of the U.S. Army in the Vietnam War and was used to break through heavy thickets in the midst of the jungle to attack and overrun enemy positions. It was largely known as an "APC" or an "ACAV" ( armored cavalry assault vehicle) by the allied forces. The M113
9372-620: The M113A2 upon which it is based, changes to the CM-26 are mostly limited to its engine and transmission. The vehicle is fitted with a 248 hp (185 kW) Perkins TV8.640 turbo-diesel which provides significantly more power than the 212 hp (158 kW) of the Detroit Diesel 6V-53 fitted to the M113A2/M577A12. The engine is coupled to a locally built automatic transmission developed by Taiwans' Industrial Technology Research Institute and
9514-508: The M2 and M3 Bradleys , but large numbers are still used in support roles such as armored ambulance, mortar carrier, engineer vehicle, and command vehicle. The U.S. Army's heavy brigade combat teams are equipped with approximately 6,000 M113s and 6,724 Bradleys. The M113's versatility spawned a wide variety of adaptations that live on worldwide and in U.S. service. These variants together currently represent about half of U.S. Army armored vehicles. It
9656-494: The M551s they replaced, have also been modified to resemble enemy tanks and APCs, such as the T-80 and BMP-2 . One of the advantages of the M113 being used to simulate the latter is that the infantry squad can now ride inside the simulated BMP instead of in a truck accompanying a tank masquerading as one, as was often the case with the M551s. The M113 has received a variety of nicknames over
9798-562: The M577 and M577A1 received different fire extinguishing and heating systems, modified periscopes and SEM 25/30 radios, and were known as the M577G and M577GA1 Gefechtsstandspanzer (GefStdPz) . In the late 1980s M577GA1s were upgraded to A2 standard and were designated M577GA2. These vehicles operated in four different roles: Vehicles received further upgrades under the Nutzungsdauerverlängerung (NDV) program consisting of: The M112GA2
9940-520: The M577 in service, many specific to a particular country's army. In 1965 the Australian Army purchased 58 M577A1s in 1965 with some vehicles immediately shipped to Vietnam for operational duty with the 1st APC Troop. Operational experience with the M113A1 showed that vehicles of this family were vulnerable to hull damage from enemy mines, and an indigenous armor upgrade kit was soon developed and fitted to all vehicles. The upgraded armor consisted of
10082-433: The M577 is within the company's Global Combat Systems Ground Vehicles portfolio of current products in the subsidiary BAE Systems Platforms & Services . The M577 is produced or remanufactured locally in several countries under licence from or in partnership with BAE. This includes: In total, more than 7,300 vehicles have been built, of which around 3,900 were M577A1, making the M577 the most numerous single variant of
10224-513: The M577 was then only used as emergency treatment vehicles (e.g. battalion aid stations). When configured as an ambulance, compared to a M113 which could be fitted with up to four litters , the extra room inside the M577 allowed it to carry two additional litters i.e. up to a maximum of six. Vehicles configured for other roles were configured with specialized equipment accordingly e.g. M577 Fire Control Vehicles were often fitted with TACFIRE artillery control consoles . A tent extension attaches to
10366-514: The U.S. Army developed kits that allowed the M47 Dragon and BGM-71 TOW anti-tank missile systems to be mounted. In the case of the M47, the system mated to the existing machine gun mount, without having to remove the machine gun. This allowed the commander to use both weapons. A large array of turrets and fixed mounts are available to mount high explosive cannon ranging from 20 mm to 105 mm on to
10508-842: The U.S. Army's Detroit Arsenal. They were designated the XM577, and were conversions of M113 APCs. Upon completion in March 1962 the first vehicle was shipped to the Aberdeen Proving Ground for engineering tests, while the remaining three vehicles were shipped to the Armour, Infantry and Artillery Boards for evaluation tests. The results of all tests were generally positive, and the vehicle went into immediate production. The first batch of 270 vehicles were accepted into U.S. Army service between in December 1962 and March 1963. In March 1963 under Standard A Acceptance
10650-479: The XM577 was redesignated as the M577, indicating official status as a regular production vehicle. Production began on a second batch of 674 vehicles in November 1963, all of which entered service by the middle of 1964. The M577 shares the chassis, lower hull and running gear from the M113 upon which it is based. The hull sides from the engine firewall to the rear cargo ramp were extended by 25.25 in (64 cm) for
10792-601: The additional armor and other changes, the K277 is heavier than the M577. Commencing service with the Republic of China Army in 1982, the CM-26 command track is a locally built variant based upon the M577A2 that shares key components from the CM-21A1 armored infantry fighting vehicle . Unlike the CM-21A1, which varies extensively (it resembles the armored infantry fighting vehicle (AIFV) ) from
10934-509: The aluminum T113 – a thickly and a more thinly-armored one, along with the similar but mostly steel T117. The thickly-armored version of the T113 – effectively the prototype of the M113 – was chosen because it weighed less than its steel competitor, whilst offering the same level of protection. An improved T113 design, the T113E1, was adopted by the U.S. Army in 1960 as the "M113". A diesel prototype, T113E2,
11076-499: The antenna. The limited power handling ability of the microphone severely limited the power of the first radiotelephones; many of the microphones were water-cooled. The 1912 discovery of the amplifying ability of the Audion tube , invented in 1906 by Lee de Forest , solved these problems. The vacuum tube feedback oscillator , invented in 1912 by Edwin Armstrong and Alexander Meissner ,
11218-500: The arrival of the army's conventional forces in 1965. The vehicles continued to operate in the role of a light tank and reconnaissance vehicle, and not as designed in theater. Still, the M113 could carry 11 infantrymen inside, with two crewmen operating it. The U.S. Army, after berating the South Vietnamese for flouting battle doctrine, came out with their own ACAV version. This more or less standardized ACAV kit included shields and
11360-411: The available bandwidth. A simple form of amplitude modulation is the transmission of speech signals from a traditional analog telephone set using a common battery local loop. The direct current provided by the central office battery is a carrier with a frequency of 0 Hz. It is modulated by a microphone ( transmitter ) in the telephone set according to the acoustic signal from the speaker. The result
11502-401: The bandwidth of an AM signal is narrower than one using frequency modulation (FM), it is twice as wide as single-sideband techniques; it thus may be viewed as spectrally inefficient. Within a frequency band, only half as many transmissions (or "channels") can thus be accommodated. For this reason analog television employs a variant of single-sideband (known as vestigial sideband , somewhat of
11644-571: The bench seat. Further folding tables and chairs are often carried, stowed while the vehicle is in transit. Equipment fitted within the rear compartment of the M577/M1068 varies according to the vehicle's purpose. Vehicles are equipped with additional radio sets as found in a standard M113 APC, to provide command and control facilities across the unit (e.g. battalion) and coordinate with other units and higher levels of command (e.g. regimental HQ). Removable antenna masts are usually carried and attached to
11786-451: The carrier frequency. For that reason, standard AM continues to be widely used, especially in broadcast transmission, to allow for the use of inexpensive receivers using envelope detection . Even (analog) television, with a (largely) suppressed lower sideband, includes sufficient carrier power for use of envelope detection. But for communications systems where both transmitters and receivers can be optimized, suppression of both one sideband and
11928-454: The carrier frequency. Passing the modulated signal through another nonlinear device can extract the original baseband signal. His analysis also showed that only one sideband was necessary to transmit the audio signal, and Carson patented single-sideband modulation (SSB) on 1 December 1915. This advanced variant of amplitude modulation was adopted by AT&T for longwave transatlantic telephone service beginning 7 January 1927. After WW-II, it
12070-400: The carrier itself remains constant, and of greater power than the total sideband power. The RF bandwidth of an AM transmission (refer to figure 2, but only considering positive frequencies) is twice the bandwidth of the modulating (or " baseband ") signal, since the upper and lower sidebands around the carrier frequency each have a bandwidth as wide as the highest modulating frequency. Although
12212-468: The carrier represent a net advantage and are frequently employed. A technique used widely in broadcast AM transmitters is an application of the Hapburg carrier, first proposed in the 1930s but impractical with the technology then available. During periods of low modulation the carrier power would be reduced and would return to full power during periods of high modulation levels. This has the effect of reducing
12354-460: The carrier so that the reproduced audio level stays in a fixed proportion to the original modulation. On the other hand, with suppressed-carrier transmissions there is no transmitted power during pauses in the modulation, so the AGC must respond to peaks of the transmitted power during peaks in the modulation. This typically involves a so-called fast attack, slow decay circuit which holds the AGC level for
12496-450: The carrier wave to spell out text messages in Morse code . They could not transmit audio because the carrier consisted of strings of damped waves , pulses of radio waves that declined to zero, and sounded like a buzz in receivers. In effect they were already amplitude modulated. The first AM transmission was made by Canadian-born American researcher Reginald Fessenden on 23 December 1900 using
12638-631: The commander. On 30 March 1962, the first batch of 32 M113s arrived in Vietnam, and were sent to two Army of the Republic of Vietnam (ARVN) mechanized rifle companies, each equipped with 15 of the APCs. On 11 June 1962, the two mechanized units were fielded for the first time. During the Battle of Ap Bac in January 1963, at least fourteen of the exposed .50 caliber gunners aboard the M113s were killed in action, necessitating modifications to improve crew survivability. Makeshift shields formed from metal salvaged from
12780-537: The communication range the command post, necessitating the dismantling and removal of the structure to a new location. Experience gained in the snow and mud in the Korean War showed the advantage of tracked over wheeled vehicles. In 1960, no such vehicle existed in the U.S. Army inventory that was able to satisfy all of these requirements. The first four prototypes were built in February 1962 by United Defense Industries at
12922-443: The country operating them and internal configuration and equipment varied accordingly, which was also defined as to whether they were used as an emergency evacuation (ambulance) or treatment vehicles. In U.S. service it appears that M577s were only used as emergency evacuation vehicles very early in their operation careers, i.e. in the early years of the Vietnam War . This role was soon provided solely by M113 "armored ambulances", and
13064-543: The following upgrades during its service life: The NM198 Kommandopanservogn was the local variant of the M577A2 command post vehicle. This vehicle saw the following upgrade(s) during its service life: Developed in the 1980s, the K277 is a locally produced version of the M577A1 command post vehicle featuring a different engine and transmission – a MAN D2848T V8 diesel engine made under licence by Doosan and Allison X200-5K automatic transmission . The upper and lower hull of
13206-493: The former frequencies above the carrier frequency is known as the upper sideband, and those below constitute the lower sideband. The modulation m(t) may be considered to consist of an equal mix of positive and negative frequency components, as shown in the top of figure 2. One can view the sidebands as that modulation m(t) having simply been shifted in frequency by f c as depicted at the bottom right of figure 2. The short-term spectrum of modulation, changing as it would for
13348-427: The frequencies and number of channels, and transmission and reception range determined by the set. Communication suites were originally analogue, but with the introduction of the M577A3 and A4, have mostly been upgraded to digital. Analogue radio sets fitted to the M577 in U.S. service include: It must be recognized that there was no such thing as a standardized M577 medical vehicle. Vehicles were configured according to
13490-775: The front line, always stopping at least 100 meters from enemy lines. M113s were subsequently used by both the IDF and the South Lebanon Army during the South Lebanon conflict . The IDF utilized M113s during the First Intifada and the Second Intifada . In May 2004, two fully laden IDF M113s were destroyed by IEDs in the Gaza Strip , killing 11 soldiers, all those inside the vehicles on both occasions. This became known in Israel as
13632-424: The front of the raised upper hull, centrally located to the right of the driver's hatch, is a 4.2 kW 28V 150A gasoline auxiliary power unit generator, that provides power to the M577/M1068's auxiliary equipment, dependent upon variant as specified below, without the vehicle's main engine running. The unit can be used to power two vehicles, and can be removed from its mounting basket using a lifting davit located on
13774-448: The huge, expensive Alexanderson alternator , developed 1906–1910, or versions of the Poulsen arc transmitter (arc converter), invented in 1903. The modifications necessary to transmit AM were clumsy and resulted in very low quality audio. Modulation was usually accomplished by a carbon microphone inserted directly in the antenna or ground wire; its varying resistance varied the current to
13916-466: The hulls of sunken ships were soon fitted to the carriers, affording better protection. However, it was found that this material could be penetrated by small arms fire, so subsequent shields were constructed from scrapped armored vehicles. The ARVN 80th Ordnance Unit in South Vietnam developed the shield idea further and commenced engineering general issue gun shields for the M113. These shields became
14058-580: The incorporation of spall liners and provision for mounting external armor. The M113 has also been adopted to replace the aging fleet of visually modified M551s being used to simulate Russian-made combat vehicles at the U.S. Army's National Training Center in Fort Irwin, California as well as the M60A3s formerly at the Combat Maneuver Training Center near Hohenfels, Germany. These M113s, like
14200-457: The modular design of MCPS allows more tents to be easily connected. Ownership of title for and production of the M577 has changed many times over the vehicle's history due to corporate buy-outs and take-overs. Originally produced by FMC's combat vehicles division United Defense Industries (UDI), in 1995 UDI was purchased by Harsco Corporation to become United Defense (UD). In 2005 UD was then purchased by BAE Systems (BAE). As of February 2020,
14342-489: The modulating signal beyond that point, known as overmodulation , causes a standard AM modulator (see below) to fail, as the negative excursions of the wave envelope cannot become less than zero, resulting in distortion ("clipping") of the received modulation. Transmitters typically incorporate a limiter circuit to avoid overmodulation, and/or a compressor circuit (especially for voice communications) in order to still approach 100% modulation for maximum intelligibility above
14484-443: The modulation amplitude and carrier amplitude, respectively; the modulation amplitude is the peak (positive or negative) change in the RF amplitude from its unmodulated value. Modulation index is normally expressed as a percentage, and may be displayed on a meter connected to an AM transmitter. So if m = 0.5 {\displaystyle m=0.5} , carrier amplitude varies by 50% above (and below) its unmodulated level, as
14626-409: The modulation index is below 100%. Such systems more often attempt a radical reduction of the carrier level compared to the sidebands (where the useful information is present) to the point of double-sideband suppressed-carrier transmission where the carrier is (ideally) reduced to zero. In all such cases the term "modulation index" loses its value as it refers to the ratio of the modulation amplitude to
14768-461: The next generation modernized version of the M577 command post vehicle production version developed by BAE Systems and in partnership with FNSS. Fitted with upgraded digital systems and communications suites, applique armor and external armored fuel tanks similar to those fitted to the M113A3 on both sides of the rear ramp, freeing up more internal space. An improved version of the 6V53T turbo-diesel engine with power increased to 350 hp (261 kW)
14910-534: The next section. High-power AM transmitters (such as those used for AM broadcasting ) are based on high-efficiency class-D and class-E power amplifier stages, modulated by varying the supply voltage. Older designs (for broadcast and amateur radio) also generate AM by controlling the gain of the transmitter's final amplifier (generally class-C, for efficiency). The following types are for vacuum tube transmitters (but similar options are available with transistors): The simplest form of AM demodulator consists of
15052-542: The noise. Such circuits are sometimes referred to as a vogad . However it is possible to talk about a modulation index exceeding 100%, without introducing distortion, in the case of double-sideband reduced-carrier transmission . In that case, negative excursions beyond zero entail a reversal of the carrier phase, as shown in the third waveform below. This cannot be produced using the efficient high-level (output stage) modulation techniques (see below) which are widely used especially in high power broadcast transmitters. Rather,
15194-404: The other large application for AM: sending multiple telephone calls through a single wire by modulating them on separate carrier frequencies, called frequency division multiplexing . In 1915, John Renshaw Carson formulated the first mathematical description of amplitude modulation, showing that a signal and carrier frequency combined in a nonlinear device creates a sideband on both sides of
15336-489: The overall power demand of the transmitter and is most effective on speech type programmes. Various trade names are used for its implementation by the transmitter manufacturers from the late 80's onwards. The AM modulation index is a measure based on the ratio of the modulation excursions of the RF signal to the level of the unmodulated carrier. It is thus defined as: where M {\displaystyle M\,} and A {\displaystyle A\,} are
15478-495: The predecessor to the standardized armored cavalry assault vehicle (or ACAV) variant and were issued to all ARVN mechanized units during the early 1960s. The ARVNs had modified the M113s to function as " amphibious light tanks " and not as battle taxis as U.S. designers had intended. Instead of an armored personnel carrier, the ARVN used the carried infantry as extra "dismountable soldiers" in "an oversized tank crew". These "ACAV" sets were eventually adapted to U.S. Army M113s with
15620-539: The rear compartment. A personal heater is located at the front right of the compartment, which serves as an equipment heater in Arctic and winter operations. A 5-man bench seat could be fitted to either or both sides of the rear compartment, although in some vehicles no seating was fitted whatsoever. The rearward-facing seat on the commander's station was removed. For the M1068, inward-facing individual seats for two operators replaced
15762-427: The rear left, is replaced by two 60 gallon tanks, located each side near the rear, providing a greater operating range than a M113. They also serve as the base for fold-out tables. Radios are usually fitted along the left wall, as well as the front of the right wall. Map boards are usually fitted along the walls, along with additional storage facilities for maps and code books etc. Overhead dome lights were fitted within
15904-403: The rear of the vehicle above and around the rear cargo ramp, increasing the workspace available to operators, and in the case of the emergency treatment vehicles, to function as a field dressing station or hospital. The tent is erected over collapsible steel tubing, which is carried in brackets on the rear of the vehicle. The tent can be connected to up to four vehicles parked in a cross, to provide
16046-622: The scope and size of the theatre of operations, and mobile command and control posts are necessary to co-ordinate operations at the divisional, brigade and battalion levels. Whereas tanks and armored cars offered a level of protection against weapons fire, they usually did not provide sufficient internal room to permit the extra personnel needed to operate all the radio sets. Lightly or unarmed vehicles could be used to transport temporary structures (e.g. tents) that gave greater work space, but these structures lacked protection from direct and indirect weapons fire, and advancing front line units could exceed
16188-685: The seated troops to fire even while under cover. Although neither the XM701 or XM734 were deemed worthwhile to produce, FMC continued development of their version as the XM765 advanced infantry fighting vehicle (AIFV). The AIFV was sold to a number of third party-users in the 1970s, including the Netherlands, the Philippines and Belgium. Modified versions of the Vietnam War ACAV sets were deployed to Iraq to equip
16330-579: The second largest user of the M113 after the United States, with over 6000 of the vehicles in service. In 1967 some Jordanian M113 were captured in the West Bank during the Six-Day War and were integrated into the Israeli Army. In 1970 Israel started to receive M113A1 to replace the antiquated half-tracks. The IDF M113s were armed with M2 HB machine guns, and two MAG 7.62 mm machine guns on either side of
16472-432: The signal. Increasing the received signal-to-noise ratio , say, by a factor of 10 (a 10 decibel improvement), thus would require increasing the transmitter power by a factor of 10. This is in contrast to frequency modulation (FM) and digital radio where the effect of such noise following demodulation is strongly reduced so long as the received signal is well above the threshold for reception. For this reason AM broadcast
16614-701: The standard M113s still in service. The circular .50 caliber gun shields have been modified, while the rear port and starboard gun stations have been deleted for service in that region. Some of these modified vehicles have been utilized for convoy escort duties. The M113 has relatively light armor, but it can be augmented with add-on steel plates for improved ballistic protection. Reactive armor and slat armor can be added for protection against rocket-propelled grenades . Band tracks made of rubber are in use by Canadian and other forces to enable stealthy operation, less damage to paved roads, higher speed, less maintenance, access to terrain where operation of wheeled vehicles
16756-468: The term A ( t ) is constant and the second term of the equation has a functional relationship to the modulating message signal. Angle modulation provides two methods of modulation, frequency modulation and phase modulation . In amplitude modulation, the angle term is held constant and the first term, A ( t ), of the equation has a functional relationship to the modulating message signal. The modulating message signal may be analog in nature, or it may be
16898-434: The time-varying amplitude of the sinusoidal carrier wave and the cosine-term is the carrier at its angular frequency ω {\displaystyle \omega } , and the instantaneous phase deviation ϕ ( t ) {\displaystyle \phi (t)} . This description directly provides the two major groups of modulation, amplitude modulation and angle modulation . In angle modulation,
17040-422: The top graph (labelled "50% Modulation") in figure 4. Using prosthaphaeresis identities , y ( t ) can be shown to be the sum of three sine waves: Therefore, the modulated signal has three components: the carrier wave c(t) which is unchanged in frequency, and two sidebands with frequencies slightly above and below the carrier frequency f c . A useful modulation signal m(t) is usually more complex than
17182-494: The transmission medium. AM remains in use in many forms of communication in addition to AM broadcasting : shortwave radio , amateur radio , two-way radios , VHF aircraft radio , citizens band radio , and in computer modems in the form of QAM . In electronics , telecommunications and mechanics , modulation means varying some aspect of a continuous wave carrier signal with an information-bearing modulation waveform, such as an audio signal which represents sound, or
17324-479: The types of amplitude modulation: Amplitude modulation was used in experiments of multiplex telegraph and telephone transmission in the late 1800s. However, the practical development of this technology is identified with the period between 1900 and 1920 of radiotelephone transmission, that is, the effort to send audio signals by radio waves. The first radio transmitters, called spark gap transmitters , transmitted information by wireless telegraphy , using pulses of
17466-613: The upper crew compartment door. The M113 took part in the Yom Kippur War in October 1973, when the IDF was equipped with 448 M113s that saw action on the Sinai and Golan fronts. They proved inadequate for direct fighting due to their poor armor protection. In the Battle of Buq'atta most of the 7th Recon Company was wiped out while trying to assault Syrian commandos with their M113s. They were used by
17608-414: The use of a relatively small engine to power the vehicle, a Detroit 6V53 V6 two-stroke diesel engine of 318 cubic inches (5,210 cc) with an Allison TX-100-1 three-speed automatic transmission . This allows the vehicle to carry a large payload cross-country and to be transported by fixed- and rotary-wing aircraft. Original production M113s can swim without deploying flotation curtains, using only
17750-554: The vehicle in this role include: M113 armored personnel carrier The M113 is a fully tracked armored personnel carrier (APC) that was developed and produced by the FMC Corporation . The M113 was sent to United States Army Europe in 1961 to replace the mechanized infantry's M59 APCs. The M113 was first used in combat in April 1962 after the United States provided the South Vietnamese army (ARVN) with heavy weaponry such as
17892-579: The vehicle is fitted with a layer of spaced laminate steel armor similar to that fitted to the K200 IFV which provides increased ballistic protection as well as extra buoyancy. The front of the vehicle is fitted with the armored trim vane from the K2000. Vehicles are usually armed with a Browning M2 HB 12.7mm heavy machine gun. The K277A1 is an upgraded version with a more powerful engine and transmission, NBC protection and an automatic fire extinguishing system. With
18034-525: The vehicle's freeboard when afloat, and it was no longer required to be amphibious. Four-tube smoke grenade launchers were added on each side of the trimvane on the front of the vehicle. Specifications and performance are as follows: In 1987, further improvements were introduced based upon the Reliability Improved Selected Equipment (RISE) package fitted to the M113A3. This included a yoke for steering instead of laterals (tillers),
18176-562: The vehicle's radios. Commencing in 2002 as part of the Land 106 program, the M113 major upgrade project saw 43 M577A1 ACVs upgraded to local AS3 standard and redesignated as the M113AS3 ACV. The upgrade package consisted of: The Australian Army also operated a number of M577A1 armored ambulances, which effectively serve as both emergency treatment and evacuation vehicles. As part of the M113 major upgrade project, 15 of these vehicles were converted to
18318-402: The vehicle's roof and operated from within or alongside the vehicle using a 50 ft (15.24 m) extension cable. As part of the A3 upgrade, a more powerful 5.0 kW unit was fitted. Unlike the previous gasoline-fuelled unit, the new unit operates on diesel fuel, providing more hours of operation on an equivalent fuel load. The single 80 gallon internal fuel tank of the M113, located at
18460-439: The vehicle's roof. In U.S. Army service, each vehicle usually carries three of four different communications suites (radio sets), each providing a specific communication network according to the communications roles they were assigned e.g. to divisional headquarters, across all vehicles within the unit (battalion), etc. The suites operated over amplitude modulation (AM), continuous wave (CW) and frequency modulation (FM), with
18602-682: The vehicle. As a result, the IDF faced calls from the Israeli public to build more Namer APCs over the next decade and to gradually reduce the number of M113s used in its future combat operations. A group of 30 Israeli reserve soldiers subsequently notified their commanders that they would refuse to enter the Gaza Strip in M113s. M113s were fielded in Palestine and Lebanon during the Israel–Hamas war . On 15 June 2024, eight soldiers were killed, possibly due to
18744-503: The war. In Australian service the M577A1 ACV was originally fitted with both U.S. and British radio sets, reflecting the dual origins of their pieces of major equipment. Vehicles would normally carry up to five sets e.g. three AN/GRC-125, one AN/VRC-49 and one AN/GRC-106. AS-1729/VRC antennae were mounted on the vehicle's roof, and an RC-292 antenna could be set up outside the vehicle when it was static to provided significantly more range for
18886-485: The years. The South Vietnamese Army ( ARVN ) called it the "green dragon". United States troops tended to refer to the M113 simply as a "113" (spoken as "one-one-three"), or a "track". The Israel Defense Forces employ the M113 in many different variants, all designed in Israel, and have given each of them official names, from the baseline "Bardelas" ( lit. Cheetah ) to the "Nagmash" (Hebrew acronym equivalent to "APC"), "Nagman", and "Kasman" variants for urban combat up to
19028-427: Was a cheap source of continuous waves and could be easily modulated to make an AM transmitter. Modulation did not have to be done at the output but could be applied to the signal before the final amplifier tube, so the microphone or other audio source didn't have to modulate a high-power radio signal. Wartime research greatly advanced the art of AM modulation, and after the war the availability of cheap tubes sparked
19170-402: Was developed for military aircraft communication. The carrier wave ( sine wave ) of frequency f c and amplitude A is expressed by The message signal, such as an audio signal that is used for modulating the carrier, is m ( t ), and has a frequency f m , much lower than f c : where m is the amplitude sensitivity, M is the amplitude of modulation. If m < 1, (1 + m(t)/A)
19312-443: Was one of the first researchers to realize, from experiments like the above, that the existing technology for producing radio waves, the spark transmitter, was not usable for amplitude modulation, and that a new kind of transmitter, one that produced sinusoidal continuous waves , was needed. This was a radical idea at the time, because experts believed the impulsive spark was necessary to produce radio frequency waves, and Fessenden
19454-453: Was put into production in 1964 as the "M113A1", and quickly supplanted the gasoline-engined M113. In 1994, FMC transferred the M113's production over to its newly formed defense subsidiary, United Defense . Then in 2005, United Defense was acquired by BAE Systems . The M113 was developed to provide a survivable and reliable light tracked vehicle able to be air-lifted and air-dropped by C-130 and C-141 transport planes. The original concept
19596-556: Was ridiculed. He invented and helped develop one of the first continuous wave transmitters – the Alexanderson alternator , with which he made what is considered the first AM public entertainment broadcast on Christmas Eve, 1906. He also discovered the principle on which AM is based, heterodyning , and invented one of the first detectors able to rectify and receive AM, the electrolytic detector or "liquid baretter", in 1902. Other radio detectors invented for wireless telegraphy, such as
19738-484: Was similar to the gun shield used on the U.S. M113 ACAV version. In addition, the Australians operated an M113 variant fitted with a Saladin armored car turret, with a 76 mm gun as a fire support vehicle, or FSV, for infantry fire support. This has now also been removed from service. Subsequent to Vietnam all Australian M113 troop carriers were fitted with the T50 turret. The FSV was eventually phased out and replaced with
19880-443: Was that the vehicle would be used solely for transportation, bringing the troops forward under armor and then having them dismount for combat, after which the M113 would retreat to the rear. Entering service with the U.S. Army in 1960, the M113 required only two crewmen, a driver and a commander, and carried 11-15 passengers inside the vehicle. Its main armament was a single .50-caliber (12.7 mm) M2 Browning machine gun operated by
20022-407: Was the first aluminum hull combat vehicle to be put into mass production. Much lighter than earlier similar vehicles, its aluminum armor was designed to be thick enough to protect the crew and passengers against small arms fire, but light enough that the vehicle was air transportable and moderately amphibious. In the U.S. Army, the M113 series have long been replaced as front-line combat vehicles by
20164-532: Was the first U.S. Army armor unit deployed to Vietnam. It originally consisted of three platoons of M113s and a platoon of 90 mm M56 Scorpion self-propelled anti-tank guns (SPAT). It was the only independent armor company in the history of the U.S. Army. Upon the company's arrival in Vietnam, a fourth line platoon was added; this was equipped with M106 4.2 in. mortar carriers (modified M113s). The mortar platoon often operated with Brigade infantry units to provide indirect fire support. It also deployed at times as
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