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Topic: TWTA

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	Public Lessons Learned Entry: 0404
		A subsequent attempt to operate this TWTA during the extended mission late in 1978 also failed to produce downlink.
		TWTA No. 1 produced normal carrier and telemetry sidebands; however, the ranging subcarrier was suppressed by noise by 6 to 8 dB.
		The TWTA went through its 90-second cathode warm-up period, and the failure must have occurred shortly after the high-voltage was programmed to come on.
	www.nasa.gov /offices/oce/llis/0404.html (623 words)

	Satellite Communications FAQ - S+AS Limited
		TWTA - A Travelling Wave Tube Amplifier is a single, wide band device [typically 500MHz] used in satellite communication systems where high power and the ability to transmit several carriers simultaneously, across the entire band, is required.
		TWTAs are available in output powers rated @ Hundreds of Watts and are typically found in large earth stations.
		TWTA - v - SSPA - One important thing to remember when contemplating a TWTA over an SSPA for use in digital uplink systems, is that they are less linear than a solid state amplifier and therefore require a larger Output Back Off to maintain most satellite operators spectral masking.
	www.sasltd.com /T/faq/faq2.html (3283 words)

	Multiple traveling wave tube amplifier electronic power conditioner with centralized low voltage and distributed high ...
		As opposed to the prior art TWTAs, the central EPC or CPS offers the advantages of a single EPC, or dual EPCs, by combining a plurality of low voltage converters and their circuitry into a common redundant CPS for reduced payload mass and increased layout efficiency.
		Accordingly, in the TWTA system 100, the number of traveling wave tube members 124 equals the number of high voltage conditioner members 122.
		In this configuration, the combined weight of both the PPT 150 and the voltage regulator 160 is expected to be significantly less than the weight of the IPC 104 described in the previous embodiment and shown in FIG.
	www.freepatentsonline.com /6489842.html (4036 words)

	THALES Electron Devices
		The signal is attenuated and mixed with the input signal of the TWTA, with a 180 phase shift.
		The noise-to-power ratio (NPR) is used to predict the multicarrier performance of a TWTA.
		Meassurements are based on a white noise RF signal, with a notch in a given bandwith (e.g., 200 MHz) to simulate multicarrier operation.
	www.thales-electron-devices.de /produkte_sat_enhanced_efficiency.php (314 words)

	AN/ALQ-167
		The tray assembly houses the DLQ-3 RF oscillator, G/I-Band TWTA and VDA.
		The tray assembly houses the WCO with the TVCO, E/F-Band TWTA, MTDA, and the MM.
		The tray assembly houses the WCO with the TVCO, E/F-Band TWTA, and MTDA.
	www.fas.org /man/dod-101/sys/ac/equip/an-alq-167.htm (710 words)

	Traveling Wave Tube Amplifiers vs. Solid State Power Amplifiers
		Figure 2 shows a comparison between the TWTA and the SSPA transfer curves for the amplifiers chosen which have the same linearity.
		Traditionally TWTAs have been used for FM applications where they have been operated in saturation thus the TWTA amplifier in this case which has a saturation output power of 56 dBm minimum is called a 400 W amplifier.
		These tradeoff points are also valid for the size and weight of the amplifiers with TWTAs having the advantage at higher powers because of their higher power added efficiencies.
	www.djmelectronics.com /articles/twt-vs-solid-state.html (1137 words)

	Ulysses Telemetry, Tracking, and Command Subsystem
		The X-band downlink path is shown by the blue line running from Transponder 2, to the TWTA Interface Unit and Travelling Wave Tube Amplifier 2 (TWTA2), eventually to the High Gain Antenna (HGA).
		A critical role of the TWTA interface is to automatically maintain the downlink in the event of a TWTA2 failure.
		In such as case, the TWTA Interface unit will reposition the waveguide switch to connect the new TWTA to the High Gain antenna.
	ulysses-ops.jpl.esa.int /ulsfct/spacecraft/TWTA.html (126 words)

	Techniques for Predicting Nonlinear Distortion Effects in Ka-Band Uplink Gateways
		To aid in the study of distortion sensitivity to amplifier properties, a model is proposed that permits an empirical fit of common TWTA and SSPA transfer curve shapes to a 12-term parametric model, illustrated in Figure 3.
		Linearized TWTAs consist of a TWTA preceded by a predistorting linearizer.
		In Ka-band gateways, a common technique to achieve high EIRP is to use nominally-identical linearized TWTAs in parallel, together with quadrature phase combiners on the input and output.
	www.andrew.com /products/antennas/esa/articles/techniques-for-predicting-ka.aspx (2676 words)

	Smaller, higher-power travelling wave tube amplifier
		AR Worldwide RF/Microwave Instrumentation has responded to customers' needs with new custom Travelling Wave Tube Amplifiers (TWTA's) that are significantly smaller than standard TWTA's yet deliver up to 1000 watts of power.
		The AR Worldwide TWTA's provide coverage for a wider range of high-power microwave test applications than any other brand of microwave amplifiers.
		No part of this material may be reproduced, translated, transmitted, framed or stored in a retrieval system for public or private use without the written permission of the publisher.
	www.ferret.com.au /articles/z1/view.asp?id=87737 (252 words)

	Slow Food International - Sloweb
		TWTA is the most highly prized truffle in the world.
		TWTA will only grow near oak trees, but it is said that a couple of birch trees in the vicinity will do the world of good for soil conditions.
		Farmers and scientists have long been falling over themselves trying to grow white truffles but TWTA remains elusive and just as the growth of truffles is a complicated, mysterious business, so is finding them.
	www.slowfood.com /sloweb/eng/dettaglio.lasso?cod=en_ed00171 (1747 words)

	TII Products Help TWA Fly High (Site not responding. Last check: )
		TWTA, a subsidiary of Trans World Airlines, developed its program from scratch in order to address the need for technicians who are trained to work on heavy jet transport-type aircraft.
		During the course of the 2,100 hour program which includes instruction in landing gear systems, rigging and assembly, fluid lines and fittings, and principles of hydraulic and pneumatic systems, trainees will be taught how to troubleshoot, operate and maintain aircraft systems in an innovative way.
		Early in 1994, TWTA decided to expand their original 560-hour program and submit the revised program to the FAA for certification approval.
	www.tii-tech.com /welcomenews1.html (458 words)

	Traveling wave tube amplifier - Wikipedia, the free encyclopedia
		A TWTA consists of a traveling wave tube (TWT) coupled with its protection circuits (as in klystron)) and regulated power supply (EPC, electronic power conditioner), which may be supplied and integrated by a different manufacturer.
		A TWTA whose output drives an antenna is a specific type of transmitter.
		TWTA transmitters are commonly used in satellite transponders.
	en.wikipedia.org /wiki/TWTA (334 words)

	[No title] (Site not responding. Last check: )
		However, in implementation with the ideal TWTA collector, the Markov chain often enters basins and discontinuities in the design surface that prevent the intended constant state proposals.
		However, in implementation with the TWTA ideal collector, satisfaction of equation (\ref{epsilonreq}) does not appear to be necessary for good algorithm performance.
		After a pre-set number of sweeps (set in the TWTA collector implementation to be $300M$), the algorithm begins choosing points in the design space arrived at from the sweeps to perform \emph{fast} SA.
	www.math.ucla.edu /~radke/article.txt (2232 words)

	Chapter 1: Experimental Satellites (cont.)
		Normally, one of the redundant 20-W TWTAs was the power amplifier for one channel as well as the low-level driver for the 200-W TWTA on the second channel.
		In a backup mode, the 200-W TWTA was bypassed, and the output of the 20-W TWTA was divided between the two channels.
		The high-power TWTA was used for transmission to the remote terminals that used relatively small antennas.
	www.aero.org /publications/martin/martin-10.html (1139 words)

	10 GHz 50 Watt Home Station
		In this application the TWTA will only need < 1 mW to drive so a combination of coax loss (The TWTA is mounted remotely) and attenuation has been used to provide the exciter with a good 50 ohm load and reduce the power level to ~0dbm.
		The coax and attenuators between the Transverter and the TWTA have been selected so that it is impossible for the drive level to exceed 0dbm under conditions of overdrive/saturation.
		The The output of the TWTA is switched to a 50 Ohm load during receive.
	members.ozemail.com.au /~tecknolt/10Ghz/10ghz50.htm (1454 words)

	Digital Distortion Caused by Traveling-Wave-Tube Amplifiers
		In particular, intersymbol interference caused by the TWTA becomes a major consideration for accurate data detection at the receiver.
		Experimentally investigating the effects of the physical TWTA on intersymbol interference would be prohibitively expensive, as it would require manufacturing numerous amplifiers in addition to acquiring the required digital hardware.
		Thus, an accurate computational model is essential to predict the effects of the TWTA on system-level performance when a communication system is being designed with adequate digital integrity for high data rates.
	www.grc.nasa.gov /WWW/RT2001/5000/5620kory.html (498 words)

	Satellite transponder and earth station performance optimization using computer simulation
		These satellites and most of their cohorts in the geostationary orbit have bent-pipe repeaters using C and Ku bands; a bent pipe repeater is simply one that receives all signals in the uplink beam, block translates them to the downlink band, and separates them into individual transponders of a fixed bandwidth.
		For an input sine wave of frequency f and amplitude r, the TWTA is characterized by the relationship
		Another and simpler approach is to enter the measured TWTA data into a text file and use simple table look up for the required values.
	www.applicationstrategy.com /Communications_simulation.htm (2865 words)

	VisSim/Comm Channel Blocks
		Furthermore, the average ray power in any given cluster is assumed to tdecay exponentially, and its phase is uniformly distributed over [0, 2pi].
		This block provides an analytical model of a traveling wave tube amplifier (TWTA) channel, which is frequently found in satellite links.
		The TWTA block simulates a nonlinear amplifier and exhibits both AM/AM conversion and AM/PM conversion.
	www.eritek.com /ChannelBlocks.asp (1057 words)

	Boeing: Boeing EDD Awarded Amplifier Contract For JCSAT-9
		In communication satellites, traveling wave tube amplifiers (TWTA) are used to amplify and transmit very low-level radio frequency signals back to Earth for a variety of applications including voice, video and data.
		A typical TWTA consists of a traveling wave tube and an electronic power conditioner.
		On satellites that carry a large number of signals, a linearized channel amplifier is often added to cancel the amplifier distortion.
	www.boeing.com /news/releases/2003/q3/nr_030808s.html (419 words)

	TRW Develops Ultracompact Radio Upconverter for Communication Satellites (November 2000) - News - Compound Semiconductor
		The upconverter's small size permits placing it next to the TWTA, an arrangement impossible with larger, conventional upconverters.
		First, it permits the upconverter to draw its power from the TWTA's power supply, eliminating the need for separate power supplies.
		In addition, location near the TWTA reduces signal loss in the payload signal routing path.
	compoundsemiconductor.net /articles/news/4/11/23/1 (493 words)

	Your Daily Briefing Of Satellite
		The TWTA, according to CPI Satcom, breaks new ground in high power, C-Band performance.
		According to CPI Satcom, the Super Linear TWTA meets Intelsat linearity requirements at RF output power levels up to 1000 watts.
		The amplifier also features a large, color graphical user display similar to the company’s industry-leading GEN IV klystron power amplifier, as well as Ethernet interface and uplink power control.
	www.satnews.com /stories2005/484.htm (198 words)

	TWT Amplifiers, Solid State Replacement Kits : Stealth Microwave, Inc. (Site not responding. Last check: )
		For the past 40 years, Traveling Wave Tube Amplifiers (TWTAs) have been used as the output amplifying stage for radio links in the common carrier bands at 4, 5, 6, 8, and 11 GHz.
		Stealth Microwave offers SSPA kits, which are exact TWTA replacements for all existing Siemens/Thomson models.
		Simply remove the failed TWTA and install the SSPA and power supply using the same mounting holes and hardware.
	www.stealthmicrowave.com /radio_replacement.htm (131 words)

	Travelling Wave Tube Amplifier (TWTA) (Site not responding. Last check: )
		(TWTA), the input signal is used to modulate the velocity of electrons near the source of an electron beam.
		After modulation the velocity variations evolve into electron density variations which can be translated back into a more-powerful electromagnetic signal before the electrons arrive at a collecting electrode.
		(TWTA) the signals travel along a wire helix while electrons in a high-voltage beam travel through the helix and transfer their energy to the electromagnetic wave in the wire.
	www.argospress.com /Resources/transmitters-receivers/ytravewavtubamplif.htm (153 words)

	DC-DC converter military satellites
		The TWTA is capable of about 200 W, and efficiency can be as high as 60% to 65%.
		The voltage requirements for a TWTA are usually a combination of low and high voltage in the order of a few hundred volts for anode and grid voltage, and in the order of kV for cathode and collector depending on the type of the TWTA.
		The power requirement for an SSPA or a TWTA from an EPC is dictated by the transmitter power requirement and the efficiency of an SSPA/TWTA.
	rfdesign.com /mag/radio_military_satellites_pose/index.html (2996 words)

	Cassini-Huygens: News-Significant Events-2007
		This particular trip caused a loss of power to a Traveling Wave Tube Amplifier (TWTA), subsequent RF loss, a call to System Fault Protection (SFP), and put the spacecraft in "safe mode".
		On Tuesday of last week, as soon as the SSPS trip had been confirmed as the cause of SFP execution, real time commanding was begun to initiate the process of putting the spacecraft back in a nominal operational configuration, and to play back the remaining on-board Iapetus data.
		With OTM-128 having been successfully executed, commands were sent to swap from TWTA-A back to TWTA-B. The TWTA RF Loss algorithm causes hardware swaps in both the Telemetry and Command Units and the TWTAs.
	saturn.jpl.nasa.gov /news/sig-event-details.cfm?newsID=776 (1028 words)

	Mimix Broadband™
		In addition to MMIC products, Mimix Broadband also manufactures solid-state traveling wave tube (TWTA) replacement amplifiers as well as broadband and custom multi-function modules for terrestrial radio link and military applications.
		TWTA part numbers include but are not limited to RW89, RW89D, RW90, RW90D, RW248, RW289, RW289B, RW290, RW1125, RW1125D and RW2135.
		Specific TWT part numbers are not required, since SMaRTPAKs are designed to “drop-in” to your existing radios.
	www.mimixbroadband.com /TWTA.html (246 words)

	Dudley Lab TWTA Caution Used Test Equipment. TWTA, TWT (http://www.dudleylab.com/about.html)
		General Precautions for TWTA Operation, Most of these items are contained in the operation Manuals.
		The longest life for a TWTA is when the unit is operated near its full RF power output or in storage.
		CAUTION when the unit is turned ON, it should be put to the OPERATE mode (OPERATE, RF ON, BEAM ON) within a short time.
	www.dudleylab.com /caution.htm (355 words)

	Satellite Systems
		Two (plus one backup) 50W TWTA 5858-5930 /2550-2630MHz up/down S-band all-India BSS beam, 36MHz bandwidth, 42 dBW EOL EIRP.
		12 C-band (2x50W TWTA, tx10WSSPA and 3x4W SSPA) all-India beam.
		One 50W TWTA 2670-2690/2500Mhz up/down S-band all-India mobile communications beam.
	www.bharat-rakshak.com /SPACE/space-satellite3.html (604 words)

	TWTA's & Solid State Instrumentation Amplifiers
		PTC6704 1.0-1.5 GHz 10 kW kW Pulsed TWTA NEW!!
		PTC6706 1.5-2.0 GHz 6 kW Pulsed TWTA NEW!!
		Developing alongside the rugged amplifiers for radar has been a range of commercial microwave amplifiers, using TWTs, or solid state technology for such applications as EMC and RF testing, radar simulation and calibration, jamming, satellite communications, Passive Intermodulation Testing (PIM) for space components, scientific experimentation and medical LINACs.
	www.tmd.co.uk /instrumentation/index.asp (525 words)

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