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What is the radar control that reduces weak echoes out to a limited distance from the ship?
Wiki User
∙ 11y ago
receiver gain control
Wiki User
∙ 11y ago
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What are radar reflections?
radar is acronym for radio detection and ranging--ergo a high freq. pulse is sent out and returned be it reflection from weather planes autos.etc. the time it takes to transmit and receive this pulse gives range. In most cases directly received power from the transmitter to the target and back to the receiver are termed echoes (or target echoes) and indirect received power from the transmitter power bouncing off some intermediate surface between the transmitter and the target and/or the target and the receiver are what people call reflections, this is also called "multi-path effects". You should also look at glint and scintillation. All object the "reflect power" or provide a echo are termed scatters.
Why negative feedback is preferred in amplifier?
Because the feedback of an amplifier tends to reduce the gain of an amplifier and also, the bandwidth of feedback increases the gain of an amplifier, so in an high gain amplifier as to be stabilized. BY ENGINEER MUHAMMED OLALEYE OLUWATOSIN TELECOMMUNICATION STUDENT, RUFUS GIWA POLYTECHNIC, OWO
How ultrasonic flaw detector constructed?
ANSWER I'm assuming you are referring to a machine used to conduct an ultrasonic non-destructive test. Generally speaking, the machine works like this sonar: an ultrasonic transceiver creates a mechanical pulse and measures the time it takes for the echo to return. The echo delay time indicates how far into the material the sound wave went before it was reflected. This reflection happens because the material stops -- usually it's either the far side of the material, or a flaw. For instance, inspecting a solid metal plate of constant thickness is pretty straightforward. Visualize, or mark, an inspection grid on the plate being inspected. Place the transceiver at the first grid location and fire a pulse. Measure the echo time and store it. Repeat for all the grid locations, and then plot the times. The plot could be a three dimensional plot, in which case it would look very much like a scaled drawing of the plate. Or it could be two dimensional and use color to indicate the echo times. Either way, a flaw is indicated where the time changes from the expected value. Naturally, you would typically take multiple readings and average them. You might also calculate the variation in readings to determine how good a measurement you have. Also, there is usually another medium required to help couple the ultrasonic signal into the material to be inspected, called a couplant. It usually is a clear gel. The test could be run on a machine that positions the transceiver (or moves the plate and holds the transceiver still) using an X-Y table. It could also use a line of multiple transceivers and move the plate past them in one direction. Or an entire array of transceivers could be placed over the plate and the entire echo time map could be measured all at the same time. The transceiver is usually driven with a single strong pulse. You usually get better results if the pulse looks more like a sine than a square wave, because square waves include other frequencies besides the one you are driving and these other frequencies use some of the power. The reason to prefer a single frequency is that the received signal usually is passed through a very tight bandpass filter to avoid recording false echoes. A single pulse reduces uncertainty in the time measurement, where multiple pulses are easier to detect. The receiver is usually not enabled until the transmitter has finished driving the output signal, and this establishes a minimum echo time that can be measured. Some receivers use adjustable gain amplifiers with the gain increasing with time because the longer it takes for the echo to return, the more material the signal has to pass through, and the weaker the echo will be. [note that I've left out any discussion of propagation velocity, signal spread, etc.]
What are the major components of radar?
Radar Technology - The Main ComponentsAll radars are composed of the items listed below. Their operation is organised in a processing chain and hence it is the weakest part that defines the systems capabilities.The TransmitterTransmitters are built around semiconductors (often contained in MMICs, millimetre-wave integrated circuits) or powerful vacuum tubes. The latter are rather complicated and sophisticated devices and often carry weird names ending in '-tron', such as Amplitron, Magnetron, Carcinotron, Stabilitron or Klystron.Owners of a microwave oven are also owners of a magnetron. The fact that microwaves can heat up food was discovered by serendipity, when during the 1940s a radar researcher was astonished to see that a chocolate bar was melting in his trouser pocket while he was performing experiments with an unshielded magnetron1.The AntennaThe radar antenna serves as the coupling element between the wiring in the radar hardware and free space. Radar antennae can be as small as a thumbtack or as big as a 30-storey building, depending on their operating frequency and beamwidth.The ReceiverThe receiver's task is to pick up the echo that was bounced off a target, filter out unwanted parts outside the radar's bandwidth, amplify the rest and feed it into the signal processor for further analysis. A good receiver is a radar's best defence against noise, its toughest enemy.A receiver must be very sensitive in order to pick up weak echoes from far away. But usually it is located near the transmitter which can easily 'blind' or even destroy it by 'spillover' leaking into the receiver's input circuitry. In a pulsed radar, damage can be avoided by using a Transmit/Receive-Switch or T/R switch that disconnects the receiver's input from its antenna while the transmitter is operating. In a Continuous Wave Radar, the transmitter operates all the time and receiver protection is only feasible by blocking the frequency that is currently used. Both measures do fulfil their purpose but at the same time they introduce some problems of their own: they produce blind ranges and blind speeds.Until not long ago, travelling wave tubes (TWT) were the mainstay of receiver construction. Like the -tron devices mentioned above, their inner workings are rather complicated as they are built around some chamber or structure where strong magnetic fields or electron beams interact with low power, high frequency signals. During the 1980s, TWTs were gradually replaced by semiconductors.The SignalThe signal is what the radar transmits into space. A wide variety of types is available, and perhaps more than all the hardware components, the signal is what determines the quality and capabilities of a radar. The most powerful radar, equipped with an ultra-low sidelobe antenna of incredibly high gain can be blind at the most important range or target speed if the signal was chosen wrong. Some signals are likely to produce 'angels' and 'ghosts' on a screen - things that really make a radar operator's life interesting. More often than not, a single type of signal will not meet all the requirements, and fierce discussion about necessary expenditures ensues between manufacturer and customer.The Signal ProcessorThe Signal Processor is the central element of a radar. It has to decide whether an echo really is an echo and whether or not it is worth being reported and displayed. This is not a simple task, as there is much natural noise around, and in the case of military applications there is man-made interference too.The SystemA collection of sophisticated components is a precondition, but not a guarantee, for a good radar. The first step during the design phase is to determine which part of the electromagnetic spectrum is to be used, followed by the selection of the signal that is most appropriate for the purpose in question. All this needs to be composed into a system that is more than the sum of its parts. There are only a few things that a radar cannot do, and the easiest way to find these is to look into the requirement specifications written by the customer.
What are the release dates for Echoes of the Past - 2005?
Echoes of the Past - 2005 was released on: USA: 9 September 2005 (limited)
Are echoes important?
Yes, echoes are important because they can provide information about the surroundings, such as the size and distance of objects. In nature, echoes are used by animals for navigation and communication. In technology, echoes are utilized in echo-location systems like sonar and radar for a variety of applications.
What has the author G Sewell written?
G. Sewell has written: 'Echoes of a century' -- subject(s): Southern Newspapers Limited
How are echoes actually produced?
An echo is a reflection of sound that may come from many places. Examples of echoes could be when sound bounces off the bottom of a well or a large room. There is a delay depending on distance.
Describe ways that echoes are used in measurement?
The speed of sound is the distance travelled by the sound waves in the time between the original sound and the echo. For a direct echo, the distance travelled is double the distance to the reflecting surface.
When was The Echoes created?
The Echoes was created in 1959.
What is the plural possessive of echo?
The plural form is echoes. The plural possessive is echoes'.
When was Echoes of Refuge created?
Echoes of Refuge was created in 2006.
When was Echoes of Honor created?
Echoes of Honor was created in 1998.
When was Eternal Echoes created?
Eternal Echoes was created in 2001.
When was Echoes from the Ocean created?
Echoes from the Ocean was created in 1999.
When was Imperial Echoes created?
Imperial Echoes was created in 1928.
