A rangefinder is described that uses the propagation time of a beam of infrared radiation to measure distances of up to 120 meters with errors of less than 50 µm. The instrument is capable of measuring up to five different distances per second by directing an amplitude modulated infrared beam to a retroreflector located at the far end of each path. The instrument is being tested with the expectation that such a system could be used to make precise and rapid measurements on a large radio telescope. Such measurements would be used to adjust the shape of the telescope reflector surface to correct for thermal and gravitational deformations taking place during astronomical observations. It is possible that the measuring system could be extended to relate the positions of certain moving parts of the structure to a reference system fixed in the ground, thus opening the possibility of making corrections to the telescope pointing.
The National Radio Astronomy Observatory (NRAO) is constructing a fully-steerable radio telescope at Green Bank, West Virginia, to be known as the Green Bank Telescope (GBT). The telescope design provides a reflector surface which is a part of a paraboloid, so positioned that radiation can reach the reflector and then pass to one of two focal points without meeting any obstructions. This clear aperture collects radiation from a circular area of 100 meters diameter. The goal of the design is to have an instrument which performs well at radio wavelengths down to 6 mm. It may be possible in the future to lower this short-wavelength limit to 3 mm; this depends on several factors, one of which is the outcome of the present work.
To achieve satisfactory performance at short wavelengths, a radio telescope must meet two main requirements:
The reflector surface must maintain its required shape.
The position of the telescope beam on the sky must always be controlled with precision.
These can be thought of as the "surface" and "pointing" requirements; the precision with which they must be met is related to the shortest wavelength at which the telescope is to be used, and both are very dependent on the environmental conditions at the telescope site. As an example, if the GBT were being used at a wavelength of 3 mm, it would be expected to have a surface whose departures in shape from perfection had an RMS value of at most 0.2 mm,...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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