what do you mean by blind speed?

Question

it's related to RADARS.

Answer 1

radar blind speed: The magnitude of the radial component of velocity of an object, i.e., a target, relative to a radar site, that cannot be measured by the radar unit. Note: Radar blind speeds occur because of the relationship between the transmitted pulse repetition rate (PRR) and the received pulse-repetition rate. The Doppler pulse repetition rate is the difference between the transmitted and received pulse repetition rates. For example, when the object is stationary with respect to the radar site, the reflected PRR is the same as the transmitted PRR and therefore a net zero signal is indicated for the radial component of velocity. If it happens that the Doppler PRR is the same as the transmitted PRR, i.e., the illuminating PRR, or it is a multiple of the transmitted PRR, a zero signal is also obtained and hence the radar is blind to these speeds, one for each multiple of the transmitted pulse repetition rate. It is not the absolute magnitude of the speed of the object that is measured, but only the radial component of the speed. The radial components of blind speeds, vm , are given by vm = m f /102, where v is the blind speed in knots, m is the multiple of the radar pulse repetition rate and the number of the blind speed, namely a positive integer, 1, 2, 3, 4, . . ., for the first, second, third, fourth, and so on, blind speed, is the wavelength of the illuminating radar in centimeters; f is the transmitter pulse repetition rate in pps (pulses per second); and the 102 is a units conversion factor.

Answer 2

The magnitude of the radial component of velocity of an object, i.e., a target, relative to a radar site, that cannot be measured by the radar unit. Note: Radar blind speeds occur because of the relationship between the transmitted pulse repetition rate (PRR) and the received pulse-repetition rate. The Doppler pulse repetition rate is the difference between the transmitted and received pulse repetition rates. For example, when the object is stationary with respect to the radar site, the reflected PRR is the same as the transmitted PRR and therefore a net zero signal is indicated for the radial component of velocity. If it happens that the Doppler PRR is the same as the transmitted PRR, i.e., the illuminating PRR, or it is a multiple of the transmitted PRR, a zero signal is also obtained and hence the radar is blind to these speeds, one for each multiple of the transmitted pulse repetition rate. It is not the absolute magnitude of the speed of the object that is measured, but only the radial component of the speed. The radial components of blind speeds, vm , are given by vm = m f /102, where v is the blind speed in knots, m is the multiple of the radar pulse repetition rate and the number of the blind speed, namely a positive integer, 1, 2, 3, 4, . . ., for the first, second, third, fourth, and so on, blind speed, is the wavelength of the illuminating radar in centimeters; f is the transmitter pulse repetition rate in pps (pulses per second); and the 102 is a units conversion factor. [From Weik '89]

Answer 3

Blind Speed In Radar

Answer 4

If you want me to cut and paste the answer from a source I can! But simply there are times technically when due to the pulse rate of the radar and the return time of the signal from the target that the speed cannot be determined! This only happens in one thousandths of a second when signals overlap and the frequency shift due to doppler cannot be measured! Thus the radar is BLIND for this one small fraction millisecond!

Hope this clears it up for you!

APS

Answer 5

The blind speed is a radial speed of the airplane at which the phase shifting of the echo-signal has the value ±n · 360° between two pulse periods. With blind speeds moving targets are suppressed by a MTI system like ground clutters.

Answer 6

Blind speed ni mwendokasi wa taarifa inayotumwa kutoka kwenye Tx kwenda kwenye kizuizi na kurudi kwenye Rx,hii taarifa inayorudishwa baada ya kufika kwenye kizuizi huwa inajulikana kama echo signal, nahii spidi huwa kubwa mpaka Radar ikashindwa kuitambua kwa mara moja.

By Eng. Morice Tirukaizile from TZ

Answer 7

The radar system send a pulse of energy and senses the reflection from targets(echo) to detects its existence. however constant targets (clutter, terrain, buildings, etc) have much reflections that apear as a strong targets while they r not. so pulse radar normally depends on the difference between a pulse and its succeder. This is called MTI radar. The characteristic of this system (filter) are similer to the rectified sinsoid (in fact squared) which is periodic and have null response at some velocities of the target. these nulls corresponds to velocities that give doppler frequency equal to integer multiples of pulse repetition rates.

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response....*...........*........*..........*.......*..........*..............
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........... 0__________________________________........
...................................1/T................ 2/T................ 3/T.....



so if a target moves with a radial velocity that gives a doppler shift equal to multiple of pulse repetition rate then it is said to have a blind speed that it is theoritically not detected since the response of the receiver is zero.

Answer 8

Hi. Take a look here: http://www.atis.org/tg2k/_radar_blind_speed.html