Ranging radar including a modulating reflector
AssigneeRCA Corporation
InventorHenry C. Johnson
Life of this patent
Estimating the term…
Abstract
A ranging radar of the radio frequency (RF) frequency modulated-continuous wave (FM-CW) type transmits an RF FM-CW signal to a reflecting surface at an unknown range R from the radar. The reflecting surface reflects the signal to a modulating device. The modulating device further modulates the signal at a frequency F which is high in comparison to the modulating frequency of the FM-CW signal. The further modulated signal is transmitted by the device to the reflecting surface and back to the ranging radar where it is subtractively mixed with a sample of a transmitted signal. The mixed signal is at frequency F amplitude modulated by a beat frequency, the period of which corresponds to range R. The frequency F is removed from the mixed signal leaving the beat frequency signal from which is determined range R.
Claims9
A radio frequency (RF) frequency modulated-continuous wave (FM-CW) ranging radar system for measuring the range to an RF reflecting surface, comprising in combination:
- means producing an RF FM-CW signal at a relatively low modulation rate f;
- means including a first antenna means for transmitting said signal to said reflecting surface;
- means including a second antenna means for receiving said RF FM-CW signal affected by said surface;
- means coupled to said second antenna means and responsive to said signal reflected thereto for further modulating said signal at a relatively high rate F, where F>>f, and for retransmitting said further modulated signal by said second antenna means to said reflecting surface to be reflected thereby to said first antenna means;
- means responsive to said further modulated signal received at said first antenna means and to said transmitted RF FM-CW signal for producing a signal having a relatively high frequency corresponding to that of said further modulating signal of rate F amplitude modulated by a relatively low frequency signal indicative of the range of said reflecting surface from said first and second antenna means;
- means responsive to said signal having said relatively high frequencey modulated by said relatively low frequency for extracting said signal indicative of said range;
- and
- means responsive to said extracted signal for determining said range.
Dependencies are inferred from the claim text.