1. A method for determining the distance of a movable object from an immobile object and determining the speed of the movable object with respect to the immobile object comprising the steps of,
(a) generating a pulse train at an immobile object at first location for a first fixed-period-of-time, wherein said pulse train is composed of a predetermined number of pulses having a known width and period;
(b) modulating the pulse train with a high frequency carrier radio wave during said first fixed-period-of-time;
(c) transmitting said high frequency carrier radio wave to a movable object at a second location during said first fixed-period-of-time;
(d) receiving said high frequency carrier radio wave at said movable object during said first fixed-period-of-time;
(e) demodulating said pulse train at said movable object while generating said pulse train during said first fixed-period-of-time;
(f) remodulating said pulse train at said movable object with a second high frequency carrier radio wave during said first fixed-period-of-time;
(g) transmitting said second high frequency carrier radio wave from said movable object to said immobile object during said first fixed-period-of-time, wherein said pulse train remains unchanged as to the number of pulses, pulse width and period;
(h) receiving at said immobile object that portion of said second high frequency carrier radio wave that can be received during said first fixed-period-of-time;
(i) demodulating the pulse train received at the immobile object in that portion of said second high frequency carrier radio wave;
(j) counting the number of pulses in the pulse train in that portion of said second high frequency carrier radio wave;
(k) determining the number of missing pulses from that portion of the pulse train in relation to the number of pulses generated in the first fixed-period-of time;
(l) dividing the number of missing pulses by two to obtain an average number of pulses traveling between the immobile object and the movable object;
(m) calculating the delay time by dividing said first fixed-period-of-time by the predetermined number of pulses and multiplying the result by said average number of pulses;
(n) determining a first distance between said immobile object and said movable object by multiplying said delay time by the radio wave propagation velocity;
(o) repeating steps (a) through (n) for a second fixed-period-of-time equal to the first fixed period of time to determine a second distance; and,
(p) determining the speed of the movable object with respect to the immobile object by taking the difference between the first distance and the second distance and dividing the result by the time between the termination of the first fixed-period-of-time and the start of the second fixed-period-of-time.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An imaging system, comprising:
at least one bus line;
a row and column array of active pixels, each of which has an associated pitch and is periodically reset to a known state, said pixel producing a reset level which includes noise components, and a signal level which includes signal and noise components, in response to respective control signals;
a plurality of column buffers, each of which conveys the outputs of a respective column of pixels, in turn, to one of said at least one bus lines, each of said column buffers comprising:
\u2018odd row\u2019 and \u2018even row\u2019 sample and hold(S&H)correlated double sampling (CDS) circuits which are switchably connected to said pixels and arranged to process the pixel outputs of odd and even rows, respectively, each S&HCDS circuit further arranged to subtract the reset level from the signal level of the pixel to which it is connected to suppress correlated noise components present in said signal level and produce a net output signal; and
a buffer amplifier arranged to receive said net output signal and convey it to one of said at least one bus lines,
each of said column buffers having a pitch which is equal to or less than said pixel pitch;
each of said bus lines conveying the outputs of a plurality of said buffer amplifiers; and
at least one gain amplifier external to said column buffer, said at least one gain amplifier coupled at an input to a respective one of said bus lines such that said gain amplifier amplifies the outputs of a plurality of column buffers.
2. The imaging system of claim 1, wherein said at least one gain amplifier external to said column buffer is a capacitance transimpedance amplifier (CTIA).
3. The imaging system of claim 2, wherein said at least one bus line comprises a first bus line which conveys the outputs of the buffer amplifiers in the column buffers located in the system’s \u2018odd\u2019 columns and a second bus line which conveys the outputs of the buffer amplifiers in the column buffers located in the system’s \u2018even\u2019 columns, and wherein said at least one gain amplifier comprises first and second gain amplifiers coupled at respective inputs to said first and second bus lines, respectively.
4. The imaging system of claim 1, wherein said pixel pitch is less than or equal to 2 \u03bcm.
5. The imaging system of claim 1, wherein said noise components include kTC, 1f and fixed pattern noise.
6. The imaging system of claim 1, wherein each of said pixels includes a photodiode and a source follower circuit, said source follower circuit coupled at an input to said photodiode output and producing said pixel’s output.
7. The imaging system of claim 1, said system further arranged to provide a feedback path between the output of said gain amplifier and the input to each column buffer’s buffer amplifier when the output of said column buffer’s buffer amplifier is coupled to said gain amplifier, such that said buffer amplifier reduces the magnitude of the bus capacitance to which said column buffer’s net output signal is subjected compared with the magnitude of the bus capacitance that said net output signal would be subjected if connected directly to said gain amplifier.
8. The imaging system of claim 7, further comprising a capacitance which can be switchably connected into said feedback path such that the voltage gain realized by said buffer and gain amplifier varies with the size of said capacitance.
9. The imaging system of claim 7, further comprising a capacitance which can be switchably connected into said feedback path such that the noise gain realized by said buffer and gain amplifier varies with the size of said capacitance.
10. The imaging system of claim 1, further comprising an output amplifier which is driven by the outputs of said gain amplifiers.
11. The imaging system of claim 1, further comprising a feedback capacitor connected between the output of said gain amplifier and the input of said gain amplifier which is coupled to a respective one of said bus lines such that the stability of said gain amplifier is improved.
12. An imaging system, comprising:
at least one bus line;
a row and column array of active pixels, each of which has an associated pitch and is periodically reset to a known state, said pixel producing a reset level which includes noise components, and a signal level which includes signal and noise components, in response to respective control signals;
a plurality of column buffers, each of which conveys the outputs of a respective column of pixels, in turn, to one of said at least one bus lines, each of said column buffers comprising:
\u2018odd row\u2019 and \u2018even row\u2019 sample and hold(S&H)correlated double sampling (CDS) circuits which are switchably connected to said pixels and arranged to process the pixel outputs of odd and even rows, respectively, each S&HCDS circuit further arranged to subtract the reset level from the signal level of the pixel to which it is connected to suppress correlated noise components present in said signal level and produce a net output signal; and
a buffer amplifier arranged to receive said net output signal and convey it one of said at least one bus lines,
each of said column buffers having a pitch which is equal to or less than said pixel pitch;
each of said bus lines conveying the outputs of a plurality of said buffer amplifiers;
at least one capacitance transimpedance amplifier (CTIA) external to said column buffer, said at least one CTIA coupled at an input to a respective one of said bus lines such that said CTIA amplifies the outputs of a plurality of column buffers, said system arranged to provide a feedback path between the output of said CTIA and the input to each column buffer’s buffer amplifier when the output of said column buffer’s buffer amplifier is coupled to said CTIA; and
a capacitance which can be switchably connected into said feedback path, said buffer amplifier, CTIA and feedback path forming a feedback amplifier, the voltage and noise gain realized by said feedback amplifier varying with the size of said capacitance;
such that said buffer amplifier reduces the magnitude of the bus capacitance to which said column buffer’s net output signal is subjected compared with the magnitude of the bus capacitance that said net output signal would be subjected if connected directly to said CTIA.
13. The imaging system of claim 12, wherein said at least one bus line comprises a first bus line which conveys the outputs of the buffer amplifiers in the column buffers located in the system’s \u2018odd\u2019 columns and a second bus line which conveys the outputs of the buffer amplifiers in the column buffers located in the systems \u2018even\u2019 columns, and wherein said at least one CTIA comprises first and second CTIAs coupled at respective inputs to said first and second bus lines, respectively.
14. The imaging system of claim 12, wherein said pixel pitch is less than or equal to 2 \u03bcm.
15. The imaging system of claim 12, wherein said noise components include kTC, 1f and fixed pattern noise.