Some Interesting Points on What a Robotic Asteroid Flyby (Remote Data Acquisition) might consist of, in general terms, that avoids the necessity of "gravity traps" inherent in Moon or Mars landings, and the sort of useless technology that helps to perpetrate boondoggle exploits of most of U.S.'s eventual abysmally expensive budgeting, (by both our NASA and Congress), should help to bring about a new "gold rush", as long as our most popular, yet most monstrously prohibitive mountain of Congressional pork and anti-space rhetoric is overcome - by a hugely massive leap into overcoming the curse of super-heavy lift, earth-to-orbit technology, that so many at the Fed seem to overlook. If this (simple enough) task were overcome, by eliminating the barriers to space exploration on-the-cheap, then there not only would be more competition, but the asteroids would open up a new gold rush, not unlike what America experienced in the 1800's.
Vessels which bring more scanning and radar equipment are key for an initial flyby, to be followed up later with mining and cargo ships. A robotic flyby would consist of a radar system passing the data from a matched filter to a subsystem, referred to as a Detection Processor (DP), that accomplishes data compression by comparing the matched filtered data to a threshold. The potential targets (i.e., those that exceed the threshold) are flagged and the remaining data may be rejected. A block diagram of one possible general DP structure is shown here:
At the input of the DP is the MCA, or Multi-Channel Analyzer, which involves a FWD radix-4 and INVERSE radix-4 pipeline FFT. After the MCA, is a magnitude calculation which involves a subsystem that approximates the magnitude to the I and Q samples, where I is the intensity of the signal and Q is the number of samples over the block size. Next an amplitude estimator calculates an estimate of the peak amplitude of the signal based upon the amplitude of the three nearest samples.
The constant false alarm rate (CFAR) subsystem provides an estimate of the ambient noise or clutter level so that the threshold can be varied dynamically to stabilize the false alarm rate. The threshold logic unit selects which of several possible thresholds is to be compared with the estimated signal amplitude thru the CFAR or Multi-Channel Analyzer.
There used to be an interesting CFAR data site that listed CFAR processing code, but the link has since expired. However, there are some very unique locations for downloading software to calculate CFAR:
Synthetic aperture radar is a bit more complicated. A typical scintillation circuit diagram is given here:
A Monoline Crystal Assembly which includes a high resolution NaI(TI) crystal, a photomultiplier tube, an internal magnetic/light shield and a chrome plated aluminum housing. Specifications (were): Resolution approximately 8% at 662 keV of Cs-137, Window 0.02 in. aluminum, density 147.9 mg/cm^2, Reflector: oxide 1/16 in. thick, density 88 mg/ cm^2, Magnetic/Light Shield: Conetic lined steel, Typical Operating Voltages: Cathode to Anode +1100 V DC, Dynode to Dynode: + 80 V DC, Cathode to Dynode: + 150 V DC
The pulse is further amplified and analyzed by a multichannel pulse height selector (referring to the MCA component, older pic here: