Abstract: The remote sensing clutter’s simulation widely applies in the remote sensing image formation, the electronic countermeasure and so on related domain. The article uses TMS320C64x the DSP processor basis real-time reconnaissance gain the remote sensing parameter to carry on the real-time clutter signal the simulation production, has the big relevance with the gross data comparison.
Key word: Clutter; DSP; TMS320C64x
1 introduction
When surveys located in the land or the sea level goal, not only the receive has the goal echo, moreover superimposes has does not need to shine the region the echo, this part of echoes are called in the radar terminology the clutter. The clutter has the major impact on the remote sensing equipment’s examination performance. Using rapidly expand’s digital technique, the simulation produces now satisfies the specific distribution the clutter, regarding the equipment performance appraisal, the denoising image formation, the electronic countermeasure application has the very strong use value. In order to satisfy the simulation production clutter the distributed characteristic as well as the timely request, this article uses TI Corporation TMS320C64x, in the gain needs the remote sensing plant parameter under the condition the real-time production to satisfy the specific distribution the simulation clutter signal, summarizes the clutter signal with the experience to compare, both basic similar, may satisfy the real-time simulation the request.
2 clutter model establishment
The clutter produces the mechanism to be complex, relies on the factor to be numerous, including radar’s working condition (incidence angle, transmitting frequency, polarization, resolution and so on) as well as the background condition (for example ground vegetation condition, ground roughness, sea condition, wind speed, wind direction and so on), is a stochastic process. The complete description is difficult, highlights part of key characteristics frequently in the practical application. In the nowadays clutter’s descriptive study, the key point is the clutter scope distributed and the related characteristic (or spectrum).
The clutter simulation, is uses one fast algorithm to produce both satisfies certain scope distribution, and satisfies the certainly related characteristic random sequence. At present is mainly carries on to the clutter sequence’s research by the steady stochastic process modelling, in many situations, the Doppler radar the clutter signal which receives under the downward looking condition is the oscillation amplitude obeys Rayleigh to distribute, the phase obedience uniform distribution random signal, namely its real part and the imaginary component satisfy the Gaussian distribution, because Gaussian distribution signal after linear substitution the statistical property maintains invariable, therefore may produce has the specific power spectrum, the scope to conform to Rayleigh to distribute, the phase in [O,2π] the sector uniform distribution clutter time series.
This article produces the clutter signal sequence form is as follows:
3 clutter simulator design
3.1 TMS320C64x unique feature
TMS320C64x is the TI Corporation 64 series digital signal processor. The instruction cycle is shortest may reach 1.67 ns, the clock rate may reach 600MHz, is compatible with 62 series softwares, and 6415 and 6416 uses the same pin structure with the homologous series, each second highest may carry out 4800 M instructions (MI/s).
The TMS320C64x central processor has 64 32 general memories and 8 independent arithmetical units, uses Veloci TI.2 including 2 32 multipliers and 6 to expand the structure 32 arithmetic logic unit (ALU). TMS320C64x uses the Ll/L2 two level of memory structures. Respectively is 128 kb the LlP program memory and 128 kb the L1D data-carrier storage as well as 8 Mb the L2 addressable periphery memory. On piece periphery component including 3 multichannel serial port (McB-SPs). 1 programmable main engine control port (HPI). 1 general input/output port (GPIO), as well as 2 exterior memory interfaces (EMI-FA64 position, EMIFBl6 position). Clutter simulator hardware architecture as shown in Figure 1.
The clutter simulation production algorithm needs the radar parameter to transmit orally into the TMS320C6414 central processing module by McBSPs, the central processing module acts according to this parameter through clutter simulation algorithm production simulation clutter each parameter. Because TMS320C64x unique EDMA (strengthens direct procedure addressing) the structure, the following plant parameter will not have the interrupt to the central processor module clutter production algorithm, raised the counting yield greatly. The parameter which produces after the computation spreads to the external storage unit through the EMIFA module, the TMS320C64x EMIFA module uses 64 bit parallel connection, the transmission speed satisfies the live transmission request completely.
3.2 real-time processing operand analysis
In Bunsen photometer becomes in the algorithm, if must cover is away from the unit integer is M, if every other K unit carries on a disturbance production (dependent unbalance to realize the entire cover), and these M distance unit approximate is M/(NK) and so on compared to the sector, then the computation load (take most cover unit consideration) probably as 2×(15M/(NK) 2) multiplication, 2x(11M/(NK) 1) addition. Other pulse data’s operand may be approximate is 1 multiplication. If 20μs pulse width, 20μs cover, 100 MHz band widths, K=10, N=500, then needs 10 times the multiplication, 8 additions. The TMS320C6414 each clock cycle may carry on 2 time 16 multiplications and 6 32 additive operations, each second clock rate may reach 600MHz, may satisfy the true-time operation request.
4 clutter simulation algorithm realizes
TMS320C64x uses with the C62x completely compatible software and the platform, has the greatly strengthened probability, and uses Veloci which strengthens the TI.2 order structure, causes to the higher order language translation efficiency big enhancement, is advantageous for the development and the debugging. Clutter production algorithm diagram as shown in Figure 2.
5 simulation results and comparison
For inspection system performance, supposition transmitter transmitting message initial frequency 10 GHz, pulse widths 5 μs, pulse recurrence period 10 μs, modulation slope 1×1013 Hz/s, then baseband signal’s band width is 50 MHz, latency resolution 20 ns.
The simulation production’s clutter time domain signal and experience signal time domain image comparison as shown in Figure 3. The simulation production clutter signal frequency spectrum and experience signal frequency spectrum comparison as shown in Figure 4.
6 concluding remark
The clutter simulation is an echo simulation system’s part, in the equipment evaluation, the denoising image formation, the electronic countermeasure and so on related domain has the strong usability. Uses the TMS320C64x simulation clutter signal, may the real-time production satisfy certain scope distribution under certain bandwidth condition simultaneously to have the certainly related characteristic clutter signal, has the strong relevance with the experience signal.
