(HP67/97) RADAR  Speckle Target Calculations

01262019, 07:29 PM
Post: #1




(HP67/97) RADAR  Speckle Target Calculations
An extract from Turbulence Effects …, MIT, TST33, 1979 JUL (98 pages).
… programs for performing speckle target calculations on … HP67, HP97 programmable calculators … included in an Appendix … APPENDIX. PROGRAMMABLE HAND CALCULATOR PROGRAMS pg87 BEST! SlideRule 

01272019, 08:29 AM
(This post was last modified: 01282019 07:23 PM by StephenG1CMZ.)
Post: #2




RE: (HP67/97) RADAR  Speckle Target Calculations
Archive.org seems to be unreachable from the uk... Using Vodafone.
Update: Rather than simply failing, Vodafone now reports an agerelated block to archive.org (unless a credit card is provided). Stephen Lewkowicz (G1CMZ)... USA's changing goals In 1960s, delivering a man to the Moon... In 2020s, delivering a vote to the electors. 

01272019, 11:59 AM
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RE: (HP67/97) RADAR  Speckle Target Calculations
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01272019, 01:18 PM
Post: #4




RE: (HP67/97) RADAR  Speckle Target Calculations
(01272019 08:29 AM)StephenG1CMZ Wrote: Archive.org seems to be unreachable from the uk... Using Android and Vodafone. Also available at Turbulence Effects … (dtic.mil) BEST! SlideRule 

01272019, 06:15 PM
Post: #5




RE: (HP67/97) RADAR  Speckle Target Calculations
From page 13.
Eq. (11) becomes \(P_D=\frac{1}{\sqrt{\pi}} \int_{\infty}^{\infty} \: d\tau \: e^{\tau^2} \: P_F \: ^{\frac{1}{1 \, + \, CNR_s \, e^{2\sigma(\tau\sqrt{2}\sigma)}}}\) \((21)\) Eq. (21) has a form suitable for GaussianHermite quadrature. A 16point quadrature provided sufficient accuracy for \(\sigma^2 \leq 0.2\). For larger \(\sigma^2\) values the number of quadrature points was increased to 32. From APPENDIX, page 87. PROGRAMMABLE HAND CALCULATOR PROGRAMS Evaluation of the speckle target detection probability Eq. (21 ) is straightforward and yields excellent accuracy for quadratures with a relatively small number of points. This, coupled with the fact that most objects exhibit a significant diffuse reflection component at optical and infrared wavelengths, has prompted us to develop a program suitable for evaluation on a programmable hand calculator. In Table 21 we detail a program usable with either a HewlettPackard HP67 or HP97 calculator. This program calculates \(P_D(CUR_s;P_F,\sigma^2)\) for \(P_F\) stored in register A, \(\sigma^2\) stored in register B, and \(CNR_s\) entered as \(x\) using an 18point GaussianHermite quadrature. The quadrature points and weighing coefficients are entered via a data card. Computation time of this program is roughly 60 seconds and the relative accuracy in \(P_D\) is better than about 0.3%, for \(\sigma^2 = 2.0\) and improves rapidly as \(\sigma^2\) decreases. … The preceding programs were also modified for use with a HewlettPackard HP29C calculator. The modified programs are detailed in Table 22. Because of the larger number of storage registers available, a 24—point GaussianHermite quadrature was used. Computation time of this program is roughly 75 seconds and the relative accuracy in \(P_D\) is approximately 0.03% for \(\sigma^2 = 2.0\) and improves rapidly as \(\sigma^2\) decreases. Nodes and Weights These tables were calculated with the Nodes and Weights of GaussHermite Calculator. n = 18 Code: 1 0.2582677505190967592581 0.4834956947254555528764 n = 24 Code: 1 0.2244145474725155851511 0.4269311638686992496532 It's interesting to note that these values were arranged differently in the registers of the HP67 and the HP29. In case of the HP67 the primary and secondary banks were swapped using the P<>S command. But since these registers were only addressed indirectly the same approach as for the HP29 could have been used. Efficiency Both program could be improved, though I consider the 2nd one for the HP29 slightly better. At least they knew that they could swap \(x\) and \(y\): HP67 Code: 050 STO D HP29 Code: 047 RCL 3 It appears they were not aware of the LAST X command. Both programs use: Code: RCL B The register B contains the parameter \(\sigma^2\) which is constant during the calculation. They could have stored \(\sigma\) instead of calculating the square root twice in the loop again and again. Cheers Thomas 

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