(12) Patent Application Publication (10) Pub. No.: US 2016/ A1

Transcription

1 (19) United tate (12) Patent Appliation Publiation (10) Pub. No.: U 2016/ A1 NOGA et al. U A1 (43) Pub. Date: De. 15, 2016 (54) (71) (72) (21) (22) APPARATU FOR EFFICIENT FREQUENCY MEAUREMENT Appliant: GOVERNMENT OF THE UNITED TATE A REPREETNED BY THE ECRETARY OF THE AIR FOR, ROME (IT) Inventor: ANDREW J. NOGA, ROME, NY (U); DANIEL L. TEVEN, MARCY, NY (U) Appl. No.: 14/737,542 Filed: Jun. 12, 2015 Publiation Claifiation (51) Int. Cl. G06F 7/4 ( ) (52) U.. Cl. CPC... G06F 17/142 ( ) (57) ABTRACT An apparatu for effiient frequeny meaurement (JKLMTM) whih provide preie and aurate meaure ment of a ingle input tone frequeny and/or multiple eparable input tone frequenie. Tone eparability an be ahieved by proper eletion of the parameter N, the ample length of the DFT/FFT. ((t) O f 02 X. In DFT or FFT Xa k eletor ka Xak pa a-a-a-a- Xnk X k X, k + 1-2X, k,

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11 U 2016/ A1 De. 15, 2016 APPARATU FOR EFFICIENT FREQUENCY MEAUREMENT TATEMENT OF GOVERNMENT INTERET The invention deribed herein may be manufa tured and ued by or for the Government for governmental purpoe without the payment of any royalty thereon. BACKGROUND OF THE INVENTION 0002 Prior art i repreented by the well-known direte Fourier tranform (DFT) or it ae-peifi effiient imple mentation, the fat Fourier tranform (FFT). Effiient ingle and multi-tone frequeny meaurement an be ahieved uing the prior art. However, even though uh prior art i effiient and ha deirable noie-redution propertie, diret frequeny meaurement auray i limited to 27C/N radian. OBJECT AND UMMARY OF THE INVENTION It i therefore an objet of the preent invention to provide an apparatu that improve the auray of fre queny meaurement It i a further objet of the preent invention to provide an apparatu that perform aurate frequeny mea urement without the introdution of bia and diretiza tion It i till a further objet of the preent invention to provide an apparatu that ahieve frequeny meaurement with greater than 27 L/N radian auray It i till a further objet of the preent invention to provide an apparatu that ahieve frequeny meaurement with low proe omplexity Briefly tated, the preent invention ahieve thee and other objet through an apparatu for frequeny mea urement (JKLMTM) whih provide preie and aurate meaurement of a ingle input tone frequeny and/or mul tiple eparable input tone frequenie. Tone eparability an be ahieved by proper eletion of the parameter N, the ample length of the DFT/FFT Aording to an embodiment of the invention, an apparatu for frequeny meaurement, omprie a ignal onditioner having an input and an output, an analog-to digital onverter having an input and an output; a parer having an input and an output; a Fourier Tranformer having an input and an output; a eletor having an input and an output; and a proeor having a ignal input, an output, and a oeffiient input, where an external analog ignal to be meaured i input into the input of the ignal onditioner, the output of aid ignal onditioner i onneted to the input of the analog-to-digital onverter; the output of aid analog to-digital onverter i onneted to the input of parer; the output of the parer onneted to the input of the Fourier Tranformer; the output of the Fourier Tranformer i on neted to the input of the proeor and to the input of the eletor; and where the output of the eletor i onneted to the oeffiient input of the proeor The above and other objet, feature and advan tage of the preent invention will beome apparent from the following deription read in onjuntion with the aom panying drawing, in whih like referene numeral deig nate the ame element. BRIEF DECRIPTION OF THE DRAWING 0010 FIG. 1 depit the preent invention, referred to hereinafter a a DFT/FFT-baed jakknife-loalized multi tone frequeny meaurement (JKLMTM) apparatu FIG. 2 depit an example meaurement perfor mane of the JKLMTM ompared to the Hanning-win dowed, peak-piked FFT. The input frequeny hown on the X-axi repreent the true frequeny, and the y-axi i the meaured frequeny; the input ignal i noie-free; the FFT ize i 128 ample FIG. 3 depit an example meaurement perfor mane of the JKLMTM ompared to the Hanning-win dowed, peak-piked FFT. The input frequeny hown on the X-axi repreent the true frequeny, and the y-axi i the meaured frequeny; the input ignal-to-noie power ratio i 9 db; the FFT ize i 128 ample FIG. 4 depit an example meaurement perfor mane of the JKLMTM ompared to the Hanning-win dowed, peak-piked FFT. The input frequeny hown on the X-axi repreent the true frequeny, and the y-axi i the meaured frequeny; the input ignal-to-noie power ratio i 6 db; the FFT ize i 128 ample FIG. 5 depit an example meaurement perfor mane of the JKLMTM ompared to the Hanning-win dowed, peak-piked FFT. The input frequeny hown on the X-axi repreent the true frequeny, and the y-axi i the meaured frequeny; the input ignal-to-noie power ratio i 3 db; the FFT ize i 128 ample FIG. 6 depit an example meaurement perfor mane of the JKLMTM ompared to the Hanning-win dowed, peak-piked FFT. The input frequeny hown on the X-axi repreent the true frequeny, and the y-axi i the meaured frequeny; the input ignal-to-noie power ratio i 0 db; the FFT ize i 128 ample FIG. 7 depit an example meaurement perfor mane of the JKLMTM ompared to the Hanning-win dowed, peak-piked FFT. The input frequeny hown on the X-axi repreent the true frequeny, and the y-axi i the meaured frequeny; the input ignal-to-noie power ratio i 9 db; the FFT ize i 64 ample FIG. 8 depit an example meaurement perfor mane of the JKLMTM ompared to the Hanning-win dowed, peak-piked FFT. The input frequeny hown on the X-axi repreent the true frequeny, and the y-axi i the meaured frequeny; the input ignal-to-noie power ratio i 9 db; the FFT ize i 32 ample FIG. 9 depit an example meaurement perfor mane of the JKLMTM ompared to the Hanning-win dowed, peak-piked FFT. The input frequeny hown on the X-axi repreent the true frequeny, and the y-axi i the meaured frequeny; the input ignal-to-noie power ratio i 9 db; the FFT ize i 16 ample. DETAILED DECRIPTION OF THE PREFERRED EMBODIMENT (0019. The preent invention i the DFT/FFT-baed jak knife-loalized multi-tone frequeny meaurement (JKLMTM) apparatu whih provide preie and aurate meaurement of a ingle input tone frequeny and/or, mul tiple eparable input tone frequenie. Here, tone eparabil ity an be ahieved by proper eletion of the parameter N. the ample length of the DFT/FFT. Pratial appliation of the JKLMTM of the preent invention inlude but i not

12 U 2016/ A1 De. 15, 2016 limited to tet and meaurement, where preie and aurate meaurement of tonal frequenie i needed Referring to FIG. 1, the DFT/FFT-baed jakknife loalized multi-tone frequeny meaurement (JKLMTM) apparatu i ompried of the omponent and ub-ompo nent a hown. Operation of the JKLMTM i a follow. An input ignal, X(t), i onditioned by Conditioner 101, ampled by Analog-to-Digital-Converter (ADC) 102 to form the equene Xn, and then pared into length N egment by Parer 103. Here, n i an indexing variable orreponding to time, and i integer valued. Likewie, m i an integer valued index reulting from the paring of Xn, orrepond ing to the egment number The mth egment input to the devie i deignated a Xin, and i proeed by omponent 201 whih per form an N-point Direte Fourier Tranform (DFT) or Fat Fourier Tranform (FFT). Xk. The integer index, 1kN. i the kth frequeny bin along the direte frequeny inde pendent variable. The output of omponent 201, Xk i input to both eletor 202 and ub-omponent 302 of omponent 301. eletor 202 identifie a et of frequeny indie, ko, for whih frequeny meaurement are to be determined. eletor 202 an, for example, be implemented a a threhold and detet proe, but i not limited to uh a proe Component 301 i a novel element in the apparatu and i now deribed in detail. For effiieny, the proeing in omponent 301 i performed for the et of value k-ko. Proeing in omponent 301 proeed a follow. ub omponent 302 determine the ratio, Rik (Xk-1-X, k+1)/(xk-1+xk+1-2xk). Thi erve a input to ub-omponent 303, whih determine rk=re{rik}, the real part of Rik. Completing the proeing tep, ub-omponent 304 output the modulo differene, wik -mod{k-rk.n}-1, for any k from 1 to N. Thi output an be aled, depending on the deired unit of the frequeny meaurement. Index hift deignated a either k-1 or k--1 in omponent 301 are performed in a irular fahion to be onitent with the propertie of direte Fourier tranform. Advantage of the Preent Invention 0023 Prior art i repreented by omponent 201 and 202 hown in FIG. 1. Effiient ingle and multi-tone frequeny meaurement an be ahieved uing the prior art. However, even though uh prior art i effiient and ha deirable noie-redution propertie, frequeny meaurement au ray i limited to 2L/N radian. The JKLMTM of the preent invention leverage the noie-redution propertie of om ponent 201 in ahieving inreaed frequeny meaurement auray FIG. 2 through FIG. 9 are example performane plot generated for variou enario, a imulated in the Matlab'TM environment. The baeline hoen for omparion i the peak-piked FFT. A een in FIG. 2, the peak-piked FFT i limited to integer-valued frequeny bin loation, and therefore only provide a diretized, biaed meaurement of the input frequeny. Converely, the JKLMTM performane i hown to give the orret meaurement, without intro duing bia and without diretization. Likewie, FIG. 3 through FIG. 9 are additional enario hoen to diplay the performane apability of the JKLMTM of the preent invention relative to the baeline peak-piked FFT. Note that a input ignal-to-noie power ratio dereae, the baeline perform erratially when the input ignal frequeny i near an FFT bin edge. Thi i problemati for the baeline performane, beaue the input frequeny i generally unknown, and ould be loated near uh a frequeny bin edge. In ontrat, the JKLMTM of the preent invention perform well in all frequeny range of potential interet. Alternative to the Preent Invention 0025 Variou mode of the invention an inlude oft ware implementation, firmware implementation, hardware implementation and/or hybrid (oftware/firmware/hard ware) implementation. Variation alo inlude peifi method of aomplihing the omponent and ub-ompo nent uh a uing look-up-table, Field Programmable Gate Array (FPGA), trigonometri identitie, ombining omponent or ub-omponent into mathematial equiva lent, et Having deribed preferred embodiment of the invention with referene to the aompanying drawing, it i to be undertood that the invention i not limited to thoe preie embodiment, and that variou hange and modi fiation may be effeted therein by one killed in the art without departing from the ope or pirit of the invention a defined in the appended laim. What i laimed i: 1. An apparatu for effiient frequeny meaurement, ompr11ng: a ignal onditioner having an input and an output; an analog-to-digital onverter having an input and an output; a parer having an input and an output; a Fourier Tranformer having an input and an output; a eletor having an input and an output; and a proeor having a ignal input, an output, and a oeffiient input, wherein, an external analog ignal to be meaured i input into aid input of aid ignal onditioner; the output of aid ignal onditioner i onneted to the input of aid analog-to-digital onverter, the output of aid analog-to-digital onverter i on neted to the input of aid parer; the output of aid parer i onneted to the input of aid Fourier Tranformer; the output of aid Fourier Tranformer i onneted to the input of aid proeor and to the input of aid eletor; and wherein the output of aid eletor i onneted to the oeffiient input of aid proeor. 2. The apparatu of laim 1, wherein aid parer pare the digital output of aid analog-to-digital onverter Xn into m data egment of length N, wherein the m aid egment i repreented a Xin. 3. The apparatu of laim 1, wherein aid Fourier Tran former perform an N-point Direte Fourier Tranform on Xn, reulting in Xk. wherein k i the k" frequeny bin along a direte frequeny independent variable, and Xk i the Direte Fourier Tranform of any aid data egment. 4. The apparatu of laim 1, wherein aid Fourier Tran former perform a Fat Fourier Tranform on Xin, reult ing in Xk, wherein

13 U 2016/ A1 De. 15, 2016 k i the k" frequeny bin along a direte frequeny independent variable, and Xk i the Fat Fourier Tranform of any aid data egment. 5. The apparatu of laim 1, wherein aid eletor elet a et of frequeny indie for whih frequeny meaure ment are to be performed. 6. The apparatu of laim 5, wherein aid eletor per form a threhold and detet funtion. 7. The apparatu of laim 4, wherein aid proeor perform a firt tep of proeing a ratio Rik repreented by and; input the reult into a eond tep of proeing. 8. The apparatu of laim 7, wherein aid proeor perform a eond tep of proeing rak repreented by and input the reult into a third tep of proeing. 9. The apparatu of laim 8, wherein aid proeor perform a third tep of proeing a frequeny meaure ment wik repreented by 10. The apparatu of laim 1, wherein aid apparatu omprie eletroni hardware. 11. The apparatu of laim 1, wherein aid apparatu omprie eletroni firmware. 12. The apparatu of laim 1, wherein aid apparatu omprie oftware. 13. The apparatu of laim 1, wherein aid apparatu omprie eletroni hardware, eletroni firmware, and oftware in ombination. k k k k k