| タイトル | The MRIS feasibility study |
| 本文（外部サイト） | http://hdl.handle.net/2060/19940008331 |
| 著者（英） | Cross, Aubrey E.; Neece, Robert T.; Schrader, James H. |
| 著者所属（英） | NASA Langley Research Center |
| 発行日 | 1993-06-01 |
| 言語 | eng |
| 内容記述 | The Microwave Reflectometer Ionization Sensor (MRIS) is an instrument being developed for use in detecting and ranging of electron density layers in the reentry plasma of a space transfer vehicle. The rationale for the selection of the Double Sideband Suppressed Carrier (DSBSC) system used in the feasibility study for the MRIS is presented. A 25 GHz single-oscillator system and a 220 GHz double-oscillator system are described. The 25 GHz system was constructed and tested in the laboratory and test results are presented. As developed, the system employs a sideband spacing of 160 MHz. Based on an estimated electromagnetic wave velocity in the plasma, a round-trip phase shift measurement accuracy of +/- 7.6 degrees was required for the desired +/- 1/2 cm distance measurement accuracy. The interaction of parallel ground and reflecting planes produces interference that prevents the basic DSBSC system from meeting the accuracy goal so a frequency modulation was added to the system to allow averaging of the measured phase deviation. With an FM deviation of +/- 1 GHz, laboratory measurements were made for distances from 5 to 61 cm tip free space. Accounting for the plasma velocity factor, 82 percent of the data were equal to or better than the desired accuracy. Based on this measured result a sideband spacing to 250 MHz could be expected to yield data approximately 96 percent within the accuracy goal. |
| NASA分類 | COMMUNICATIONS AND RADAR |
| レポートNO | 94N12804
NASA-TM-107763
NAS 1.15:107763 |
| 権利 | No Copyright |
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