X Band Receiver for Spaceborne FMCW Radar Altimeter for Gaganyaan
Bibliographic record
Abstract
This paper presents the design and development of space grade X-band receiver subsystem which will be used in radar altimeter sensor of a lander craft. The receiver provide a low noise figure of$\mathbf{5 d B}$, high gain of$\mathbf{8 5 d B}$over a wide input dynamic range of- 25 dBm to -100 dBm. As the altimeter has to operate till the lander touch down, the receiver is designed to handle a maximum input power of +15 dBm. The receiver is realized in coherent configuration with 240 MHz signal bandwidth and delivers in-phase and quadrature-phase IF output. The transmit output, a$9780 \pm 120 \text{MHz}$FM-CW signal, is sampled as an LO to the receiver. The received FM-CW input signal is quadrature demodulated using the LO. This deramping of the received signal results in a beat frequency which is proportional to the altitude. The demodulated signal exhibits amplitude and phase imbalance of 0.5 dB and 5°. The receiver is characterized over an operating temperature range of$-15^{\circ} \mathrm{C}$to 55° C. The receiver has been realized using microwave integrated circuits (MIC) & monolithic microwave integrated circuits (MMIC). The receiver package has dimensions of 192.9$\text{mm} \times 205.8 \text{mm} \times 38.6 \text{mm}$, weight less than 1.2 kg, and DC power consumption of 0.8 Watts.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.006 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".