A segmented matched filter for CDMA code synchronization in systems with Doppler frequency offset
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Bibliographic record
Abstract
This paper presents a segmented matched filter (SMF) for codephase acquisition in direct sequence spread spectrum systems. While conventional matched filters provide fast acquisition in the presence of high co-user noise, they are unable to handle significant carrier frequency offset (Doppler). This problem is alleviated by segmentation with non-coherent summation. The paper develops expressions to approximately relate the matched filter partitioning to the pre-detection filter and dwell time integrator of the conventional non-coherent correlator. It also investigates 1-bit versus 2-bit quantization. A mixed-signal application specific integrated circuit (ASIC) has been fabricated to implement a 512 chip SMF with half chip codephase resolution. The paper presents calculated and measured probability density functions (pdf) for the filter output decision variable for 10, 25, and 50 co-users with 0 to 20 kHz Doppler shift. For the example of a GPS receiver, expected acquisition time is shown as a function of multiple access interference and carrier Doppler shift.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 it