Double Quadrature Mixer for Adaptive System-Level Spur Cancellation in UWB Radios
Bibliographic record
Abstract
Direct Digital Synthesizers (DDS) are known to be very spurious due to the use of Digital-to-Analog Convertors (DAC).This thesis presents the phase behaviour of spurs of the commercial AD9912 DDS and its SpurKiller cancellation system.A great variation in spur-carrier phase offset and a large variation of over 20 dB in its increased Spurious-Free Dynamic Range (SFDR) was observed.As a result, an adaptive system is proposed using a Double Quadrature Mixer and a variable phase Local Oscillator (LO).This system is tested at an Intermediate Frequency (IF) of 1.2 GHz, simulating the input of an Ultra-Wideband (UWB) radio.In simulation, an increase in SFDR of 29 dB resulted.In system prototype, an increase in SFDR of 10 dB was achieved.The spur-carrier phase offset was found to be unrelated to the phase of the Double Quadrature LO to achieve maximum spur reduction.iii I would like to provide tremendous thanks to my supervisor, Dr. Jim Wight in his unique approach within the department towards combining academic and industrial research endeavours.Our relationship over seven years continues to grow.I hope to one day build a network in Ottawa as strong as his.Also, I would like to thank Dr. Dipak Roy, Angsuman Rudra, and all the staff at D-TA Systems for my unorthodox questions, approaches and innovations that I created over the 22 months I spent collaborating with them.They have been a great help financially, and educationally, maximizing my experience in advanced sensor processing.Their flexibility and understanding have been one of a kind.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".