STATISTICAL DESIGN AND PERFORMANCE OF HIGH-SENSITIVITY FREQUENCY-FEEDBACK RECEIVERS
Abstract
A design theory and an analytical threshold determination are presented for a high-sensitivity frequency-feedback receiver. Current interest in high-sensitivity receivers for frequency modulation is centered around two implementations of the device: phase-lock and frequency-feedback. The derivation of quasi-linear model for the frequency-feedback receiver, for the situation of Gaussian signals and noise, is presented. A statistical optimization is then performed giving the loop transfer function and threshold performance for a maximum sensitivity receiver. The design theory is based on a single threshold concept discarding the previous twin threshold approach. It is shown that in an optimum design the modulation error is less than 1 rad. This allows the use of a narrow-band i-f filter and obviates the need to consider threshold characteristics of the discriminator within the loop. A significant result of this analysis is that al though the quasi-linear receiver models differ in detail, threshold for a maximum sensitivity FM feedback and phase-lock receiver is identical. It was found that in FM feedback, as previously determined by Develet for the phase-lock reveiver, threshold occurs at 10 log 10 (e) 4.34 db above the ultimate limit determined by information theory arguments. This 4.34 db degradation is ind pendent of modulation index.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 31, 1963
- Accession Number
- AD0408639
Entities
People
- Jean A. Develet
Organizations
- The Aerospace Corporation