THE CASCADE PHASE SHIFT MODULATOR EMPLOYING NEGATIVE FEEDBACK
Abstract
A novel low noise FM ramp generator to be used as a component of an FM system is described. The FM ramp is generated by means of a cascade phase shift modulator in a negative feedback loop which is followed by a frequency multiplier to provide the required output frequency deviation of 400 kc in 2 ms. The maximum permissible distortion of the FM output ramp measured as a departure from an ideally linear ramp is one per cent of the total ramp deviation. In analyzing the system behavior, special attention was given to those problem areas associated with linearity and noise. Measurements demonstrated that the generator meets the linearity requirements of the over-all FM system. The noise performance is more difficult to project. It appears that except in a limited band, some 10 to 20 kc on either side of the carrier, the noise requirements will be fully met. In this band the noise may exceed the specification for the FM system, but by no more than 6 db. A description of each component circuit, together with schematic diagrams and a step-by-step operating procedure, are included. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1961
- Accession Number
- AD0266511
Entities
People
- A. Boutross
- H. Stein
- L. Baum
Organizations
- Columbia University