Browse Prior Art Database

Digital Gain and Frequency Control

IP.com Disclosure Number: IPCOM000095686D
Original Publication Date: 1964-May-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Hopner, E: AUTHOR [+3]

Abstract

This receiver is for use in a communications system in which the actual transmission of information is preceded by a control signal at carrier frequency and of predetermined amplitude. The control signal serves as a standard by which the gain to the receiver and the frequency of the local oscillator can be set in order to properly receive the subsequently transmitted information.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 79% of the total text.

Page 1 of 2

Digital Gain and Frequency Control

This receiver is for use in a communications system in which the actual transmission of information is preceded by a control signal at carrier frequency and of predetermined amplitude. The control signal serves as a standard by which the gain to the receiver and the frequency of the local oscillator can be set in order to properly receive the subsequently transmitted information.

The received control signal operates the Schmitt trigger. The latter operates flip-flop 1 which opens gate 1 so as to allow oscillator f to step counter 1. Counter 1 drives a digital-analog (D to A) converter, the output of which serves as the automatic gain control (AGC) voltage for wide band amplifier 2. By operation of oscillator f and counter 1 the AGC output of the D to A converter rises until it reaches the value of the AGC voltage derived directly from the control signal. At this point, the comparator operate s to close gate 1, stopping counter 1, and freezing the output of the D to A converter so that wide band amplifier 2 is held at the desired gain during the subsequent transmission of information.

The output of the comparator also operates flip-flop 2 which opens gate 2 so as to allow oscillator f to step counter 2. Counter 2 drives a D to A converter, the output of which controls the frequency of a voltage controlled oscillator (VCO). The output of the VCO feeds a phase detector, the other input of which is the carrier frequency control sign...