Digital memory system

• US 4,700,327 A
• Filed: 12/31/1984
• Issued: 10/13/1987
• Est. Priority Date: 12/31/1984
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Hilton, Richard F.
• Primary Examiner(s): Shaw, Gareth D.
• Assistant Examiner(s): Eakman, Christine M.
• Application Number:
  US06/688,112
• Time in Patent Office: 1,016 Days
• Field of Search: 364/200, 364/900, 375/61, 375/78, 375/94, 375/122, 455/75, 455/87, 455/86, 455/18
• US Class Current: 369/6
• CPC Class Codes: G11C 27/02 Sample-and-hold arrangements G11C27/04 takes precedence

Abstract

An apparatus for digitally storing samples of a received signal having a carrier frequency component and an angle modulation component and for subsequently reconstructing such received signal from the stored samples. The system includes a pair of digital memory systems, a first one storing samples of a signal fed thereto at a relatively high rate, and a second one storing samples of a signal fed thereto at a relatively low rate. The received signal is coupled to the first memory system for a relatively short period of time for storing therein samples representative of the carrier frequency component. The received signal is also coupled to the second memory system for a relatively long period of time for storing therein samples representative of the angle modulation component. The samples stored in the first memory system representative of the carrier frequency component are cyclically retrieved over a relatively long period of time and at the relatively high rate, while the samples stored in the second memory system representative of the angle modulation component are retrieved over the relatively long period of time and at the relatively low rate. The samples cyclically retrieved from the first memory system are combined with the samples retrieved from the second memory system to produce a composite signal, such composite signal being reconstruction of the received signal. With such arrangement, the memory storage efficiency is increased by the ratio of the bandwidth of the wideband memory to the bandwidth of the narrow band memory.

Claims

1. An apparatus for digitally storing samples of a received signal having a carrier frequency component and an angle modulation component and for subsequently reconstructing such received signal from the stored sample comprising:

(a) a pair of digital memory systems, a first one thereof storing samples of a signal fed thereto at a relatively high rate and, a second one of the pair of memory systems storing samples of a signal fed thereto at a relatively low rate;

(b) means for coupling the received signal to the first one of the pair of digital memory systems for a relatively short period of time for storage in such first of one of the pair of memory systems samples representative of the carrier frequency component, for coupling the received signal to the second one of the pair of memory systems for a relatively long period of time for storage in such second one of the pair of memory systems samples representative of the angle modulation component of the received signal, and for cyclically retrieving, over a relatively long period of time and at the relatively high rate, the samples stored in the first one of the pair of memory systems representative of the carrier frequency component while retrieving, over the relatively long period of time and at the relatively low rate, the samples stored in the second one of the pair of memory systems representative of the angle modulation component; and

,

(c) means, for mixing the samples cyclically retrieved from the first one of the pair of memory systems with the samples retrieved from the second one of the memory systems to produce a composite signal, such composite signal being a reconstruction of the received signal.

2. In combination:

(a) a pair of digital memory systems, a first one thereof storing samples of a signal fed thereto at a relatively high rate and a second one of the pair of memory systems storing samples of a signal fed thereto at a relatively low rate;

(b) means for coupling an input signal to the first one of the pair of digital memory systems;

(c) a mixer;

(d) means for coupling the input signal to the mixer;

(e) means for;

enabling storage in such first one of the pair of digital memory systems samples of an initial portion of the input signal;

for cyclically retrieving the samples stored in the first one of the pair of memory systems at the relatively high rate; and

for electrically coupling such cyclically retrieved samples to the mixer simultaneously as a portion of the input signal subsequent to the initial portion of the input signal is also electrically coupled to the mixer;

(f) means for coupling the output of the mixer to the second one of the pair of memory systems; and

(g) means for enabling storage in such second one of the pair of memory systems samples of the signal produced at the output of the mixer, such samples being stored at the relatively low rate.

3. The combination recited in claim 2 including an additional mixer fed by the outputs of the pair of digital memory systems for combining samples cyclically retrieved from the first one of the pair of memory systems with samples retrieved from the second one of the pair of memory systems.

4. In combination:

(a) means for directing an input signal to a pair of signal channels;

(b) a pair of digital memory systems, each one being disposed in a corresponding one of the pair of signal channels;

(c) a combiner coupled to the output of the pair of digital memory systems; and

(d) a mixer, disposed in the second one of the pair of the channels and fed by the output of the first one of the pair of digital memory systems disposed in the first one of the pair of signal channels, the output of such mixer being coupled to an input of the second one of the pair of digital memory systems.