US 7,835,421 B1
Electric detector circuitGeneral
US 7,835,421 B1
Electric detector circuit
Tech Center:
3600 Transportation, Construction, Electronic Commerce, Agriculture, National Security and License and Review
Examiner:
Isam Alsomiri
Art Unit:
3662 Computerized Vehicle Controls and Navigation, Radio Wave, Optical and Acoustic Wave Communication, Robotics, and Nuclear Systems
Agent:
Inventors:
GEOFFREY C. BAGLEY
Assignee:
Priority:
01/04/83
Filed:
01/22/90
Granted:
11/16/10
Expiration:
12/19/22
Abstract
A detector is provided for determining the carrier frequency of symmetrical, direct sequence, spread spectrum (DSSS) signals. The DSSS signal is divided between two signal paths, one path containing a frequency band inverter and the other a time delay unit. The outputs of the inverter and delay unit are connected to a multiplier and thence to a filter isolating the difference frequency of the inverted and non-inverted DSSS signals. The frequency inverter comprises an input band pass filter, a local oscillator, a second multiplier and a band pass filter. Frequency inversion is carried out by the multiplier and filter providing the difference signal between the local oscillator signal and the DSSS signal. The difference frequency provided by the filter is the known local oscillator frequency minus twice the DSSS carrier frequency.