GB1336255A - Micro-wave intruder detector systems - Google Patents
Micro-wave intruder detector systemsInfo
- Publication number
- GB1336255A GB1336255A GB1336255DA GB1336255A GB 1336255 A GB1336255 A GB 1336255A GB 1336255D A GB1336255D A GB 1336255DA GB 1336255 A GB1336255 A GB 1336255A
- Authority
- GB
- United Kingdom
- Prior art keywords
- receivers
- transmitter
- comparator
- doppler
- alarm
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/50—Systems of measurement based on relative movement of target
- G01S13/52—Discriminating between fixed and moving objects or between objects moving at different speeds
- G01S13/56—Discriminating between fixed and moving objects or between objects moving at different speeds for presence detection
Landscapes
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Burglar Alarm Systems (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
1336255 Radar SHORROCK DEVELOPMENTS Ltd 14 March 1972 [19 March 1971] 7357/71 Heading H4D [Also in Division G4] In an intruder alarm a micro-wave field is provided in a protected area PA by at least one transmitter T1, signals reflected from objects in the protected area being picked up by two receivers R1, R2 each producing a Doppler signal, a comparator C being included to provide an alarm-initiating output when the Doppler signals from the two receivers R1, R2 are substantially alike. As shown, two transmitters T1, T2 operate at 10,000 MHz and prevent false alarms due to transmitter noise. The receivers R1, R2 are synchronized by a reference signal from the respective transmitter. The comparator may be responsive to Doppler frequency, phase or amplitude, and may feed an AND gate D1, D2, D3 which only provides an output to the alarm B in the presence of Doppler signals from both receivers and a similarity signal from the comparator. The use of two receivers prevents false alarms due to movement of small objects. The two transmitters T1, T2 may operate on the same or slightly differing frequencies. In Fig. 1 (not shown) only one transmitter is employed and the AND gate is omitted.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB735771 | 1971-03-19 |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1336255A true GB1336255A (en) | 1973-11-07 |
Family
ID=9831568
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB1336255D Expired GB1336255A (en) | 1971-03-19 | 1971-03-19 | Micro-wave intruder detector systems |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB1336255A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4112419A (en) * | 1975-03-28 | 1978-09-05 | Hitachi, Ltd. | Apparatus for detecting the number of objects |
GB2199715A (en) * | 1986-03-27 | 1988-07-13 | C S Jennings | Detection of metal and other materials |
GB2322029A (en) * | 1997-02-04 | 1998-08-12 | Plessey Semiconductors Ltd | Microwave vehicle alarm |
US5999090A (en) * | 1997-02-04 | 1999-12-07 | Mitel Semiconductor Limited | Alarm sensor and antenna arrangement |
-
1971
- 1971-03-19 GB GB1336255D patent/GB1336255A/en not_active Expired
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4112419A (en) * | 1975-03-28 | 1978-09-05 | Hitachi, Ltd. | Apparatus for detecting the number of objects |
GB2199715A (en) * | 1986-03-27 | 1988-07-13 | C S Jennings | Detection of metal and other materials |
GB2199715B (en) * | 1986-03-27 | 1990-11-21 | C S Jennings | Detection of metal and other materials |
GB2322029A (en) * | 1997-02-04 | 1998-08-12 | Plessey Semiconductors Ltd | Microwave vehicle alarm |
US5999090A (en) * | 1997-02-04 | 1999-12-07 | Mitel Semiconductor Limited | Alarm sensor and antenna arrangement |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed | ||
PLNP | Patent lapsed through nonpayment of renewal fees |