GB1562185A - Detecting arrangements - Google Patents
Detecting arrangements Download PDFInfo
- Publication number
- GB1562185A GB1562185A GB3453275A GB3453275A GB1562185A GB 1562185 A GB1562185 A GB 1562185A GB 3453275 A GB3453275 A GB 3453275A GB 3453275 A GB3453275 A GB 3453275A GB 1562185 A GB1562185 A GB 1562185A
- Authority
- GB
- United Kingdom
- Prior art keywords
- radiometer
- detecting
- detecting arrangement
- arrangement
- focussing
- 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
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V8/00—Prospecting or detecting by optical means
- G01V8/005—Prospecting or detecting by optical means operating with millimetre waves, e.g. measuring the black losey radiation
Landscapes
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- Geophysics (AREA)
- Geophysics And Detection Of Objects (AREA)
- Radiation Pyrometers (AREA)
Description
(54) IMPROVEMENTS IN OR RELATING TO DETECTING
ARRANGEMENTS
(71) We, THE PLESSEY COMPANY
LIMITED, a British Company, of 2/60
Vicarage Lane, Ilford, Essex, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to detecting arrangements and relates more specifically to detecting arrangements for detecting metallic objects.
According to the present invention there is provided a detecting arrangement for detecting metallic objects, the detecting arrangement comprising radiometer means having scanning means associated with it for causing it to scan a required area, means operable on the output of the radiometer means for affording an indication of radiometric temperature anomalies in the scanned area which are indicative of metallic objects therein, and forming means for focussing the radiometer means.
In carrying out the invention it may be arranged that the detecting arrangement operates at microwave frequencies.
In one arrangement according to the invention it may be arranged that the focussing means comprises a parabolic reflector having a front feed, the front feed being preferably adjustable for varying the focus of the focussing means.
In one preferred arrangement it may be arranged that the output of the radiometer means is applied to display means, which may conveniently incorporate a storage display tube and in another preferred arrangement it may be arranged that the output of the radiometer means is applied to processing means, the processing means preferably including a computer processor.
In an especially contemplated arrangement it may be arranged that the scanning means may be effective for causing the radiometer means to be mechanically scanned in azimuth and elevation, and in another arrangement the scanning means may be effective for causing the radiometer means to be mechanically scanned in one plane e.g. elevation and electronically scanned in the other plane e.g. azimuth.
In the microwave region, metals have an emissivity of substantially zero and consequently they reflect rather than emit.
When a metallic object is embedded in a background of a material of higher emissivity e.g. soil or vegetation, its presence can be inferred by measuring the brightness temperature (radiometric) change associated with the two emissivities.
Thus in the open air, a metal object on a person or in a bag will reflect the sky temperature and will produce an anomolous cold spot. The object of the present invention is to detect the apparent brightness temperature and to process this to locate temperature anomalies and therefore metallic objects.
An exemplary embodiment of the invention will now be described. The detection of brightness temperature is effected by a microwave radiometer which is arranged to scan an area, the output of the radiometer being processed, conveniently using computer techniques, in order to locate temperature anomalies. The microwave radiometer may take any convenient form but typically may operate in accordance with the well known Dicks switch principle in the 15GHz band, with an
R.F. bandwidth of 0.8 GHz and a temperature resolution of 0.4so r.m.s. The radiometer may incorporate a parabolic antenna with a front feed which is preferably adjustable so that the beam can be focussed to the range of interest.The antenna of the radiometer is arranged to scan, either mechanically, electronically, or electromechanically e.g. mechanically scanned in elevation and electronically scanned in azimuth, a prescribed area and the radiometer output (proportional to brightness temperature) may be recorded together with data which corresponds to the pointing of the antenna or alternatively may be displayed on a storage tube type display.
The recorder radiometer output together with the positional data may then be subjected to a computer processing operation in which the raw data is first arranged in the form of a rectanular grid.
This is then subjected to various two dimensional signal processing techniques for enhancement and target detection.
Gross temperature trends can be removed by the use of a 2-dimensional Fast Slant
Transform. Various enhancement techniques may be used including filtering in the
Fast Fourier Transform frequency domain and the Hadamard sequency domain. Also techniques in which rectangular grid patterns are compared to obtain composite data arrays coveniently by the subtraction of similar images to detect significant temperature anomolies.
As well as being used for the detection of small, low emissivity objects in high emissivity backgrounds, the detecting technique described may be used for perimeter monitoring at ranges beyond that suitable for infra-red systems and also possibly for the detecting of people crossing a fixed beam looking at both natural and artificial cold spots.
WHAT WE CLAIM IS:
A detecting arrangement for detecting
metallic objects, the detecting arrangement comprising radiometer means having scanning means associated with it for causing it to scan a required area, means operable on the output of the radiometer means for affording an indication of radiometric temperature anomalies in the scanned area which are indicative of metallic objects therein and focussing means for focussing the radiometer means.
2. A detectingarrangement as claimed in claim 1, which operates at microwave frequencies.
3. A detecting arrangement as claimed in claim 1 or 2, in which the focussing means comprises a parabolic reflector having a front feed.
4. A detecting arrangement as claimed in claim 3, in which the front feed is adjustable for varying the focus of the focussing means.
5. A detecting arrangement as claimed in any preceding claim, in which the output of the radiometer means is applied to display means.
6. A detecting arrangement as claimed in claim 5, in which the display means incorporates a storage display tube.
7. A detecting arrangement as claimed in any of claims 1 to 4, in which the output of the radiometer is applied to processing means.
8. A detecting arrangement as claimed in claim 7, in which the processing means includes a computer processor.
9. A detecting arrangement as claimed in any preceding claim, in which the scanning means is effective for causing the radiometer means to be mechanically scanned in azimuth and elevation.
10. A detecting arrangement as claimed in any preceding claim, in which the scanning means is effective for causing the radiometer means to be mechanically scanned in one plane e.g. elevation and electronically scanned in the other plane e.g. azimuth.
12. A detecting arrangement substantially as hereinbefore described.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (1)
- **WARNING** start of CLMS field may overlap end of DESC **.together with data which corresponds to the pointing of the antenna or alternatively may be displayed on a storage tube type display.The recorder radiometer output together with the positional data may then be subjected to a computer processing operation in which the raw data is first arranged in the form of a rectanular grid.This is then subjected to various two dimensional signal processing techniques for enhancement and target detection.Gross temperature trends can be removed by the use of a 2-dimensional Fast Slant Transform. Various enhancement techniques may be used including filtering in the Fast Fourier Transform frequency domain and the Hadamard sequency domain. Also techniques in which rectangular grid patterns are compared to obtain composite data arrays coveniently by the subtraction of similar images to detect significant temperature anomolies.As well as being used for the detection of small, low emissivity objects in high emissivity backgrounds, the detecting technique described may be used for perimeter monitoring at ranges beyond that suitable for infra-red systems and also possibly for the detecting of people crossing a fixed beam looking at both natural and artificial cold spots.WHAT WE CLAIM IS: A detecting arrangement for detecting metallic objects, the detecting arrangement comprising radiometer means having scanning means associated with it for causing it to scan a required area, means operable on the output of the radiometer means for affording an indication of radiometric temperature anomalies in the scanned area which are indicative of metallic objects therein and focussing means for focussing the radiometer means.2. A detectingarrangement as claimed in claim 1, which operates at microwave frequencies.3. A detecting arrangement as claimed in claim 1 or 2, in which the focussing means comprises a parabolic reflector having a front feed.4. A detecting arrangement as claimed in claim 3, in which the front feed is adjustable for varying the focus of the focussing means.5. A detecting arrangement as claimed in any preceding claim, in which the output of the radiometer means is applied to display means.6. A detecting arrangement as claimed in claim 5, in which the display means incorporates a storage display tube.7. A detecting arrangement as claimed in any of claims 1 to 4, in which the output of the radiometer is applied to processing means.8. A detecting arrangement as claimed in claim 7, in which the processing means includes a computer processor.9. A detecting arrangement as claimed in any preceding claim, in which the scanning means is effective for causing the radiometer means to be mechanically scanned in azimuth and elevation.10. A detecting arrangement as claimed in any preceding claim, in which the scanning means is effective for causing the radiometer means to be mechanically scanned in one plane e.g. elevation and electronically scanned in the other plane e.g. azimuth.12. A detecting arrangement substantially as hereinbefore described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB3453275A GB1562185A (en) | 1976-08-11 | 1976-08-11 | Detecting arrangements |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB3453275A GB1562185A (en) | 1976-08-11 | 1976-08-11 | Detecting arrangements |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1562185A true GB1562185A (en) | 1980-03-05 |
Family
ID=10366805
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB3453275A Expired GB1562185A (en) | 1976-08-11 | 1976-08-11 | Detecting arrangements |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1562185A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997025633A1 (en) * | 1996-01-11 | 1997-07-17 | Lockheed Martin Corporation | Vehicle detection radiometer |
| CN113671476A (en) * | 2021-07-27 | 2021-11-19 | 杭州电子科技大学 | Novel passive millimeter wave imaging method |
-
1976
- 1976-08-11 GB GB3453275A patent/GB1562185A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997025633A1 (en) * | 1996-01-11 | 1997-07-17 | Lockheed Martin Corporation | Vehicle detection radiometer |
| CN113671476A (en) * | 2021-07-27 | 2021-11-19 | 杭州电子科技大学 | Novel passive millimeter wave imaging method |
| CN113671476B (en) * | 2021-07-27 | 2024-04-02 | 杭州电子科技大学 | Novel passive millimeter wave imaging method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PE20 | Patent expired after termination of 20 years |
Effective date: 19960810 |