GB1315873A - Telecommunications systems - Google Patents
Telecommunications systemsInfo
- Publication number
- GB1315873A GB1315873A GB2166571A GB2166571A GB1315873A GB 1315873 A GB1315873 A GB 1315873A GB 2166571 A GB2166571 A GB 2166571A GB 2166571 A GB2166571 A GB 2166571A GB 1315873 A GB1315873 A GB 1315873A
- Authority
- GB
- United Kingdom
- Prior art keywords
- function
- modulation
- frequency
- delay
- pfi
- 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
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
- H04K3/00—Jamming of communication; Counter-measures
- H04K3/20—Countermeasures against jamming
- H04K3/25—Countermeasures against jamming based on characteristics of target signal or of transmission, e.g. using direct sequence spread spectrum or fast frequency hopping
-
- 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
- G01S13/06—Systems determining position data of a target
- G01S13/08—Systems for measuring distance only
- G01S13/10—Systems for measuring distance only using transmission of interrupted, pulse modulated waves
- G01S13/26—Systems for measuring distance only using transmission of interrupted, pulse modulated waves wherein the transmitted pulses use a frequency- or phase-modulated carrier wave
- G01S13/28—Systems for measuring distance only using transmission of interrupted, pulse modulated waves wherein the transmitted pulses use a frequency- or phase-modulated carrier wave with time compression of received pulses
- G01S13/284—Systems for measuring distance only using transmission of interrupted, pulse modulated waves wherein the transmitted pulses use a frequency- or phase-modulated carrier wave with time compression of received pulses using coded pulses
- G01S13/288—Systems for measuring distance only using transmission of interrupted, pulse modulated waves wherein the transmitted pulses use a frequency- or phase-modulated carrier wave with time compression of received pulses using coded pulses phase modulated
-
- 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
- G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
- G01S13/76—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted
- G01S13/78—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
- H04K3/00—Jamming of communication; Counter-measures
- H04K3/80—Jamming or countermeasure characterized by its function
- H04K3/82—Jamming or countermeasure characterized by its function related to preventing surveillance, interception or detection
- H04K3/827—Jamming or countermeasure characterized by its function related to preventing surveillance, interception or detection using characteristics of target signal or of transmission, e.g. using direct sequence spread spectrum or fast frequency hopping
Landscapes
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Signal Processing (AREA)
- Compression, Expansion, Code Conversion, And Decoders (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
1315873 Frequency modulation systems SIEMENS AG 19 April 1971 [24 Feb 1970] 21665/71 Heading H4P A plurality of code elements having a discontinuous modulation function have each element subjected to a further modulation before transmission and at the receiver compression is carried out both on the additional and discontinuous modulation functions. The additional modulation may be a function of the frequency. Received signals are applied to pulse compression filters PFI, PFII followed by demodulators DI, DII: the outputs are fed through a subtracting device S feeding a delay element VG designed as a delay line or a shift register provided with a series of tappings into monitoring circuits USI, USII. Due to the delay in VG the outputs on the tappings are available simultaneously. A switch control unit SU controlled by a code generator SC distributes values + 1, - 1 such distribution being controlled according to generator SC so that all the outputs are of like sign which are added in AN as an output D with a stage SAG being set at a threshold level. If an incorrect signal is received at A, in the example given there would not be seven identical amplitudes fed into AN i.e. an incorrect character would result in - 1 instead of + 1 thus reducing the output of AN by two units hence output D does not reach the value set by thres - hold circuit SAG. A seven unit character is illustrated in Fig. 2a the broken lines rising towards the right indicating that frequency of each element rises with passage of time (+1) and conversely in a falling direction (-1). Pulse compression filter PFI is arranged so that frequencies with a rising f.m. function are dealt with compressively and with a falling f.m. function, dispersively, and it is known to employ devices which produce a frequency dependent delay in signals. Pulse compression filter PFII has an f.m. function inverse to that of PFI with a clearly defined maxima occurring with a falling function (- 1) and only a small secondary maxima with rising f.m. (+1) this being described more fully with relation to Figs. 2b, 2c (not shown). The additional modulation may be frequency keyed or phase shift. As the correctness of the incoming signals is monitored by the coding sequence in SC the arrangement may be applied to a "secure" system or may be utilized in "friend or foe" systems employing secondary radars.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19702008560 DE2008560C3 (en) | 1970-02-24 | 1970-02-24 | Message transmission system using pulse code modulation and pulse compression on the receiver side |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1315873A true GB1315873A (en) | 1973-05-02 |
Family
ID=5763234
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB2166571A Expired GB1315873A (en) | 1970-02-24 | 1971-04-19 | Telecommunications systems |
Country Status (3)
Country | Link |
---|---|
DE (1) | DE2008560C3 (en) |
GB (1) | GB1315873A (en) |
NL (1) | NL7102464A (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NO129973B (en) * | 1972-10-16 | 1974-06-17 | Kongsberg Vapenfab As | |
FR2248517B1 (en) * | 1973-10-23 | 1978-08-04 | Sercel Rech Const Elect | |
DE2365675C1 (en) * | 1973-11-09 | 1988-11-10 | Siemens AG, 1000 Berlin und 8000 München | Query-response system with a primary radar and with filters in the response station |
CH613527A5 (en) * | 1976-02-27 | 1979-09-28 | Patelhold Patentverwertung | Circuit arrangement for separating responses arriving simultaneously in a secondary radar system |
DE2808545C2 (en) * | 1978-02-28 | 1984-10-25 | Siemens AG, 1000 Berlin und 8000 München | Combined radar and communications equipment |
-
1970
- 1970-02-24 DE DE19702008560 patent/DE2008560C3/en not_active Expired
-
1971
- 1971-02-24 NL NL7102464A patent/NL7102464A/xx unknown
- 1971-04-19 GB GB2166571A patent/GB1315873A/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
DE2008560C3 (en) | 1974-03-07 |
DE2008560A1 (en) | 1971-09-09 |
NL7102464A (en) | 1971-08-26 |
DE2008560B2 (en) | 1973-07-12 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed | ||
PLNP | Patent lapsed through nonpayment of renewal fees |