GB1251789A - - Google Patents
Info
- Publication number
- GB1251789A GB1251789A GB1251789DA GB1251789A GB 1251789 A GB1251789 A GB 1251789A GB 1251789D A GB1251789D A GB 1251789DA GB 1251789 A GB1251789 A GB 1251789A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signal
- received
- interrogating
- transponder
- car
- 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
- G01S13/74—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
Abstract
1,251,789. Transponders. STANDARD TELEPHONES & CABLES Ltd. 10 June, 1970, No. 28097/70. Heading H4L. A transponder is provided with means enabling it to respond to an interrogating signal only if it is the nearest transponder in a plurality thereof to the source of the interrogating signal. The invention is described in relation to a road traffic control system in which each car is equipped with an interrogator and transponder for determining the distance between it and the car in front and with means for maintaining a predetermined distance between the cars. A primary interrogating signal is received by the transponder, Fig. 2, frequency-changed at 20 to give a binary address code identifying the lane in which the car is travelling, and compared at 22 with the address set up manually or automatically when the car enters the lane. If the correct address is recognized a response is initiated in circuit 23 and a modulator 24 generates a short R.F. pulse constituting a preliminary signal which is transmitted via transmitter 25. A portion of this signal is supplied via a directional coupler to a mixer 27 together with the received preliminary signal from other transponders which have received the interrogating signal. If a coincidence between the transmitted and a received preliminary signal is detected a second start circuit 29 remains unenergized. If there is no coincidence, circuit 29 is energized and triggers a modulator 30 so that a coded signal giving the information required by the interrogating vehicle is transmitted. Fig. 3 shows the timing of the various signals. Vehicle X sends out a coded interrogation signal X T and vehicles A, B, C in the same lane respond with preliminary signals A T , B T , C T respectively after a delay td. The propagation time from X to A, A to B and B to C is t 1 , t 2 and t 3 respectively. Thus signal A T will be received by B as it is transmitting B T and signal B T will be received by C coincident with the transmission of C T so that further transmission from B and C is blocked.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB2809770 | 1970-06-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1251789A true GB1251789A (en) | 1971-10-27 |
Family
ID=10270217
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1251789D Expired GB1251789A (en) | 1970-06-10 | 1970-06-10 |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1251789A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110234366A1 (en) * | 2008-12-04 | 2011-09-29 | Koninklijke Philips Electronics N.V. | Methods for selecting and controlling devices |
-
1970
- 1970-06-10 GB GB1251789D patent/GB1251789A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110234366A1 (en) * | 2008-12-04 | 2011-09-29 | Koninklijke Philips Electronics N.V. | Methods for selecting and controlling devices |
| US9578722B2 (en) * | 2008-12-04 | 2017-02-21 | Philips Lighting Holding B.V. | Methods for selecting and controlling devices |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| 435 | Patent endorsed 'licences of right' on the date specified (sect. 35/1949) | ||
| PCNP | Patent ceased through non-payment of renewal fee |