Data transmission system
View Patent ↗A data transmission system for short but frequent data pulses comprises a transmitter ( 10 ) and a receiver ( 12 ). The transmitter comprises a pseudo-random signal generator ( 16 ) which governs the time delay between successive timing points and a local oscillator ( 15 ) which controls the time of data transmission, and the receiver comprises a corresponding pseudo-random signal generator ( 22 ) and local oscillator ( 24 ). Power is applied to the receiver substantially only corresponding in time to the timing of the data bursts. Multiple collisions between adjacent systems operating on the same wavelength are avoided and the receiver is controlled to consume power only around the timing of the data bursts.
1. A data transmission system, comprising a transmitter and a receiver, wherein the transmitter is arranged to send data bursts with a low duty cycle at transmission timing points, the transmitter comprising a pseudo-random signal generator which governs the time delay between successive timing points and a local oscillator which controls the time of data transmission, and wherein the receiver comprises a corresponding pseudo-random signal generator and local oscillator, and wherein power is applied to the receiver substantially only corresponding in time to the timing of the data bursts, wherein at least one of the data bursts includes data that is utilized by the pseudo-random signal generator of the receiver to synchronize the pseudo-random signal generator of the receiver to the pseudo-random signal generator of the transmitter.
2. A system as claimed in claim 1 , wherein the transmitter is arranged to send data bursts with a duty cycle of less than 1%.
3. A system as claimed in claim 1 , wherein the transmitter and receiver each include a power source comprising a non-rechargeable battery.
4. A system as claimed in claim 1 , wherein each pseudo-random signal generator comprises a maximal length feedback shift register, and where the data comprises data bits that are utilized to update a sequence of each maximal length feedback shift register.
5. A system as claimed in claim 1 , wherein each data burst comprises a header section and a data section, and wherein the header section for a sub-set of the data bursts comprises a sequence which is unique compared to the header section and data section of the data bursts other than the sub-set of the data bursts, thereby to enable the receiver to obtain bit timing information.
6. A system as claimed in claim 5 , wherein the header comprises address data which identifies the transmitter to the receiver.
7. A system as claimed in claim 6 , wherein the address data is used in combination with a current output from the pseudo-random signal generator of the transmitter to generate a modified pseudo random sequence output by each of the pseudo-random signal generators.
8. A system as claimed in claim 5 , wherein the unique header comprises an additional bit of data compared to the header section of the data bursts other than the sub-set of the data bursts.
9. A system as claimed in claim 5 , wherein the unique header comprises a repeating sequence that is unique.
10. A system as claimed in claim 9 , wherein the repeating sequence is a repeating sequence of a single digit.
11. A system as claimed in claim 1 , wherein each data burst comprises a header section and a data section, and wherein the header section for a sub-set of the data bursts comprises the data that modifies a sequence of the pseudo-random signal generator of the receiver and thereby, modifies a time period to the next message.
12. A system as claimed in claim 11 , wherein the header comprises address data which identifies the transmitter to the receiver.
13. A system as claimed in claim 12 , wherein the address data is used in combination with the pseudo-random signal generator to generate a modified pseudo random sequence.
14. A system as claimed in claim 1 , wherein the transmitter is for attachment to a shoe, and comprises an accelerometer and a processing unit, the processing unit integrating the detected acceleration over time to obtain instantaneous speed values which are transmitted in the data bursts.
15. A system as claimed in claim 14 , wherein the receiver is for wearing on the wrist of the user of the system.
16. A system as claimed in claim 1 , wherein each local oscillator comprises a 32768 Hz quartz oscillator.
17. A system as claimed in claim 1 , wherein each data burst comprises a header section and a data section, and wherein the data section is an encoded data section.
18. A system as claimed in claim 17 , wherein the encoded data is compared at the receiver to data bit patterns that are potentially valid for error trapping.
19. A system as claimed in claim 1 , wherein the data bursts comprises speed data and distance data related to a transported speed and distance of the transmitter.
20. A system as claimed in claim 19 , wherein the data bursts are transmitted in one of two modes, a first mode is a static mode wherein housekeeping data is transmitted and speed data is not transmitted and a second mode is a moving mode wherein the speed and distance data is transmitted.