Pulse or digital communications – Synchronizers – Frequency or phase control using synchronizing signal
Patent
1992-11-09
1995-07-11
Chin, Stephen
Pulse or digital communications
Synchronizers
Frequency or phase control using synchronizing signal
375368, 375340, H04L 700
Patent
active
054328250
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to apparatus for the radiotransmission of data between a radiotransmitting station and a radioreceiving station and more specifically, to the recognition of enabling codes capable of enabling the receiving station to recognise and to process transmitted data encoded according to a predetermined key.
It is known for radioreceivers to be provided with devices which recognise enabling codes to enable the radioreceiver to receive data transmitted through air. Generally, the enabling code is a sequence of bits, and follows a group of bits used to synchronise the receiver to the transmission frequency. In some cases, as a result of radio frequency disturbances or of interferences with other transmissions, these enabling codes are erroneously interpreted by the recognising device as other synchronisation signals, but out of phase with the true transmitted synchronisation signals transmitted. The result is that the radioreceiver is not longer capable of recognising and processing the data transmitted.
SUMMARY OF THE INVENTION
The present invention aims to overcome the problem outlined above and to provide apparatus which has an enabling code recognition device which, in association with a particular code or key structure, is very rugged, and has a low susceptibility to incorrectly recognising codes, and also has the ability to improve the synchronisation of the radioreceiver with the data transmission frequency.
According to the invention, there is provided for the radiotransmission of data as defined in claim 1.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the invention will now be defined, by way of example, and with reference to the accompanying drawings, in which:
FIG. 1 is a block diagram showing, in outline, the general structure of an embodiment of the invention;
FIG. 2 shows a complete bit string containing the information transmitted by the apparatus of claim 1;
FIG. 3 shows wave forms of digital signals processed by the apparatus of FIG. 1;
FIG. 4 shows a functional logic diagram of a portion of the structure in FIG. 1;
FIG. 5 shows a simplified block diagram of a phase locking circuit of the apparatus of FIG. 1;
FIG. 6 is a representative in binary form of information processed by the apparatus of FIG. 4;
FIG. 7 shows an example of the sampling performed by the apparatus of FIG. 4;
FIG. 8a shows a signal corresponding to the sequence of an optimised recognition key, and
FIG. 8b shows the harmonic content of the signal of FIG. 8a.
DETAILED DESCRIPTION
The apparatus for radiotransmission of data is designed to transmit data in digital form at radio frequencies between two or more personal computers which are located in the same building or in separate buildings within a radius of no greater than approximately 500 m.
FIG. 1 shows a typical configuration of the above mentioned apparatus for transmission, in which a first system for processing data, for example a personal computer PC1, processes in known manner data to be transmitted in digital form to a second system for processing data, for example a personal computer PC2. PC1 is equipped with a digital radiotransmitting apparatus 12 of known type, which is capable of transmitting the data processed by PC1 by means of a transmitting antenna 14. The electromagnetic signals transmitted are picked up by a receiving antenna 16 which is connected to a radio receiving apparatus 18 which is incorporated in the form of an additional card or module in the personal computer PC2. The signals transmitted by the radiotransmitting apparatus 12 are organised in the form of successive blocks or strings ST of bits (FIG. 2). Each string ST is made up in total of 480 bits, the first 32 bits of which constitute the so-called synchronisation sequence SS, while the following group of bits SD represents the set of data transmitted. Each string ST is followed by a group of 64 non-significant bits, not shown in FIG. 2, which are used to separate the strings ST from one another.
The synchronisation sequence SS is in
REFERENCES:
patent: 4847877 (1989-07-01), Besseyre
N. R. Sollenberger et al., Architecture and Implementation of an Efficient and Robust TDMA Frame Structure for Digital Portable Communications, 39th IEEE Vehicular Tech. Conf. (May 1, 1989, San Francisco, Calif.) vol. 1, at 169-74.
M. W. Willard, Optimum Code Patterns for PCM Synchronization, Proceedings of the Nat'l Telemetering Conf. (May 23-25, 1962, Washington, D.C.), at 5.5.1-5.5.11.
P. F. Driessen, Binary Frame Synchronisation Sequences for Packet Radio, Elec. Lett., vol. 23, No. 22 (Oct. 22, 1987) at 1190-91.
T. Schaub, Improved Binary Frame Synchronization Scheme for Packet Transmission, Elec. Lett., vol. 24, No. 6 (Mar. 17, 1988) at 301-02.
Bocure Tesfaldet
Chin Stephen
Sixtel, S.p.A. Corp.
LandOfFree
Enabling code for radiotransmission of data does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Enabling code for radiotransmission of data, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Enabling code for radiotransmission of data will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-509280