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AssigneeKoninklijke Philips Electronics N.V.
InventorsHendrik Boezen, Stefan Gerhard Erich Butselaar, Harm Gerwin Joan Voss
Estimating the term…
In a network a star node (SN1) interconnects a plurality of stations (ST1–ST3). The star node (SN1) has interfaces (I1–I3), each having a connection terminal (BP) for connecting a selected one of the stations to the star node (SN1) and each interface receives at a connection terminal (BP) a signal from the station associated with that interface and forwards the received signal to the connection terminal (BP) of the other interfaces. The star node (SN1) further has a common terminal (RT1) and each interface has a receiver (CMP1) coupled to the connection terminal (BP) for receiving the signal from the associated station, a transmitter (TR) coupled to the connection terminal (BP), a first activity detector (A1) for generating a first activity signal (AS1) in response to signal transitions at an input (CIP1) of the receiver (CMP1), a second activity detector (A2) for generating a second activity signal (AS2) in response to signal transitions at the common terminal (RT1), a first switch (SW1) for disabling signal transfer from the receiver (CMP1) to the common terminal (RT1) in response to the second activity signal (AS2), and a second switch (SW2) for disabling signal transfer from the common terminal (RT1) to the transmitter (TR) in response to the first activity signal (AS1). The structure of the interface allows easy expansion of the number of interfaces within the star node (SN1) and a data protocol without a preamble.
A star node for interconnecting a plurality of stations in a network, the star node comprising interfaces each having a connection terminal for connecting a selected one of the stations to the star node, each interface having means for accepting at the connection terminal a signal from the station associated with the interface and for forwarding said signal to the connection terminal of the other interfaces, characterized in that the star node comprises a common terminal and in that the interface comprises a receiver having an input coupled to the connection terminal for receiving the signal from the associated station, a transmitter having an output coupled to the connection terminal, a first activity detector for generating a first activity signal in response to signal transitions at the input of the receiver, a second activity detector for generating a second activity signal in response to signal transitions at the common terminal, a first switching means for disabling signal transfer from an output of the receiver to the common terminal in response to the second activity signal, and a second switching means for disabling signal transfer from the common terminal to an input of the transmitter in response to the first activity signal.
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]: star or tree networks
Digital communication
Term ended 25 Oct 2024 (estimated)
The invention relates to a star node (SN1) for interconnecting a plurality of stations (ST1–ST3) in a network, the star node (SN1) comprising interfaces (I1–I3), each having a connection terminal (BP) for connecting a selected one of the stations to the star node (SN1), each interface having means for accepting at the connection terminal (BP) a signal from the station associated with the interface and for forwarding said signal to the connection terminal (BP) of the other interfaces.
The invention also relates to a network of stations interconnected by such a star node. This kind of networks may be used, for example, in cars and other noisy environments.
In a network, in particular a high speed network, reflections in the network can cause signal integrity problems. This is especially important if the bit time is not large with respect to the propagation delay through the network. A network can be made where all stations are connected to a star node with properly terminated transmission lines. In such a star type network, the star node's task is to retransmit data received from one of the stations to all other stations. Such a star type network and star node are known from U.S. Pat. No. 4,903,015. This known network has properly terminated transmission lines and is hence suitable for high speed. The signals sent to and received from the stations run through the same transmission line, which saves connectors and wires. However, in the star node of this known network a fairly complicated logic circuit is required to realize the send-and-receive switching mechanism. The complexity of the logic circuit grows with the number of stations that can be connected to the star node.
These and other aspects of the invention will now be described and elucidated with reference to the accompanying drawings, in which
FIG. 1 shows a network with stations interconnected through a star node according to the invention;
FIG. 2 shows a block diagram of a first interface for use in a star node according to the invention;
FIG. 1 shows a network comprising, by way of example, three stations ST1, ST2 and ST3 interconnected through a star node SN1 according to the invention. In a car the station can be a temperature sensor, a brake sensor, a door sensor, and the like provided with a suitable interface for connection of the sensor to the network. The star node SN1 comprises, again by way of example, three interfaces I1, I2 and I3. The interfaces I1, I2 and I3 have respective connection terminals BP and BM for connection of a respective one of the stations ST1, ST2 and ST3 to the star node SN1. The stations ST1, ST2 and ST3 are connected to the interfaces I1, I2 and I3 by twisted pair transmission lines TWP1, TWP2 and TWP3. However, other types of transmission lines are also possible, such as coaxial cables and single wire lines. The number of stations and interfaces is not limited to three; any number greater than two is possible.
The interfaces I1, I2 and I3 have balanced inputs BP and BM for connection of the twisted pair transmission lines and further have balanced common terminals RT1 and RT2. The common terminals RT1 of the interfaces I1, I2 and I3 are all connected to a positive supply terminal PST through a first common pull-up resistor RP1. The common terminals RT2 of the interfaces I1, I2 and I3 are similarly all connected to the positive supply terminal PST through a second common pull-up resistor RP2.
FIG. 2 shows a block diagram of the interfaces I1–I3. The interface has a receiver comprising of two comparators CMP1 and CMP2 and a transmitter TR. Comparator CMP1 has a non-inverting input CIP1 connected to the connection terminal BP and has an inverting input CIN1 connected to the connection terminal BM. Comparator CMP2 has a non-inverting input CIP2 connected to the connection terminal BM and has an inverting input CIN2 connected to the connection terminal BP. The inputs of the two comparators are thus oppositely connected to the connection terminals. The transmitter TR has balanced outputs TO1 and T02 connected to the connection terminals BM and BP, respectively. A termination resistor RTM is connected between the connection terminals BP and BM for providing a correct termination impedance to the twisted pair transmission line of the connected station.