A low power radio frequency transceiver is arranged to form a network of communicating low power radio frequency transceivers. It comprises a transmitter for transmitting packets of data and means for controlling the transmitter to transmit a series of messages of a first type outside the network of transceivers, for maintaining synchronisation.
1. An apparatus comprising:
means for controlling a transmitter to transmit a series of messages of a first type outside a network of low power radio frequency transceivers, the apparatus being configured to form the network of transceivers,
means for punctuating the series of messages of a first type with messages of a second type, transmitted within the network of transceivers, for maintaining synchronization.
2. The apparatus as claimed in claim 1 arranged to operate as a master of the radio network of slave transceivers.
3. The apparatus as claimed in claim 1 wherein the network of transceivers uses a first frequency hopping sequence.
4. The apparatus as claimed in claim 3 wherein the messages of a first type transmitted outside the network of transceivers are transmitted using a second frequency hopping sequence.
5. The apparatus as claimed in claim 1 wherein the messages of the second type are broadcast.
6. The apparatus as claimed in claim 1 wherein the means for punctuating, punctuates the series of messages of a first type with a message of a second type periodically.
7. The apparatus as claimed in claim 1 wherein the messages of the second type do not initiate a response from any of the transceivers in the network.
8. The apparatus as claimed in claim 1 wherein the messages of the second type comprise a synchronization word dependent upon the identity of the apparatus.
9. The apparatus as claimed in claim 1 wherein messages of the second type are transmitted at a frequency dependent upon the identity of the apparatus.
10. A method comprising:
punctuating a series of messages of a first type transmitted by a master transceiver outside a network of low power radio frequency transceivers, the network of transceivers comprising the master transceiver and at least one slave transceiver, with messages of a second type transmitted within the network of communicating transceivers for maintaining synchronization.
11. A method as claimed in claim 10 , wherein the network of transceivers uses a first frequency hopping sequence.
12. A method as claimed in claim 11 , wherein the messages of a first type transmitted outside the network of transceivers are transmitted using a second frequency hopping sequence.
13. A method as claimed in claim 10 , wherein the messages of the second type are broadcast.
14. A method as claimed in claim 10 , wherein the series of messages of a first type are punctuated with a message of a second type periodically.
15. A method as claimed in claim 10 , wherein the messages of the second type do not initiate a response from any of the transceivers in the network.
16. A method as claimed in claim 10 , wherein the messages of the second type comprise a synchronization word dependent upon the identity of the transmitting low power radio frequency transceiver.
17. A method as claimed in claim 10 , wherein messages of the second type are transmitted at a frequency dependent upon the identity of the transmitting low power radio frequency transceiver.
18. A computer program product comprising program instructions for causing a computer to perform the method of claim 10 .
19. A storage medium encoded with instructions that, when executed by a controller of a low power radio frequency transceiver perform punctuating transmission of a series of messages of a first type comprising a first synchronization word independent of the identity of the low power radio frequency transceiver, with messages of a second type comprising a second synchronization word dependent upon the identity of the low power radio frequency transceiver.
20. A storage medium as claimed in claim 19 , wherein the punctuating punctuates the series of messages of a first type with a message of a second type periodically.
21. An apparatus comprising:
a controller configured for controlling a transmitter to transmit a series of messages of a first type outside a network of low power radio frequency transceivers, the apparatus being configured to form the network of transceivers, and configured for punctuating the series of messages of a first type with messages of a second type, transmitted within the network of transceivers, for maintaining synchronization.
22. The apparatus as claimed in claim 21 configured to operate as a master of the radio network of slave transceivers.
23. The apparatus as claimed in claim 21 , wherein the network of transceivers is configured to use a first frequency hopping sequence.
24. The apparatus as claimed in claim 23 wherein the messages of a first type transmitted outside the network of transceivers are configured to be transmitted using a second frequency hopping sequence.
25. The apparatus as claimed in claim 21 , wherein the messages of the second type are configured to be broadcast.
26. The apparatus as claimed in claim 21 , wherein the controller is configured to punctuate the series of messages of a first type with a message of a second type periodically.
27. The apparatus as claimed in claim 21 wherein the messages of the second type are configured to not initiate a response from any of the transceivers in the network.
28. The apparatus as claimed in claim 21 , wherein the messages of the second type comprise a synchronization word dependent upon the identity of the apparatus.
29. The apparatus as claimed in claim 21 , wherein messages of the second type are configured to be transmitted at a frequency dependent upon the identity of the apparatus.