Tag frequency control
First Claim
1. A communication system comprising one or more transceiver units of a first type and one or more transceiver units of a second type capable of communicating with the transceiver units of the first type;
- each transceiver unit of the first type comprising;
a frequency comparison unit for comparing the frequency of a signal received from a transceiver unit of the second type with a reference frequency;
a feedback signal generator for generating a feedback signal dependent on the result of that comparison; and
a transmitter for transmitting that signal to the transceiver unit of the second type; and
each transceiver unit of the second type comprising;
a local frequency reference unit on which the frequency of signals transmitted by it are dependent; and
a frequency adjustment unit for receiving the feedback signal and adjusting the local frequency reference unit in dependence on the feedback signal;
the communication system further comprising at least one transceiver unit of a third type with which the transceivers of the second type are capable of communicating; and
a database accessible to the transceiver units of the first type and the transceiver units of the third type; and
wherein;
the transceiver units of the first type are arranged to, on comparing the frequency of a signal received from a transceiver unit of the second type with the reference frequency, store in the database an indication of the result of that comparison together with an identity of that transceiver unit of the second type; and
each transceiver unit of the third type comprises;
a local frequency reference unit on which the operating frequency of that transceiver unit is dependent; and
a frequency adjustment unit for, on receiving a signal from a transceiver unit of the second type for which the database holds an indication of the result of a comparison, comparing the frequency of the signal received from the transceiver unit of the second type with the frequency of the respective local frequency reference unit and adjusting the frequency reference unit in accordance with that comparison.
2 Assignments
0 Petitions
Accused Products
Abstract
A communication system comprising one or more transceiver units of a first type and one or more transceiver units of a second type capable of communicating with the transceiver units of the first type; each transceiver unit of the first type comprising: a frequency comparison unit for comparing the frequency of a signal received from a transceiver unit of the second type with a reference frequency; a feedback signal generator for generating a feedback signal dependent on the result of that comparison; and a transmitter for transmitting that signal to the transceiver unit of the second type; and each transceiver unit of the second type comprising: a local frequency reference unit on which the frequency of signals transmitted by it are dependent; and a frequency adjustment unit for receiving the feedback signal and adjusting the local frequency reference unit in dependence on the feedback signal.
14 Citations
18 Claims
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1. A communication system comprising one or more transceiver units of a first type and one or more transceiver units of a second type capable of communicating with the transceiver units of the first type;
- each transceiver unit of the first type comprising;
a frequency comparison unit for comparing the frequency of a signal received from a transceiver unit of the second type with a reference frequency; a feedback signal generator for generating a feedback signal dependent on the result of that comparison; and a transmitter for transmitting that signal to the transceiver unit of the second type; and
each transceiver unit of the second type comprising;a local frequency reference unit on which the frequency of signals transmitted by it are dependent; and a frequency adjustment unit for receiving the feedback signal and adjusting the local frequency reference unit in dependence on the feedback signal; the communication system further comprising at least one transceiver unit of a third type with which the transceivers of the second type are capable of communicating; and a database accessible to the transceiver units of the first type and the transceiver units of the third type; and
wherein;the transceiver units of the first type are arranged to, on comparing the frequency of a signal received from a transceiver unit of the second type with the reference frequency, store in the database an indication of the result of that comparison together with an identity of that transceiver unit of the second type; and
each transceiver unit of the third type comprises;a local frequency reference unit on which the operating frequency of that transceiver unit is dependent; and a frequency adjustment unit for, on receiving a signal from a transceiver unit of the second type for which the database holds an indication of the result of a comparison, comparing the frequency of the signal received from the transceiver unit of the second type with the frequency of the respective local frequency reference unit and adjusting the frequency reference unit in accordance with that comparison. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
- each transceiver unit of the first type comprising;
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18. A method of adjusting a local frequency reference of a transceiver unit in a communication system comprising one or more transceiver units of a first type, one or more transceiver units of a second type capable of communicating with the transceiver units of the first type, one or more transceiver units of a third type with which the transceiver units of the second type are capable of communicating, wherein each transceiver unit of the third type comprises a local frequency reference unit on which the operating frequency of that transceiver unit is dependent;
- the method comprising;
comparing the frequency of a signal received from a transceiver unit of the second type with a reference frequency; generating a feedback signal dependent on the result of that comparison; transmitting that signal to the transceiver unit of the second type; and
at the transceiver unit of the second type;receiving the feedback signal; adjusting a local frequency reference unit on which the frequency of signals transmitted by the transceiver unit of the second type are dependent in dependence on the feedback signal; storing an indication of the result of the comparison of the frequency of a signal received from a transceiver unit of the second type with the reference frequency together with an identity of that transceiver unit of the second type; and on receiving a signal from a transceiver unit of the second type for which an indication of the result of a comparison is stored, comparing the frequency of that signal with the frequency of the respective local frequency reference unit and adjusting the frequency reference unit in accordance with that comparison.
- the method comprising;
Specification