Wireless communication synchronization

1. A method of communicating among wireless devices comprising a target device and a transmitting device, the method comprising the steps of:

providing from the transmitting device a frequency hopping schedule to the target device, wherein the frequency hopping schedule comprises a sequence of frequencies;

at the target device, alternately sleeping and listening on a frequency in the sequence of frequencies according to the frequency hopping schedule;

exchanging time base information between the target device and the transmitting device;

at the transmitting device, using the time base information to determine a current frequency of the target device; and

from the transmitting device, transmitting a packet of information uniquely addressed to the target device using the said current frequency.

2. The method of claim 1 , wherein exchanging time base information between the target device and the transmitting device comprises:

from the transmitting device, sending an address of the target device on sequential ones of the frequencies in the frequency hopping schedule; and

at the transmitting device, receiving a response from the target device, wherein the response includes the time base information.

3. The method of claim 2 , wherein exchanging time base information between the target device and the transmitting device further comprises transmitting blips on each of a plurality of the frequencies in the frequency hopping schedule, wherein a blip signals any target device to at least temporarily cease alternately sleeping and listening.

4. The method of claim 1 , wherein the transmitting device and the target device are comprised by an industrial sensing network.

5. The method of claim 1 , wherein the target device comprises a wireless, self-powered, sensing device.

6. The method of claim 5 , wherein the packet of information uniquely addressed to the target device comprises at least a portion of an instruction for the sensing device to report sensing information.

7. The method of claim 5 , wherein the sensing device comprises a selection from a group consisting of temperature sensor, pressure sensor, and vibration sensor.

8. The method of claim 1 , wherein the sequence of frequencies comprises 53 channels comprised by a range of frequencies from about 902 MHz to about 928 MHz.

9. A wireless sensing device, comprising:

a control system;

a self-contained power source connected for energization of the control system;

a bidirectional radio operably connected to the control system;

a sensor operably connected to the control system; and

wherein the control system is programmed to cause the sensing device to:

receive a frequency hoping schedule, wherein the frequency hopping schedule comprises a sequence of frequencies over which the radio is configured to communicate;

alternately sleep and listen on a frequency in the sequence of frequencies according to the frequency hopping schedule;

respond to a blip on a given frequency by at least temporarily ceasing alternately sleeping and listening;

receive a uniquely addressed transmission from a transmitting device;

respond to the uniquely addressed transmission with an acknowledgement transmission, wherein the acknowledgement transmission includes time base information; and

receive a packet of uniquely-addressed information on a frequency determined, at least in part, by the time base information and the frequency hoping schedule.

10. The device of claim 9 , wherein the device is comprised by an industrial sensing network.

11. The device of claim 9 , wherein the device comprises a selection from a group consisting of temperature sensor, pressure sensor, and vibration sensor.

12. The device of claim 9 , wherein the packet of uniquely-addressed information comprises at least a portion of an instruction for the device to report sensing information.

13. The device of claim 9 , wherein the sequence of frequencies comprises 53 channels comprised by a range of frequencies from about 902 MHz to about 928 MHz.

14. A wireless field sensing network, comprising:

at least one transmitting device; and

at least one target device having a radio;

wherein the at least one target device is configured to:

receive a frequency hoping schedule, wherein the frequency hopping schedule comprises a sequence of frequencies over which the radio is configured to communicate;

alternately sleep and listen on a frequency in the sequence of frequencies according to the frequency hopping schedule;

respond to a blip from said at least one transmitting device on a given frequency by at least temporarily ceasing alternately sleeping and listening;

receive a uniquely addressed transmission from the transmitting device;

respond to the uniquely addressed transmission with an acknowledgement transmission, wherein the acknowledgement transmission includes time base information; and

receive a packet of uniquely-addressed information on a frequency determined, at least in part, by the time base information and the frequency hoping schedule.

15. The wireless field sensing network of claim 14 , wherein the target device comprises a selection from a group consisting of temperature sensor, pressure sensor, and vibration sensor.

16. The wireless field sensing network of claim 15 , wherein the packet of uniquely-addressed information comprises at least a portion of an instruction for the target device to report sensing information to the transmitting device.

17. The wireless field sensing network of claim 14 , wherein the sequence of frequencies comprises 53 channels comprised by a range of frequencies from about 902 MHz to about 928 MHz.

18. The wireless field sensing network of claim 14 , wherein the field sensing network comprises an industrial sensing network.