Detecting cargo status and load activity
A cargo detection unit that detect the status of cargo and loading activity within a container. The device transmits microwave radio frequency energy pulses and detects reflections from cargo. Similar to the operation of a radar, the reflected pulses are then analyzed to determine (a) the presence of cargo, such as by comparing the reflected pulses against stored empty containers signature signals and/or (b) detecting a Doppler effect, as caused by loading and/or unloading cargo from the container. The device may use standard radar signal processing techniques, i.e., a digital signal processor, to generate and analyze the reflected pulses cargo status. Activity reports can be forwarded to a cargo tracking unit such as one that uses a wireless mobile telephone communication network to report cargo status to a central location.
1 . A method for detecting presence of cargo within a container comprising:
transmitting microwave radio frequency (RF) energy pulses within the container from a defined location;
detecting reflected RF energy pulses at the defined location, to generate a return signal;
comparing the return signal to a reference signal, to determine whether cargo is present within the container.
2 . A method as in claim 1 additionally comprising:
detecting a Doppler effect on the reflected RF energy pulses; and
in response to the presence thereof, determining there is movement within the container as caused by cargo loading and/or unloading activity.
3 . A method as in claim 1 wherein the RF energy pulses are at a carrier frequency of about 10 GigaHertz (GHz).
4 . A method as in claim 1 wherein the RF energy pulses are focused in both an E-plane and H-plane.
5 . A method as in claim 1 wherein the RF energy pulses are generated at an output power level that is suitable for covering the length of the cargo container.
6 . A method as in claim 5 wherein the output power level is about 12 dBm.
7 . A method as in claim 1 wherein the RF energy pulses are transmitted by a horn antenna angled downward to project the RF energy pulses toward a floor area of the container.
8 . A method as in claim 1 wherein the reflected RF energy pulses are further subjected to a range determination based on a time of arrival and/or amplitude detection.
9 . A method as in claim 2 additionally comprising:
reporting a cargo state from the result of comparing the return signal to a release signal and from the result of detecting a Doppler effect, the reported cargo state being selected from one of
a loaded state, indicating an object is inside the cargo area;
an unloaded state, indicating the absence of objects inside the cargo area; and
activity, indicating that cargo is being added to or removed from the cargo area.
10 . A method as in claim 9 additionally comprising:
forwarding the cargo state information to a central location via a wireless data network.