Method and apparatus for measurement of the contents of a bunker or silo

Claim 2

Apparatus for measuring the contents of a bunker or silo, comprising a transmitter mounted over the bunker to beam down on to the surface of the bunker contents a very high frequency signal, sweep generator means for modulating the transmitted signal to cause the frequency to rise and fall repeatedly with either a constant sweep time and a progressively changing amplitude or a constant amplitude and a progressively changing sweep time, a mixer responsive to both the transmitted signal and the target signal returns to deliver a beat frequency, a filter for said beat frequency, a control unit receiving the filtered beat frequency, said control unit both controlling the sweep generator means and also computing from the filtered beat frequency the distance of the bunker contents surface below the transmitter as indicated by the particular frequency sweep of the transmitted signal with which each target return from the contents surface is associated, said control unit including means for discriminating against target signal returns from fixed structure of the bunker which discriminating means comprises a long-term memory store for pre-storing signals corresponding to signal returns from fixed structure of the bunker, a short-term memory store for receiving the incoming filtered beat frequency signals, and comparator means for comparing the incoming beat frequency signals in the short-term store with the pre-stored signals in the long-term store and rejecting any of the incoming beat frequency signals that corresponds to a pre-stored signal.

Claim 3

Apparatus according to claim 1, wherein the control unit includes processing means arranged to distinguish between incoming signals derived from target returns from fixed targets and those derived from a moving target moving toward or away from the transmitter.

Claim 4

Apparatus according to claim 1, including a learning mode switch operable to enable signals appearing in the short term memory to be loaded into the long term memory, so that signals representing returns from fixed structure can be pre-stored by performing one or more operating cycles of the apparatus with the bunker empty.

Claim 5

Apparatus according to claim 2 or claim 3 or claim 1, wherein the waveform of the transmitted modulated frequency signal is triangular or sawtooth with time delays between successive frequency sweeps.

Claim 6

Apparatus according to claim 2 or claim 3 or claim 1, wherein the waveform of the transmitted modulated frequency signal is triangular or sawtooth with no time delays between successive frequency sweeps.

Claim 7

Apparatus for measuring the contents of a bunker or silo, comprising a transmitter mounted over the bunker to beam down onto the surface of the bunker contents a very high frequency signal, cyclically-operating sweep generator means for modulating the transmitted signal to cause the frequency to rise and fall in a multiplicity of sweeps per cycle, the successive sweeps in each cycle having a constant sweep time and a progressively decreasing rate of change of frequency, said successive sweeps corresponding to progressively increasing target distances, a mixer responsive to both the transmitted signal and the target signal returns to deliver a beat frequency, a filter for said beat frequency, a control unit receiving the filtered beat frequency, said control unit both controlling the sweep generator means and also computing from the filtered beat frequency the distance of the bunker contents surface below the transmitter as indicated by the particular frequency sweep of the transmitted signal with which each target return from the contents surface is associated, said control unit including means for discriminating against target signal returns from fixed structure of the bunker which discriminating means comprises a long-term memory store for pre-storing signals corresponding to signal returns from fixed structure of the bunker, a short-term memory store for receiving the incoming filtered beat-frequency signals, and comparator means for comparing the incoming beat frequency signals in the short-term store with the pre-stored signals in the long-term store and rejecting any of the incoming beat frequency signals that corresponds to a pre-stored signal.

Claim 8

Apparatus for measuring the contents of a bunker or silo, comprising a transmitter mounted over the bunker to beam down onto the surface of the bunker contents a very high frequency signal, cyclically-operating sweep generator means for modulating the transmitted signal to cause the frequency to rise and fall in a multiplicity of sweeps per cycle, the successive sweeps in each cycle having a constant sweep time and a progressively decreasing rate of change of frequency, said successive sweeps corresponding to progressively increasing target distances, a mixer responsive to both the transmitted signal and the target signal returns to deliver a beat frequency, a filter for said beat frequency, a control unit receiving the filtered beat frequency, said control unit both controlling the sweep generator means and also computing from the filtered beat frequency the distance of the bunker contents surface below the transmitter as indicated by the particular frequency sweep of the transmitted signal with which each target return from the contents surface is associated, said control unit including means for discriminating against target signal returns from fixed structure of the bunker which discriminating means comprises a long-term memory store for pre-storing signals corresponding to signal returns from fixed structure of the bunker, a short-term memory store for receiving the incoming filtered beat-frequency signals, and comparator means for comparing the incoming beat frequency signals in the short-term store with the pre-stored signals in the long-term store and rejecting any of the incoming beat frequency signals that corresponds to a pre-stored signal.

Claim 9

Apparatus for measuring the contents of a bunker or silo, comprising a transmitter mounted over the bunker to beam down onto the surface of the bunker contents a very high frequency signal, cyclically-operating sweep generator means for modulating the transmitted signal to cause the frequency to rise and fall in a multiplicity of sweeps per cycle, the successive sweeps in each cycle having a constant amplitude of frequency change and a progressively decreasing rate of change of frequency, said successive sweeps corresponding to progressively increasing target distances, a mixer responsive to both the transmitted signal and the target signal returns to deliver a beat frequency, a filter for said beat frequency, a control unit receiving the filtered beat frequency, said control unit both controlling the sweep generator means and also computing from the filtered beat frequency the distance of the bunker contents surface below the transmitter as indicated by the particular frequency sweep of the transmitted signal with which each target return from the contents surface is associated, said control unit including means for discriminating against target signal returns from fixed structure of the bunker which discriminating means comprises a long-term memory store for pre-storing signals corresponding to signal returns from fixed structure of the bunker, a short-term memory store for receiving the incoming filtered beat frequency signals, and comparator means for comparing the incoming beat frequency signals in the short-term store with the pre-stored signals in the long-term store and rejecting any of the incoming beat frequency signals that corresponds to a pre-stored signal.

Claim 10

Apparatus for measuring the contents of a bunker or silo, comprising a transmitter mounted over the bunker to beam down onto the surface of the bunker contents a very high frequency signal, cyclically-operating sweep generator means for modulating the transmitted signal to cause the frequency to rise and fall in a multiplicity of sweeps per cycle, the successive sweeps in each cycle having a constant amplitude of frequency change and a progressively decreasing rate of change of frequency, said successive sweeps corresponding to progressively increasing target distances, a mixer responsive to both the transmitted signal and the target signal returns to deliver a beat frequency, a filter for said beat frequency, a control unit receiving the filtered beat frequency, said control unit both controlling the sweep generator means and also computing from the filtered beat frequency the distance of the bunker contents surface below the transmitter as indicated by the particular frequency sweep of the transmitted signal with which each target return from the contents surface is associated, said control unit including means for discriminating against target signal returns from fixed structure of the bunker which discriminating means comprises a long-term memory store for pre-storing signals corresponding to signal returns from fixed structure of the bunker, a short-term memory store for receiving the incoming filtered beat frequency signals, and comparator means for comparing the incoming beat frequency signals in the short-term store with the pre-stored signals in the long-term store and rejecting any of the incoming beat frequency signals that corresponds to a pre-stored signal.