Radiometer gain control reference

Claim 2

In transmission line apparatus for generating broad band noise signals: transmission line means capable of supporting an electromagnetic field therein, heatable fine wire resistor means in energy exchanging relation with said transmission line means for excitation of said electromagnetic field, bridge means having plural arms and including said wire resistor means in a first arm thereof, photo-sensitive means in a second arm of said bridge means, tuned amplifier means responsive to unbalance of said bridge for automatically balancing said bridge, and means for controlling the resistivity characteristic of said photo-sensitive means.

Claim 3

Apparatus as described in claim 1 wherein: said bridge means has first and second opposed pairs of terminal means, said first pair of terminal means being connected through said heatable fine wire resistor means and said photosensitive means in series relation.

Claim 4

Apparatus as described in claim 2 wherein: said first pair of opposed terminal means is connected to the input of said tuned amplifier means for supplying a bridge unbalance signal to said amplifier.

Claim 5

Apparatus as described in claim 3 wherein: said second pair of opposed terminal means is connected to the output of said tuned amplifier means for the purpose of supplying bridge balancing power to said bridge means.

Claim 6

Apparatus as described in claim 1 comprising: means for generating light for controlling said resistivity characteristic of said photo-sensitive means, and means for supplying a square wave electrical signal for modulating said light.

Claim 7

Apparatus as described in claim 5 wherein said photo-sensitive means comprises a photo-sensitive resistor.

Claim 8

Apparatus as described in claim 1 comprising: means for generating light, optical shutter means, and motive means for cyclically operating said shutter means for controlling said photo-sensitive device.

Claim 9

Radiometer receiver means comprising: unitary gain control, dual output-level, noise reference signal generator means, variable gain amplifier means in series circuit within said radiometer receiver means and responsive to said noise reference signal generator means, control means for cyclically switching said noise reference signal generator means between first and second output levels, synchronous demodulator means responsive to said variable gain amplifier means, said synchronous demodulator means being controlled by said control means for cyclically demodulating the envelope of the output of said variable gain amplifier means for generating a uNidirectional gain control signal for continuously controlling the gain of said variable gain amplifier means thereby continuously controlling the gain of said radiometer receiver.

Claim 10

Radiometer receiver means comprising: unitary gain control, dual output-level, noise reference signal generator means, variable gain amplifier means in series circuit within said radiometer receiver means and responsive to said noise reference signal generator means, control means for cyclically switching said noise reference signal generator means between first and second output levels, synchronous demodulator means responsive to said variable gain amplifier means, said synchronous demodulator means being controlled by said control means for cyclically demodulating the envelope of the output of said variable gain amplifier means for generating a uNidirectional gain control signal for continuously controlling the gain of said variable gain amplifier means thereby continuously controlling the gain of said radiometer receiver.

Claim 11

Apparatus as described in claim 8, wherein said unitary noise reference signal generator means comprises: transmission line means coupled to said variable gain amplifier means, heatable resistor means in electromagnetic energy exchanging relation with said transmission line means, multi-arm bridge means including said heatable resistor means in a first arm thereof, means having a square wave modulatable characteristic in a second arm of said bridge means, means for modulating said modulatable characteristic, and means for automatically balancing said multi-arm bridge means in response to said modulation.

Claim 12

Apparatus as described in claim 9 wherein said means for automatically balancing said multi-arm bridge means comprises: first and second opposed pairs of opposed terminal means in said bridge means, tuned amplifier means, means connecting said first opposed pair of terminal means to the input of said tuned amplifier means, and means connecting said second opposed pair of terminal means to the output of said tuned amplifier means.

Claim 13

Apparatus as described in claim 10 wherein a photo-sensitive resistor device is coupled in an arm of said bridge means in series relation with said heatable resistor means.

Claim 14

Apparatus as described in claim 11 comprising means for modulating a characteristic of said photo-sensitive resistor device for the purpose of modulating the amplitude of current passing through said heatable resistor means.

Claim 15

In radiometric receiver means of the comparison type comprising in series relation input means for cyclically switching between first and reference noise signal source means, variable gain amplifier means responsive to said input means, and output means responsive to said variable gain amplifier means for synchronously demodulating the envelope of said cyclically switched signal for comparison purposes, gain control means comprising: switchable unitary gain control dual-level, noise source means, control means for switching said gain control dual-level noise-source means in phase quadrature with respect to said cyclically switched input means for producing cyclic dual-level noise signals, means for coupling said cyclic, dual-level noise signals to said variable gain amplifier means, means for synchronously demodulating the envelope of said cyclic, dual-level noise signals for the purpose of generating a unidirectional gain control signal, and means for supplying said unidirectional gain control signal to said variable gain amplifier means for gain control purposes.

Claim 16

In radiometric receiver means of the comparison type comprising in series relation input means for cyclically switching between first and reference noise signal source means, variable gain amplifier means responsive to said input means, and output means responsive to said variable gain amplifier means for synchronously demodulating the envelope of said cyclically switched signal for comparison purposes, gain control means comprising: switchable unitary gain control dual-level, noise source means, control means for switching said gain control dual-level noise-source means in phase quadrature with respect to said cyclically switched input means for producing cyclic dual-level noise signals, means for coupling said cyclic, dual-level noise signals to said variable gain amplifier means, means for synchronously demodulating the envelope of said cyclic, dual-level noise signals for the purpose of generating a unidirectional gain control signal, and means for supplying said unidirectional gain control signal to said variable gain amplifier means for gain control purposes.