Method and apparatus for active temperature compensation in a radiowave transmitter
First Claim
Patent Images
1. A signal generator having a temperature stabilized frequency, comprising:
- (a) an oscillator having a first control input, the oscillator producing an output signal at an output frequency, the output frequency of the oscillator corresponding to a voltage applied to the control input;
(b) a step generator producing a step voltage having a leading edge;
(c) a timing circuit having a temperature-dependent time constant, the timing circuit being connected to receive the step voltage from the step generator, the timing circuit producing an output voltage reaching a reference voltage a temperature-dependent time period after the leading edge in response to the step voltage, the time period being determined by the time constant;
(d) a timer connected to receive the step voltage and the output voltage from the timing circuit, the timer determining the time period by measuring the elapsed time between the leading edge and the time when the output voltage reaches a reference voltage, the timer producing a timing signal indicating the time period;
(e) a first memory having a plurality of locations, each location having an address, each location containing a data sequence;
(f) a random number memory containing random number data;
(g) a controller connected to receive the timing signal and to retrieve a selected one of the data sequences from the first memory in response to the timing signal, the controller further being connected to retrieve random number data from the random number table, the controller producing a digital signal in response to the data sequence retrieved from the first memory and the retrieved random number data; and
(h) a voltage generator having an output connected to the control input of the oscillator, the voltage generator having a digital input connected to receive the digital signal from the controller, the voltage generator producing at its output the voltage for input to the control input, the voltage corresponding to the digital signal at the digital input.
12 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for producing a temperature stabilized frequency from a signal generator in a monitoring station is described. The signal generator monitors the voltage response of an RC circuit where the resistive portion is formed by a thermistor, to produce a time-dependent signal. A comparator compares the time-dependent signal to a reference voltage to determine a rise time of the voltage across the capacitor. Based upon a software timer loop, the signal generator determines a temperature range by selecting data from a look-up table based upon the rise time of the RC circuit.
63 Citations
20 Claims
-
1. A signal generator having a temperature stabilized frequency, comprising:
-
(a) an oscillator having a first control input, the oscillator producing an output signal at an output frequency, the output frequency of the oscillator corresponding to a voltage applied to the control input; (b) a step generator producing a step voltage having a leading edge; (c) a timing circuit having a temperature-dependent time constant, the timing circuit being connected to receive the step voltage from the step generator, the timing circuit producing an output voltage reaching a reference voltage a temperature-dependent time period after the leading edge in response to the step voltage, the time period being determined by the time constant; (d) a timer connected to receive the step voltage and the output voltage from the timing circuit, the timer determining the time period by measuring the elapsed time between the leading edge and the time when the output voltage reaches a reference voltage, the timer producing a timing signal indicating the time period; (e) a first memory having a plurality of locations, each location having an address, each location containing a data sequence; (f) a random number memory containing random number data; (g) a controller connected to receive the timing signal and to retrieve a selected one of the data sequences from the first memory in response to the timing signal, the controller further being connected to retrieve random number data from the random number table, the controller producing a digital signal in response to the data sequence retrieved from the first memory and the retrieved random number data; and (h) a voltage generator having an output connected to the control input of the oscillator, the voltage generator having a digital input connected to receive the digital signal from the controller, the voltage generator producing at its output the voltage for input to the control input, the voltage corresponding to the digital signal at the digital input. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A monitoring station for monitoring the power usage of a facility, comprising:
-
(a) a power monitor producing power usage data; (b) an oscillator having a first control input, the oscillator producing an output signal at an output frequency, the output frequency of the oscillator corresponding to a voltage applied to the control input; (c) a step generator producing a step voltage having a leading edge; (d) a timing circuit having a temperature-dependent time constant in thermal contact with the power monitor, the timing circuit being connected to receive the step voltage from the step generator, the timing circuit producing an output voltage reaching a reference voltage a temperature-dependent time period after the leading edge in response to the step voltage, the time period being determined by an RC time constant; (e) a timer connected to receive the step voltage and the output voltage from the timing circuit, the timer determining the time period by measuring the elapsed time between the leading edges and the time when the output voltage reaches a reference voltage, the timer producing a timing signal indicating the time period; (f) a random number memory containing random number data; (g) a controller connected to receive the timing signal, the controller being connected to retrieve random number data from the random number table, the controller producing a digital signal in response to the random number data; (h) a voltage generator having its output connected to the control input of the oscillator, the voltage generator having a digital input connected to receive the digital signal from the controller, the voltage generator producing at its output the voltage for input to the control oscillator, the voltage corresponding to the digital signal at the digital input; and (i) an antenna connected to receive the power usage data and the output signal from the oscillator, the antenna emitting a radiowave signal corresponding to the output signal and the power usage data. - View Dependent Claims (11, 12, 13, 14)
-
-
15. A method of transmitting monitor data at a temperature stabilized output frequency from a transmitter in a monitoring station connected to a facility, comprising the steps of:
-
(a) monitoring power usage of the facility with the monitoring station; (b) producing monitor data corresponding to the power usage; (c) producing with a step generator a step voltage; (d) applying the step voltage to an RC circuit having a temperature-dependent time constant and a capacitive portion to raise the voltage of the capacitive portion; (e) comparing the voltage of the capacitive portion to a reference voltage to determine when the voltage of the capacitive portion reaches the reference voltage; (f) monitoring the voltage of the capacitive portion of the RC circuit to determine a time difference between the time when the step voltage is applied and the time the voltage of the capacitive portion reaches the reference voltage; (g) retrieving a data sequence from a memory location, the memory location determined in response to the determined time difference; (h) producing an RF signal at the output frequency, the output frequency being determined in response to the retrieved data sequence; (i) combining the monitor data and the RF signal to produce an output signal; and (j) transmitting the output signal with an antenna transmitter. - View Dependent Claims (16, 17, 18, 19, 20)
-
Specification