What is claimed:
1. A dual band voltage controlled oscillator comprising:
first and second bipolar transistors, each transistor having a collector cross coupled to a base of the other transistor;
a common current source connected to supply to emitters of said first and second transistors an operating current;
a pair of inductors serially connected between each of said collectors and a power supply terminal;
tuning capacitor means connected between each of said collectors for forming a resonant circuit which said inductors at a resonant frequency;
a first output terminal connected to one of said collectors to produce a signal having a frequency equal to said resonant frequency; and
a second output terminal connected to said emitter terminals for producing a harmonic signal which is a multiple of the frequency of said resonant frequency.
2. The circuit according to claim 1 further comprising means for controlling the amount of coupling between said collectors and base connections whereby the level of the harmonic signal is controlled.
3. The circuit according to claim 2 wherein the means for controlling the amount of coupling comprises first and second digital devices serially connecting a respective base of each bipolar transistor to a base of an opposite transistor.
4. The circuit according to claim 1 wherein said tuning capacitor means comprises first and second varactor diodes serially connecting said bipolar transistor collectors, and connected to receive a tuning voltage for continuously varying the frequency of oscillation of said circuit.
5. The circuit according to claim 1 further comprising means for varying the amount of harmonic signal at said second output terminal.
6. The circuit according to claim 5 wherein said means for varying the amount of harmonic signal comprises a series resonant filter having a series resonance frequency which is the second harmonic connected at one end to one end of said current source; and
resistance means connecting a second end of said series resonant filter to a second end of said current source.
7. The circuit according to claim 6 wherein said resistance means is a field effect transistor connected to receive a control voltage on a gate thereof and to change the amount of current flowing through said series resonant filter.
8. The circuit according to claim 3 wherein said digital devices comprise first and second field effect transistors having source and drain connections connected to a respective base of said bipolar transistors, and a gate connection connected to a respective collector connection of an opposite transistor, and first and second resistors connected to each of said transistor gates for applying a voltage for operating said switches.
9. The circuit according to claim 1 wherein said resonant frequency is substantially 900 MHZ and said harmonic frequency is at substantially 1800 MHZ.
10. The circuit according to claim 6 wherein said series resonant frequency is 1800 MHZ.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for the continuous torrefaction of biomass to obtain a fuel of specified or constant properties, said method comprising:
sensing a property of biomass; and
controlling the torrefaction in proportion to said property,
wherein said sensing senses a mid-infrared spectra of torrefied biomass, and wherein said controlling includes utilizing a correlation of mid-infrared spectra and two ratios of H, C, and O atoms to estimate, based on said correlation and said sensed spectra, two ratios of H, C, and O atoms in the sample, and changing torrefaction parameters to approach the target values of H, C, and O atoms.
2. The method of claim 1, where said sensing estimates the heating value of biomass.
3. The method of claim 2, where said sensing includes sensing the heating value of biomass.
4. The method of claim 2, where said sensing includes sensing an optical property of biomass.
5. The method of claim 4, where said optical property is sensed using visible light.
6. The method of claim 4, where said optical property is sensed using mid-infrared light.
7. The method of claim 1, where said sensing estimates the moisture content of the biomass.
8. The method of claim 1, where said controlling controls the torrefaction temperature.
9. The method of claim 1, where said controlling controls the time during which the biomass is torrefied.
10. The method of claim 1, where said sensing estimates a physical or chemical property of the biomass, and where said controlling controls the conditions of torrefaction to obtain target fuel properties.
11. The method of claim 1, further including logging information related to the biomass or fuel.
12. The method of claim 1, further including storing fuel samples.
13. The method of claim 1, where said sensing a property of the biomass senses the property during the torrefaction of the biomass.
14. A method for the continuous torrefaction of biomass to obtain a fuel of specified or constant properties, said method comprising:
sensing a property of the biomass during the torrefaction of the biomass; and
controlling the torrefaction in proportion to said property.
15. The method of claim 14, where said sensing estimates the heating value of biomass.
16. The method of claim 15, where said sensing includes sensing the heating value of biomass.
17. The method of claim 15, where said sensing includes sensing an optical property of biomass.
18. The method of claim 17, where said optical property is sensed using visible light.
19. The method of claim 17, where said optical property is sensed using mid-infrared light.
20. The method of claim 14, where said sensing estimates the moisture content of the biomass.
21. The method of claim 14, where said controlling controls the torrefaction temperature.
22. The method of claim 14, where said controlling controls the time during which the biomass is torrefied.
23. The method of claim 14, where said sensing estimates a physical or chemical property of the biomass, and where said controlling controls the conditions of torrefaction to obtain target fuel properties.
24. The method of claim 14, further including logging information related to the biomass or fuel.
25. The method of claim 14, further including storing fuel samples.