What is claimed is:
1. A partial fractionally spaced equalizer for a digital television comprising:
a feedforward filter unit for receiving an input signal sampled at a predetermined frequency, which is divided a first region having a symbol spaced tap and a second region having fractional spaced taps narrower than the symbol spaced tap;
a feedback filter unit having symbol spaced taps;
a equalizer signal generator for processing feedforward tap signals outputted from the feedforward filter unit and the feedback tap signals outputted from the feedback filter unit and generating equalizer signals;
a slicer for slicing the equalizer signals to generate a decision data and outputting the decision data to the feedback filter unit; and
an error generator for generating a compensating error signal by subtracting the equalizer signal from the decision data.
2. The equalizer according to claim 1, wherein the input signal has a sampling frequency of 21.52 MHz.
3. The equalizer according to claim 1, wherein the first region is formed by setting coefficients to zero at except the positions of symbols or between symbols.
4. The equalizer according to claim 1, wherein the first and the second regions process the input signal at the same sampling frequency as the frequency of the input signal.
5. The equalizer according to claim 1, wherein the equalization signal generator comprising:
a first adder for adding the feedforward tap signals;
a decimeter for sampling the addition result outputted from the first adder at the same frequency as that of the input signal;
a third adder for adding the feedback tap signals; and
a second adder for adding the sampled signal outputted from the decimeter and the addition result outputted from the third adder, and generating the equalizer signal.
6. The equalizer according to claim 5, wherein the decimeter samples a signal corresponding to the symbol time among inputted signals.
7. The equalizer according to claim 5, wherein the decimeter comprises a flip-flop.
8. The equalizer according to claim 5, wherein the error generator comprising:
a subtractor for subtracting the equalizer signal from the decision data and outputting an error signal; and
a multiplier for multiplying the error signal by a predetermined step size and generating the compensation error signal.
9. The equalizer according to claim 1, wherein the feedback filter unit further comprises decimeter unit for sampling the input signal and signals from the first and second regions.
10. The equalizer according to claim 9, wherein the decimeter comprises a flip-flop.
11. The equalizer according to claim 9, wherein the equalization signal generator comprising:
a first adder for adding the feedforward tap signals;
a third adder for adding the feedback tap signals; and
a second adder for adding the addition results outputted from the first and third adders, and generating the equalizer signal.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A polymeric fuel additive made by a method comprising the steps of:
(a) isothermally mixing substantially equimolar amounts of an ethoxylated alcohol and an amide, said ethoxylated alcohol comprising at least about 75 weight percent of at least one linear straight-chain alcohol having a hydrocarbon chain length of about nine to about fifteen carbon atoms, and said amide being a substantially equimolar reaction product of an alcohol amine and an alkyl ester of a fatty acid; and,
(b) isothermally mixing the product of step (a) and with an ethoxylated fatty acid or derivative having a hydrocarbon chain length of about nine to about fifteen carbon atoms to form said polymeric fuel additive.
2. The additive of claim 1, wherein said ethoxylated fatty acid or derivative is a reaction product of an unmodified fatty acid or derivative having a hydrocarbon chain length of about nine to about fifteen carbon atoms and ethylene oxide.
3. The additive of claim 2, wherein said ethoxylated fatty acid or derivative is formed by reacting the unmodified fatty acid or derivative with at least about seven moles of the ethylene oxide per mole of unmodified fatty acid.
4. The additive of claim 2, wherein said unmodified fatty acid derivative is an alkyl ester of a fatty acid.
5. The additive of claim 1, wherein said alkyl ester of a fatty acid is methyl ester of a fatty acid, said fatty acid having a hydrocarbon chain length of at least about nine carbon atoms
6. The additive of claim 1, wherein said ethoxylated alcohol and said amide are isothermally mixed at a temperature of about 55 C. to about 58 C.
7. The additive of claim 1, wherein said amide is formed by reacting said alkyl ester of a fatty acid and said alcohol amine at a temperature of about 100 C. to about 110C.
8. The additive of claim 1, wherein said alcohol amine comprises one or more compounds selected from the group consisting of ethanolamine, diethanolamine, and triethanolamine.
9. The additive of claim 1, wherein said isothermal mixing of step (b) occurs at a temperature of about 55 C. to about 58 C.
10. The additive of claim 1, wherein said straight-chain alcohols have hydrocarbon chain lengths of about eleven carbon atoms.
11. The additive of claim 1, wherein said ethoxylated alcohol has an average molecular weight of less than about 200.
12. The additive of claim 1, wherein said ethoxylated alcohol has an average molecular weight of less than about 160.
13. A method of making a polymeric fuel additive, said method comprising the steps of:
(a) isothermally mixing substantially equimolar amounts of an ethoxylated alcohol and an amide, said ethoxylated alcohol comprising at least about 75 weight percent of at least one linear straight-chain alcohol having a hydrocarbon chain length of about nine to about fifteen carbon atoms, and said amide being the substantially equimolar reaction product of an alcohol amine and an alkyl ester of a fatty acid; and,
(b) isothermally mixing the product of step (a) and with an ethoxylated fatty acid or derivative having a hydrocarbon chain length of about nine to about fifteen carbon atoms to form said polymeric fuel additive.
14. The additive of claim 13, wherein said ethoxylated fatty acid or derivative is a reaction product of an unmodified fatty acid or derivative having a hydrocarbon chain length of about nine to about fifteen carbon atoms and ethylene oxide.
15. The additive of claim 14, wherein said ethoxylated fatty acid or derivative is formed by reacting the unmodified fatty acid or derivative with at least about seven moles of the ethylene oxide per mole of unmodified fatty acid.
16. The additive of claim 14, wherein said unmodified fatty acid derivative is an alkyl ester of a fatty acid.
17. The additive of claim 13, wherein said alkyl ester of a fatty acid is methyl ester of a fatty acid, said fatty acid having a hydrocarbon chain length of at least about nine carbon atoms
18. The additive of claim 13, wherein said ethoxylated alcohol and said amide are isothermally mixed at a temperature of about 55 C. to about 58 C.
19. The additive of claim 13, wherein said amide is formed by reacting said alkyl ester of a fatty acid and said alcohol amine at a temperature of about 100 C. to about 110 C.
20. The additive of claim 13, wherein said alcohol amine comprises one or more compounds selected from the group consisting of ethanolamine, diethanolamine, and triethanolamine.
21. The additive of claim 13, wherein said isothermal mixing of step (b) occurs at a temperature of about 55 C. to about 58 C.
22. The additive of claim 13, wherein said straight-chain alcohols have hydrocarbon chain lengths of about eleven carbon atoms.
23. The additive of claim 13, wherein said ethoxylated alcohol has an average molecular weight of less than about 200.
24. The additive of claim 13, wherein said ethoxylated alcohol has an average molecular weight of less than about 160.
25. A polymeric fuel additive comprising the reaction product of:
(a) a mixture of an ethoxylated alcohol and an amide, said ethoxylated alcohol comprising at least about 75 weight percent of at least one linear straight-chain alcohol having a hydrocarbon chain length of about nine to about fifteen carbon atoms, and said amide being a substantially equimolar reaction product of an alcohol amine and an alkyl ester of a fatty acid; and,
(b) an ethoxylated fatty acid or derivative having a hydrocarbon chain length of about nine to about fifteen carbon atoms, said acid formed by reacting an unmodified fatty acid or derivative with ethylene oxide.
26. A fuel composition comprising:
(a) a hydrocarbon-based fuel having hydrocarbon chain lengths of about four to about thirty carbon atoms; and
(b) a polymeric fuel additive comprising the reaction product of:
(i) a mixture of an ethoxylated alcohol and an amide, said ethoxylated alcohol comprising at least about 75 weight percent of at least one linear straight-chain alcohol having a hydrocarbon chain length of about nine to about fifteen carbon atoms, and said amide being a substantially equimolar reaction product of an alcohol amine and an alkyl ester of a fatty acid; and,
(ii) an ethoxylated fatty acid or derivative having a hydrocarbon chain length of about nine to about fifteen carbon atoms.