All The Claims

1-43. (canceled)
44. A semiconductor memory device, comprising:
an internal signal generation unit configured to generate a plurality of delay signals by delaying an external signal for a predetermined latency shorter than a latency set by the semiconductor memory device in synchronism with a drive clock and select one of the delay signals to output an internal signal; and
a drive clock generation unit configured to output an internal clock as the drive clock in response to the latency set by the semiconductor memory device.
45. The semiconductor memory device as recited in claim 44, wherein the internal signal generation unit includes:
a flip-flop unit configured to generate the plurality of delay signals by delaying the external signal for the predetermined latency; and
a selection unit configured to select one of the delay signals corresponding to a latency signal having information about the latency to thereby output the internal signal.
46. The internal signal generator as recited in claim 45, wherein the flip-flop unit includes:
a plurality of flip-flops serially connected to one another, each of which outputs a first and a second output respectively through a first and a second output terminal, wherein the first output is transmitted to an input terminal of the next flip-flop and the second output is output as the delay signal; and
an latch unit configured to output the first output of the last flip-flop as the last delay signal in response to the drive clock,
wherein the first flip-flop receives the external signal and the plurality of the flip-flops are respectively reset by corresponding latency signals.
47. The internal signal generator as recited in claim 46, wherein each of the flip-flops resets the first and the second outputs in response to the activation of the corresponding latency signal and outputs an input signal through the second output terminal in synchronism with a falling edge of the drive clock or through the first output terminal in synchronism with a rising edge of the drive clock when the corresponding latency signal is inactivated.
48. The internal signal generator as recited in claim 46, wherein each of the flip-flops resets the first and the second outputs in response to the activation of the corresponding latency signal and outputs an input signal through the second output terminal in synchronism with a rising edge of the drive clock and through the first output terminal in synchronism with a falling edge of the drive clock when the corresponding latency signal is inactivated.
49. The internal signal generator as recited in claim 47, wherein each of the flip-flops includes:
a first transmission gate for transmitting the input signal in response to the drive clock of a first logic level;
a first latch for resetting the second output to a second logic level when a reset signal is activated and latching an output of the first transmission gate to output the delay signal through the second output terminal when the reset signal is inactivated;
a second transmission gate for transmitting an output of the first latch in response to the drive clock of the second logic level; and
a second latch for resetting the first output to the first logic level when the reset signal is activated and latching an output of the second transmission gate to output the first output when the reset signal is inactivated,
wherein the reset signal is the corresponding latency signal.
50. The internal signal generator as recited in claim 49, wherein the first latch includes:
a first inverter for inverting the reset signal;
a NAND gate for logically combining an output of the first inverter and the output of the first transmission gate; and
a second inverter for inverting an output of the NAND gate, wherein an output terminal of the second inverter is connected to an output terminal of the first transmission gate.
51. The internal signal generator as recited in claim 50, wherein the second latch includes:
a NOR gate for logically combining the reset signal and the output of the second transmission gate; and
a third inverter for inverting an output of the NOR gate, wherein an output terminal of the third inverter is connected to an output terminal of the second transmission gate.
The claims below are in addition to those above.
All refrences to claims which appear below refer to the numbering after this setence.

1. A compound of the formula I:
wherein:
R1 is C1-4 alkyl, C1-4 haloalkyl, C1-4 alkoxy(C1-4)alkyl or C1-4 haloalkoxy(C1-4)alkyl;
R2 is C1-4 haloalkyl, C1-4 alkyl, C1-4 alkoxy(C1-4)alkyl, C1-4 haloalkoxy or C1-4 haloalkoxy(C1-4)alkyl;
R3 is hydrogen, C1-4 alkyl, C2-4 alkenyl, C2-4alkynyl, halogen or cyano;
R4 is hydrogen, C1-4 alkyl, CH2CH\u2550CHR4a, CH2C\u2261CR4b or COR4c;
R4a and R4b are each, independently, hydrogen, C1-C6alkyl, C1-C6haloalkyl, C2-C6alkenyl, C2-C6alkynyl, C3-C7cycloalkyl, COOC1-C4alkyl, COOC3-C6alkenyl, COOC3-C6alkynyl or CN;
R4c is C1-C6alkyl, C1-C6alkyl substituted by halogen, C1-C6alkoxy, C1-C6haloalkoxy, C1-C6alkylthio, C1-C6haloalkylthio, C1-C6alkoxy, C1-C6haloalkoxy, C3-C6alkenyloxy, C3-C6haloalkenyloxy, C3-C6alkynyloxy or C3-C6haloalkynyloxy;
X is oxygen or sulfur; and
A is
wherein:
R6 is a C1-12 alkyl, C2-12 alkenyl or C2-12 alkynyl group, which may be substituted by 1 to 6 substituents, each substituent independently selected from halogen, cyano, C1-4 alkoxy, C1-4 thioalkyl, COO-C1-4 alkyl, \u2550N\u2014OH, \u2550N\u2014O\u2014(C1-4 alkyl), C3-8 cycloalkyl, which may itself be substituted by 1 to 3 substituents, each substituent independently selected from C1-4 alkyl, halogen, C1-4 alkoxy and C1-4 haloalkoxy, and C4-8 cycloalkenyl, which may itself be substituted by 1 to 3 substituents, each substituent independently selected from C1-4 alkyl, halogen, C1-4 alkoxy and C1-4 haloalkoxy;
or R6 is a C3-8 cycloalkyl, C4-8 cycloalkenyl or C5-8 cycloalkadienyl group, which may be substituted by 1 to 3 substituents, each substituent independently selected from halogen, C1-4 alkyl, C1-4 haloalkyl, C1-4 alkoxy, C1-4 haloalkoxy, C1-4 thioalkyl, C3-6 cycloalkyl, which may itself be substituted by 1 to 3 substituents, each substituent independently selected from C1-4 alkyl, halogen, C1-4 alkoxy and C1-4 haloalkoxy, and phenyl, which may itself be substituted by 1 to 5 independently selected halogen atoms;
or R6 is a C6-12 bicycloalkyl, C6-12 bicycloalkenyl or C6-12 bicycloalkadienyl group, which may be substituted by 1 to 3 substituents, each substituent independently selected from halogen, C1-4 alkyl and C1-4 haloalkyl;
Z is C1-4 alkylene;
p is 0 or 1;
R25 is hydrogen, halogen, C1-4 alkyl, C1-4 haloalkyl, C1-4 alkoxy(C1-4)alkyl, C1-4 haloalkoxy(C1-4)alkyl or Si(C1-4 alkyl)3;
R26 and R27 are each independently hydrogen, halogen, C1-4 alkyl or C1-4 haloalkyl;
R28 is hydrogen, C1-4 alkyl or C1-4 haloalkyl;
Ra, Rb, Rc and Rd are each independently hydrogen or a C1-4 alkyl group, which may substituted by 1 to 6 substituents, each substituent independently selected from halogen, hydroxy, cyano, carboxyl, methoxycarbonyl, ethoxycarbonyl, methoxy, ethoxy, methylsulfonyl, ethylsulfonyl, difluoromethoxy, trifluoromethoxy, trifluoromethylthio and trifluorothiomethoxy;
Cy is a carbocyclic or heterocyclic 3-7 membered ring, which may be saturated, unsaturated or aromatic and which may contain a silicon atom as a ring member, wherein (CRaRb)m and (CRcRd)n may be bound either to the same carbon or silicon atom of Cy or to different atoms separated by 1, 2 or 3 ring members, wherein the carbocyclic or heterocyclic 3-7 membered ring may be substituted by 1 to 6 substituents, each substituent independently selected from halogen, C1-4 alkyl, C2-4 alkenyl, C1-4 haloalkyl, C1-4 alkoxy and halo-C1-4 alkoxy;
Y1 is Si(Op1Z1)(OqZ2)(OsZ3), and provided that Cy contains a silicon atom as a ring member, then Y1 may also be hydrogen;
Z1 and Z2 are each independently methyl or ethyl;
Z3 is a C1-4 alkyl or a C2-4 alkenyl group, which may be interrupted by one heteroatom selected from O, S and N, and wherein the C1-4 alkyl or C2-4 alkenyl group may be substituted by 1 to 3 independently selected halogen atoms;
m and n are each independently 0, 1, 2 or 3;
p1,q and s are each independently 0 or 1;
R7, R8, R9, and R10 are each independently hydrogen, halogen, cyano, nitro, C1-4 alkyl, C1-4 haloalkyl, C1-4 alkoxy, C1-4 haloalkoxy, C1-4 thioalkyl or C1-4 thiohaloalkyl;
R18 is hydrogen, C1-4 alkyl, formyl, C1-4 alkoxy(C1-4)alkyl, C(\u2550O)C1-4 alkyl, which may be substituted by halogen or C1-4-alkoxy, or C(\u2550O)O\u2014C1-6 alkyl, which may be substituted by halogen, C1-4 alkoxy or CN;
R19, R20, R21, R22, R23 and R24 are each independently hydrogen, halogen, hydroxy, C1-4 alkoxy, C1-6 alkyl, which may be substituted by 1 to 3 substituents selected from halogen, hydroxy, \u2550O, C1-4 alkoxy, O\u2014C(O)\u2014C1-4 alkyl, phenyl, naphthyl, anthracyl, fluorenyl, indanyl or a 3-7 membered carbocyclic ring which itself may be substituted by 1 to 3 methyl groups, C1-6 alkenyl, which may be substituted by 1 to 3 substituents selected from halogen, hydroxy, \u2550O, C1-4 alkoxy, O\u2014C(O)\u2014C1-4 alkyl, phenyl, naphthyl, anthracyl, fluorenyl, indanyl or a 3-7 membered carbocyclic ring which itself may be substituted by 1 to 3 methyl groups, or a 3-7 membered carbocyclic ring, which may contain 1 heteroatom selected from nitrogen and oxygen, and wherein the 3-7 membered carbocyclic ring may be substituted by 1 to 3 methyl groups;
or R19R20 together with a carbon atom to which it is attached form a carbonyl-group, a 3-5 membered carbocyclic ring, which may be substituted by 1 to 3 methyl groups, C1-6 alkylidene, which may be substituted by 1 to 3 methyl groups, or C3-6 cycloalkylidene, which may be substituted by 1 to 3 methyl groups;
m1 is 0 or 1;
n1 is 0 or 1;
or a tautomer, stereoisomer or enantiomer of these compounds.
2. A compound of formula I according to claim 1, wherein R2 is C1-4 haloalkyl, C1-4 alkyl, C1-4 alkoxy(C1-4)alkyl or C1-4 haloalkoxy(C1-4)alkyl.
3. A compound of formula I according to claim 1, wherein R6 is:
a group of the form
wherein:
R7b and R7c are each independently hydrogen, C1-C3alkyl or C1-C3haloalkyl; and

R8b and R9b are each independently C1-C3alkyl or C1-C3haloalkyl;

or a group of the form
wherein:
R7d and R7e are each independently hydrogen, C1-C3alkyl or C1-C3haloalkyl;
R10b and R11b are each independently hydrogen or halogen; and
n2 is 1 or 2.
4. A compound according to claim 3, wherein R4 is hydrogen.
5. A compound of formula I according to claim 1, wherein R6 is a C3-8 cycloalkyl group, which may be substituted by 1 to 3 substituents, each substituent independently selected from halogen, C1-4 alkyl, C1-4 haloalkyl, C1-4 alkoxy, C1-4 haloalkoxy, C1-4 thioalkyl, C3-6 cycloalkyl, which may itself be substituted by 1 to 3 substituents, each substituent independently selected from C1-4 alkyl, halogen, C1-4 alkoxy and C1-4 haloalkoxy, and phenyl, which may itself be substituted by 1 to 5 independently selected halogen atoms.
6. A compound according to claim 5, wherein R4 is hydrogen.
7. A method for protecting against phytopathogenic microorganisms, wherein a compound of formula I according to claim 1 or a composition comprising the compound of formula I as active ingredient is applied to the plants, to parts thereof or the locus thereof.
8. A composition for protecting against phytopathogenic microorganisms comprising the compound of formula I according to claim 1 and an inert carrier.
9. A compound of formula I according to claim 1, wherein:
R1 is a methyl group;
R2 is a difluoromethyl group;
R3 is hydrogen; and
X is oxygen.
10. A composition for controlling and protecting against phytopathogenic microorganisms comprising the compound of formula I according to claim 9 and an inert carrier.

1. In a given router of a label-switching network, a method for distributing label binding information to other routers in the label-switching network, the method comprising:
identifying a group of routers in the label-switching network to receive common label information for routing packets along multiple respective paths through the label-switching network;
for the group of routers, allocating memory resources;
populating the memory resources with a set of label information; and
distributing the set of label information stored in the memory resources to each router in the group of routers.
2. A method as in claim 1, wherein identifying the group of routers in the label-switching network includes:
analyzing policies associated with downstream routers in the label-switching network, the downstream routers being downstream with respect to the given router in the label-switching network; and
selecting a set of routers from the downstream routers having a substantially same egress policy as each other; and
wherein distributing the set of label information includes:
transmitting the set of label information to each router in the selected set of routers.
3. A method as in claim 1, wherein transmitting the set of label information includes transmitting LDP binding information to each router in the selected set of routers.
4. A method as in claim 1, wherein the group of routers is a first group of routers and the set of label information is a first set of label information, the method further comprising:
identifying a second group of routers in the label-switching network to receive label information for routing packets along the multiple respective paths through the label-switching network;
for the second group of routers, allocating a second set of memory resources;
populating the second set of memory resources with a second set of label information; and
distributing the second set of label information stored in the second set of memory resources to each router in the second group of routers.
5. A method as in claim 4, wherein identifying the group of routers includes:
defining the group of routers in the label-switching network to be a set of peer routers that have a common egress filtering LDP (Label Distribution Protocol) configuration.
6. A method as in claim 5, wherein distributing the label information includes:
distributing the common label information to the group of routers according to LDP (Label Distribution Protocol).
7. A method as in claim 1, wherein steps of identifying, allocating, populating, and distributing occur during convergence of the label-switching network in which routers in the label-switching network communicate amongst each other to create respective forwarding tables establishing the multiple paths through the label-switching network.
8. A method as in claim 1 further comprising:
receiving a set of label information from an upstream router in the label-switching network;
utilizing the received set of label information to generate a forwarding table in the given router, the forwarding table later used by the given router to forward data packets through the label-switching network in which an entry in the forwarding table binds an incoming label to a respective route through the label-switching network to a downstream router towards an egress node of the label-switching network; and
wherein populating the memory resources includes, populating the memory resources with the set of label information based at least in part on the received set of label information from the upstream router and label binding information in the forwarding table.
9. A label-switching network system comprising:
a first router;
a plurality of downstream routers with respect to the first router; and
the first router supporting operations of:
identifying a group of routers in the label-switching network to receive common label information for routing packets along multiple respective paths through the label-switching network;
for the group of routers, allocating a set of memory resources;
populating the memory resources with a set of label information; and
distributing the set of label information stored in the memory resources to each router in the group of routers.
10. A label-switching network as in claim 9, wherein identifying the group of routers in the label-switching network includes:
analyzing policies associated with the plurality of downstream routers in the label-switching network, the downstream routers being downstream with respect to the given router in the label-switching network; and
selecting a set of routers from the downstream routers having a substantially same egress policy as each other; and
wherein distributing the set of label information includes:
transmitting the set of label information to each router in the selected set of routers over respective communication sessions between the first router and each router in the selected set of routers.
11. A label-switching network as in claim 10 further comprising:
at least one upstream router;
the first router further supporting operations of:
receiving a set of label information from the at least one upstream router in the label-switching network;
utilizing the received set of label information to generate a forwarding table in the first router, the forwarding table later used by the first router to forward data packets through the label-switching network after convergence of the network, entries in the forwarding table binding incoming labels to respective routes through the label-switching network to a downstream router towards an egress node of the label-switching network; and
wherein populating the memory resources includes, populating the memory resources with the set of label information based at least in part on the received set of label information from the upstream router and label binding information in the forwarding table.
12. A computer system for distributing label information in a label-switching network, the computer system comprising:
a processor;
a memory unit that stores instructions associated with an application executed by the processor; and
an interconnect coupling the processor and the memory unit, enabling the computer system to execute the application and perform operations of:
identifying a group of routers in the label-switching network to receive common label information for routing packets along multiple respective paths through the label-switching network;
for the group of routers, allocating memory resources;
populating the memory resources with a set of label information; and
distributing the set of label information stored in the memory resources to each router in the group of routers.
13. A computer system as in claim 12, wherein identifying the group of routers in the label-switching network includes:
analyzing policies associated with downstream routers in the label-switching network, the downstream routers being downstream with respect to the given router in the label-switching network;
selecting a set of routers from the downstream routers having a substantially same egress policy as each other; and
wherein distributing the set of label information includes:
transmitting the set of label information to each router in the selected set of routers.
14. A computer system as in claim 12, wherein transmitting the set of label information includes transmitting LDP binding information to each router in the selected set of routers.
15. A computer system as in claim 12, wherein the group of routers is a first group of routers and the set of label information is a first set of label information, the method further comprising:
identifying a second group of routers in the label-switching network to receive label information for routing packets along the multiple respective paths through the label-switching network;
for the second group of routers, allocating a second set of memory resources;
populating the second set of memory resources with a second set of label information; and
distributing the second set of label information stored in the second set of memory resources to each router in the second group of routers.
16. A computer system as in claim 12, wherein identifying the group of routers includes:
defining the group of routers in the label-switching network to be a set of peer routers that have a common egress filtering LDP (Label Distribution Protocol) configuration.
17. A computer system as in claim 12, wherein distributing the label information includes:
distributing the common label information to the group of routers according to LDP (Label Distribution Protocol).
18. A computer system as in claim 12, wherein steps of identifying, allocating, populating, and distributing occur during convergence of the label-switching network in which routers in the label-switching network communicate amongst each other to create respective forwarding tables establishing the multiple paths through the label-switching network.
19. A computer system as in claim 12 that additionally performs operations of:
receiving a set of label information from an upstream router in the label-switching network;
utilizing the received set of label information to generate a forwarding table in the given router, the forwarding table later used by the given router to forward data packets through the label-switching network in which an entry in the forwarding table binds an incoming label to a respective route through the label-switching network to a downstream router towards an egress node of the label-switching network; and
wherein populating the memory resources includes, populating the memory resources with the set of label information based at least in part on the received set of label information from the upstream router and label binding information in the forwarding table.
20. A computer system for tracking an ability to convey messages over a network, the computer system including:
means for identifying a group of routers in the label-switching network to receive common label information for routing packets along multiple respective paths through the label-switching network;
means for allocating memory resources for the group of routers;
means for populating the memory resources with a set of label information; and
means for distributing the set of label information stored in the memory resources to each router in the group of routers.
The claims below are in addition to those above.
All refrences to claims which appear below refer to the numbering after this setence.

1. A method for simulcast communication, the method comprising:
modulating a simulcast signal using 8-level modulation;
increasing a time interval spacing between signal pulses of the simulcast signal;
spreading in time the signal pulses of the simulcast signal; and
communicating a stretched modulated simulcast signal formed by increasing the time interval spacing and spreading in time the signal pulses.
2. A method in accordance with claim 1 wherein the modulating comprises modulating the simulcast signal at a bit rate of one of 12 kilobits per second (kbps) and 9.6 kbps.
3. A method in accordance with claim 1 wherein the communicating comprises transmitting the stretched modulated simulcast signal using a Project 25 Time Division Multiple Access (TDMA) standard.
4. A method in accordance with claim 1 wherein the communicating comprises transmitting the stretched modulated simulcast signal using defined channel spaced of one of about 12.5 kilo-Hertz (kHz) apart and 25 kHz apart.
5. A method in accordance with claim 1 further comprising converting an input stream of data to 8-level symbols using three data bits.
6. A method in accordance with claim 5 wherein two most significant bits of the three data bits correspond to two bits of a phase shift level for 4-level mapping.
7. A method in accordance with claim 1 wherein the spreading in time comprises generating signal pulses having a Gaussian curve form.
8. A method in accordance with claim 1 wherein the 8-level modulation comprises one of 8 phase-shift keying (8PSK) modulation and harmonized differential quadrature phase shift keying (H-DQPSK) modulation.
9. A method in accordance with claim 1 wherein the increasing and spreading define a stretched eye pattern opening for the modulated simulcast signal.
10. A method in accordance with claim 1 further comprising encoding the stretched modulated simulcast signal with a protocol code word indicating the 8-level modulation.
11. A method in accordance with claim 10 wherein the encoding comprises using one of an inter-slot signaling channel and a trunking control channel to encode the protocol code.
12. A method in accordance with claim 1 wherein the spreading in time comprises spreading a symbol width of the simulcast signal or increasing a time duration between symbols relative to a time duration of symbols of a 4-level modulation.
13. A method for simulcast communication, the method comprising:
selecting one of a 4-level modulation and an 8-level modulation for modulating a simulcast signal; and
modulating the simulcast signal based on the selected modulation, wherein a bit rate for the simulcast signal is the same for different modulation types; and
selecting said 8-level modulation to include generating a sequence of 8-level pulses, each having a pulse width that is larger than a pulse width of a 4-level pulse generated during said 4-level modulation.
14. A method for simulcast communication, the method comprising:
selecting one of a 4-level modulation and an 8-level modulation for modulating a simulcast signal;
modulating the simulcast signal based on the selected modulation, wherein a bit rate for the simulcast signal is the same for different modulation types;
increasing a spacing between signal pulses of the simulcast signal, and
spreading in time the pulse width of the simulcast signal when using the 8-level modulation.
15. A method in accordance with claim 13 further comprising dynamically switching between the 4-level modulation and the 8-level modulation based on the selected modulation.
16. A method in accordance with claim 13 further comprising using a signal protocol in the modulated simulcast signal to identify the selected modulation.
17. A method in accordance with claim 16 wherein the signal protocol is encoded in one of an inter-slot signaling channel and a trunking control channel.
18. A method in accordance with claim 13 wherein the 4-level modulation comprises one of compatible 4-level Frequency modulation (C4FM), quadrature phase-shift keying (QPSK) modulation and compatible Quadrature Phase Shift Keying (CQPSK) modulation, and wherein the 8-level modulation comprises one of 8 phase-shift keying (8PSK) modulation and harmonized differential quadrature phase shift keying (H-DQPSK) modulation.
19. A method in accordance with claim 13 further comprising communicating at one of a 9.6 kilobits per second (kbps) rate and a 12 kbps rate when using the 8-level modulation.
20. A simulcast communication system comprising:
a transmitter configured to switch between a 4-level modulation mode and an 8-level modulation mode; and
a receiver configured to switch between a 4-level modulation mode and an 8-level modulation mode based on an encoded signal protocol in a simulcast transmission from the transmitter;
wherein said transmitter in said 8-level modulation mode generates a sequence of 8-level pulses, each having a pulse width that is larger than a pulse width of a 4-level pulse generated when said transmitter operates in said 4-level modulation mode.
21. A simulcast communication system comprising:
a transmitter configured to switch between a 4-level modulation mode and an 8-level modulation mode; and
a receiver configured to switch between a 4-level modulation mode and an 8-level modulation mode based on an encoded signal protocol in a simulcast transmission from the transmitter;
wherein the transmitter is further configured to (i) increase a spacing between signal pulses of the simulcast transmission and (ii) spread in time the pulse width of the simulcast transmission when using the 8-level modulation.
22. A simulcast communication system in accordance with claim 21 wherein the transmitter comprises a Gaussian impulse filter configured to perform the stretching.
23. A simulcast communication system in accordance with claim 20 wherein the 4-level modulation comprises one of compatible 4-level Frequency modulation (C4FM), quadrature phase-shift keying (QPSK) modulation and compatible Quadrature Phase Shift Keying (CQPSK) modulation, and wherein the 8-level modulation comprises one of 8 phase-shift keying (8PSK) modulation and harmonized differential quadrature phase shift keying (H-DQPSK) modulation.
24. A simulcast communication system in accordance with claim 20 communicating at a 9.6 kilobits per second (kbps) rate when using the 4-level modulation and at a 12 kbps rate when using the 8-level modulation.
25. A simulcast communication system in accordance with claim 20 wherein the transmitter comprises a first converter configured to convert two bits to a 4-level phase shift in the 4-level modulation mode and a second converter configured to convert three bits to an 8-level phase shift in the 8-level modulation mode.
26. A simulcast communication system in accordance with claim 20 wherein the receiver comprises a first converter configured to convert a 4-level phase shift to two bits in the 4-level modulation mode and a second converter configured to convert an 8-level phase shift to three bits in the 8-level modulation mode.
27. A method for simulcast communication, the method comprising:
generating a sequence of 4-level pulses in which adjacent pulses are spaced apart from each other a duration defined by a first time interval;
generating a sequence of 8-level pulses in which adjacent pulses are spaced apart from each other a duration defined by a second time interval, said second time interval larger than said first time interval; and
increasing a pulse width of each said 8-level pulse by a predetermined amount so that a pulse width of each said 8-level pulse is larger than a pulse width of each said 4-level pulse.