1. A method for transforming a first signal into a second signal comprising supplying the first signal to a signal transforming device to produce the second signal, wherein the signal transforming device has a codebook and is selected from the group consisting of a) an encoder, wherein the first signal is coded into the second signal and b) a decoder, wherein the first signal is decoded into the second signal,
wherein:
the codebook comprises a set of pulse amplitude/position combinations;
each pulse amplitude/position combination defines a number of different positions and comprises both zero-amplitude pulses and non-zero-amplitude pulses assigned to respective positions of the combination; and
each non-zero-amplitude pulse assumes one of a plurality of possible amplitudes; and

wherein the codebook pulse amplitudes and positions are indexed by:
forming a set of at least one track of said pulse positions;
restraining the positions of the non-zero-amplitude pulses of the combinations of the codebook in accordance with the set of at least one track of pulse positions;
indexing according to a first procedure, hereinafter named procedure 1, the position and amplitude of one non-zero-amplitude pulse when only the position of said one non-zero-amplitude pulse is located in one track of said set;
indexing according to a second procedure, hereinafter named procedure 2, the positions and amplitudes of two non-zero-amplitude pulses when only the positions of said two non-zero-amplitude pulses are located in one track of said set; and
when the positions of a number X of non-zero-amplitude pulses are located in one track of said set, wherein Xâx89§3:
dividing the positions of said one track into two sections;
using a further procedure associated wit said number X, hereinafter named procedure X, for indexing the positions and amplitudes of said X non-zero-amplitude pulses, said procedure X comprising:
identifying in which one of the two track sections each non-zero-amplitude pulse is located;
calculating subindices of said X non-zero-amplitude pulses using the procedures 1 and 2 in at least one of said track sections and entire track; and
calculating a position-and-amplitude index of said X non-zero-amplitude pulses by combining said subindices.', 'wherein:
the codebook comprises a set of pulse amplitude/position combinations;
each pulse amplitude/position combination defines a number of different positions and comprises both zero-amplitude pulses and non-zero-amplitude pulses assigned to respective positions of the combination; and
each non-zero-amplitude pulse assumes one of a plurality of possible amplitudes; and', 'the codebook comprises a set of pulse amplitude/position combinations;', 'each pulse amplitude/position combination defines a number of different positions and comprises both zero-amplitude pulses and non-zero-amplitude pulses assigned to respective positions of the combination; and', 'each non-zero-amplitude pulse assumes one of a plurality of possible amplitudes; and', 'wherein the codebook pulse amplitudes and positions are indexed by:', 'forming a set of at least one track of said pulse positions;', 'restraining the positions of the non-zero-amplitude pulses of the combinations of the codebook in accordance with the set of at least one track of pulse positions;', 'indexing according to a first procedure, hereinafter named procedure 1, the position and amplitude of one non-zero-amplitude pulse when only the position of said one non-zero-amplitude pulse is located in one track of said set;', 'indexing according to a second procedure, hereinafter named procedure 2, the positions and amplitudes of two non-zero-amplitude pulses when only the positions of said two non-zero-amplitude pulses are located in one track of said set; and', 'when the positions of a number X of non-zero-amplitude pulses are located in one track of said set, wherein Xâx89§3:', 'dividing the positions of said one track into two sections;', 'using a further procedure associated wit said number X, hereinafter named procedure X, for indexing the positions and amplitudes of said X non-zero-amplitude pulses, said procedure X comprising:', 'identifying in which one of the two track sections each non-zero-amplitude pulse is located;', 'calculating subindices of said X non-zero-amplitude pulses using the procedures 1 and 2 in at least one of said track sections and entire track; and', 'calculating a position-and-amplitude index of said X non-zero-amplitude pulses by combining said subindices.

2. A method for transforming a first signal into a second signal as defined in claim 1, comprising interleaving the pulse positions of each track with the pulse positions of the other tracks.

3. A method for transforming a first signal into a second signal as defined in claim 1, wherein calculating a position-and-amplitude index of said X non-zero-amplitude pulses comprises:
calculating at least one intermediate index by combining at least two of said subindices; and
calculating the position-and-amplitude index of said X non-zero-amplitude pulses by combining the remaining subindices and said at least one intermediate index.', 'calculating at least one intermediate index by combining at least two of said subindices; and', 'calculating the position-and-amplitude index of said X non-zero-amplitude pulses by combining the remaining subindices and said at least one intermediate index.

4. A method for transforming a first signal into a second signal as defined in claim 1, wherein said procedure 1 comprises producing a position-and-amplitude index including a position index indicative of the position of said one non-zero-amplitude pulse in said one track, and an amplitude index indicative of the amplitude of said one non-zero-amplitude pulse.

5. A method for transforming a first signal into a second signal as defined in claim 4, wherein the position index comprises a first group of bits, and the amplitude index comprises at least one bit.

6. A method for transforming a first signal into a second signal as defined in claim 5, in which said at least one bit of the amplitude index is a bit of higher rank.

7. A method for transforming a first signal into a second signal as defined in claim 5, wherein said plurality of possible amplitudes of each non-zero-amplitude pulse comprises +1 and âx88x921, and wherein said at least one bit of the amplitude index is a sign bit.

8. A method for transforming a first signal into a second signal as defined in claim 1, wherein:
said plurality of possible amplitudes of each non-zero-amplitude pulse comprises +1 and âx88x921; and
the procedure 1 comprises producing a position-and-amplitude index of said one non-zero-amplitude pulse having the form:
I 1p =p+sÃx972M

wherein p is a position index of said one non-zero-amplitude pulse in said one track, s is a sign index of said one non-zero-amplitude pulse, and 2M is the number of positions in said one track.', 'said plurality of possible amplitudes of each non-zero-amplitude pulse comprises +1 and âx88x921; and', 'the procedure 1 comprises producing a position-and-amplitude index of said one non-zero-amplitude pulse having the form:
I 1p =p+sÃx972M', 'I 1p =p+sÃx972M', 'wherein p is a position index of said one non-zero-amplitude pulse in said one track, s is a sign index of said one non-zero-amplitude pulse, and 2M is the number of positions in said one track.

9. A method for transforming a first signal into a second signal as defined in claim 8, wherein the number of positions in said one track is 16, and wherein the position-and-amplitude index is a 5-bit index represented in the following table:', 'Sign
Position












s
b3
b2
b1
b010. A method for transforming a first signal into a second signal as defined in claim 1, wherein said procedure 2 comprises producing a position-and-amplitude index including:
first and second position indices respectively indicative of the positions of the two non-zero-amplitude pulses in said one track; and
an amplitude index indicative of the amplitudes of said two non-zero-amplitude pulses.', 'first and second position indices respectively indicative of the positions of the two non-zero-amplitude pulses in said one track; and', 'an amplitude index indicative of the amplitudes of said two non-zero-amplitude pulses.11. A method far transforming a first signal into a second signal as defined in claim 10, wherein, in the position-and-amplitude index:
the amplitude index comprises at least one bit;
the first position index comprises a first group of bits; and
the second position index comprises a second group of bits.', 'the amplitude index comprises at least one bit;', 'the first position index comprises a first group of bits; and', 'the second position index comprises a second group of bits.12. A method for transforming a first signal into a second signal as defined in claim 11, wherein, in the position-and-amplitude index:
said at least one bit of the amplitude index is a bit of higher rank;
the bits of the first group are bits of intermediate rank; and
the bits of the second group are bits of lower rank.', 'said at least one bit of the amplitude index is a bit of higher rank;', 'the bits of the first group are bits of intermediate rank; and', 'the bits of the second group are bits of lower rank.13. A method for transforming a first signal into a second signal as defined in claim 11, wherein said plurality of possible amplitudes of each non-zero-amplitude pulse comprises +1 and âx88x921, and wherein said at least one bit of the amplitude index is a sign bit.14. A method for transforming a first signal into a second signal as defined in claim 10, wherein the procedure 2 comprises:
when said two pulses have a same amplitude, producing an amplitude index indicative of the amplitude of the non-zero-amplitude pulse whose position is indicated by the first position index, producing a first position index indicative of the smaller position of the two non-zero-amplitude pulses in said one track, and producing a second position index indicative of the larger position of the two non-zero-amplitude pulses in said one track; and
when said two pulses have different amplitudes, producing an amplitude index indicative of the amplitude of the non-zero-amplitude pulse whose position is indicated by the first position index, producing a first position index indicative of the larger position of the two non-zero-amplitude pulses in said one track, and producing a second position index indicative of the smaller position of the two non-zero-amplitude pulses in said one track.', 'when said two pulses have a same amplitude, producing an amplitude index indicative of the amplitude of the non-zero-amplitude pulse whose position is indicated by the first position index, producing a first position index indicative of the smaller position of the two non-zero-amplitude pulses in said one track, and producing a second position index indicative of the larger position of the two non-zero-amplitude pulses in said one track; and', 'when said two pulses have different amplitudes, producing an amplitude index indicative of the amplitude of the non-zero-amplitude pulse whose position is indicated by the first position index, producing a first position index indicative of the larger position of the two non-zero-amplitude pulses in said one track, and producing a second position index indicative of the smaller position of the two non-zero-amplitude pulses in said one track.15. A method for transforming a first signal into a second signal as defined in claim 1, wherein the procedure 2 comprises, when the position of a first non-zero-amplitude pulse of position index p0 and sign index Ïx830, and the position of a second non-zero-amplitude pulse of position index p1 and sign index Ïx831 are located in one track of said set, producing a position-and-amplitude index of said first and second non-zero-amplitude pulses of the form:', 'If Ïx830 = Ïx831





If p0 âx89¦ p1




I2p = p1 + p0 Ãx97 2M + Ïx830 Ãx97 22M



If p0 âx89§ p1




I2p = p0 + p1 Ãx97 2M + Ïx830 Ãx97 22M


If Ïx830 âx89xa0 Ïx831



If p0 âx89¦ p1




I2p = p0 + p1 Ãx97 2M + Ïx831 Ãx97 22M



If p0 âx89§ p1




I2p = p1 + p0 Ãx97 2M + Ïx830 Ãx97 22M', 'where 2M is the number of positions in said one track.16. A method for transforming a first signal into a second signal as defined in claim 15, wherein the number of positions in said one track is 16, and wherein the position-and-amplitude index is a 9-bit index represented in the following table:', 'Sign
Position p0

Position p1
















s
b
b
b
b
b
b
b
b


b3
b3
b2
b0
b3
b2
b1
b017. A method for transforming a first signal into a second signal as defined in claim 1, wherein, when X=3;
dividing the positions of said one track into two sections comprises dividing the positions of said one track into lower and upper track sections; and
the procedure 3 comprises:
identifying one of the upper and lower track sections which contains the positions of at least two non-zero-amplitude pulses;
calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track section using the procedure 2 applied to the positions of said one track section;
calculating a second subindex of the remaining non-zero-amplitude pulse using the procedure 1 applied to the positions of the entire said one track; and
producing a position-and-amplitude index of the three non-zero-amplitude pulses by combining said first and second subindices.', 'dividing the positions of said one track into two sections comprises dividing the positions of said one track into lower and upper track sections; and', 'the procedure 3 comprises:', 'identifying one of the upper and lower track sections which contains the positions of at least two non-zero-amplitude pulses;', 'calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track section using the procedure 2 applied to the positions of said one track section;', 'calculating a second subindex of the remaining non-zero-amplitude pulse using the procedure 1 applied to the positions of the entire said one track; and', 'producing a position-and-amplitude index of the three non-zero-amplitude pulses by combining said first and second subindices.18. A method for transforming a first signal into a second signal as defined in claim 17, wherein:
calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track section using the procedure 2 comprises, when the positions of said at least two non-zero-amplitude pulses are located in the upper section, shifting the positions of said at least two non-zero-amplitude pulses from the upper section to the lower section.', 'calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track section using the procedure 2 comprises, when the positions of said at least two non-zero-amplitude pulses are located in the upper section, shifting the positions of said at least two non-zero-amplitude pulses from the upper section to the lower section.', "19. A method for transforming a first signal into a second signal as defined in claim 18, wherein shifting the positions of said at least two non-zero-amplitude pulses from the upper section to the lower section comprises masking a number of least significant bits of the position indices of said at least two non-zero-amplitude pulses with a mask consisting of said number of 1's.", '20. A method for transforming a first signal into a second signal as defined in claim 17, wherein calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track section using the procedure 2 comprises inserting a section index indicating the one of said lower and upper track sections in which said at least two non-zero-amplitude pulses are located.

21. A method for transforming a first signal into a second signal as defined in claim 17, wherein the number of positions in said one track is 16, and wherein the position-and-amplitude index is a 13-bit index represented in the following table:', 'Position of
Section
2 pulses in section k








Sign
3rd pulse
Index
s0
p0
p1

















s
b
b
b
b



b
b
b
b
b


b3
b2
b1
b0
k
s
b2
b1
b0
b2
b1
b0

22. A method for transforming a first signal into a second signal as defined in claim 1, wherein:
said procedure 1 comprises producing a position-and-amplitude index including a position index indicative of the position of said one non-zero-amplitude pulse in said one track, and an amplitude index indicative of the amplitude of said one non-zero-amplitude pulse, wherein the position index comprises a first group of bits, and the position index comprises at least one bit;
said procedure 2 comprises producing a position-and-amplitude index including first and second position indices respectively indicative of the positions of the two non-zero-amplitude pulses in said one track, and an amplitude index indicative of the amplitudes of said two non-zero-amplitude pulses, wherein the amplitude index comprises at least one bit, the first position index comprises a first group of bits, and the second position index comprises a second group of bits;
when X=3:
dividing the positions of said one track into two sections comprises dividing the positions of said one track into lower and upper track sections; and
the procedure 3 comprises:
identifying one of the upper and lower track sections which contains the positions of at least two non-zero-amplitude pulses;
calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track section using the procedure 2 applied to the positions of said one track section;
calculating a second subindex of the remaining non-zero-amplitude pulse using the procedure 1 applied to the positions of the entire said one track; and
producing a position-and-amplitude index of the three non-zero-amplitude pulses by combining said first and second subindices.', 'said procedure 1 comprises producing a position-and-amplitude index including a position index indicative of the position of said one non-zero-amplitude pulse in said one track, and an amplitude index indicative of the amplitude of said one non-zero-amplitude pulse, wherein the position index comprises a first group of bits, and the position index comprises at least one bit;', 'said procedure 2 comprises producing a position-and-amplitude index including first and second position indices respectively indicative of the positions of the two non-zero-amplitude pulses in said one track, and an amplitude index indicative of the amplitudes of said two non-zero-amplitude pulses, wherein the amplitude index comprises at least one bit, the first position index comprises a first group of bits, and the second position index comprises a second group of bits;', 'when X=3:', 'dividing the positions of said one track into two sections comprises dividing the positions of said one track into lower and upper track sections; and', 'the procedure 3 comprises:', 'identifying one of the upper and lower track sections which contains the positions of at least two non-zero-amplitude pulses;', 'calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track section using the procedure 2 applied to the positions of said one track section;', 'calculating a second subindex of the remaining non-zero-amplitude pulse using the procedure 1 applied to the positions of the entire said one track; and', 'producing a position-and-amplitude index of the three non-zero-amplitude pulses by combining said first and second subindices.

23. A method for transforming a first signal into a second signal as defined in claim 22, wherein when X=4:
dividing the positions of said one track into two sections comprises dividing the positions of said one track into lower and upper track sections; and
the procedure 4 comprises:
when the upper track section contains the positions of the four non-zero amplitude pulses:
further dividing the upper track section into lower and upper track subsections;
identifying one of the upper and lower track subsections which contains the positions of at least two non-zero-amplitude pulses;
calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track subsection using the procedure 2 applied to the positions of said one track subsection;
calculating a second subindex of the remaining two non-zero-amplitude pulse using the procedure 2 applied to the positions of the entire upper track section; and
producing a position-and-amplitude index of the four non-zero-amplitude pulses by combining said first and second subindices;
when the lower track section contains the position of one non-zero-amplitude pulse and the upper track section contains the positions of the three other non-zero amplitude pulses:
calculating a first subindex of said one non-zero-amplitude pulses located in the lower track section using the procedure 1 applied to the positions of said lower track section;
calculating a second subindex of the remaining three non-zero-amplitude pulses located in the upper track section using the procedure S applied to the positions of the upper track section; and
producing a position-and-amplitude index of the four non-zero-amplitude pulses by combining said first and second subindices;
when the lower tack section contains the positions of two non-zero-amplitude pulses and the upper track section contains the positions of the two other non-zero amplitude pulses:
calculating a first subindex of said two non-zero-amplitude pulses located in the lower track section using the procedure 2 applied to the positions of said lower track section;
calculating a second subindex of the remaining two non-zero-amplitude pulses located in the upper track section using the procedure 2 applied to the positions of the upper track section; and
producing a position-and-amplitude index of the four non-zero-amplitude pulses by combining said first and second subindices;
when the lower tack section contains the positions of three non-zero-amplitude pulses and the upper track section contains the position of the other non-zero amplitude pulse: calculating a first subindex of said three non-zero-amplitude pulses located in the lower track section using the procedure 3 applied to the positions of said lower track section;
calculating a second subindex of the remaining non-zero-amplitude pulse located in the upper track section using the procedure 1 applied to the positions of the upper track section; and
producing a position-and-amplitude index of the four non-zero-amplitude pulses by combining said first and second subindices;
when the lower tack section contains the positions of the four non-zero amplitude pulses:
further dividing the lower track section into lower and upper track subsections;
identifying one of the upper and lower track subsections which contains the positions of at least two non-zero-amplitude pulses;
calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track subsection using the procedure 2 applied to the positions of said one track subsection;
calculating a second subindex of the remaining two non-zero-amplitude pulse using the procedure 2 applied to the positions of the entire lower track section; and
producing a position-and-amplitude index of the three non-zero-amplitude pulses by combining said firs: and second subindices.', 'dividing the positions of said one track into two sections comprises dividing the positions of said one track into lower and upper track sections; and', 'the procedure 4 comprises:', 'when the upper track section contains the positions of the four non-zero amplitude pulses:', 'further dividing the upper track section into lower and upper track subsections;', 'identifying one of the upper and lower track subsections which contains the positions of at least two non-zero-amplitude pulses;', 'calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track subsection using the procedure 2 applied to the positions of said one track subsection;', 'calculating a second subindex of the remaining two non-zero-amplitude pulse using the procedure 2 applied to the positions of the entire upper track section; and', 'producing a position-and-amplitude index of the four non-zero-amplitude pulses by combining said first and second subindices;', 'when the lower track section contains the position of one non-zero-amplitude pulse and the upper track section contains the positions of the three other non-zero amplitude pulses:', 'calculating a first subindex of said one non-zero-amplitude pulses located in the lower track section using the procedure 1 applied to the positions of said lower track section;', 'calculating a second subindex of the remaining three non-zero-amplitude pulses located in the upper track section using the procedure S applied to the positions of the upper track section; and', 'producing a position-and-amplitude index of the four non-zero-amplitude pulses by combining said first and second subindices;', 'when the lower tack section contains the positions of two non-zero-amplitude pulses and the upper track section contains the positions of the two other non-zero amplitude pulses:', 'calculating a first subindex of said two non-zero-amplitude pulses located in the lower track section using the procedure 2 applied to the positions of said lower track section;', 'calculating a second subindex of the remaining two non-zero-amplitude pulses located in the upper track section using the procedure 2 applied to the positions of the upper track section; and', 'producing a position-and-amplitude index of the four non-zero-amplitude pulses by combining said first and second subindices;', 'when the lower tack section contains the positions of three non-zero-amplitude pulses and the upper track section contains the position of the other non-zero amplitude pulse: calculating a first subindex of said three non-zero-amplitude pulses located in the lower track section using the procedure 3 applied to the positions of said lower track section;', 'calculating a second subindex of the remaining non-zero-amplitude pulse located in the upper track section using the procedure 1 applied to the positions of the upper track section; and', 'producing a position-and-amplitude index of the four non-zero-amplitude pulses by combining said first and second subindices;', 'when the lower tack section contains the positions of the four non-zero amplitude pulses:', 'further dividing the lower track section into lower and upper track subsections;', 'identifying one of the upper and lower track subsections which contains the positions of at least two non-zero-amplitude pulses;', 'calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track subsection using the procedure 2 applied to the positions of said one track subsection;', 'calculating a second subindex of the remaining two non-zero-amplitude pulse using the procedure 2 applied to the positions of the entire lower track section; and', 'producing a position-and-amplitude index of the three non-zero-amplitude pulses by combining said firs: and second subindices.

24. A method for transforming a first signal into a second signal as defined in claim 23, wherein the procedure 4 comprises:
when said one track subsection is the upper subsection,
calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track subsection using the procedure 2 comprises shifting the positions of said at least two non-zero-amplitude pulses from the upper track subsection to the lower track subsection.', 'when said one track subsection is the upper subsection,', 'calculating a first subindex of said at least two non-zero-amplitude pulses located in said one track subsection using the procedure 2 comprises shifting the positions of said at least two non-zero-amplitude pulses from the upper track subsection to the lower track subsection.', "25. A method for transforming a first signal into a second signal as defined in claim 24, wherein shifting the positions of said at least two non-zero-amplitude pulses from the upper subsection to the lower subsection comprises masking a number of least significant bits of the position indices of said at least two non-zero-amplitude pulses with a mask consisting of said number of 1's.", '26. A method for transforming a first signal into a second signal as defined in claim 23, wherein when X=5:
dividing the positions of said one track into two track sections comprises dividing the positions of said one track into lower and upper sections; and
the procedure 5 comprises:
detecting one of the lower and upper tack sections in which the positions of at least three non-zero amplitude pulses are located;
calculating a first subindex of three non-zero-amplitude pulses located in said one track section using the procedure 3 applied to the positions of said one track section;
calculating a second subindex of the remaining two non-zero-amplitude pulses using the procedure 2 applied to the positions of the entire said one track; and
producing a position-and-amplitude index of the five non-zero-amplitude pulses by combining said first and second subindices.', 'dividing the positions of said one track into two track sections comprises dividing the positions of said one track into lower and upper sections; and', 'the procedure 5 comprises:', 'detecting one of the lower and upper tack sections in which the positions of at least three non-zero amplitude pulses are located;', 'calculating a first subindex of three non-zero-amplitude pulses located in said one track section using the procedure 3 applied to the positions of said one track section;', 'calculating a second subindex of the remaining two non-zero-amplitude pulses using the procedure 2 applied to the positions of the entire said one track; and', 'producing a position-and-amplitude index of the five non-zero-amplitude pulses by combining said first and second subindices.

27. A method for transforming a first signal into a second signal as defined in claim 23, wherein when X=5:
dividing the positions of said one track into two sections comprises dividing the positions of said one track into lower and upper track sections; and
the procedure 5 comprises:
when the upper track section contains the positions of the five non-zero amplitude pulses:
calculating a first subindex of three non-zero-amplitude pulses located in said upper track section using the procedure 3 applied to the positions of said upper track section;
calculating a second subindex of the remaining two non-zero-amplitude pulses using the procedure 2 applied to the positions of the entire said one track; and
producing a position-and-amplitude index of the five non-zero-amplitude pulses by combining said first and second subindices;
when the lower track section contains the position of one non-zero-amplitude pulse and the upper track section contains the positions of the four other non-zero amplitude pulses:
calculating a first subindex of three non-zero-amplitude pulses located in the upper track section using the procedure 3 applied to the positions of said upper track section;
calculating a second subindex of the remaining two non-zero-amplitude pulses using the procedure 2 applied to the positions of the entire said one track; and
producing a position-and-amplitude index of the five non-zero-amplitude pulses by combining said first and second subindices;
when the lower track section