1. A circuit to calibrate a scalar in an adaptive equalizer during a training sequence, the circuit comprising:
a discrete-time FIR (Finite Impulse Response) filter comprising n multiplier units to implement a filter response h(t)i, i=0,1, . . . , n\u22121, where t is a time index;
a data generator to provide a discrete-time sequence of desired voltages d(t), t=1,2, . . . , T,
a multiplier to provide a sequence of voltages Kd(t), t=1,2, . . . , T, where K is the scalar;
a filter increment generator to provide, for t=1,2, . . . , T, n voltages indicative of n filter increments \u03b4 h(t)i, i=0,1, . . . , n\u22121;
at least one summer to perform the sum h(t)i,+\u03b4 h(t)i, i=0,1, . . . , n\u22121, to update the filter response;
an overflow counter to provide an overflow count indicative of the number of numerical overflows in the at least one summer during the time period t=1,2, . . . , T;
wherein the scalar K is increased by a first increment if after completion of the time period t=1,2, . . . , T the overflow count and a threshold satisfy a first relationship, and
wherein the scalar K is used during the training sequence to update the adaptive equalizer.
2. The circuit as set forth in claim 1, wherein the scalar K is decreased by a second increment if after completion of the time period t=1,2, . . . , T the overflow count and the threshold satisfy a second relationship.
3. The circuit as set forth in claim 2, wherein the first increment is equal to the second increment.
4. The circuit as set forth in claim 3, wherein
the overflow count and the threshold satisfy the first relationship if and only if the overflow count is greater than the threshold;
the overflow count and the threshold satisfy the second relationship if and only if the overflow count is less than or equal to the threshold; and
the first increment is positive.
5. The circuit as set forth in claim 1, wherein
the overflow count and the threshold satisfy the first relationship if and only if the overflow count is greater than the threshold; and
the first increment is positive.
6. The circuit as set forth in claim 5, the multiplier comprising:
a voltage-to-current converter to provide as output a current IvC, indicative of the voltage d(t); and
a current steering digital-to-analog converter to shunt a portion of IvC, to provide as output at time t a current indicative of Kd(t).
7. The circuit as set forth in claim 2, wherein
the overflow count and the threshold satisfy the first relationship if and only if the overflow count is greater than the threshold;
the overflow count and the threshold satisfy the second relationship if and only if the overflow count is less than or equal to the threshold; and
the first increment and the second increment are positive.
8. The circuit as set forth in claim 1, wherein the voltage d(t) is a differential voltage.
9. A computer system for use in calibrating a scalar in an adaptive equalizer during a training sequence comprising:
a board comprising a first transmission line and a second transmission line; and
a receiver coupled to the first and second transmission lines, the receiver comprising:
a discrete-time FIR (Finite Impulse Response) filter comprising n multiplier units to implement a filter response h(t)i, i=0,1, . . . , n\u22121, where t is a time index;
a data generator to provide a discrete-time sequence of desired voltages d(t), t=1,2, . . . , T,
a multiplier to provide a sequence of voltages Kd(t), t=1,2, . . . , T, where K is the scalar;
a filter increment generator to provide, for t=1,2, . . . , T, n voltages indicative of n filter increments \u03b4 h(t)i, i=0,1, . . . , n\u22121;
at least one summer to perform the sum h(t)i, +\u03b4 h(t)i, i=0,1, . . . , n\u22121 to update the filter response;
an overflow counter to provide an overflow count indicative of the number of numerical overflows in the at least one summer during the time period t=1,2, . . . , T;
wherein the scalar K is increased by a first increment if after completion of the time period t=1,2, . . . , T the overflow count and a threshold satisfy a first relationship, and
wherein the scalar K is used during the training sequence to update the adaptive equalizer.
10. The computer system as set forth in claim 9, wherein the scalar K is decreased by a second increment if after completion of the time period t=1,2, . . . , T the overflow count and the threshold satisfy a second relationship.
11. The computer system as set forth in claim 9, wherein the voltage d(t) is a differential voltage.
12. A method to calibrate a scale factor in an adaptive equalizer, the scale factor being used to multiply a sequence of desired voltages used in updating the equalizer during a training sequence, the method comprising:
updating the adaptive equalizer over the training sequence;
counting the number of numerical overflows occurring while updating the adaptive equalizer over the training sequence; and
increasing the scale factor by a first increment if the number of numerical overflows and a threshold satisfy a first relationship,
wherein the scale factor is calibrated once for a communication channel.
13. A method to calibrate a scale factor in an adaptive equalizer, the scale factor being used to multiply a sequence of desired voltages used in updating the equalizer during a training sequence, the method comprising:
updating the adaptive equalizer over the training sequence;
counting the number of numerical overflows occurring while updating the adaptive equalizer over the training sequence; and
increasing the scale factor by a first increment if the number of numerical overflows and a threshold satisfy a first relationship,
wherein the scale factor is decreased by a second increment if the number of numerical overflows and the threshold satisfy a second relationship.
14. The method as set forth in claim 13, wherein the first increment is equal to the second increment.
15. The method as set forth in claim 14, wherein
the overflow count and the threshold satisfy the first relationship if and only if the overflow count is greater than the threshold;
the overflow count and the threshold satisfy the second relationship if and only if the overflow count is less than or equal to the threshold; and
the first increment is positive.
16. A method to calibrate a scale factor in an adaptive egualizer, the scale factor being used to multiply a sequence of desired voltages used in updating the equalizer during a training sequence, the method comprising:
updating the adaptive equalizer over the training sequence;
counting the number of numerical overflows occurring while updating the adaptive equalizer over the training sequence; and
increasing the scale factor by a first increment if the number of numerical overflows and a threshold satisfy a first relationship,
wherein
the overflow count and the threshold satisfy the first relationship if and only if the overflow count is greater than the threshold; and
the first increment is positive.
17. The method as set forth in claim 13, wherein the overflow count and the threshold satisfy the first relationship if and only if the overflow count is greater than the threshold;
the overflow count and the threshold satisfy the second relationship if and only if the overflow count is less than or equal to the threshold; and
the first increment and the second increment are positive.
18. The method as set forth in claim 12, wherein the sequence of desired voltages are differential voltages.
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 shifter for operating a bicycle gear change device, the shifter mountable to a handlebar of the bicycle inboard of a handgrip element, the shifter comprising:
a shifter housing mountable to the handlebar;
a cable spool for pulling and releasing a control cable connected to the gear change device;
a cable pull lever mechanism for rotating the cable spool in the cable-pull direction; and
a cable release lever mechanism for rotating the cable spool in the cable-release direction,
the cable pull lever mechanism configured to be adjustable relative to the cable release lever mechanism and to the handgrip element on the handlebar of the bicycle.
2. The shifter according to claim 1 wherein the cable pull lever mechanism comprises a cable pull lever and a driver element operatively connected to the cable spool, the cable pull lever disposed on the driver element such that a swept motion of the cable pull lever defines a plane of motion substantially perpendicular to a rotational axis of the cable spool.
3. The shifter according to claim 2 wherein the cable pull lever is frictionally engaged with an outer surface of the driver element.
4. The shifter according to claim 2 wherein the cable pull lever includes first and second clamping arms and a tension screw nonrotatably connecting the first and second arms to an outer surface of the driver element.
5. The shifter according to claim 4 wherein the driver element includes a groove, the tension screw having a shaft arranged between two walls of the groove.
6. The shifter according to claim 2 wherein the cable pull lever is adjustably attachable to the driving element within an angular range of at least 120 degrees.
7. The shifter according to claim 1 wherein the cable pull lever includes a first contact surface displaceable through a first plane of motion, and the cable release lever includes a second contact surface displaceable through a second plane of motion, the first and second planes of motion forming an angle of approximately 60 degrees therebetween.
8. The shifter according to claim 7 wherein the first contact surface of the cable pull lever and the second contact surface of the cable release lever are disposed relative to each other to be alternatively operable by a thumb of a hand located on the handgrip element on the handlebar.
9. A shifter for operating a bicycle gear change device, the shifter mountable to a handlebar inboard of a handgrip element, the shifter comprising:
a shifter housing;
a cable spool for pulling and releasing a control cable connected to the gear change device;
a cable pull lever mechanism for rotating the cable spool in a cable-pull direction;
a cable release lever mechanism for rotating the cable spool in a cable-release direction; and
a clamp for mounting the shifter housing to the handlebar, the clamp adjustably attachable to the shifter housing.
10. The shifter according to claim 9 wherein the shifter housing includes a base having at least two bores, the bores spaced from each other.
11. The shifter according to claim 10 wherein the base of the shifter housing has a longitudinal guide parallel to the handgrip element on the handlebar, the longitudinal guide including the bores, the clamp mounted to the longitudinal guide by a fastener received in one of the bores.
12. The shifter according to claim 9 wherein the pull and cable release levers include contact surfaces, the contact surface of the cable release lever having a plane of motion inclined at an angle approximately 60 degrees relative to a plane of motion of the contact surface of the cable pull lever.
13. The shifter according to claim 12 wherein the contact surface of the cable pull lever and the contact surface of the cable release lever are configured relative to each other such that the pull and cable release levers are alternatively operated by a thumb of a hand located on the handgrip element on the handlebar.
14. A method for adjusting a shifter mountable to a bicycle handlebar inboard of a handgrip element, the shifter including a shifter housing having at least two bores, a clamp mounted to the shifter housing, a cable pull lever mechanism including a driver element and a cable pull lever having a contact surface and first and second clamping arms, a cable release lever mechanism having a cable release lever having a contact surface, the method comprising the following steps:
determining where to position the clamp on the handlebar;
fastening the clamp onto the shifter housing by screwing a clamp screw into the bore closest to the handgrip element when mounting the shifter housing between the handgrip element and a brake lever mechanism;
fastening the clamp onto the shifter housing by screwing the clamp screw into the bore farthest from the handgrip element when mounting the shifter housing inboard of the handgrip element and the brake lever mechanism;
sliding the clamp and the shifter housing onto the handlebar;
sliding the brake lever mechanism onto the handlebar;
sliding the handgrip element onto the handlebar;
attaching the cable pull lever on the driver element and loosely fastening together the first and second clamping arms with a tension screw;
tightening the clamp screw in one of the bores of the shifter housing after the position of the housing and clamp has been selected by the rider while sitting on the bicycle;
tightening the tension screw after the position of the contact surface of the cable pull lever relative to the contact surface of the cable release lever has been selected by the rider while sitting on the bicycle;
riding the bicycle to determine whether the position of the shifter needs to be adjusted; and
correcting the position of the clamp and the cable pull lever by loosing and retightening the clamp screw and the tension screw.