Abstract: A dynamically adjustable digital gyrator device for a telephone line interface (e.g., a DAA) utilizing extended feedback and a dynamically adjustable filter to achieve stable convergence in the control of DC line current on a telephone line a short period of time. The low pass filter of the digital gyrator includes at least two (2) different fast filter settings and at least two (2) different slow filter settings based on possible load terminations (e.g., PBX, TAS, etc.), which can be determined based on the dynamic detection of an oscillation on the line. For instance, in a disclosed example, a voice band modem system is allowed to go off-hook with a 1 Hz cutoff low pass filter, and then the output of the low pass filter is checked for an oscillation. If an oscillation is detected, then the poles and/or zeroes of the low pass filter cutoff are changed to a slower convergence rate cutoff frequency (e.g., to 0.1 Hz). As a result, the exemplary voice band modem will converge stably and quickly (e.g.

Abstract: The bicycle trainer includes a frame having a head tube, a top tube, and a rear fork, wherein a foot bar and a front fork are mounted at a lower part of the head tube, a front part of the top tube is pivotally connected to the head tube, and the rear fork is connected to the top tube; a handle connected to the front fork of the frame and properly connected to the front fork; a front wheel and a rear wheel pivotally connected to front wheel and rear wheel; and a flexible device connecting the frame with a rear pivot shaft at one side of the rear wheel, wherein the flexible device drive the rear wheel to rotate and is recovered by using a swirling spring installed at the other side of the rear wheel.

Abstract: The bicycle trainer includes a frame having a head tube, a top tube, and a rear fork, wherein a foot bar and a front fork are mounted at a lower part of the head tube, a front part of the top tube is pivotally connected to the head tube, and the rear fork is connected to the top tube; a handle connected to the front fork of the frame and properly connected to the front fork; a front wheel and a rear wheel pivotally connected to front wheel and rear wheel; and a flexible device connecting the frame with a rear pivot shaft at one side of the rear wheel, wherein the flexible device drive the rear wheel to rotate and is recovered by using a swirling spring installed at the other side of the rear wheel.

Abstract: A dynamically adjustable digital gyrator device for a telephone line interface (e.g., a DAA) utilizing extended feedback and a dynamically adjustable filter to achieve stable convergence in the control of DC line current on a telephone line a short period of time. The low pass filter of the digital gyrator includes at least two (2) different fast filter settings and at least two (2) different slow filter settings based on possible load terminations (e.g., PBX, TAS, etc.), which can be determined based on the dynamic detection of an oscillation on the line. For instance, in a disclosed example, a voice band modem system is allowed to go off-hook with a 1 Hz cutoff low pass filter, and then the output of the low pass filter is checked for an oscillation. If an oscillation is detected, then the poles and/or zeroes of the low pass filter cutoff are changed to a slower convergence rate cutoff frequency (e.g., to 0.1 Hz). As a result, the exemplary voice band modem will converge stably and quickly (e.g.