Methods and devices for switching filters and medical apparatuses using the same

A device for switching filters, comprising:

• a detecting component configured to detect whether or not a frequency range of an input signal is changed from a first frequency range into a second frequency range, wherein the first frequency range is a frequency range within which a first filter is able to work, and the second frequency range is a frequency range within which a second filter is able to work;
• n input branches of the first filter configured to receive a sample value of the input signal at a current moment and sample values of the input signal at n moments before the current moment to the first filter in an order of n moments before the current moment and at the current moment;
• one or more delayers in the n input branches of the first filter configured to receive the sample value of the input signal at the current moment and the sample values of the input signal at the n moments before the current moment;
• one or more switches configured to switch from the first filter to the second filter when the frequency range of the input signal is changed from the first frequency range into the second frequency range at the current moment to push, upon detection that the frequency range of the input signal is changed from the first frequency range into the second frequency range, the sample values of the input signal at the n moments before the current moment and the sample value of the input signal at the current moment from the one or more delayers in the n input branches of the first filter to n delay-amplifier branches of the second filter;
• and
• an output value obtaining component configured to take output values of the first filter at m moments before the current moment as output values of the second filter at the m moments, to obtain an output value of the second filter at the current moment using the output values of first filter at the m moments, the sample value of the input signal at the current moment, and the sample values of the input signal at the n moments, wherein n and m are both positive integers.

A medical detecting apparatus, wherein the medical detecting apparatus comprises:

• a detecting component configured to detect whether or not a frequency range of an input signal is changed from a first frequency range into a second frequency range, wherein the first frequency range is a frequency range within which a first filter is able to work, and the second frequency range is a frequency range within which a second filter is able to work;
• n input branches of the first filter configured to receive a sample value of the input signal at a current moment and sample values of the input signal at n moments before the current moment to the first filter in an order of n moments before the current moment and at the current moment;
• one or more delayers in the n input branches of the first filter configured to receive the sample value of the input signal at the current moment and the sample values of the input signal at the n moments before the current moment;
• one or more switches configured to switch from the first filter to the second filter when the frequency range of the input signal is changed from the first frequency range into the second frequency range at the current moment to push, upon detection that the frequency range of the input signal is changed from the first frequency range into the second frequency range, the sample values of the input signal at the n moments before the current moment and the sample value of the input signal at the current moment from the one or more delayers in the n input branches of the first filter to n delay-amplifier branches of the second filter;
• and
• an output value obtaining component configured to take output values of the first filter at m moments before the current moment as output values of the second filter at the m moments, to obtain an output value of the second filter at the current moment using the output values of first filter at the m moments, the sample value of the input signal at the current moment, and the sample values of the input signal at the n moments, wherein n and m are both positive integers.