JPH0321180B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a Doppler signal reproducing method and recording/reproducing apparatus of an ultrasonic Doppler diagnostic apparatus, which is mainly used as a medical device. More specifically, a pair of direction-specific baseband (audio) Doppler signals recorded in a recording means is reproduced, reanalyzed by an analysis circuit including a complex FFT calculator and a linear combiner, and the result is observed. The present invention relates to a method and a recording/reproducing apparatus for recording baseband (audio) Doppler signal pairs for each direction in a recording means, reproducing them, reanalyzing them by the analysis circuit, and observing them.

(Prior art) Ultrasonic Doppler diagnostic equipment uses CW (continuous wave) or
Pulse-modulated ultrasound is emitted into the body, the amount of Doppler shift of the echo signal is measured, and the velocity and flow rate of moving bodies (targets) in the body, such as blood flow, are measured.

Figure 2 shows the conventional analog calculation method.
FIG. 2 is a block diagram showing a receiving section of a CW Doppler device. In FIG. 2, the echo signal is amplified by a receiving amplifier 1 and then divided into two channels.
Detected by a quadrature detection circuit. That is, after the signal pair is multiplied by two reference waves having a phase difference of 90 degrees from each other from the carrier oscillator 2 in a multiplier 3, unnecessary high frequency components and low frequency components are removed by a band pass filter 4. The Doppler signal pair obtained at this stage is generally i (in-phase)
and q (orthogonal) baseband Doppler signal. This signal pair is 90
Direction separation is performed by a Hilbert transformer (a wideband 90 degree phase shifter) 5 that outputs a phase difference of degrees, and a linear coupler 6 that outputs the addition and subtraction results for two input signals. . In other words, it is the Doppler signal of the target approaching in the line of sight direction.
It is separated into the USB (upper sideband) and the LSB (lower sideband), which is the Doppler signal of the target moving away. Thereafter, the USB and LSB signals are analyzed in each direction by a frequency analyzer 7 such as a sonagraph, and the results are displayed on a display device 8.

FIG. 3 is a block diagram showing a receiving section of a CW Doppler device using a digital calculation method. still,
Each symbol in FIG. 3 has the same meaning as in FIG. 2. In FIG. 3, the Doppler signal pair i and q, which is the output of the bandpass filter 4, is a complex
Analysis circuit 9 consisting of an FFT calculator and a linear combiner
Enter. Here, frequency analysis and linear combination are performed, and outputs for each direction of USB and LSB are given to the display device 8 and displayed. Since such a digital calculation method provides more accurate analysis results than the analog method described above, it is currently used in place of the analog method described above.

Incidentally, in such a Doppler receiver, a two-channel recording means, ie, a stereo tape recorder, or the like is generally used as a recording means for Doppler signals. If a pair of i and q baseband Doppler signals is recorded in each channel of this recording means, there will be problems with left and right phase matching due to the pinch roller contact, one-sided tape stretching, etc. during playback. Therefore, the baseband Doppler signal pair of i and q is usually processed by a Hilbert transformer and a linear combiner.
It is converted into Doppler signal pairs in USB and LSB format and recorded on a stereo tape recorder.

(Problems to be Solved by the Invention) Generally, hardware and software for FFT calculations are required to operate at extremely high speeds. For this reason, the conventional
Adding functions such as inputting Doppler signal pairs in the form of USB and LSB reproduced from a stereo tape recorder to an analysis circuit including an FFT calculation unit, analyzing the signals, and displaying them results in a lot of wasted hardware and software. or a decline in performance may occur.

The present invention reproduces Doppler signal pairs in the form of USB and LSB recorded on a stereo tape recorder without causing such waste or performance degradation, and reproduces the complex FFT of the conventional i and q signal input type.
It is an object of the present invention to provide a Doppler signal reproducing method and recording/reproducing apparatus that can perform signal analysis using an analysis circuit comprising an arithmetic unit and a linear coupler.

(Means for Solving the Problems) In order to achieve the above object, the Doppler signal reproducing method and recording/reproducing apparatus of the present invention have the following configuration.

That is, in the first invention, a pair of i (in-phase) and q (quadrature) Doppler signals obtained by quadrature detection of an ultrasound echo signal from a subject is recorded in the form of a USB signal and an LSB signal by an external recording means. 2 obtained by playing back the recorded signal and performing addition and subtraction operations on the two signals corresponding to the USB signal and LSB signal.
i and q with a phase difference of 90 degrees for the two results.
After creating a Doppler signal pair of the form, the complex FFT
(Fast Fourier Transform) is input to an analysis circuit consisting of an arithmetic unit and a linear coupler, performs frequency analysis and linear combination, and converts the USB (upper sideband) signal and LSB (lower sideband)
The configuration is such that the signal and direction are separated and displayed.

In the second invention, during recording, the output from the quadrature detection circuit that inputs the ultrasonic echo signal from the subject and converts it into a pair of i and q Doppler signals is
A USB signal created by guiding the two input signals through a Hilbert transformer that outputs them with a 90 degree phase difference, and a linear combiner that outputs the addition and subtraction results for two input signals. and LSB
A signal is input to a recording means, and at the time of playback, the USB signal and LSB signal from the recording means are input to a primary coupler,
It has a complex FFT operator and a linear combiner to convert the i and q signal pairs created and guided through the path of the Hilbert transformer into a USB (upper sideband) signal and an LSB (lower sideband) signal. ) switching means for inputting the signal to the analysis circuit which outputs it as a signal.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a receiving section of a CW Doppler device for implementing the present invention. In FIG. 1, parts having the same functions as those in FIG. 3 are denoted by the same symbols as in FIG. 3, so their explanations will be omitted here.

In the circuit configuration shown in Figure 1, 10 is the USB and
This is an external two-channel stereo tape recorder that records and plays back Doppler signal pairs in the form of LSB.
11 is a signal exchange board (signal switch), and the white and black circles at the intersections of the vertical and horizontal lines are switches between these two lines. During normal use, when measuring and analyzing on one hand and simultaneously recording Doppler signals on the other, only the black circle switch is turned on. On the other hand, when reproducing and analyzing the Doppler signal pair recorded in the form of USB and LSB and displaying it on the display device 8, only the white circle switch is turned on.

During normal use in the above configuration,
The pair of i and q Doppler signals output from the bandpass filter 4 is input to the signal exchange board 11, and via the switch point indicated by the black circle, one is input to the analysis circuit 9 including an FFT calculator and a linear combiner. Then, frequency analysis and linear combination are performed to obtain outputs for each direction of USB and LSB, which are displayed on the display device 8. Then, the other signal is again input to the Hilbert converter 5 via the switch point of the black circle, and its output is input again to the signal exchange board 11, and then input to the primary coupler 6, and is converted into a Doppler signal pair of USB and LSB. separated. The output of the primary coupler 6 is given to a stereo tape recorder 10 via a signal exchange board 11, and a Doppler signal pair of USB and LSB is recorded in each channel.

Next, the operation when reproducing the recorded Doppler signal pair and analyzing and displaying it will be explained. In this case, the switch marked with a black circle on the signal exchange board 11 is turned off, and the switch marked with a white circle is turned on.
Output of stereo tape recorder 10 (USB and
The LSB signal) is input to the signal exchange board 11 and then input to the primary coupler 6 via the white circle switch point. This output is inputted again to the signal exchange board 11, and then inputted to the Hilbert transformer 5, where it undergoes Hilbert inverse transformation and is converted into a Doppler signal pair of i and q. This signal pair is transmitted via the signal exchange board 11,
The signal is input to an analysis circuit 9 consisting of a complex FFT calculator and a linear combiner, and the output for each direction is displayed on the display device 8 in the same manner as described above.

As explained above, switching between the two modes of recording and playback analysis display is performed using the signal exchange board, and during recording, the i and q baseband Doppler signal pairs are transferred to the USB and
It is converted into a pair of Doppler signals in the form of LSB and recorded, and during playback, this signal is once converted into a pair of Doppler signals in the form of i and q using a linear combination circuit and a Hilbert transformer. A predetermined analysis and display can be performed by inputting this into an analysis circuit including a linear coupler.

Note that the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the claims. For example, it may be used in a receiving section of a pulsed ultrasound Doppler device.

(Effects of the Invention) As explained above, according to the Doppler signal reproducing method and recording/reproducing apparatus of the present invention, the following effects can be obtained.

That is, the USB signal and LSB signal with good phase matching are regenerated, and they are converted into an i and q format Doppler signal pair by linear combination and Hilbert transformation, and then a complex FFT calculator with i and q signal input format and a linear An analysis circuit consisting of a coupler allows the signal to be analyzed and redisplayed. Therefore, without increasing the burden on hardware or software for FFT calculations, you can simply rearrange the processing performed by ordinary ultrasound Doppler diagnostic equipment in a predetermined order.
Redisplay can be performed by reproducing with good phase consistency.

In particular, in the case of Doppler signal recording and reproducing devices, it is possible to realize a device that performs redisplay through playback with good phase consistency by simply adding a switching means to the configuration of a normal ultrasonic Doppler diagnostic device. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a receiving section of a CW Doppler device using a digital calculation method according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a receiving section of a CW Doppler device using a conventional analog calculation method. Figure 3 shows the conventional digital calculation method.
FIG. 2 is a block diagram showing a receiving section of a CW Doppler device. 1... Receiving amplifier, 2... Carrier oscillator, 3
... Multiplier, 4 ... Bandpass filter, 5 ...
Hilbert transformer, 6... linear coupler, 7... frequency analyzer, 8... display device, 9... analysis circuit,
10... Stereo tape recorder, 11... Signal exchange board.

Claims (1)

[Claims] 1 A pair of i (in-phase) and q (quadrature) Doppler signals obtained by orthogonal detection of an ultrasound echo signal from a subject is processed by a complex FFT (fast Fourier transform) calculator and a linear combiner. A Doppler signal processing method performs frequency analysis and linear combination using an analysis circuit consisting of A pair of Doppler signals recorded in the form of USB signal and LSB signal is played back, and the two results obtained by adding and subtracting the two signals corresponding to the USB signal and LSB signal are set at 90 degrees. With a phase difference i
A method for reproducing a Doppler signal, which comprises creating a pair of Doppler signals in the form of and q, and then inputting the pair to the analysis circuit. 2 Input the ultrasound echo signal from the subject and
It has a quadrature detection circuit that outputs a pair of (in-phase) and q (quadrature) Doppler signals, a complex FFT calculator, and a linear coupler, and outputs the pair of Doppler signals using a USB (upper sideband).
An analysis circuit that converts the signal into an LSB (lower sideband) signal and outputs it, and an analysis circuit that inputs the signal from the circuit and outputs it as an LSB (lower sideband) signal.
In a Doppler signal processing device equipped with a display device that displays signals based on signals and LSB signals, a Hilbert transformer that outputs two input signals with a 90 degree phase difference, and a Hilbert transformer that outputs two input signals with a 90 degree phase difference. a linear combiner that outputs the addition and subtraction results;
recording means for recording and reproducing USB signals and LSB signals; and during recording, a pair of i and q signals from the orthogonal detection circuit is guided through a path of a Hilbert transformer and a linear coupler, and the created USB signal and LSB
A signal is input to a recording means, and at the time of playback, the USB signal and LSB signal from the recording means are input to a primary coupler,
1. A Doppler signal recording/reproducing apparatus, comprising: switching means for inputting the i and q signal pairs created and guided through the path of the Hilbert transformer to the analysis circuit.