JPS601609A - Magnetic recording and reproducing device of digital signal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital signal magnetic recording and reproducing device such as a digital audio chip recorder.

[Background technology and its problems]

General Q: In digital recording type tape recorders, an alternating current erasing method using a wire-wound erasing head is employed to erase digital signals recorded on a magnetic tape.

In order to perform efficient erasing using the AC erasing method, it is necessary to supply the erasing head with an erasing current having a frequency that causes less loss in the erasing head. The frequency of the erasing current is preferably low in order to perform efficient erasing, since at high frequencies the loss of the erasing head increases due to an increase in eddy current, etc. Also, in the case of AC elimination method,
Due to the occurrence of crossfeed and crosstalk caused by the erase current flowing through the erase head, the erase current frequency component imparts waveform distortion to the reproduced signal, causing an increase in reproduced data detection errors. In order to eliminate the effects of the above-mentioned crossfeed and crosstalk, it is sufficient to set the erasing current frequency far away from the frequency range of the reproduced signal.

However, in a digital signal recording and reproducing apparatus that performs baseband recording, the erase current frequency cannot be set very low because the frequency range from DC to low frequency is used for recording and reproducing signals. Therefore, if we try to increase the erasing efficiency, the detection errors of the reproduced data due to the above-mentioned crossfeed and crosstalk will increase, and if we try to reduce the detection errors, the erasing efficiency will decrease, which are contradictory problems. there were.

[Purpose of the invention]

Therefore, in view of the above-mentioned conventional problems, the present invention effectively utilizes the characteristics of the data transmission system to perform efficient erasure using the AC erasure method, and also aims to reduce detection errors in reproduced data. The present invention provides a digital signal magnetic recording and reproducing device having a novel configuration.

[Summary of the invention]

In order to achieve the above-mentioned object, a digital signal magnetic recording and reproducing apparatus according to the present invention is a digital signal recording and reproducing apparatus equipped with a recording system and a reproducing system for recording and reproducing digitized signals via a magnetic recording medium. A waveform equalization means having a frequency transfer characteristic in which one or more zero points exist in addition to the DC component is provided in the reproduction system, and AC cancellation is performed at an erase current frequency equal to the zero point frequency of l of the frequency transfer characteristic of the waveform equalization means. It is equipped with an erasing means.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a digital signal magnetic recording and reproducing apparatus according to the present invention will be described in detail below with reference to the drawings.

The embodiment shown in FIGS. 1 to 3 is an application of the present invention to a fixed head type digital audio table recorder.

In the block diagram of FIG. 1 showing the configuration of this embodiment,
The input audio signal is input from the signal input terminal 1 to the analog
is supplied to a digital (A/D) converter 2, and this A/D
It is digitized by converter 2. The decile audio signal obtained by the A/I) converter 2 is supplied to an encoding processing circuit 3, and is converted into, for example, a PCM take by the encoding processing circuit 3. The PCM take is supplied to a recording head 5 via a recording amplifier 4, and is recorded on a magnetic tape 1o by this recording head 5.

Here, along the running direction of the magnetic tape 1o (arrow X direction in FIG. 1), a reproducing head 11 is arranged downstream of the magnetic head 5, and an erasing head 22 is arranged upstream. has been done.

The reproducing head 11 supplies a reproducing signal reproduced from the magnetic tape 10 to a waveform equalizer 13 via a reproducing amplifier 12.

The waveform equalizer 13 is configured to detect code errors, so-called code amount, which occur due to the transmission characteristics of the recording/reproducing system in which the signal recorded on the magnetic tape 10 by the recording node 5 is reproduced by the reproducing head 11. Correct interference. This waveform equalizer 1
The reproduced PCM data equalized by 3 is supplied to the decoding processing circuit 14, where it is subjected to error correction processing and PCM encoding processing, and then sent to the digital-to-analog (A,/D) converter 15. The signal is then output from the signal output terminal 16 as a reproduced audio signal.

Here, in this example, we will use the PCM take as an example.
When direct recording and reproduction is performed at a transmission rate of 35 Kbit/s, the spectrum to be transmitted via the recording/reproducing system is 135 KHz due to the Nyquist condition.
up to the required amount. Therefore, the waveform equalizer 13 provided in the reproduction system
must have a frequency transfer characteristic that equalizes the spectrum of the reproduction signal reproduced by the reproduction head 11 up to 135 KHz.

The waveform equalizer 13 in this embodiment realizes the necessary frequency characteristics with one universal filter, and the second
The configuration is as shown in the figure.

That is, in the block diagram of FIG. 2 showing the specific configuration of the waveform equalizer 13, the reproduction input signal supplied from the reproduction head 11 via the reproduction amplifier 12 is 1.
One delay element DL l, I) I, 2 .

..., I)Ln are connected in series. The delay elements DL l, DL 2 ,...
, DJ, , have a delay amount equal to the hit period T (T-135 KHz) of I) CM data, respectively. Then, the reproduction input signal and each delay element 1)L
r, I)L2.

..., DLn is supplied to an adder 33 via a weighted circuit 32 consisting of 1]+1 coefficient multipliers Ko, K+, ..., Kn.

The addition output obtained by the adder 33 is repeated on the angular frequency axis with a period of 4π/T as shown in FIG.
The frequency transfer characteristics of the transversal filter are given such that zero point frequencies exist at 2π/T, 4π/T, . . . . It should be noted that - to each coefficient multiplier Ko of the weighting circuit 32.

..., Kn are given respective weighting coefficients so that the frequency transfer characteristics exhibit waveform equivalent filter characteristics.

Then, the addition output from the adder 33 is sent to the integrator 34.
The data is supplied to the data detection/demodulation circuit 35 via the data detection/demodulation circuit 35, and is outputted from the data detection/demodulation circuit 35 as reproduced PCM data.

The erasing head 22 in this embodiment is a general wire-wound erasing head, and has an oscillation frequency fP.
AC erasing of the magnetic tape 10 is performed by an erasing current supplied from an oscillator 20 with a frequency of 135 KHz through a drive circuit 21. That is, in this embodiment, the erasing current frequency fE of AC erasing by the erasing head 22 is set to the lowest angular frequency 2π/T excluding the zero point frequency ω-0 of the frequency transfer characteristic of the waveform equalizer 13 of the reproduction system.
is set to match.

In the embodiment configured as described above, even if cross fee 1 due to the erase current flowing through the erase button 1 or cross fee 1 due to the erase current frequency fE and acid component remaining on the magnetic tape 1o occurs during erasing, the playback will not be possible. Since the spectrum of the erasing current frequency fE is removed by the frequency transfer characteristics of the waveform equalizer 13 in the system, the crossfeed and crosstalk do not cause detection errors in the reproduced data, and recording and recording with extremely high fidelity is possible. Can be played.

Note that by setting the above-mentioned erasing current frequency fE to an arbitrary zero point frequency other than ω-0 on the frequency transfer characteristic of the waveform equalizer 13 provided in the reproduction system, the reproduction data due to the above-mentioned crosstalk etc. can be set. It can be set to a low frequency near the reproduced signal frequency band, as in this embodiment, without adversely affecting the detection of the signal. Therefore, the efficiency of AC erasing using the erasing head 22 can also be increased.

〔Effect of the invention〕

As is clear from the description of the above-mentioned embodiments, the digital signal magnetic recording and reproducing apparatus according to the present invention employs the AC cancellation method to improve the erasing efficiency without causing reproduction data detection errors due to crossfeed or crosstalk. High signal cancellation can be achieved, and the intended purpose can be fully achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a digital signal magnetic recording/reproducing apparatus according to the present invention. FIG. 2 is a block diagram showing a specific example of the configuration of the formation control device applied to the above embodiment. FIG. 3 is a characteristic diagram showing the frequency transfer characteristics of the waveform equalizer. 1......Signal input terminal 2...
・・・・・・A, /D converter 3・・・・・・・・・・・・
Encoding processing circuit 5... Recording head 10... Magnetic tape 11... Playback head 13... Waveform equivalent device 14...Decoding processing circuit 15...
...... D/A converter 16 ...... Signal output terminal 20 ...... Erase current frequency oscillator 22.
... Erasing head patent applicant Nonny Co., Ltd. agent Patent attorney Kodo Koike 1) Sakae Mura - Figure 1 Figure 3 Abundant number F, Calendar

Claims (1)

[Claims] In a digital signal recording and reproducing device that includes a recording system and a reproducing system for recording and reproducing digitalized signals via a magnetic recording medium, a waveform equivalent means having a frequency transfer characteristic in which one or more zero points exist in addition to the DC component is used. A digital signal magnetic recording and reproducing apparatus characterized in that an erasing means is provided in the reproduction system and performs alternating current erasing at an erasing current frequency equal to one zero point frequency of the frequency transfer characteristic of the waveform equalizing means.