JP2651437B2 - Program monitoring device in digital tape recorder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a program monitoring apparatus for detecting an error in program management information in a digital tape recorder.

(Conventional technology and its problems) The present age is in the transition period from analog technology to digital technology, and in the field of tape recorders, the conventional analog type is being developed to digital tape recorder (DAT). Many proposals have been made for digital tape recorders.

FIG. 3 shows a tape track format of the helical scan type DAT.

The tape T is wound diagonally around the rotating head drum,
A recording pattern of an oblique track is formed alternately by two magnetic heads arranged 180 degrees apart (wrapped by 90 degrees) around the outer circumference of the rotary head drum. Arrow A indicates the tape running direction, and arrow B indicates the head moving direction.

The format of each tape track is as shown in the figure.
PCM data area PCM which is divided into 16 areas and converts audio data etc. into PCM and sub-code area which records music number, address information, time code and other information related to programs formed before and after it SUB1, SUB2
And an automatic tracking finding area ATF in which an automatic tracking frequency signal for accurately tracking the magnetic head with respect to the tape track is recorded. After the PCM data area PCM and the subcode areas SUB1 and SUB2, a space for preventing data from being destroyed in other areas due to misregistration or the like when performing partial recording on a tape track by performing after-recording or the like. POST AMBLEs are formed, and four interblock gaps IBG for preventing interference between areas on the tape track are formed.

When searching for a program recorded on a tape according to the tape format configured as described above, the search is performed using the subcode information recorded on the track.

The sub-coat information includes the program number (program number), address, and the like of each program recorded on the tape.
This is management information such as various flags (described later) for searching for each program, including the performance time, the time from the tape start point, and the like.

The sub-code information can be recorded at a plurality of locations on the tape track format shown in FIG. 3, and the PCM recorded as an ID code in the PCM area PCM.
-ID, SUB-ID recorded as an ID code in the sub-coat areas SUB1 and SUB2, and SUB-DATA recorded as data in the sub-code area can be used together. However, the subcode information recorded in the subcode area is PCM
Priority is assigned so that PCM-ID recorded in the area is prioritized. SUB-DATA is the same item as SUB-ID, with the same contents recorded as data in PACK format. There is no contradiction between the two.

The TOC (Table of Contents) records the management information of all the programs recorded on the tape.
contents) may be formed. The TOC provides a dedicated area at the beginning of the tape and
When recorded in PACK format on 1, SUB2, subcode area SU
When recording in B1 and SUB2 in PACK format and over the entire area of the tape, a TOC area is provided at the beginning of the tape and the Auxiliary
When recorded using the ary code, the Auxiliar is added to the PCM-ID.
Four formats for recording over the entire area of the tape using y Code have been proposed, and when these are duplicated, priorities are given in the order of explanation.

However, the TOC recorded in the dedicated area at the beginning of the tape
Other than (hereinafter referred to as U-TOC), rewriting is difficult, so that a TOC that can be changed when a general user performs post-recording or partial editing will be a U-TOC in practical use.

Therefore, in the digital tape recorder, any program on the tape can be searched at a very high speed based on the above-mentioned subcode information and TOC information.

When actually performing a search, the method of this search is
Many combinations and applications such as search between tracks by program number and program time, cueing by program number designation, search by program number and index, high-speed search by absolute time from TOC and tape start point, search by START-ID, etc. there is a possibility.

Here, sub-code information closely related to the above-described search will be described.

FIGS. 4 (a) to 4 (d) show the track format on the tape in a stepwise manner.

FIG. 4 (a) shows the format of one entire track, which itself corresponds to one track in FIG.

FIG. 13B shows the contents of the subcode area SUB1. Although there are two subcode areas SUB1 and SUB2 in one track, the formation is the same, so that SUB1 will be described.

The subcode area SUB1 is a block synchronization signal for clearing the delimiter for converting serial input data to parallel symbols and indicating block boundaries even if bit synchronization is shifted due to jitter etc. to restore synchronization.
SYNC, SUB-COD for recording subcode information as ID signal
Word W1, SUB-CODE ID and SUB-COD corresponding to E ID
BLO that records each address of 8 blocks that constitute E ID
Parity P and subcode information given by exclusive OR of words W2, W1 and W2 constituting CK ADDRESS
It consists of SUB-CODE DATA recorded as data in PACK format.

FIG. 3C further shows the contents of the words W1 and W2 in an exploded manner. Each word is composed of 8 bits, word W1 is SUB-CODE ID, word W2 is SUB-CODE
It consists of 4 bits for ID and 4 bits for BLOCK ADDRESS.

FIG. 3D is a more detailed breakdown of the contents of the SUB-CODE ID in FIG. Subcode is SUB1, SUB
Both are composed of eight blocks, and the SUB-CODE ID is composed of one set of two blocks. In other words, considering one set of two blocks, SUB-CODE I
D is assigned to CONTROL-ID, DATA-ID, FORMAT-ID,
In the other block, PNO-ID (2), PNO-ID (3), PNO
-Assigned to ID (1).

As shown in FIG. 5, the CONTROL-ID is recorded with the same contents in both SUB1 and SUB2, and each bit is a TOC-I
D, SHORTENING-ID, START-ID, and PRIORITY-ID are assigned to four flags.

TOC-ID (hereinafter referred to as T-ID) means that the program
A flag that is set to 1 when it is registered in the program, 0 when it is not registered, and has a START-ID (S-ID) of 1 at the start point of each program and 0 during the program.
The -ID (hereinafter referred to as P-ID) indicates the validity of the program number PNO in order to eliminate the inconsistency of the sub-code which occurs when performing a partial post-recording or the like. Where 1 is a flag indicating that the program number PNO at that time is valid, and 0 is a flag indicating that it is invalid. If the SHORTENING-ID is 1 at the beginning of the abbreviated part that can be skipped on the tape, SKI until the next START-ID
P is a flag determined to be 0 when it is not set.

Returning to FIG. 4 (d), the DTA-ID is for giving the SUB-DATA format (for example, when the content of the DATA-ID is "0000", all the SUB-DATA is recorded in the PACK format. There is.)

The FORMAT-ID gives the number of PACKs used in the SUB-DATA. PNO-ID (2), PNO-ID (3), PNO
-ID (1) indicates a program number recorded on the tape. PNO-ID is (1)-(3)
Each shows one digit of binary coded decimal, and can represent a three-digit number as a whole.

The above is the main configuration of the subcode information. Next, program management based on the subcode information such as these flags S-ID, P-ID, T-ID, and PNO-ID will be described.

In addition, "1" can be recorded only in the place where the S-ID exists in the P-ID,
Meaning that the PNO-ID of the program is valid,
The T-ID is set to "1" at least in the S-ID portion if the program is registered in the TOC.

FIG. 6 shows four types of program management patterns CASE A to CASE D using these flags.

CASE A is "0" for both P-ID and T-ID where S-ID exists.
In this case, the PNO in the program area of the program specified by the S-ID is invalidated, indicating that this program does not exist in the TOC.

CASE B is a case where the P-ID is "1" and the T-ID is "0" at the location of the S-ID, and the program specified by this S-ID is Indicates that the PNO is valid.
However, this program does not exist in TOC.

CASE C is when the P-ID is "0" and the T-ID is "1" at the location of the S-ID, and the program specified by the S-ID is such that the PNO in the program area is invalid. Indicates that However, this program exists in TCO.

CASE D is "1" for both P-ID and T-ID where S-ID exists.
And the program defined by this S-ID is S
-The PNO where the ID is located is valid and is also present in the TOC.

For digital tape recorders, the above four CAs
SE is stipulated, and program management is to be operated based on these CASEs.

In this way, in the digital tape recorder, high-quality recording / reproducing by PCM recording and high-speed search using subcode information (100 to 2 times of normal recording / reproducing speed) are performed.
(00 times speed), but is significantly different from conventional digital audio devices such as compact discs in that general users can record and edit.

That is, any music tape that has already been recorded may be used, but if the user records or edits the program contents, it is necessary to simultaneously and surely manage information about the program, that is, subcode information. In operations such as re-recording, it is highly probable that conflicts will occur. For example, after dubbing and partial re-recording, the effective PNO (P-ID in place of S-ID)
In some cases) may be blurred or reduced, or the order may be random.

In a set of the type using the TOC (U-TOC), the user must return to the beginning of the tape and rewrite the U-TOC each time recording or editing is performed.

In addition, CASE A ~ CASE
As shown in D, a system that performs advanced management using TOC like CASE C and CASE D is not always adopted in all sets, and there is no guarantee especially for consumer equipment.

CASE without TOC, which is generally considered to be widely adopted
In the case of A, CASE B, if a search is performed on a tape on which the above contradiction occurs, various inconveniences occur.

For example, the PNO is currently playing 3 programs.
Here, if the PNO wants to search for five programs, it will naturally search toward the end of the tape.
If the program with the PNO of 5 is physically located before the program with the PNO of 3, the search is performed to the end of the tape and then to the beginning of the tape again. Therefore, even if the high-speed search is performed, it takes time to find a desired program, and the high-speed search which is a feature of the digital tape recorder cannot be utilized.

If there is no more PNO to search, it may be possible to continue the search without finding the program.If more than one PNO exists, accurate search is impossible. Become.

(Object of the Invention) The purpose of the present invention is to solve the above-mentioned problems.
Detects anomalies in program management information and informs the user of situations such as high-speed search impossible and accurate search impossible.
It is an object of the present invention to provide a program monitoring device for realizing a digital tape recorder.

(Summary of the Invention) In subcode information serving as program management information,
The program number is read at the timing when the S-ID flag indicating the start point of the program and the P-ID flag for determining the validity / invalidity of the program number (PNO) rise at the same time. If a discrepancy occurs between the result of comparing the read program number with at least the magnitude relationship and the result of determining whether the program read from the tape running direction is in ascending or descending order, a warning flag is set. A new digital tape recorder configured to indicate that there is an error in the program management information.

(Embodiment) FIG. 2 is a block diagram for explaining the principle of the digital tape recorder of the present invention.

1 is a tape drive mechanism, 2 is magnetic head h _1, h ₂
A rotary head drum, which is 180 degrees apart (wrapped by 90 degrees) on the outer periphery, 3 is a capstan, 4a and 4b are reel shafts. Reference numerals 5a and 5b denote movable guide posts for pulling out a tape from a mounted cassette (not shown) and loading or unloading the tape onto the rotary head drum 2. A drum drive system 6 for driving the rotary head drum, a capstan drive system 7 for driving the capstan 3, a reel shaft drive system 8 for driving the reel shafts 4a and 4b according to the operation mode, guide posts 5a and 5b, etc. A loading drive system 9 for driving the loading mechanism is provided.

The drum drive system 6, the capstan drive system 7, and the reel shaft drive system 8 are connected to a control block 11 via a mechanism control interface 10, and controls the tape drive mechanism to a predetermined mode according to a command from the control block 11. It has become. The loading drive system 9 is also connected to the control block 11 via the loading control interface 12, and is controlled by this.

The control block 11 also includes various sensors (not shown) for detecting the start and end of the tape and detecting dew condensation.
Input interface 1 for inputting data
3, a key input interface 15 for supplying data of operation keys 14, a display output interface 17 for outputting data to a display unit 16 for performing various displays according to operation modes, and a signal processing system and A subcode interface 18 for transmitting and receiving code information, and a PNO, P-ID, S-ID,
Interfaces 19 for supplying necessary information such as DIR (indicating a tape running direction, which will be described later in detail) are connected to each other.

 Here, the signal processing system will be described.

The magnetic heads h ₁ and h ₂ are connected to a recording / reproducing switching block 20 for selectively switching and connecting a recording system and a reproducing system.

To explain the recording system, an analog signal input from a recording input terminal IN is adjusted to a predetermined level by a level control circuit 21, then sampled by a sample and hold circuit 22, supplied to an A / D conversion circuit 23, and supplied to a digital converter. It is converted into a signal (PCM signal). Further PCM coded signal is interleaved by the signal processing system 25 of the signal processing block 24, the addition of error correction code, after modulating the like is performed, and the magnetic head h _1, h ₂ via the recording head amplifier 26 Supplied and recorded on tape.

To explain the reproducing system, the PCM signal reproduced from the magnetic head h ₁ h ₂ is supplied to the reproducing head amplifier 27 by the recording / reproducing switching block 20, and the waveform is shaped by the waveform shaping circuit 28 including an equalizer, a comparator, and the like. Thereafter, it is supplied to the signal processing block 24. The signal is read out in synchronization with the clock signal extracted from the digital signal by the PLL circuit 29 in the signal processing block 24, and is read out by the signal processing system.
Demodulated by 25. At this time, error detection, error correction, error correction, deinterleaving, etc. are performed at the same time.
PAM (Pulse Amplitude Mo) is supplied to the D / A conversion circuit 30.
duration) signal. Further, the PAM signal is output to the reproduction output terminal OUT via the low-pass filter 31 and the level control circuit 32.

Also, the ATF signal on the tape track and the servo FG and PG signals in each drive system are constantly transmitted from the playback system and the signal processing system 25, the rotary head drum 2, the capstan 3, and the reel shafts 4a and 4b to the drum, capstan, and reel. It is supplied to a drive servo system 33 that performs servo of the shaft and the like, and various controls such as rotation control of a rotary head drum, automatic tracking, and capstan rotation control are performed by the servo system 33.

Reference numeral 34 denotes a program monitoring circuit which is a main part of the present invention.
An error in the program management information on the tape is detected from flags such as the ID, PNO, and the tape running direction identification signal DIR.

FIG. 1 is a block diagram showing the configuration of the program monitoring circuit 34.

In the figure, 35 is a first register to which the program number PNO (PNO-ID) in the subcode information extracted from the control block 11 via the interface 19 is transferred, and 36 is a PNO to the first register. This is the second register to which the contents stored in the first register immediately before the transfer are transferred.

Reference numeral 37 denotes a comparison unit that uses information as to whether the tape running direction is in ascending or descending order of the program number PNO as a determination condition.
A comparison control unit which transfers the data to 38, and judges whether the reproduction or search is being performed in the forward direction or the reverse direction from the tape running direction obtained via the mechanism control interface 10 from the control block. Things. That is, if there is no inconsistency between the program recorded on the tape and its management information, the tape is running in the forward direction (the tape may be running in both the playback mode and the search mode). Is based on the fact that the program numbers are arranged in ascending order, and if the tape is running in the reverse direction, the program numbers should be arranged in descending order.

38 compares the result of comparing the magnitude relationship between the contents of the first register 35 and the second register 36 with the judgment condition from the comparison control unit 37, and sets a warning flag when there is a contradiction between the two. Department.

Reference numeral 39 denotes a flag latch circuit which, when a warning flag is output from the comparison unit 38, latches the warning flag and holds the state until reset, and displays a warning on the display unit 16.

Numeral 40 designates the flag P-ID and S-ID in the subcode information via the interface 19, and when the P-ID and S-ID are simultaneously inputted (the PNO at that time is valid), the PNO transfer timing is set. The generated timing generation circuit transfers the effective program number PNO at that time to the first register 35 by this timing, and at the same time, transfers the contents stored immediately before in the first register 35 to the second register 36. Then, a tape running direction identification flag DIR based on the tape running direction is transferred to the comparison control unit 37. Then, the comparing unit 38 determines whether or not there is a contradiction between the comparison result of the magnitude relation between the contents of the first register 35 and the contents of the second register 36 and the judgment condition given from the comparison control unit 41. Is done.

Also the same timing (actually delayed slightly)
If a warning flag is output from the comparing section 38 to the flag latch circuit 39, this is latched and a warning is displayed on the display section 16.

Reference numeral 41 denotes a first register 35, a second register 36, and a comparison control unit 3 which are operated by taking out a cassette (the mechanism thereof is not shown), turning on the power, and operating a reset button (not shown).
7, a reset circuit for resetting all of the comparing unit 38, the flag latch circuit 39, and the display unit 16 to the initial state.

The program monitoring circuit 34 is configured as described above, and its operation will be described below.

The program monitoring circuit of the present invention detects inconsistencies in the program management information from the PNO, -ID, S-ID in the subcode information recorded on the tape and the tape running direction identification flag. Therefore, if the tape is running, it can be in playback mode or high-speed search mode,
There is no effect of the operation mode.

For example, when performing a high-speed search operation, when a search for a program is instructed by the operation key 14, a command from the operation key 14 is input to the control block 11 via the interface 15 and decoded, and the head drive system is operated in accordance with the command. 6, capstan drive system 7, reel shaft drive system 8
Etc. are in the high-speed feed mode (actually, about 100 to 200 times the normal recording and playback speed). At this time, the rotation speed of the rotary head drum 2 also changes according to the tape speed, and is controlled so that the recorded information on the tape can be reliably reproduced.

The signals read by the magnetic heads h ₁ and h ₂ from the tape are read into the signal processing block 24 via the waveform shaping circuit 28, and the subcode information on the tape track is controlled via the subcode interface 18. Provided to block 11. Then, from the control block 11, the program number PNO,
The P-ID and S-ID are read and supplied to the program monitoring circuit 34.

The S-ID and the P-ID are supplied to a timing generation circuit 40, and when the S-ID and the P-ID are input simultaneously, a PNO transfer timing is generated. The fact that the S-ID and the P-ID are input at the same time indicates that the program number PNO at that time is valid, as described in FIG.

When the timing is generated by the timing generation circuit 40, the valid PNO at that time is read into the first register 35. Then, at the same timing, the contents stored so far in the first register 35 are transferred to the second register 36. These operations are performed by generating a timing each time the S-ID and the P-ID are input simultaneously.

A tape running direction identification signal DIR indicating whether the search is being performed in the forward direction or the reverse direction is supplied. That is, as described above, if there is no inconsistency between the program on the tape and its program management information, the program number PNO on the tape is:
If the search direction is the forward direction, the signals are fetched into the signal processing block 24 in ascending order, and if the search direction is the reverse direction, the signals are fetched in the descending order.

Therefore, the comparison control unit 37 is supplied with the information DIR of the search direction from the mechanism control interface 10, whereby the program number PNO is taken into the first register 35 and the second register 36 in ascending order or in descending order. The comparison unit 38 as a judgment condition
Supplied to. This operation is performed by the timing generation circuit 40.
, The program number PNO is transferred to the first register 35 and from the first register 35 to the second register 36.

On the other hand, when the above-described operation is performed, the comparing unit 38 compares the contents of the first register 35 and the second register 36, that is, the magnitude relationship of the program number PNO, and compares the result with the determination condition of the comparison control unit 37. It is determined whether there is any contradiction.

If the tape running direction is the forward direction,
The program numbers PNO should be taken into the signal processing block 24 in ascending order. Therefore P-ID and S-ID
Are input to the first register 35 each time a valid program number PNO is detected at the same time.
Is transferred to the second register 36, the contents of the first register 35 and the second register 36, that is, the effective program number PN
Comparing the magnitudes of O, the first register 35 should always be greater than the second register 36.

However, in the transfer due to the first timing occurrence after reset, the program number is still stored in the second register 36.
Needless to say, since it does not contain a PNO, it cannot be compared. That is, when the S-ID and the P-ID are simultaneously taken in for the first time, nothing can be compared in the first register 35 because nothing has been entered in the first register 35 until then. First time when S-ID and P-ID are input simultaneously for the second time
The second comparison can be made.

When the tape running direction is the reverse direction, it can be considered in exactly the same way as in the forward direction search described above, but the effective program numbers PNO to be taken are in descending order. This is because the program number PNO is sorted in descending order unless there is a contradiction because the tape is searched in reverse.

Therefore, the magnitude relationship between the contents of the first register 35 and the contents of the second register 36 should always be such that the second register 36> the first register 35... This determination condition is determined by the comparison control unit 37.
It is further provided to a comparing unit 38.

When the tape running direction is reversed, the first register 35 = the second register 36... Only for the first transfer of the program number PNO. Are set in advance so that even if the contents of the two registers are equal, they are not erroneously detected as errors in the program number management information.

Next, a case where a contradiction is found between a program and its management information will be described.

When the S-ID and the P-ID are input at the same time, the contents of the first register 35 are newly stored in the second register 36 and the program number PNO is newly stored in the first register 35 because the program number at that time is valid. The comparison operation is performed by the comparison unit 38 with reference to the tape running direction identification flag DIR of the comparison control unit 37. If the result is contrary to the expression (1), the actual position of the program is controlled by the program management. It is different from the information and there is a contradiction between the two.

Therefore, even if the search is continued in this state, a warning is issued because the management information such as the existence and position of a desired program lacks reliability. That is, a warning flag is output from the comparison unit 38, latched by the flag latch circuit 39, and subsequently output to the display unit 16 to indicate to the user that there is an error in the tape program management information.

As described above, inconsistencies in the program management information may be caused by various patterns such as a change in the order of valid program numbers due to the user's post-recording, partial editing, or the like, or a plurality of the same program numbers. However, in any case, a warning can be issued when inconsistency is detected.

The above is the operation of the program monitoring circuit in the search operation.The warning signal displayed on the display unit 16 is stored until reset, so that the search or reproduction is performed once, the search is performed again, Even if the reproduction operation is repeated, the previous information can be referred to and the program management information can be constantly monitored.

The operation of a reset button (not shown), power-on, cassette removal, etc., causes the first and second registers 35 and 3 to operate.
6. The comparison control unit 37, the comparison unit 38, the flag latch circuit 39, and the display unit 16 are all reset to the initial state, and the information thus far can be cleared.

In the above-described embodiment, the operation of the program monitoring circuit has been described in the search operation. However, since the tape is running in such a manner and the subcode information can be read,
For example, even when the reproduction mode, the reproduction mode, and the search operation are repeatedly performed, exactly the same operation and effect can be obtained.

Further, in the above-described embodiment, when there is an inconsistency in the subcode management information, a warning flag is displayed to indicate that there is an error on the display unit 16. However, errors in the program management information are extremely large, and the search itself cannot be performed. When there is no search operation, the search operation can be stopped simultaneously with the warning. Further, when an error is found, the user may be allowed to select whether to continue or stop the search, and various applications are possible.

(Effects of the Invention) As described above, in the digital tape recorder according to the present invention, the means for detecting the START-ID flag indicating the start point of the program in the subcode information and the PRIORITY- indicating the validity of the program number are provided. Means for detecting an ID flag, the START-ID flag and the PRIOR
Reading means for reading the program number when the ITY-ID flag is detected by the first and second detecting means, respectively; and first storage means for storing the program number read by the reading means. A second storage unit for transferring and storing a program number stored in the first storage unit when a new program number is read; a program number stored in the first storage unit; Comparing means for comparing the program numbers stored in the second storage means to determine the tape running direction; third means for storing the tape running direction; and a tape running direction obtained from the comparing means. The tape running direction stored in the storage means of No. 3 is compared, and if they do not match, it is determined that there is an error in the program management information. Because the error detection is not based on the TOC, the tape running direction information obtained from descending and ascending program numbers is compared with the tape running direction to detect an error in the program management information. In addition, there is an effect that operations such as search and reproduction can be performed without being affected by the lack of TOC. In addition, since the user is notified of the abnormality in the program management information, there is an effect that unnecessary operation, standby, and psychological anxiety are not given to the user at the time of the abnormality.

[Brief description of the drawings]

1 is a block diagram of the program monitoring apparatus of the present invention, FIG. 2 is a block diagram of the entire digital tape recorder of the present invention, FIG. 3 is a tape track format, and FIGS. 4 (a) to (d) are tracks. FIG. 5 shows the CONTROL-ID flag in the subcode information, and FIG. 6 shows the flags S-ID, P-ID, T-ID, and PNO (PNO-I) in the subcode information.
9 shows the program management patterns according to D). DESCRIPTION OF SYMBOLS 1 ... Tape drive mechanism 11 ... Control block 24 ... Signal processing block 34 ... Program monitoring circuit 35 ... First register, 36 ... Second register 37 ... Comparison control unit, 38 ... ... Comparator 39 ... Flag latch circuit 40 ... Timing generation circuit 41 ... Reset circuit S-ID ... START-ID, P-ID ... PRIORITY-ID T-ID ... TOC-ID, PNO ... PROGRAM NUMBER

Claims (1)

(57) [Claims] 1. A digital tape in which tracks stored on a tape include at least a PCM area in which electric signals are converted into PCM and recorded, and subcode information in which management information of a program recorded in the PCM area is recorded. A recorder, the ST representing a starting point of a program in the subcode information
A first detecting means for detecting an ART-ID flag; a second detecting means for detecting a PRIORITY-ID flag indicating validity of a program number; and the START-ID flag and the PRIORITY-ID flag are each the first. And reading means for reading the program number when both are detected by the second detecting means; first storing means for storing the read program number with the reading means; and A second storage unit for transferring and storing the program number stored in the first storage unit; a program number stored in the first storage unit; and a program number stored in the second storage unit. The program numbers are compared to determine the ascending or descending order of the program numbers. And a comparing means for comparing the ascending order and descending order of the discriminated program number obtained from the tape running direction identification signal obtained from the tape running direction identification signal. A program monitoring device in a digital tape recorder, which compares whether the results of ascending or descending program numbers are inconsistent or not, and if there is an inconsistency, indicates that there is an error in the program management information.