JP3291458B2 - Digital broadcast receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver for receiving digital broadcasts, and more particularly to a technical field of a preset technology for storing information of a broadcast station to be received in the receiver in advance.

[0002]

2. Description of the Related Art In a conventional radio receiver, reception frequencies of some of the receivable broadcasting stations are stored in a memory corresponding to a specific preset number so that the radio station can be easily selected thereafter. Some have a so-called preset function.

[0003] In order to simplify the operation of storing in a preset memory, the operation of storing in a preset memory is simplified in a radio receiver equipped with this preset function. Some have an auto-preset function in which the highest frequency is scanned from the frequency and the received frequency is stored next in the memory for sequential preset.

However, if the maximum number of memories that can be preset is stored before the scan reaches the highest frequency, the scan is terminated, and thereafter the scan is not performed. There is a problem that even if there is a station having a better reception state, the station is not preset.

As a method for improving this, there is a technique described in Japanese Patent Application Laid-Open No. 7-95012 in which receivable stations are automatically preset in descending order of electric field strength.
In a receiver for digital satellite broadcasting in which data of a plurality of channels is multiplexed on one carrier, there is a problem that this method cannot be used because the electric field strength of each channel is equal.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a receiver for receiving a broadcast in which data of a large number of channels is multiplexed. It is a technical task to auto-preset a channel having a high bit rate for which the bit rate is high.

[0007]

According to the present invention, there is provided a digital broadcast receiver for receiving a signal obtained by time-division multiplexing data of a plurality of channels having different bit rates. Data extraction means for extracting the data of the channel, bit rate detection means for detecting the bit rate of the channel, and preset memory for storing the reception channel information. Channel information is stored in the preset memory according to the value, and the data extracting means extracts data of a channel specified by the stored channel information.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a digital broadcast receiver according to the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram of a digital broadcast receiver according to the present invention.

[0010] In the figure, (1) is an antenna for receiving radio waves from a broadcasting satellite.

Here, data of each channel of a broadcast wave from a broadcast satellite is multiplexed by a TDM (time division multiplex) method,
Transmitted after PSK modulation.

FIG. 2 shows a frame configuration of channel data according to the TDM method.

In the TDM, the time width of each time slot is equal, and the number of bits in each time slot is also equal.

(2) is an RF front-end processing unit which selects a specific broadcast wave from radio waves received by the antenna (1) and converts it into an intermediate frequency.

The RF front-end processing unit (2) performs processing by a synthesizer method using a PLL circuit (3) including a programmable frequency divider. At this time, the frequency division ratio of the programmable frequency divider is determined by a microcomputer (4). The receiving frequency is selected under the control of (3).

(5) is a QPSK demodulation circuit, to which an output of the RF front end processing section (2) is inputted, and a baseband signal is demodulated from a phase-modulated carrier.

This demodulation is performed by a synchronous detection method. This synchronous detection method is a well-known technique, and a detailed description thereof will be omitted.

(6) is a TDM demodulation circuit, which is QPSK
An output signal of the demodulation circuit (5) is supplied, and data for each channel is formed and output.

In the TDM demodulation circuit (6), the TDM frame synchronization detection section (7) first establishes frame synchronization based on the synchronization signal. After the frame synchronization is established, the TDM header reading section (8) reads the header section. The data is read by the microcomputer (4).

The header section includes a TDM as shown in FIG.
, And labels 1 to n which are ID numbers for identifying which channel each of the time slots 1 to n is.

The microcomputer (4) reads from the header which time slot contains the data of the channel to be received, and inputs the slot number (one or more) to the channel decoder circuit (9).

The channel decoder circuit (9) synthesizes data included in the time slot of the time slot number input from the microcomputer (4) and reconstructs data of one channel.

As a result, the TDM demodulation circuit (6)
The operation shown in FIG.

This example has four channels (A, B, C,
D) is divided into seven time slots (slots 1 to 7) and transmitted.

Channel A has time slots 1, 4, 6
, And the TDM for each frame.
The data of channel A is extracted by extracting the data of time slots 1, 4, and 6 from the bit stream and combining them. The microcomputer (4) has memories P (1) to P (T) for presetting, and the tuning information (label or slot number) of the broadcasting station detected in the auto-preset processing of the flow shown in FIG. It is memorized.

An operation switch section (10) has a preset channel selection switch (P1 to PT) for calling a stored broadcast station and a preset start switch (S).

The microcomputer (4) performs an auto-preset process under program control.

Various methods are conceivable for this program control. Hereinafter, description will be made with reference to embodiments.

In the first embodiment, it is checked how many time slots are used for each channel, and the number is stored in the work memory. Then, the channels are stored in the preset memory in order of the number of used time slots. The control is performed according to the flowchart of FIG.

The variables used in this control flow are as follows.

N: Total number of time slots in one frame of TDM, which is a predetermined value.

P (1), P (2),..., P (T): preset memory LABEL (i): label of time slot i LABEL_CHK (i): check whether the ith label has been checked or not LIST (M, 0): Label of Mth channel LIST (M, 1): Number of slots of Mth channel COUNT: Number of channels When the preset start switch (S) is pressed, the microcomputer (4) starts the auto-preset process of FIG.

When the process is started, first, an initial value is set in step 1, the initial values of variables I and M are set to 1, and label check flags LABEL_CHK (i) to LABEL_C are set.
Set the value of HK (n) to 0.

When the initial value setting is completed, in step 2, the value of the used time slot number counter COUNT is reset.

Next, in step 3, the value of the label check flag LABEL_CHK (i) of the target label is checked to determine whether the check has already been completed.

If the label has not been checked yet, that is, if the value of the label check flag LABEL_CHK (i) is 0, the same label as the label i is changed from the label i + 1 to the label n in steps 4 to 9. Find out how many are present by:

In step 4, the value of the variable K is set to i,
In step 5, it is checked whether the label value of the time slot K matches the label value of the time slot i.

If they match, the value of the variable COUNT is incremented (step 6).

Then, the label check flag of the label i
LABEL_CHK (i) is set to 1 and a flag indicating that the check has been completed for i is set.

Next, at step 8, the value of the variable K is incremented, and at step 9, it is checked whether or not the value of K has exceeded the total number n of time slots in one frame of TDM.

Here, if the value of K does not exceed n, the processing of steps 5 to 9 is repeated.

If the value of K exceeds n, step 10
And M and the label LABE of the corresponding time slot
A table list of L (i) and the COUNT value which is the number of used slots is created in the memory.

Next, at step 11, the value of M is incremented, and at step 12, the value of i is incremented.

If LABEL_CHK (i) = 1 in step 3, control is transferred to step 12.

Then, in step 13, the value of i is compared with the value of n.

As a result, if i does not exceed the value of n, the control is returned to step 2 and the processing of steps 2 to 13 is performed again to check all the channels.

Thus, the following operation is performed.

Assuming that the time of one frame is Tf and the number of bits of one time slot is a, the bit rate of each channel is a × the number of used slots (COUNT) / Tf.

For example, it is checked how many slots the channel A using the time slot 1 uses in the remaining slots 2 to n, and LIST (1,0) as shown in the table list shown in FIG. ) Represents LABEL (1) = A, which is the label of time slot 1, and LIST (1,1) represents the number of slots COUNT.
Write.

Here, a flag LABEL_CHK indicating that other slots having the same label A have been checked.
(i) is set to 1.

Then, it is checked how many slots the channel using time slot 2 uses, and slot 2 has already been checked for LABEL_CH
If K (2) = 1, proceed to the next without counting.

In step 13, if i exceeds the value of n, in step 14, referring to the table list, the labels from the higher count to the T preset memories P (1) to P (T) are stored. Remember.

When the count numbers are equal, for example, they are stored in the order of the list (using the smaller time slot numbers).

In the method of the preset memory, in addition to the method of storing the upper T counts in the order of the list, the preset memories may be stored in order from the one with the largest count.

It is also conceivable that a time slot number (one representative or all slot numbers of the same channel) is stored in a preset memory instead of a label. When the preset tuning switches P1 to PT are operated after the end of the preset, the number of the time slot having the same label as the label of the corresponding memory is input to the channel decoder, and the channel data is reproduced.

Next, a second embodiment of the present invention will be described.

In this embodiment, the label of the header is checked in order, the number of slots used is counted for each corresponding channel, the number of used slots is created, a table list is created, and the table is referred to for presetting. Control is performed according to the flowchart shown in FIG.

The variables used in this control flow are as follows.

N: Total number of time slots in one frame of TDM, which is a predetermined value.

P (1), P (2),..., P (T): Preset memory LABEL (i): Label of time slot i LIST (M, 0): Stores the label corresponding to each channel Array variable LIST (M, 1): Array variable for storing the number of used slots corresponding to each channel. When the processing is started, first, in step 21, initial values are set, and LABEL (LIST) is set to LIST (1, 0). 1) Store and LIS
Set 1 to T (1,1). Also, the initial values of i and M are set to 2.

Next, in step 22, it is determined whether or not the same item as LABEL (i) exists in LIST (1,0) to LIST (M-1,0).

That is, it is determined whether or not the target channel is a new channel.

Here, LABEL (i) is the same as LIST
If not present in (1,0) -LIST (M-1,0), LABEL (i) is added to LIST (M, 0) as a new channel in step 23.
Is set, and LIST (M, 1) is set to 1. Thereafter, the value of M is incremented.

In step 22, LABEL
If the same as (i) exists in LIST (1,0) to LIST (M-1,0), the LIST (*) corresponding to LABEL (i) of the channel already set in step 24 , 1) is incremented.

Thereafter, the value of i is incremented in step 25, and steps 22 to 25 are repeated until i exceeds n in step 26.

If i exceeds n in step 26, T labels are read from the upper count number in the preset memories P (1) to P (1) to P in step 27 with reference to the table list.
(T). By doing so, it is possible to analyze a digital broadcast signal in which a large number of channel data are multiplexed, and perform presetting in order from a channel having a higher bit rate.

[0067]

As described above, when the auto preset is executed by the digital broadcast receiver of the present invention, a broadcast station having a large number of time slots, that is, a bit rate is preferentially preset.

For example, when a music signal is transmitted after being digitized, the transmission bit rate is represented by the product of the sampling frequency and the number of quantization bits (when not compressed). The higher the bit rate, the higher the sound quality. In the case of broadcasting a news program or the like in multiple languages, it is expected that the higher the transmission bit rate, the more the channel is transmitting in more languages.

Therefore, the user can easily select a channel providing a higher quality service or a wider variety of services from a large number of channels having different bit rates.

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital broadcast receiver according to the present invention.

FIG. 2 is a diagram illustrating a frame configuration of channel data.

FIG. 3 is a schematic diagram of a TDM demodulation circuit operation.

FIG. 4 is a flowchart of control according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram of a memory table list.

FIG. 6 is a flowchart of control according to a second embodiment of the present invention.

[Explanation of symbols]

 1. Antenna 2. 2. RF front-end processing unit PLL circuit 4. Microcomputer 5. 5. QPSK demodulation circuit 6. TDM demodulation circuit 7. TDM frame synchronization detector 8. TDM header reading unit 9. Channel decoder circuit Operation switch section

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/38-5/46 H04N 3/22 H04B 1/16 H03J 5/02

Claims (6)

(57) [Claims] 1. A digital broadcast receiver for receiving a signal in which data of a plurality of channels having different bit rates is time-division multiplexed, data extracting means for extracting data of a specific channel from the signal, Bit rate detection means for detecting a rate; preset memory for storing received channel information; storing channel information in the preset memory according to a bit rate value detected by the bit rate detection means; A digital broadcast receiver, wherein the extracting means extracts data of a channel specified by the stored channel information. 2. The digital broadcast receiver according to claim 1, wherein the channel information is stored in the preset memory in descending order of the value of the bit rate detected by the bit rate detecting means. 3. The digital communication system according to claim 1, wherein said bit rate detecting means detects the bit rate by checking the number of time division multiplex time slots used by said specific channel. Broadcast receiver. 4. The time-division multiplexed signal has a header in which channel information for each slot in the frame is stored for each frame, and the bit rate detecting means determines the specific channel based on the channel information of the header. 4. The digital broadcast receiver according to claim 3, wherein the number of time division multiplexing time slots used is checked. 5. The digital broadcast receiver according to claim 4, wherein said bit rate detecting means sequentially and repeatedly checks said header information for each channel. 6. The apparatus according to claim 4, wherein said bit rate detecting means counts the number of used time slots of the channel corresponding to each header information.
Digital broadcast receiver as described.