DE19956470C5 - Method and digital radio receiver for automatic searching of channels - Google Patents

Abstract

Automatic channel search (ACS) method for automatically searching channels in an OFDM-based digital radio receiver comprising the steps of:
a) determining whether to perform an automatic channel search (ACS) based on a first value stored at a predetermined memory location within a memory and sequencing the entire channels from the first channel to the last channel in case the first value is present at the predetermined storage position;
b) finding and registering effective channels based on the intensity and the error-compensated state of the signal tuned in step (a);
c) sequential tuning of the effective channels, and
d) analyzing the signal tuned in step (c) to classify the tuned signal with respect to various necessary information, and changing the first value at the predetermined memory position to a second value indicating that the automatic channel search has been completed;
where the ...

Description

The The invention relates to a method for automatic channel search and to a digital radio receiver using this method applies.

If a radio receiver, like a TV, purchased and installed, should have an automatic channel search mode (ACS) performed to record the state of a network. When supply voltage for the first time to the radio receiver or when a user enters the ACS mode in the Select case, that this Radio service area of the radio receiver changed becomes effective channels found to be a channel configuration in relation to a network of a corresponding service area.

There the number of channels increasing by launching a digital service, it is that the ACS Operating mode performed faster becomes.

State of the art

These Meet requirements analog radio receivers, like TV and VCR, the z. B. in "radio television electronics", 1991, Issue 11, Pages 677 to 679, and "Funkschau" 1992, Issue 22, pages 44 to 46, are described.

From the JP 9-219 658 A as well as the GB 2 325 363 A Digital radio receivers are known which can receive a DAB signal to perform an automatic channel search within a predetermined frequency band and store the detected due to a certain received signal strength as effective channels. In these known devices, such an automatic channel search, for example, always carried out or performed again when the device is not in its digital receiving mode, namely, for example, performs a CD playback operation, a recording operation or an AM / FM radio mode.

task

task The invention is a method of the type specified as well as a associated digital radio receiver specify with which fast and reliable at any location the radio receiver this immediately after its first commissioning each automatically set channels received at its location and can receive.

These The object is achieved by the method specified in claim 1 as well as the specified in claim 2 digital radio receiver solved.

refinements The invention are specified in the subclaims.

The inventive method and the associated radio receiver characterized by the fact that the operating mode for automatic Channel Search (ACS) is always executed immediately when the radio receiver is initially installed is, i. first supplied with supply voltage. on the other hand However, such an automatic ACS mode can always from the respective user again set or activated.

embodiment

One preferred embodiment The invention will be explained in more detail with reference to the drawing. In detail show:

1 a block diagram of a digital television to which the inventive method can be applied, and

2 a flowchart for explaining the method according to the invention for automatic channel search.

If you look at 1 so a digital TV includes a tuner 11 for the sequential tuning of the entire channel bands from the first channel to the last channel, and a demodulator 12 for a Orthogonal Frequency Division Multiplexing (OFDM) for demodulating an OFDM signal that has been tuned and tuned 11 was entered. The OFDM demodulator 12 was designed using an LSI 64780 chip. The digital TV of the 1 also includes a unit 13 for an automatic forward error correction (FEC) for the error correction of the output signal of the OFDM demodulator 12 , which was designed using an LSI 64724 chip, and a memory unit 15 consisting of an NVRAM for pre-storing special values in positions corresponding to the particular addresses, for performing automatic channel search mode (ACS) and storing effective channels after received the execution of the ACS mode. Meanwhile, the television includes the 1 also a central processing unit (CPU) 14 , which is connected to each component block via an I ² C bus, for controlling the entire operation of each component block for performing the ACS mode. The CPU 14 Finds effective channels based on the tuned signal through the OFDM demodulator 12 is entered and the error-compensated state of the FEC unit 13 , and it registers the found effective channels in the storage unit 15 , The operation of a digital TV the 1 Having the above configuration in the ACS mode will be described below with reference to FIG 2 described.

When a TV is initially installed and the power is turned on, or when a user selects an ACS mode in the case where a service area has been changed, the CPU reads 14 a value that is in a corresponding position of the NVRAM 15 which is designated by a predetermined special address is stored. The CPU 14 judges from the read value whether the ACS mode is being performed. The CPU 14 for example, performs the ACS mode in the case where the read value corresponding to the specific address is the same as that defined in the following Table 1. Table 1 Special address Stored value 0X00 0XFF 0x40 0XFF 0x80 0XFF

The CPU controls to perform the ACS mode 14 the tuner 11 first so that it's the tuner 11 allows to tune the entire physical channel area from the first channel. In the British frequency band 474 MHz to 858 MHz, a sequential tuning between the first channel, which is channel 21 act, and the last channel, which is channel 69 is performed, wherein the frequency band is increased by 8 MHz from the first channel. The tuner 11 a receive signal matches the channel 21 which is the first channel under the control of the CPU 14 and outputs the tuned signal to the OFDM demodulator 12 out. The OFDM demodulator 12 demodulates the tuned signal into the prior-to-be modulated signal using Orthogonal Frequency Division Multiplexing (OFDM), and gives the result to the FEC unit 13 out. The OFDM demodulator 12 Designed using the LSI 64780 chip, it can determine the intensity of the matched signal according to the characteristics of the chip. Thus, the CPU can 14 find out effective channels using the intensity of the tuned signal. The FEC unit 13 performs an error correction of the OFDM demodulated signal provided by the OFDM demodulator 12 is issued by. The CPU 14 measures the intensity of the tuned signal coming from the OFDM demodulator 12 is obtained in a predetermined number of times (here, five times) and takes the average of it. The CPU 14 recognizes the tuned channel as the effective channel when the mean of the signal intensities exceeds 40%, and the error compensation in the FEC unit 13 has been performed and registers the effective channel in the NVRAM 15 , The CPU 14 continues tuning the following channels and performs the same procedure to seek effective channels. The above operation will be up to the channel 69 performed, which is the last channel. In a more detailed presentation, the CPU judges 14 in the starting step of the ACS mode, whether a current channel number is less than or equal to the last channel number "69" to judge whether the entire channels have been searched (step 201 ). If as a result of the assessment of the step 201 shows that the current channel number is greater than the last channel number "69", so does the CPU 14 determines that the entire channels have been searched and exits the ACS mode. Conversely, if arises as a result of the assessment of the step 201 indicates that the current channel number is less than or equal to the last channel number "69", the CPU 14 It determines that the entire channels have not yet been searched, and it controls the tuner 11 so that he ent. the channel signal ent speaking the current channel number (step 202 ). If the tuner 11 in step 202 the corresponding channel signal tunes, so judges the CPU 14 whether the current channel is an effective channel in which a radio signal exists (step 203 ). In step 203 judges the CPU 14 whether the current channel is an effective channel based on the average of the intensities of the matched signal obtained in the OFDM demodulator 12 receives and the error compensation state in the FEC unit 13 , That is, the CPU 14 judges that the current channel is an effective channel when the mean of the signal intensities exceeds 40% and the error compensated state in the FEC unit 13 is formed, that is, a lock is formed. If the current channel is the effective channel, the CPU registers 14 the current channel as the last channel in the NVRAM 15 (Step 204 ). In this case, the CPU increases 14 Whenever it registers the current channel as the last channel, the number of the effective channel is "1" so as to fetch the number of the effective channel (step 205 ). Then, the current channel number is incremented by "1" to change the channel number (step 206 ), and it becomes the steps of the step 201 repeatedly executed to search the effective channels from the current channel to the last channel. In step 203 If the current channel is not recognized as an effective channel, the CPU will result 14 repeats the steps from the step 206 to find out the next effective channel.

The CPU 14 searches the entire channels, that is, the channel 21 to the canal 69 , and registers the found effective channels in the NVRAM 15 to then classify the effective channels in relation to various information, such as the names of the radio stations and the titles of the programs. For this purpose, the CPU controls 14 the tuner 11 such that it tunes a radio signal to the first effective channel among the effective channels in the NVRAM 15 are stored corresponds. The OFDM signal corresponding to the radio signal of the first effective channel in the tuner 11 is tuned in the OFDM demodulator 12 demodulated and then in the FEC unit 13 subjected to error correction. The error-compensated radio signal is transmitted through a demultiplexer, located in the block, which points to the FEC unit 13 follows, is located, analyzed, and then classified on the basis of various necessary information. When the analysis in the demultiplexer is finished, the CPU controls 14 the tuner 11 such that it tunes a radio signal corresponding to the next effective channel so that it can be analyzed in the demultiplexer, and thus receives the various information necessary. Such an operation is performed until the last effective channel.

If the ACS mode has been completed by the above procedures, the CPU changes 14 the values in the NVRAM 15 stored according to the specific address, to the value "0X00", and indicates that the ACS mode has been performed.

As described above searches the automatic channel search method and the digital radio receiver according to the present Invention the entire channels, in the case of a Device for is first installed, or that a service area is changed, only the effective channels find out where radio signals exist and analyze them then various necessary information regarding the found effective channels. Thus, a classification with respect to a multiple network at fastest by the mere one-time initial Carry out of the above method, thus providing a channel configuration to quickly perform in relation to a single network.

Claims (5)

An automatic channel search (ACS) method for automatically searching channels in an OFDM-based digital radio receiver comprising the steps of: a) determining whether to perform automatic channel search (ACS) based on a first value stored at a predetermined memory location within a memory is detected and sequentially tuning the entire channels from the first channel to the last channel in the event that the first value is present at the predetermined memory position; b) finding and registering effective channels based on the intensity and the error-compensated state of the signal tuned in step (a); c) sequentially tuning the effective channels, and d) analyzing the signal tuned in step (c) to classify the tuned signal with respect to various necessary information, and changing the first value at the predetermined memory position to a second value indicative of in that the automatic channel search has been completed, the automatic channel search ACS being performed when the radio receiver is initially installed, or when a user selects an ACS mode, and the various necessary information being names of radio stations and program titles of the effective channels. Digital radio receiver, with: a tuner ( 11 ) for tuning an orthogonal frequency division multiplex signal (OFDM signal) transmitted and received; an OFDM demodulator ( 12 ) for demodulating the OFDM signal tuned in the tuner and for obtaining the intensity of the signal; a unit ( 13 forward error correction (FEC) for error correction of the signal demodulated in the OFDM demodulator; a non-volatile memory ( 15 ) for previously storing a particular value in a predefined address position for performing automatic channel search (AC) mode and storing the effective channels to be searched for; a facility ( 14 ) for judging whether or not an ACS mode is executed on the basis of the value stored in the address position indicated by a predefined address in the memory when power is supplied to the first installation of a device or when a user selects an ACS mode and then changes the stored value when the ACS mode is ended; for controlling the tuner to sequentially tune the entire channel bands from the first channel to the last channel initially when an automatic channel search mode (ACS mode) is executed, and for controlling the tuner to sequentially operate channels from the first effective channel to tune to the last effective channel to search the effective channels in which radio signals exist, analyze the searched effective channels, and analyze the analyzed signal for various necessary information based on the intensity of the signal obtained in the OFDM demodulator; and the error-compensated state in the FEC unit, the various necessary information including names of radio stations. Capture program titles regarding the effective channels. The ACS method of claim 1, wherein the step (b) the following substeps comprise: (B1) Demodulating the signal of the tuned current channel and performing a Error correction so as to obtain the intensity of the signal; (B2) Obtaining an average of the signal intensity obtained in step (b1) obtained; (B3) Comparison of the mean value of the signal intensity obtained in step (b2) gets with a reference value and judging whether the current channel is on is effective channel in which a radio signal exists on the basis of Comparison result and the error-compensated state over the Error correction in step (b1); and (b4) Register the Channel number whenever it is determined that the current channel is more effective Channel is then to increase the frequency of the current channel. ACS method according to claim 2, wherein in step (b3) the current channel is detected as an effective channel, though the mean value of the signal intensity exceeds the reference value and the signal is in the error-compensated state. A digital radio receiver according to claim 4, wherein the unit ( 14 ) an average in relation to the signal intensity of the current channel, which in the OFDM demodulator ( 12 ) and recognizes that the current channel is an effective channel when the average exceeds a reference value and the signal in the FEC unit ( 13 ) is error-compensated, thus removing the current channel in the memory ( 15 ) to register.