WO2021112348A1 - Method for detecting drm signal of 30 mhz or lower using sliding scan technique - Google Patents

Abstract

A method for detecting a DRM signal using a sliding scan technique according to an embodiment of the present invention may comprise: a sliding sampling step for collecting sampling data from a plurality of DRM signals, received for each frequency band, while sliding and moving along a time axis and a frequency axis; a data storage step for temporarily storing, for each frequency band, the sampling data collected in the sliding sampling step; and a signal detection step for determining whether to detect a signal for each frequency band on the basis of the sampling data temporarily stored for each frequency band in the data storage step.

Description

[Correction 16.06.2020 according to Rule 26]　DRM signal detection method below 30MHz using sliding scan technique

The present invention relates to a method for detecting a DRM signal using a sliding scan technique, and more particularly, to a method for detecting a DRM signal using a sliding scan technique capable of rapidly scanning and detecting a wideband signal in a single DRM receiver.

DRM (Digital Radio Mondiale) includes digital DRM AM broadcasting and DRM FM broadcasting technology that can be used in FM band and Band III used in short, medium, and long wave bands below 30MHz. Among them, DRM AM broadcasting has sound quality close to FM, multilingual audio broadcasting, data and text transmission are possible, and has various advantages of broadcasting within the existing AM broadcasting frequency band, so it is currently standardized mainly in Europe and the United States. The work is complete.

This DRM uses OFDM (Orthogonal Frequency Division Multiplexing) transmission method that is robust to the effect of multipath fading, which is a characteristic of a mobile environment transmission channel, and can be received without performance degradation in order to stably provide various services even when moving.

However, the conventional DRM of 30 MHz or less has a disadvantage that it takes a lot of time to scan a wideband signal because the physical frame length is standardized as 400 ms.

On the other hand, although an RSSI-based signal detection method can be applied through an RF tuner, in the case of DRM AM, audio decoding is possible even with sensitivity of about -110dBm, so it is not suitable as an RSSI-based signal detection method. When the DRM receivers are connected in parallel, the search time can be physically reduced, but there is a problem in that the cost for using the DRM service increases because multiple receivers are used.

On the other hand, the above-mentioned background technology is technical information that the inventor possessed for the derivation of the present invention or acquired during the derivation process of the present invention, and it cannot be said that it is necessarily known technology disclosed to the general public before the filing of the present invention. .

One aspect of the present invention provides a method for detecting a DRM signal below 30 MHz using a sliding scan technique capable of rapidly scanning and detecting a wideband signal with only a single DRM receiver.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

A DRM signal detection method using a sliding scan technique of searching a DRM broadcast channel by scanning a plurality of DRM signals received for each frequency band in a single DRM (Digital Radio Mondiale) receiver according to an embodiment of the present invention is received by frequency band Sliding sampling step of collecting sampling data while sliding the plurality of DRM signals along the time axis and the frequency axis; a data storage step of temporarily storing the sampling data collected in the sliding sampling step for each frequency band; and a signal detecting step of determining whether to detect a signal for each frequency band based on the sampling data for each frequency band temporarily stored in the data storage step.

In the sliding sampling step, a plurality of DRM signals simultaneously received for each frequency band through the RF tuner of the DRM receiver for a sampling time set based on the frame length of the DRM signal are sequentially sampled according to the frequency size, and the sampling It is characterized in that the process is repeated N times to collect sampling data, but the sliding sampling step may be performed at each reception time of FAC (Fast Access Channel) data in which the DRM signal having a frame length of 400 ms is received every 400 ms. So, the sampling time is set to 26.667ms (26.667ms x 15 = 400ms), and the sampling process is characterized in that it is repeated 15 times,

In the data storage step, while the sliding sampling step is performed, the sampling data collected for each frequency band is sequentially signal-processed for each frequency size, and the intermediate result is temporarily stored in a memory provided in the DRM receiver, but the temporary storage It is characterized in that, while the sliding sampling step is performed, a memory area allocated to a main service channel (MSC) including audio and data is allocated as an area for storing the sampling data,

The signal detecting step may include detecting parameter characteristics of the DRM signal through auto-correlation of the signal processing result for each frequency band temporarily stored in the memory.

According to the above-described aspect of the present invention, by simultaneously sampling a plurality of DRM signals collected through the RF tuner, even if a single RF tuner is used, the time required for DRM channel search can be drastically reduced, and the signal-processed Data processing efficiency can be improved by allocating memory not used in the process of temporarily storing sampling data as a memory area for temporarily storing signals.

1 is a flowchart illustrating a schematic flow of a method for detecting a DRM signal using a sliding scan technique according to an embodiment of the present invention.

2 to 5 are diagrams illustrating specific examples of detecting a signal according to the DRM signal detection method using the sliding scan technique of FIG. 1 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0023] Reference is made to the accompanying drawings, which show by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein with respect to one embodiment may be implemented in other embodiments without departing from the spirit and scope of the invention. In addition, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Accordingly, the following detailed description is not intended to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all scope equivalents to those as claimed. Like reference numerals in the drawings refer to the same or similar functions throughout the various aspects.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings.

1 is a flowchart illustrating a schematic flow of a method for detecting a DRM signal using a sliding scan technique according to an embodiment of the present invention.

The DRM signal detection method using the sliding scan technique according to the present invention may be performed by a DRM receiver.

In particular, the DRM signal detection method using the sliding scan technique according to the present invention simultaneously samples a plurality of DRM signals collected through the RF tuner of the DRM receiver, thereby reducing the time required for channel search of the DRM even when using one RF tuner. can be shortened drastically.

Specifically, the DRM signal detection method using the scan technique according to an embodiment of the present invention may include a sliding sampling step (S10), a data storage step (S20), and a signal detection step (S30).

In the sampling step (S10), sampling data may be collected while sliding the plurality of DRM signals received for each frequency band along the time axis and the frequency axis.

Specifically, for a sampling time set based on the frame length of the DRM signal, a plurality of DRM signals simultaneously received for each frequency band through the RF tuner of the DRM receiver are sequentially sampled according to the frequency size, and the sampling process is performed by N It may be characterized in that sampling data is collected by performing iteration times. In this regard, it will be described with reference to FIG. 2 .

2 is a conceptual diagram illustrating a specific example of the sampling step ( S10 ).

For the RF tuner to support the AM Band, may support a bandwidth that can include a number of frequency signals of DRM, from a signal output from the RF tuner, the frequency f ₁ of the DRM AM as shown in Figure 2, to f _N It contains N signals.

As described above, DRM uses an Orthogonal Frequency Division Multiplexing (OFDM) transmission method, and defines four robustness modes A, B, C, and D according to the conditions of a transmission channel. OFDM parameters and lengths of OFDM symbols are different according to robustness modes, and transmission parameters corresponding to modes are shown in Table 1 below.

OFDM parameters	Robustness Mode for DRM AM
	A	B	C	D
T FFT (ms)	24	21.333	14.667	9.333
T GI (ms)	2.667	5.333	5.333	7.333
T OFDM = T FFT + T GI (ms)	26.667	26.667	20	16.667
Number of symbols per frame	15	15	20	24
Frame length (ms)	400

As shown in Table 1 above, DRM has different OFDM parameters and OFDM symbol lengths depending on the robustness mode, and all DRM signal frame lengths are fixed (standardized) to 400ms, and frame synchronization and FAC ( Fast Access Channel) is decoded. Therefore, if the sampling rate is 48KHz, 1280 sampling data can be collected for 26,6667ms by dividing N frequency band signals into 15 units of 400ms, and the frequency and time of the input sample can be collected. Each signal can be inspected separately.

Therefore, in the DRM signal detection method using the sliding scan technique according to the present invention, the sliding sampling step can be performed at each reception time of the FAC (Fast Access Channel) data in which the DRM signal having a frame length of 400 ms is received every 400 ms. , the sampling time is set to 26.667 ms, and the sampling process is repeated 15 times.

_{The baseband signal of f n} collected during the sampling time (26.667ms) can be expressed as follows.

[Equation 1]

here,

is the signal of fn coming from the RF Tuner,

is the frequency offset of the signal in fn,

can be defined as the baseband signal of the signal of fn coming from the RF tuner.

In addition, the number N of the maximum frequencies that can be simultaneously sampled in the above-described sliding sampling step S10 may be calculated as follows.

[Equation 2]

here,

is the number of DRM signals that can physically fit into the bandwidth of the RF tuner,

can be defined as the time it takes to process the signal in fn.

In the data storage step S20 , the sampling data collected in the sliding sampling step S10 may be temporarily stored for each frequency band.

At this time, in the data storage step (S20), while the sliding sampling step is performed, the sampling data collected for each frequency band is sequentially signal-processed for each frequency size, and the intermediate result is temporarily stored in the memory provided in the DRM receiver. can be characterized.

Also, while the sliding sampling step is performed, a memory area allocated to a main service channel (MSC) including audio and data may be allocated as an area for storing the sampling data.

The DRM signal includes a Fast Access Channel (FAC) including synchronization information required by the receiver and information related to a transport channel, a channel encoding parameter of the MSC, and a Service Description Channel (SDC) including information on a multiplexing structure of audio and data signals. ), data such as a Main Service Channel (MSC) including audio and data, and the like, and the DRM receiver may allocate a memory area for decoding each data.

At this time, since the DRM receiver does not need to decode audio when searching for a broadcast channel, and only needs to decode FAC and SDC, a buffer memory for MSC decoding is not used.

In this case, the DRM receiver allocates the intermediate result information of 26.667ms signal processing to the memory area allocated for MSC decoding, so that the state and memory buffer of each slid signal utilizes the area for MSC without additional memory allocation. Memory usage can be kept to a minimum.

In the signal detecting step (S30), it is determined whether to detect a signal for each frequency band based on the sampling data for each frequency band temporarily stored in the data storage step.

Specifically, in the signal detection step, the signal processing result for each frequency band temporarily stored in the memory is characterized in that the parameter characteristic of the DRM signal is detected through auto-correlation.

Here, the signal processing block of fn is a block for searching for a signal and determining a robustness mode as shown in FIG. 3, which is a block that performs auto-correlation on a received signal and is configured as follows.

Then, the autocorrelation process is expressed as an equation as follows.

[Equation 3]

here,

is the guide interval length of OFDM symbol in mode M,

is the FFT length of the OFDM symbol in mode M.

4 is a diagram showing an example of a case in which a DRM signal is not detected in the signal detection process. When it is confirmed that a signal is not detected for 400 ms, the DRM receiver receives the FAC included in the next received DRM signal and then in the next signal. The DRM signal detection method using the sliding scan technique of can be re-performed.

FIG. 5 is a diagram illustrating a first example in which it is determined that a DRM signal is detected in a specific frequency band during a signal detection process. After the signal is detected primarily at fN, OFDM symbol synchronization and frame synchronization of DRM AM are performed.

In addition, when FAC CRC Error occurs by checking False Alarm of signal detection through FAC Decoding, it can be determined that there is a DRM AM signal at frequency fN as false. Finally, if it is determined that there is no DRM AM in the N signals, it is possible to prepare for the DRM AM signal inspection of the next N frequencies.

6 is a diagram illustrating a second example in which it is determined that a DRM signal is detected in a specific frequency band during the signal detection process. Similar to FIG. 5, after the signal is primarily detected at fn, OFDM symbol synchronization and frame of DRM AM proceed with motivation.

In this process, if there is no CRC error in FAC decoding, it is determined that there is a signal, and the SDC is decoded to configure a service list, and after configuring the service list, the next N frequency signals are prepared for inspection.

Therefore, when the DRM signal detection method using the sliding scan technique according to the present invention is used, a plurality of DRM signals collected through the RF tuner are simultaneously sampled, thereby dramatically reducing the time required for channel search of the DRM even when using one RF tuner. , and allocating memory not used in the process of temporarily storing the signal-processed sampling data as a memory area for temporarily storing the signal has the effect of improving data processing efficiency.

Although the above has been described with reference to the embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the following claims. will be able

[National R&D project supporting this invention]

[Project unique number] 20190017340011001

[task number] 2019001734

[Ministry Name] Small and Medium Business Development Team

[Name of task management (specialized) institution] Information and Communication Planning and Evaluation Institute

[Research project name] Technology development support for ICT innovative companies

[Research Project Title] (Phase 2: Technology Development) Driver-oriented DRM infotainment solution development for next-generation vehicles

[Contribution rate] 1/1

[Name of the organization performing the task] RF2Digital Co., Ltd.

[Research period] 2020.01.01 ~ 2020.12.31

According to the present invention, by simultaneously sampling a plurality of DRM signals collected through the RF tuner, even if a single RF tuner is used, the time required for channel search of the DRM can be drastically reduced, and in the process of temporarily storing the signal-processed sampling data, Data processing efficiency can be improved by allocating an unused memory as a memory area for temporary storage of a signal, so that it can be applied to a DRM (Digital Radio Mondiale) receiving apparatus.

On the other hand, it is apparent to those skilled in the art that various changes and modifications can be made in the present invention without departing from the spirit or scope of the present invention, and therefore, the present invention includes the changes and modifications of the present invention provided within the scope of the appended claims and their equivalents. it is intended to be

Claims (2)

1. A method for detecting a DRM signal using a sliding scan technique for searching a DRM broadcasting channel by scanning a plurality of DRM signals received for each frequency band in a single DRM (Digital Radio Mondiale) receiver, the method comprising:

   A sliding sampling step of collecting sampling data while sliding a plurality of DRM signals received for each frequency band along a time axis and a frequency axis;

   a data storage step of temporarily storing the sampling data collected in the sliding sampling step for each frequency band; and

   and a signal detection step of determining whether to detect a signal for each frequency band based on the sampling data for each frequency band temporarily stored in the data storage step.
2. According to claim 1,

   The sliding sampling step is

   During a sampling time set based on the frame length of the DRM signal, a plurality of DRM signals simultaneously received for each frequency band through the RF tuner of the DRM receiver are sequentially sampled according to the frequency size, and the sampling process is repeated N times. characterized in that sampling data is collected by

   The sampling time is set to 26.667 ms so that the sliding sampling step can be performed every time FAC (Fast Access Channel) data is received in which the DRM signal having a frame length of 400 ms is received every 400 ms, and the sampling process is 15 It is characterized in that it is performed repeatedly,

   The data storage step is

   While the sliding sampling step is performed, sampling data collected for each frequency band is sequentially signal-processed for each frequency size, and an intermediate result is temporarily stored in a memory provided in the DRM receiver,

   The temporary storage is characterized in that, while the sliding sampling step is performed, a memory area allocated to a main service channel (MSC) including audio and data is allocated as an area for storing the sampling data,

   The signal detection step is

   A method for detecting a DRM signal using a sliding scan technique, characterized in that the parameter characteristic of the DRM signal is detected through auto-correlation of the signal processing result for each frequency band temporarily stored in the memory.

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