JPH04103024U - RDS receiver - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to always set the optimum modulation detection level (threshold value) even for broadcast contents with different modulation levels, and to enable quick AF search in any noise situation.
Even in areas with strong electric fields, AF search operation is enabled when it becomes difficult to listen to broadcast content due to noise generation. [Configuration] Receives RDS data including an AF list, and uses the AF list to substitute based on the comparison result of the field strength level and modulation strength level obtained from the received data with a predetermined threshold value and the amount of noise level generated. When performing an AF search for a station, the modulation intensity level threshold can be varied and set based on the average modulation intensity level within a predetermined time, and the AF search interval time and electric field strength threshold can be varied and set according to the amount of detected noise. By doing so, it is possible to perform a quick and good AF search operation even in broadcast contents with different modulation levels, in any noise generation situation, and even in strong electric field areas.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention relates to RDS receivers, especially RDS receivers with improved AF search functions. Regarding machines.

0002

[Conventional technology]

The driver digitally multiplexes music selection and program identification data on the FM radio broadcast signal. RDS (Radio Data System), which provides various services to It has been put into practical use in Japan, and is expected to become popular not only in Europe but worldwide. Waiting. RDS radio waves transmitted from broadcasting stations are received by an in-vehicle tuner, for example, If the receiving station radio waves become weak due to a change in location while driving, the same program broadcast It has a search function that allows you to receive broadcasting station radio waves one after another.

0003 A typical RDS service identifies the country, receiving area, and program name of the broadcasting station. PI (Program Identification) service, the tuner display shows the name of the broadcasting station being received. The PS (receiving station name display) service displayed on The aforementioned AF (similar and same program broadcast frequency list) service that displays broadcast station frequencies There are TP services that identify stations that broadcast traffic information.

0004 With the one-tuner system in conventional RDS receivers, when performing an AF search operation, In some cases, a mute function is added, resulting in audio interruptions when searching. Therefore, In the conventional AF search operation, in order to improve the feeling of sound interruption, the received radio wave The modulation strength level of the signal is monitored and the modulation strength decreases (voice becomes quieter). An AF search operation is performed when the level falls below a predetermined level.

[0005] In addition, the above AF search is based on the received field strength level, multipath and adjacent interference noise. monitors the noise level of radio waves, etc., and when conditions are reached that require an alternative station search. The operation will start. At this time, in the conventional RDS receiver, when searching as above, In order to improve the sound cut-off feeling that occurs, the AF search operation is performed for a predetermined period of time (in It is carried out every period (terval time). Furthermore, the AF search operation is performed only when the received electric field strength by the antenna is below a predetermined level. The AF search function does not work under strong electric field strength.

[0006]

[Problem that the idea aims to solve]

As mentioned above, conventional RDS receivers monitor the modulation strength of the received signal. However, since it is based on a predetermined “constant” level (threshold), for example, modulation Depending on the broadcast content, such as low-level classical music and high-level pop music, In the case of program contents with significantly different modulation levels, appropriate changes must be made to satisfy both. It was difficult to set the tone level (threshold). In addition, conventional RDS receivers perform AF search at a fixed interval time. Even if noise such as multipath noise occurs frequently, the Since the AF search is performed based on time, there is a problem that a quick search cannot be performed. Ta. Furthermore, the AF search operation is performed only when the antenna reception strength is below a predetermined value. For example, in areas with strong electric fields, noise may occur due to adjacent interference, multipath, etc. AF search operation can be made possible even when the number of signals increases and it becomes difficult to hear. There is also the problem of not having one.

[0007] Therefore, the purpose of this invention was to always optimize broadcast content even if the modulation level is different. It is possible to set the modulation detection level (threshold value) and enable AF search without sound interruptions. The purpose of the present invention is to provide an RDS receiver. Another purpose of this invention is to vary the interval time at which the AF search function operates. RDS enables quick AF search in any noise situation. The purpose is to provide a receiver. A further purpose of this invention is to reduce broadcast content due to noise generation even in areas with strong electric fields. To provide an RDS receiver that enables AF search operation when listening becomes difficult. There is a particular thing.

[0008]

[Means to solve the problem]

In order to solve the above-mentioned problem, one aspect of the RDS receiver according to this invention is as follows. Receives RDS data including the AF list and calculates the field strength level obtained from the received data. The AF is performed based on the comparison result between the signal and modulation intensity level and a predetermined threshold value. In an RDS receiver that performs AF search for alternative stations using a list, The threshold value of the modulation intensity level is varied based on the average modulation intensity level within a predetermined time. It is configured so that. Further, other aspects of the RDS receiver according to this invention include: Receives RDS data including the AF list and calculates the field strength level obtained from the received data. AF an alternative station using the AF list based on the amount of bell and noise level generated. In the RDS receiver to search Detecting the amount of noise generation, and performing the AF search according to the detected amount of noise generation. It is configured so that the interval time for performing this can be varied and set. Still other aspects of the RDS receiver according to this invention include: Receives RDS data including the AF list and calculates the field strength level obtained from the received data. Based on the comparison result between the noise level and the predetermined threshold value and the amount of noise level generated, In an RDS receiver that performs an AF search for alternative stations using an F list, The amount of noise generated is detected, and the electric field strength is adjusted according to the detected amount of noise generated. The threshold value is configured to be variable.

[0009]

[Effect]

In this invention, RDS data including the AF list is received, and the data obtained from the received data is Compare the electric field strength level and modulation strength level with predetermined threshold values and When performing an AF search for an alternative station using the AF list based on the amount of noise level occurrence. , and also detect a modulation intensity level threshold based on the average modulation intensity level within a predetermined time. AF search interval time and electric field strength depending on the amount of noise generated. By variable and setting the threshold value, even broadcast contents with different modulation levels can be adjusted. , fast and good AF in any noise situation, even in areas with strong electric fields. It enables search operations.

0010

【Example】

Next, an embodiment of this invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the RDS receiver according to this invention. . The received signal (FM RF signal) received via the antenna ANT is When the IF signal is obtained and output by the mixing circuit built in end circuit (F/E) 1, In both cases, the front end 1 controls the operation of a low-pass filter (LPF) 7 and a PLL circuit 8. In collaboration with the company, we have created a well-known digital tuning system. front end An OSC signal that specifies the oscillation frequency of PLL circuit 8 is sent from circuit 1 to PLL circuit 8. A signal Vt is supplied from the LPF 7 to the front end circuit 1. The IF/DET circuit 2 amplifies the IF signal from the front end circuit 1 and It detects the data level signal and outputs it to the CPU 9, and also FM demodulates the IF signal. A composite signal is sent to the NC/MPX circuit 3. The NC/MPX circuit 3 is a pulse noise generator that cancels pulse noise from the IF signal. In addition to having an noise cancellation function, it also performs FM demodulation and provides the demodulated signal to the VOL circuit 4. supply.

[0011] The VOL circuit 4 is a circuit that also adjusts the volume of the demodulated signal, and the volume-adjusted signal is The signal is sent to a mute (MUTE) circuit 5, and a mute function is performed. The amplifier 6 amplifies the signal from the mute circuit 5 and reproduces audio from the speaker SP. is generated and output. The modulation intensity level detection circuit 10 receives a composite signal from the IF/DET circuit 2. The modulation intensity level is detected from and sent to the CPU 9. The noise detection circuit 11 converts the composite signal from the IF/DET circuit 2 into a high frequency The noise component of the composite signal is removed by passing it through a waveband filter (HPF). It is detected and output to the CPU 9. The RDS demodulation circuit 12 demodulates the RDS signal from the composite signal and synchronizes it. It is sent to the microcomputer 13.

0012 The synchronization microcomputer 13 performs synchronization processing on the received RDS data and also synchronizes the received RDS data. performs data error correction processing and outputs the data to the CPU 9. The CPU9 has a built-in RAM for storing various data, and has a built-in RAM for digital tuning. For this purpose, the so-called N value is sent to the PLL circuit 8, and the S meter level data, modulation intensity level data from the modulation intensity level detection circuit 10 After receiving the noise data from the noise detection circuit 11 and the noise detection circuit 11, perform a divine action.

[0013] FIG. 2 is a flowchart showing the processing procedure of the AF search operation in this invention. It is shown. First, after setting the timer (step S201), the detected S meter level It is determined whether or not the value Va is smaller than a predetermined threshold value Va (step S202); If it is not smaller, the process returns to step S201, and if it is smaller, the reception quality is poor. In step S203, the modulation intensity from the modulation intensity level detection circuit 10 is determined. Check the level and check the modulation intensity level N times in step S204? If it is repeated N times, calculate the average value Vx and use it for modulation level detection. is set as a threshold value (step S205).

[0014] Next, in step S206, the modulation intensity level currently being received is set to a threshold value Vx If the value is larger than Vx, the process returns to step S201, and if the value is smaller than Vx, the process returns to step S201. If so, compare the S meter level with Va (step S207), and if it is greater than Va. If so, the process returns to step S201. If it is determined in step S207 that the S meter level is smaller than Va, the AF In step S208, muting is applied to eliminate noise during AF search. prevent the occurrence of noise. Next, read the AF list, change the N value of PLL circuit 8, and receive the alternative station. (Step S209), and after waiting for PLL stabilization time in Step S210 (PLL (L lock weight) and check the S meter level of the alternative station (step S21). 1). In step S211, the S meter level of the alternative station is Vb (Vb≧Va). If it is larger than that, the mute operation is canceled (step S212) and the audio is output. Also, if it is smaller than Vb, it is determined that the reception quality is poor, and the original N value is read and set. (step S213), after PLL lock wait (after PLL stabilization), mute The broadcast station is canceled (step 212), and the audio from the original broadcast station is output. From then on, Returning to step S201, the same operation is repeated.

[0015] FIG. 3 shows a flowchart of the operation processing procedure in another embodiment of this invention. has been done. The CPU 9 receives noise data from the noise detection circuit 11, and The noise generation amount ND within a certain period of time is checked based on the noise data (step S3). 01), if ND is smaller than a predetermined threshold VN, a predetermined AF search interface is selected. Set the interval time "Ta" (step S302), and if it is large, set another AF interface. The interval time "Tb" (Ta>Tb) is set (step S303). Next, the timer elapses for the time set in step S302 or S303. It is determined whether the time has passed (step S304), and when it is determined that the time has passed, The S meter level is compared with a predetermined threshold value Va (step S305), and the S meter level is compared with a predetermined threshold value Va (step S305). If it is larger, the process returns to step S301; if it is smaller, the process returns to step S306. to move to. In step S306, the timing at which noise occurs is waited for, and the timing , the mute operation is turned on (step S307), and the timing If not, the process returns to step S305.

[0016] After mute operation is “ON”, read the AF list and change to the corresponding N value A. Performs F search operation (step S308) and stabilizes PLL with PLL lock weight. Wait for a time (step S309). Also, after the PLL has stabilized, the S meter of the alternative station Compare the level with a predetermined threshold Vb (here Va<Vb), and if it is greater than Vb, After turning off the mute operation (step S312), the process returns to the process. On the other hand, when it is determined in step S310 that it is not larger than Vb, , determines that the reception condition of the alternative station is poor, sets the original N value (original broadcasting station), and After the lock wait (step S311), the mute is turned off (step S311). S312), the process returns to step S301.

[0017] Still another embodiment of this invention will be explained with reference to the flowchart shown in FIG. Ru. Receives noise data from the noise detection circuit 11 and calculates the amount of noise ND within a certain period of time. It is compared with a predetermined threshold value VN (step S401), and if it is smaller than VN, S It is determined whether the data level is smaller than a predetermined threshold value Va (step S402), and If not, the process returns to step S401, and if it is large, AF search should be performed. Therefore, wait for the next timing when noise occurs (step S403), and turn on the mute. The boot operation is turned on (step S404). Also, in step S401, a constant When the amount of noise ND within the time is larger than VN, AF search should be performed, so the The process moves to step S403. Then, in step S405, the AF list is read and the read AF Change and set the N value according to the list, and perform the process of receiving an alternative station (AF search). cormorant. After that, the PLL lock waits (step S406), and the S meter level is set to the desired value. It is compared with fixed threshold values Vb and Vc (step S407). Here, Vc>Vb>Va It is said that In step S407, if the noise amount ND is greater than VN, When the judgment is made, the S meter level is compared with the threshold value Vc, and when it is smaller than VN is compared with a threshold value Vb.

[0018] As a result of the comparison in step S407, the S meter level is greater than Vb or Vc. If there is no signal, the original N value is set and the PLL is unsuitable as an alternative station. PLL lock wait is performed until stabilization occurs (step S408). In step S407, if the S meter level is greater than Vb or Vc, or the PLL lock wait is performed in the process of step S408 (AF search completion), turn the mute operation “OFF” (step S409), and proceed to step S409. The process returns to step 401.

[0019]

[Effect of the idea]

As explained above, the RDS receiver according to this invention can checking the average modulation level of the received signal and making changes to adapt to the changed level. Since the tonal strength detection level is set, it is suitable for source content such as classical music and pop music. Optimal modulation detection is always possible regardless of the situation, and the feeling of sound interruption during AF search is greatly reduced. Improved. In addition, this device monitors the amount of noise generated and detects when the amount of noise generated is low. sets the AF search interval to a long time to reduce the feeling of sound interruptions caused by AF search. , when there is a large amount of noise, set the AF search interval to a short time for quick search. Since it allows for automatic tracking, there is less noise and the feeling of sound being cut off is also improved. Furthermore, with this invention, AF search is possible even under strong electric fields depending on the amount of noise generated. This makes it possible to perform an AF search that always provides good reception conditions.

[Brief explanation of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of an RDS receiver according to the invention.

FIG. 2 is a flowchart showing operations and processing procedures in an embodiment of the RDS receiver according to the invention.

FIG. 3 is a flowchart showing operations and processing procedures in an embodiment of the RDS receiver according to the invention.

FIG. 4 is a flowchart showing operations and processing procedures in an embodiment of the RDS receiver according to the invention.

[Explanation of symbols]

1 Front end 2 IF/DET circuit 3 NC/MPX circuit 4 Volume circuit 5 Mute circuit 6 Amplifier 7 Low pass filter 8 PLL circuit 9 CPU 10 Modulation intensity level detection circuit 11 Noise detection circuit 12 RDS demodulation circuit 13 Synchronous microcomputer

Claims (3)

[Scope of utility model registration request] Claim 1: Receive RDS data including an AF list;
In an RDS receiver that performs an AF search for an alternative station using the AF list based on a comparison result between a field strength level and a modulation strength level obtained from received data and a predetermined threshold value, a threshold value for the modulation strength level is predetermined. An RDS receiver characterized in that the RDS receiver is variable based on the average modulation intensity level in time. Claim 2: Receive RDS data including an AF list;
The amount of noise generated is detected in an RDS receiver that performs an AF search for an alternative station using the AF list based on the electric field strength level and the amount of generated noise level obtained from received data, and the amount of generated noise is detected according to the detected amount of generated noise. An RDS receiver characterized in that an interval time for performing an AF search can be varied and set. Claim 3: Receive RDS data including an AF list;
In an RDS receiver that performs an AF search for an alternative station using the AF list based on a comparison result between a field strength level obtained from received data and a predetermined threshold value and an amount of generated noise level, detecting the amount of generated noise; An RDS receiver characterized in that the threshold value of the electric field strength is made variable according to the detected amount of noise generation.