JP2577835Y2 - Radio 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 radio receiver having a so-called auto search function for receiving a broadcast from a broadcasting station capable of automatically receiving a signal by sweeping a reception frequency.

[0002]

2. Description of the Related Art The auto search function sweeps a reception frequency in response to, for example, an operation of an auto search button by a listener, and automatically detects a receivable broadcasting station having a reception electric field strength of a predetermined level or more. This is the function to perform reception.
Such an auto search function is preferably implemented in an on-vehicle radio receiver mounted on an automobile, for example, while a listener is traveling outside of a normal living area, a preset broadcast that can be received within the living area. It is suitably used when searching for a receivable broadcasting station different from a station in the area.

[0003] In realizing the above-described auto search function, in a typical conventional technique, two reception modes for setting the predetermined level are switchable. The first reception mode is called, for example, a local mode, and is used in an area having a relatively high reception electric field strength such as an urban area, and the sweep operation is stopped for a broadcast from a distant place where the reception electric field strength is relatively low. In order to prevent this, the predetermined level is set relatively high. On the other hand, the second reception mode is called a DX mode,
The predetermined level is set relatively low so that radio broadcasting can be received even in an area having relatively poor reception conditions such as a mountain area. Thus, by switching the reception mode, that is, by switching the predetermined level,
It is configured to perform an optimum sweep operation.

[0004]

In the above-mentioned prior art,
In the area where the DX mode is optimal in the daytime, when the reception conditions are improved at night and the broadcast of a distant broadcast station can be received, the sweep operation stops erroneously even outside the service area of the broadcast station. Would. Therefore, it is necessary to switch the reception mode between daytime and nighttime, and the operation becomes complicated.

An object of the present invention is to provide a radio receiver capable of appropriately maintaining the reception frequency sweep sensitivity and improving operability.

[0006]

According to the present invention, a receiving frequency is swept in response to a channel selection operation of a listener, and a first station for receiving a broadcast from a broadcasting station having a received electric field strength equal to or higher than a predetermined first level is received. The receiving means and the receiving frequency in the receiving frequency band of the first receiving means are constantly or periodically swept, and the number of receivable broadcast stations whose received electric field strength is equal to or higher than a predetermined second level is detected. A radio receiver comprising: a second receiving unit; and a level setting unit that sets the first level in the first receiving unit in response to a detection result of the second receiving unit.

[0007]

According to the present invention, the first receiving means sweeps the reception frequency in response to the listener's channel selection operation such as the operation of the auto search button, and the reception electric field intensity is higher than the predetermined first level. Receives broadcasts from broadcasting stations. As a result, when it is used in a vehicle, it can be suitably used for receiving a broadcast station whose reception frequency is not preset outside the normal range of the listener.

[0008] A second receiving means is provided in association with the first receiving means, and the second receiving means always or in a predetermined short time within a receiving frequency band of the first receiving means. The reception frequency is swept, and the number of receivable broadcast stations whose reception electric field strength is equal to or higher than a predetermined second level is detected. Therefore, from this detection result, it can be determined whether the receiving location is a location where the number of receivable broadcasting stations is relatively large, such as an urban area, or a location where the number of receivable broadcasting stations is small, such as a mountain area. . Also, the second receiving means always or every predetermined time sweeps the receiving frequency band to set the optimal receiving level at the time of auto tuning of the first receiving means. Therefore, when the auto tuning operation is performed, The first receiving means can immediately start the auto tuning operation at the optimum receiving level.

The detection result of the second receiving means is given to a level setting means, and the level setting means responds to the detection result, that is, in response to, for example, an urban area or a mountain area. , A first level in the first receiving means is set. Therefore, the optimum sweep sensitivity corresponding to the reception conditions can be set automatically,
Particularly, even in a place where the first level is set relatively low in the daytime, when the reception conditions are improved at night and the number of receivable broadcast stations increases, the first level is automatically set. By setting it high, it is possible to prevent erroneous stop of the sweep operation for a distant broadcast station. This allows the first
The setting operation of the level is unnecessary, and the operability can be improved.

[0010]

1 shows a radio receiver 1 according to an embodiment of the present invention.
FIG. 2 is a block diagram showing an electrical configuration of the embodiment. In the radio receiver 1, two receiving circuits 2 and 3 are provided. The reception signal received by the antenna 4 is input to the detection circuit 6 via the front end circuit 5 in the first reception circuit 2, and is demodulated into an audio signal. The audio signal is provided to a speaker 8 via a low-frequency amplifier circuit 7 and is converted into an acoustic signal.

In connection with the front end circuit 5, S
A meter detection circuit 9 is provided. The S-meter detection circuit 9 receives the intermediate frequency output from the front end circuit 5, performs DC detection on the intermediate frequency output, and outputs the detected intermediate frequency output as a detection output representing the received electric field intensity. It is realized by a microcomputer or the like, and outputs to a processing circuit 11 which is a level setting means. The processing circuit 11 determines, based on the S-meter output,
In order to perform a channel selection operation as described later, data such as an N value is output to a phase lock loop (hereinafter abbreviated as PLL) circuit 10.

In connection with the processing circuit 11, a memory 12
, An operation switch 13, and a display device 14. In the memory 12, a reception frequency and the like preset by an input operation from the operation switch 13 are stored. The processing circuit 11 causes the front end circuit 5 to perform a tuning operation based on the contents stored in the memory 12 and the like in response to a tuning operation from the operation switch 13, and causes the display device 14 to perform a reception frequency and the like. Is displayed.

On the other hand, the second receiving circuit 3 is provided with a front-end circuit 15, an S-meter detecting circuit 16, and a PLL circuit 17 similar to the first receiving circuit 2. The processing circuit 11 always changes the N value of the PLL circuit 17,
Within the reception frequency band of the first reception circuit 2, the tuning frequency of the front end circuit 15 is swept, and the reception electric field strength at each frequency is read via the S-meter detection circuit 16, and the reception electric field strength is read in accordance with the read detection result. , The receiving mode of the first receiving circuit 2 is switched as described later.

That is, the processing circuit 11 includes the operation switch 1
3, the N value of the reception frequency corresponding to the operated preset switch 13a is read out from the memory 12, and the PLL circuit 10
Set to. As a result, the tuning frequency of the front end circuit 5 becomes a value corresponding to the preset frequency, and the reception is performed.

When the auto search switch 13b is operated, the N value of the PLL circuit 10 is sequentially changed, and the tuning frequency of the front end circuit 5 is swept. When the sweep operation detects that the received electric field intensity detected via the S-meter detection circuit 9 has become equal to or higher than a predetermined first level, the sweep operation is stopped,
The reception at that frequency is performed.

The first level is set to be relatively high in the local mode used in an area such as an urban area where a large number of broadcasting stations having relatively high reception electric field strength can be received, corresponding to the reception mode, DX which is preferably used in an area where the received electric field strength is weak, such as a mountain area.
In the mode, it is set to a relatively low value. Such switching of the reception mode is performed as follows. By operating the cancel switch 13c of the operation switch 13, it is possible to hold the selected state in either the local mode or the DX mode.

In the second receiving circuit 3, the processing circuit 11 performs a sweeping operation by changing the N value of the PLL circuit 17, whereby the received electric field strength detected by the S-meter detecting circuit 16 becomes equal to the predetermined second electric field intensity. Compared to the level. The second
Is selected to be the same or smaller than the level in the DX mode of the first level, for example. By such a sweeping operation, the number of broadcasting stations having the reception electric field strength equal to or higher than the second level is a predetermined value M,
For example, the receiving mode of the first receiving circuit 2 is switched according to whether or not the number is 20 or more. That is, the local mode is set when the number of broadcasting stations is equal to or more than the value M, and the DX mode is set when the number is less than the value M.

However, the switching of the reception mode as described above is performed when the auto search switch 13b is operated, and even if it is determined that the reception mode should be switched, the receiving broadcast station is switched off without the operation of the listener. It will not be replaced. Therefore, there is no possibility that the mode is switched to the local mode during the reception in the DX mode, and the broadcast that has been received until then is not received.

FIG. 2 is a flowchart for explaining the above-described reception mode setting operation. Step n1
Then, it is determined whether or not the cancel switch 13c has been operated, that is, whether or not the automatic switching function of the reception mode has been selected. If not, the process proceeds to step n10 described later, and if so, the process proceeds to step n10.
Move to 2. In step n2, it is determined whether or not the operation of counting the number of broadcast stations by the second receiving circuit 3 has been completed, that is, the first
It is determined whether the sweep operation of the entire receiving frequency band of the receiving circuit 2 has been completed, and if not, the process proceeds to step n3. In step n3, the N value of the PLL circuit 17 is updated, and in step n4, it is determined whether the received electric field strength at the updated N value is equal to or higher than the second level, and if so, in step n5. After the number of stations has been counted, the process proceeds to step n10. Otherwise, the process directly proceeds to step n10.

Steps n3 to n5 as described above are repeated. When the sweep operation of the second receiving circuit 3 has been completed in step n2, the process proceeds to step n6, where the number of broadcasting stations counted in step n5 is calculated as It is determined whether or not the value is equal to or greater than a predetermined value M. If so, at step n7, the reception mode is selected to the local mode, and then the process proceeds to step n10. If not, the DX mode is selected at step n8. After that, the routine goes to Step n10. In step n10, after receiving an input operation from the preset switch 13a and performing other processing such as display control, the process returns to step n1.

As described above, in the radio receiver 1 according to the present invention, the number of broadcast stations that can be received within the reception frequency band of the first reception circuit 2 is determined separately from the first reception circuit 2 that receives the radio broadcast. A second receiving circuit for detection is provided, and the receiving mode of the first receiving circuit is switched between a local mode and a DX mode based on the detection result. Therefore, even in an area where the reception is performed in the DX mode in the daytime, when the reception conditions are improved at night and the reception in the local mode is more preferable, the reception mode is automatically switched. The erroneous stop of the sweep operation can be prevented without any operation, and the operability can be improved.

In a radio receiver of the so-called RDS system practically used in Europe and the like, the frequency of a net station broadcasting the same contents is read from the data transmitted together with the audio signal, and the current reception is performed. With the broadcasting station inside,
Another receiving circuit is provided separately from a receiving circuit for demodulating an audio signal to track a network station so as to receive a broadcast from a broadcasting station having a higher receiving electric field strength with the network station. Therefore, this receiving circuit is the second one of the present invention.
It may be used as the receiving circuit 3.

[0023]

As described above, according to the present invention, the first receiving means for automatically receiving a broadcast from a receivable broadcast station having a received electric field strength of at least a predetermined first level by sweeping the receiving frequency. In relation to the above, the reception frequency is swept within the reception frequency band of the first reception means, and the reception electric field strength is set to a predetermined second frequency.
Of the number of receivable stations above the level
Receiving means is provided, and the first level is set in response to the detection result.

Therefore, when the number of broadcast stations is large, the first level is set relatively high, so that a so-called local broadcast station can be clearly received. Also,
When the number of the broadcast stations is small, it is possible to receive even a distant broadcast station having a relatively low received electric field strength. In this way, it is possible to switch the sweep sensitivity of the first receiving means and perform an optimum sweep operation corresponding to the receiving conditions. As a result, even in a place where the number of broadcast stations that can be received during the day is small, even if the reception conditions are improved at night and the number of receivable broadcast stations is increased, the sweep operation is erroneously stopped at a broadcast station with poor reception conditions. Can be prevented. Thus, the optimum sweep sensitivity corresponding to the reception condition can be set without complicated operation. In particular, according to the present invention, the first
While the broadcast is being received by the receiving means, the second receiving means always or every predetermined time sweeps the receiving frequency band to set the optimum receiving level at the time of auto tuning of the first receiving means. Is performed, the first receiving means can immediately start the auto tuning operation at the optimum receiving level.

[Brief description of the drawings]

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

FIG. 2 is a flowchart for explaining a reception mode setting operation of the radio receiver 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Radio receiver 2 1st reception circuit 3 2nd reception circuit 5, 15 Front end circuit 6 Detection circuit 8 Speaker 9, 16 S meter detection circuit 10, 17 PLL circuit 11 Processing circuit 13 Operation switch 13a Preset switch 13b Auto search switch 13c Cancel switch

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H03J 7/18-7/30

Claims (1)

(57) [Scope of request for utility model registration] 1. A first receiving means for sweeping a reception frequency in response to a channel selection operation of a listener and receiving a broadcast from a broadcast station having a reception electric field strength equal to or higher than a predetermined first level; A second receiving unit that sweeps the receiving frequency within the receiving frequency band of the unit at all times or every predetermined time, and detects the number of receivable broadcasting stations whose received electric field strength is equal to or higher than a predetermined second level; (2) a level setting means for setting the first level in the first receiving means in response to a detection result of the receiving means.