JPH0516733Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] This invention relates to an improvement of a radio receiver that can automatically sweep the receiving frequency, and is particularly useful for traffic information, roadside band broadcasting, and identification of emergency broadcasts, etc. The present invention relates to a radio receiving device that can reliably capture and receive broadcasts even when the field strength of the broadcast radio waves is extremely low.

[Prior Art] There is a radio receiver shown in FIG. 5 that sweeps the reception frequency by sequentially changing the local oscillation frequency to capture and receive broadcast waves.

In FIG. 5, 1 is an antenna, 2 is an RF amplifier that receives an RF signal from the antenna and amplifies it, and 3 is a mixer.
The mixer 3 receives a local signal from a local oscillator circuit 4 including a PLL and converts the RF reception signal into an intermediate frequency (IF) signal. The IF signal from the mixer 3 is amplified by an IF amplifier 5, and then demodulated by a detector circuit 6 and converted into audio (AF signal).
The AF signal is supplied to, for example, a speaker 8 via an AF amplification and mute circuit 7 .

A field strength detection circuit 9 for detecting the received field strength is connected to the IF amplifier 5.
For example, the level of the IF signal is subjected to AM detection, and the presence or absence of a receiving station and its electric field strength are detected based on the AM detection output. Reference numeral 10 denotes a reference value generation circuit that generates a sweep stop reference value, which generates, for example, three levels of reference value S=H, M, and L based on commands from the controller 11 [where H: strong (local station ), M: medium electric field station, L: weak input (DX) station], and the magnitude of the detected electric field strength with respect to this reference value S is compared in the electric field strength detector 9. Based on this comparison result, a muting control signal is generated for the AF amplification and muting circuit 7, and a sweep command signal is generated for the controller 11.

An operating section 12 is further connected to the controller 11, and from this operating section 12, a sweep command or the above-mentioned sweep stop reference value is set.

FIG. 6 is a flowchart illustrating the operation of the conventional radio receiver shown in FIG. If it was done,
A signal S=H is sent from the controller 11 to the reference value generating circuit 10, and S is read (step 1). and controller 11
From there, predetermined frequency division ratio data is sequentially sent to the PLL of the local oscillation circuit 4, and a reception channel is set (step 2). The detection value generated in the field strength detection circuit 9 of the receiver is compared with the output value S from the reference value generation circuit 10, and if the detection value is larger than the output value S, it is determined that "a station is present" (step 3). Then, from the detection circuit 9, the controller 1
1 to temporarily stop the sweep, and further issues a command to the AF amplification and muting circuit 7 to cancel muting (step 4).

The controller 11 maintains this state for 10 seconds and then operates to send the next frequency division ratio data to the PLL (step 5).

In the above-mentioned conventional radio receiver, for example, when a broadcast wave as shown in FIG. For example, when trying to receive traffic information or roadside broadcasts using a car radio, the selection must be made based on the standard value according to the electric field strength, just as with general broadcasts. .

That is, if S=H is set, only stations A and D can be selected in FIG. 4, and station B or roadside broadcasting station F, which broadcasts traffic information, cannot be received. Furthermore, if the reference value S is set to S=L in order to receive these, almost all broadcast stations including weak electric fields will be received, which is inconvenient as it takes a considerable amount of time to select the desired broadcast for reception. There is.

[Purpose] This invention was made to eliminate the drawbacks of the conventional ones mentioned above, and is a radio receiver that can receive specific broadcasting stations such as traffic information or roadside broadcasting with priority. This is what we are trying to provide.

[Summary of the idea]

In order to achieve the above object, this invention is equipped with means for lowering the sweep stop reference value when a broadcast frequency of a particular broadcasting station or a particular signal multiplexed on broadcast radio waves is detected. The feature is that the broadcast radio waves given priority can be received.

〔Example〕

In Japan, the traffic information or roadside broadcasting mentioned above is 522KHz, Ministry of Construction Roadside Broadcasting, 1620KHz and
Roadside broadcasts by the Japan Highway Public Corporation and the National Police Agency are broadcast on 1629KHz.

Also, mainly in Europe, in the FM band.
A radio data system (RDS) that multiplexes broadcast content data using 75KHz, which is the third high frequency of the 19KHz stereo pilot signal, as a subcarrier.
Something called ARI is also in operation.

In the present invention, it is possible to preferentially receive the above-mentioned roadside broadcasting whose broadcast frequency is determined in advance, and the above-mentioned RDS or ARI broadcasting in which specific signals are multiplexed. I will explain.

FIG. 1 shows a first embodiment of the present invention, in which specific broadcasts such as roadside broadcasts whose broadcast frequencies are predetermined can be received preferentially.

That is, in the drawings, the same reference numerals as those in FIG. 5 indicate the same or corresponding parts, and therefore, explanations of the structure and operation of the parts will be omitted.

In FIG. 1, a ROM 13 is provided which stores frequency division ratio data for the PLL corresponding to the frequency of the specific broadcasting station mentioned above.
3 inputs the frequency division rate data sent from the controller 11 to the PLL in the local oscillator circuit 4, and determines whether the value of this frequency division rate is a frequency division rate corresponding to the broadcast frequency of a specific broadcasting station. It is designed to compare. If the comparison results match, a match signal is sent to the reference value generation circuit 10, and even if the reference value S is set to S=H, it is forcibly shifted to S=L. There is.

FIG. 3 is a flowchart for explaining the operation. When a sweep start command is issued from the operation unit 12, the controller 11 sends predetermined frequency division ratio data to the PLL of the local oscillation circuit 4. Setting the sending and receiving channels (step by step)
10) will be carried out. At this time, the frequency division ratio data sent from the controller 11 is also applied to the ROM 13, where a comparison is made to see whether the frequency division ratio value corresponds to the frequency of a specific broadcasting station (step 11). Do this.

As a result of this comparison, if it does not correspond to a specific broadcast frequency, the sweep stop reference value S, for example S=H, given from the controller 11 is set to the reference value generation circuit 1.
0 (step 12), the detected value generated in the electric field strength detection circuit 9 and the output reference value S from the reference value generation circuit 10 are compared (step 13).

Here, when a specific station is detected in step 11, a comparison match signal with the ROM 13 is applied to the reference value generation circuit 10, and the reference value S is forcibly set to S=
Set to L (step 14).

Therefore, even if the reference value S is set to S=H in advance, broadcasting station B in FIG. 4 is received, and in this state, the detection circuit 9 issues a command to the controller 11 to temporarily stop the sweep. At the same time, an instruction is issued to the AF amplification and muting circuit 7 to cancel muting (step 15).

The controller 11 starts timing from this point, and after 10 seconds has elapsed, operates to send the next frequency division ratio data to the local oscillation circuit 4 (step 16).

FIG. 2 shows a second embodiment of this invention, in which the 57KHz subcarrier is modulated by code data indicating broadcast content, and the RDS or FM signal is multiplexed with the audio signal. indicates that ARI broadcasts can be received with priority.

Also in FIG. 2, the same reference numerals as those in FIG. 5 indicate the same or corresponding parts, and therefore the explanation of the structure and operation of the parts will be omitted.

In FIG. 2, a bandpass filter 14 is connected to the output end of the detection circuit 6, which passes only the 57KHz subcarrier that is multiplexed with the specific broadcast wave and sent out. is connected to a decoder 15 that demodulates the subcarriers provided by the filter, and the decoder 15 demodulates code data for identifying broadcast content and the like. If the decoder 15 is able to identify the broadcast radio wave as having specific code data, it sends an output to the reference value generation circuit 10, even if the reference value is set to S=H. However, this is forcibly shifted to S=L.

In the case of this second embodiment, in step 11 of the flowchart shown in FIG. 3, a determination is made as to "Is it a specific code?"
When it is determined that the code is a “specific code”, the reference value S=L in the reference value generation circuit 10 (step 14)
, and other effects are the first
This is the same as in the embodiment.

〔effect〕

As is clear from the above explanation, the radio receiver of this invention increases the acquisition and reception sensitivity during sweeping for broadcasts having a specific broadcast frequency or multiplexing a specific identification signal. Therefore, regardless of the user's setting of the sweep acquisition sensitivity, it is possible to reliably receive traffic information or roadside broadcasts, for example.

[Brief explanation of the drawing]

Figures 1 and 2 are block diagrams showing the first and second embodiments of this invention, Figure 3 is a flowchart for explaining its operation, and Figure 4 shows the arrangement of broadcast waves. FIG. 5 is a block diagram showing an example of a conventional system, and FIG. 6 is a flowchart for explaining its operation. 1... Antenna, 2... RF amplifier, 3... Mixer, 4... Local oscillation circuit, 5... IF amplifier,
6...Detection circuit, 7...AF amplification and mute circuit, 8...Speaker, 9...Field strength detection circuit, 10...Reference value generation circuit, 11...Controller, 12...Operation unit, 13... ROM, 14...
...Band pass filter, 15...Decoder.

Claims (1)

[Scope of claim for utility model registration] In a radio receiver that captures and receives broadcast radio waves by sweeping the reception frequency by sequentially changing the local oscillation frequency, a reception electric field that detects the reception field strength of the received broadcast radio waves. a sweep stop means that compares the detection output from the received electric field strength detection means with a preset sweep stop reference value, and stops the sweep operation when the detection output is equal to or higher than the reference value; and means for lowering the sweep stop reference value when a predetermined specific receiving frequency or a specific signal multiplexed to the received broadcast radio waves is detected, thereby increasing the capture and reception sensitivity for the specific broadcast radio waves. A radio receiving device characterized in that: