JPH0426267A - Facsimile broadcasting receiver - Google Patents

Abstract

PURPOSE:To confirm the receiving state of an antenna even when a facsimile broadcasting is not performed by detecting the noise level of a facsimile channel signal band during a voice detector output and deciding the receiving state according to the volume of the noise level. CONSTITUTION:When confirming the receiving state of a set antenna 1 at the time of performing a TV broadcasting and not performing the facsimile broadcasting, a received TV broadcasting radio wave selects a required channel in a tuner part 2, obtaining the voice detector output. Next, the noise in the facsimile channel signal band is separated from the voice detector output obtained by the tuner part 2 in a band pass filter 3. The separated noise is amplified in a noise level detection part 7, and the noise level is compared with a standard level set in advance to decide and display whether the receiving state is satisfactory or not according to the volume of the noise level in a receiving state decision part 8. Thus, the receiving state of the antenna can be simply confirmed even when the facsimile broadcasting is not performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a facsimile channel using a second subcarrier in the audio frequency band of television broadcast waves, multiplexes the facsimile signal with the audio signal, and transmits the multiplexed signal. The present invention relates to a facsimile broadcast receiving device that receives facsimile broadcasts.

[Conventional technology] A facsimile broadcasting method was developed in February 1989 in which a facsimile channel using a second subcarrier is provided in the audio frequency band of television broadcast waves, and the facsimile signal is multiplexed and transmitted on the audio signal. A report was submitted by the Communications Technology Council.

Part of its specifications are shown in Figures 2 and 3.

FIG. 2 is a diagram showing the configuration of a facsimile signal for one page, and FIG. 3 is a spectrum diagram illustrating how the facsimile signal is frequency-multiplexed with the audio signal.

The facsimile signal shown in FIG. 2 is composed of a control signal and an image signal. The network signal 21 in the control signal is
This is a signal for transmitting operational data between broadcast stations.

Furthermore, the program selection signal 22 in the control signal is a signal for transmitting control information regarding program selection on the receiving device side.

The page or program end signal 24 is a signal indicating to the receiving device the end of the image signal 23 for one page, and also contains information regarding the presence or absence of the next page. The image signal 23 is an image data signal for one page.

Next, a spectrum diagram of an audio signal system in which facsimile signals are frequency-multiplexed shown in FIG. 3 will be explained.

Facsimile signals are transmitted by providing a data channel using a second subcarrier (also called facsimile IJ signal subcarrier) of 70.8 kHz (4.5 fs, fH is the horizontal synchronization signal frequency) outside the band of the television audio signal. It is transmitted using four-phase differential phase modulation at a speed of 16 Kbps.

As a facsimile broadcast receiving apparatus based on such specifications, FIG. 4 shows an example of the configuration of a conventional facsimile broadcast receiving apparatus shown in Telecommunications Technology Council Report Consultation No. 15 "Technical Conditions for Facsimile Broadcasting". This is what is shown.

In FIG. 4, 1 is an antenna that receives television broadcast waves, 2 is a tuner section that receives a desired channel from the radio waves received by the antenna 1, and obtains an audio detection output;
4 is a bandpass filter that separates the facsimile channel signal from the audio detection output from the tuner section 2; 4 is a demodulation section that demodulates the facsimile channel signal separated by the bandpass filter 3 to obtain a facsimile signal; and 5 is the demodulation section 4; A signal processing section 6 separates a control signal and an image signal from the obtained facsimile signal and decodes the image signal, and a printing section 6 prints the image data signal obtained by the signal processing section 5 onto recording paper.

The operation of the conventional example shown in FIG. 4 will be explained below. A tuner section 2 selects a desired channel of the television broadcast waves received by the antenna 1 and obtains an audio detection output.

Next, the bandpass filter 3 separates the facsimile channel signal from the voice detection output and sends it to the demodulator 4-1.

The demodulator 4 demodulates the four-phase differential phase modulated facsimile channel signal to obtain a facsimile signal and sends it to the next signal processor 5.

The signal processing section 5 separates a control signal and an image signal from the facsimile machine, and decodes the image signal.

Control information obtained from the control signal is used to control each part of this receiving device.

In the printing section 6, the printing mechanism is controlled by the control information, and the data of the image signal obtained by the signal processing section 5 is printed onto recording paper.

[Problem to be solved by the invention]

Conventional facsimile broadcast receiving devices are configured as described above, so in order to check the reception status of the installed antenna, it is necessary to receive the facsimile broadcast while it is being broadcast and check the fI, or to check the reception status of the installed antenna. There were problems such as having to connect a television receiver to the antenna to receive television broadcasts and check the received images.

In other words, the specifications are such that facsimile broadcasting can be received within the service area of television broadcasting, but if there is a long ghost in the audio multiplexing mode, the audio multiplexing channel (subcarrier center frequency; 2r , ) signals may be distorted, and this second harmonic component (center frequency; 4f+) may mix into the facsimile channel signal band centered at 4 or 5 fH, causing interference. , sufficient confirmation is required.

Interference when there is a long ghost in the audio multiplex mode will be explained using the spectrum diagram shown in FIG.

In the audio multiplex mode, if there is a long ghost, the audio multiplex channel (frequency of subcarrier; 2fx
The signal of ll is distorted and generates harmonic components.

Among these harmonic components, the second harmonic component (
Since the center frequency (4fx) is mixed into the facsimile channel signal band centered at 4.5fx,
If the level is high, it will interfere with facsimile broadcasting.

This invention was made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a facsimile broadcast receiving device that can easily check the reception status of the installed antenna even when facsimile broadcasting is not being performed. purpose.

[Means for Solving the Problems] A facsimile broadcast receiving apparatus according to the present invention includes a noise level detection unit that detects a noise level in a facsimile channel signal band during voice detection output, and a noise level detection unit that detects a noise level detected by the noise level detection unit. and a reception state determination means for determining the reception state according to the reception state.

(Function) The noise level detection unit in the present invention detects the noise level of the facsimile channel signal band in the voice detection output when facsimile broadcasting is not being performed, and the reception state determination unit detects the noise level in the facsimile channel signal band in the audio detection output. to determine whether the reception condition is good.

〔Example〕

Embodiments of the facsimile broadcast receiving apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a bronch diagram showing the configuration of one embodiment.

In this FIG. 1, the parts indicated by numerals 1 to 6 are the same as those in the conventional example shown in FIG. I will mainly discuss the parts that differ from the above.

In FIG. 1, parts indicated by numerals 7 and 8 are newly added parts to the configuration of FIG. 4, and are the parts that are characteristic of the embodiment of FIG. 1.

That is, 7 is a noise level detection unit that detects the noise level of the facsimile channel signal band separated by the bandpass filter 3, and 8 is a reception status determination unit that determines and displays the reception status according to the noise level of this noise level detection unit 7. Department.

Next, the operation will be explained. Facsimile broadcasts are not always broadcast when television broadcasts are being performed, and are expected to be broadcast intermittently at the beginning of the main broadcast.

When checking the reception status of the installed antenna l, if a facsimile broadcast is being made, receive it in the same way as in the conventional case, and check whether there are any errors in the image signal data printed on the recording paper. Since this can be done by looking at , the explanation of the operation in this case will be omitted.

Next, a case will be described in which the reception status is checked when a television broadcast is being performed but a facsimile broadcast is not being performed.

First, the tuner unit 2 selects a desired channel of the television broadcast waves received by the antenna 1 and obtains an audio detection output.

Next, the bandpass filter 3 separates noise within the facsimile channel signal band from the audio detection output obtained by the tuner section 2.

The noise level detector 7 amplifies the noise separated by the bandpass filter 3 to a level that can be determined by the next reception state determiner 8.

The reception state determining section 8 compares the noise level with a preset reference level, and determines and displays whether the reception state is good or not depending on the magnitude of the noise level.

When setting the reference level, set it to a noise level value that allows facsimile broadcasts to be received normally, and if the received noise level is lower than that value,
The reception status is judged as good, and if it is large, it is judged as bad.

In the audio multiplex mode, if there is a long ghost, the audio multiplex channel (center frequency of subcarrier; 2
fH) signal is distorted, and this second harmonic component (center frequency; 4fh) mixes into the band of the facsimile transmission signal centered at 4.5 fH, and is detected as noise, so the noise level 6. (Effects of the Invention) As described above, according to the present invention, the noise level of the facsimile channel signal band in the audio detection output is detected by the noise level detection section, and the noise level is detected by the noise level detector. Since the receiving state is determined by the receiving state determining section according to the magnitude of the facsimile broadcasting, the receiving state of the installed antenna can be easily checked even when facsimile broadcasting is not being performed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a facsimile broadcast receiver according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the structure of a facsimile signal, FIG. 3 is a spectrum diagram in which a facsimile signal is frequency-multiplexed with an audio signal, FIG. 4 is a professional diagram of a conventional facsimile broadcast receiving apparatus, and FIG. 5 is a spectrum diagram when there is a long ghost. DESCRIPTION OF SYMBOLS 1... Antenna, 2... Tuner section, 3... Band pass filter, 4... Demodulation section, 5... Signal processing section, 6... Printing section, 7... Noise level Detection section, 8.
...Reception status determination unit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] In a facsimile broadcast receiving device that receives a facsimile broadcast in which a facsimile signal is multiplexed and transmitted on an audio second subcarrier of a television signal, a tuner unit receives a desired channel from the television broadcast radio wave and obtains an audio detection output; A bandpass filter that passes only the facsimile channel signal band from the audio detection output of the tuner section, and a demodulation section that demodulates the four-phase differential phase modulated facsimile channel signal separated by this bandpass filter and outputs the facsimile signal. , a signal processing unit that separates a control signal and an image signal from the facsimile signal demodulated by the demodulation unit, decodes the image signal and provides it for printing, and noise in the facsimile channel signal band of the output of the bandpass filter. A facsimile broadcast receiving apparatus comprising: a noise level detection section that detects a level; and a reception state determination section that determines and displays a reception state according to the noise level detected by the noise level detection section.