JP3687449B2 - Color video surveillance system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color video monitoring system used for a television intercom system or the like used for a detached house or an apartment house.
[0002]
[Prior art]
A conventional color video monitoring system will be described with reference to FIGS. FIG. 10 is a block diagram showing a television intercom system for an apartment house shown as an example of a conventional general color video monitoring system. FIG. 11 shows a frequency spectrum obtained when the video signal obtained by color imaging is FM-modulated into an FM video signal. (A) is an example in which the carrier frequency is about 5 MHz. b) shows examples when the carrier frequency is about 8 MHz. FIG. 12 shows the frequency spectrum of the FM video signal when waveform saturation occurs. FIG. 13 shows changes in group delay (phase) characteristics in the low-pass filter.
[0003]
In the color video monitoring system S described in FIG. 10, an imaging device 100 that FM-modulates a video signal obtained by imaging in color and transmits it as an FM video signal, a relay amplifier 200 that relays and amplifies the FM video signal, A monitor device 300 that receives the FM video signal after amplification from the relay amplifier 200 and visualizes it.
[0004]
The imaging device 100 corresponds to a so-called entrance intercom with a camera in the case of a television intercom system. Here, the imaging apparatus 100 is exemplified as a door intercom with a camera of a type that can image a visitor at the entrance (lobby) and can talk to a housekeeper in the dwelling unit.
[0005]
The imaging apparatus 100 includes a camera unit 101, an FM modulation unit 102, a transmission amplifier unit 103, a transmission low-pass filter unit 104, an unbalance / balance conversion unit 105, a CPU 106, a control signal transmission / reception unit 107, and a speaker 108. A microphone 109, a speaker amplifier 110, a microphone amplifier 111, a two-wire / four-wire converter 112, a video signal output terminal 113, a control signal input / output terminal 114, and an audio signal input / output terminal 115. Configured.
[0006]
The camera unit 101 images a visitor. The FM modulation unit 102 performs FM modulation on the video signal output from the camera unit 101. The transmission amplifier 103 amplifies and outputs the output signal (FM video signal) of the FM modulator 102. The transmission low-pass filter unit 104 filters and suppresses components outside the transmission band of the FM video signal after being amplified and output by the transmission amplifier unit 103. The unbalance / balance conversion unit 105 is a transformer provided between the transmission low-pass filter unit 104 and the video signal output terminal 113, and the FM video signal filtered by the transmission low-pass filter unit 104 is transferred from the unbalanced state. The signal is converted to an equilibrium state and transmitted to the video signal output terminal 113. The CPU 106 controls an internal circuit of the imaging device 100 and inputs / outputs a control signal such as a call response with the monitor device 300. The control signal transmission / reception unit 107 is an interface that receives a command from the CPU 106 and transmits / receives a control signal to / from the monitor device 300, and an external input / output terminal is connected to the control signal input / output terminal 114. The speaker 108, the microphone 109, the speaker amplifier 110, and the microphone amplifier 111 are for a visitor to talk with the monitor apparatus 300 through this. The two-wire / four-wire converter 112 performs two-wire / four-wire conversion so that a total of four signal lines of the speaker amplifier 110 and the microphone amplifier 111 can be transmitted and received in a pair of two wires. The video signal output terminal 113 is connected to the video signal input terminal 206 of the relay amplifier 200 via the two-wire balanced cable 10. The two-wire balanced cable 10 transmits the FM video signal after the unbalance / balance conversion by the unbalance / balance conversion unit 105 to the relay amplifier 200. The control signal input / output terminal 114 is connected to the control signal input / output terminal 314 of the monitor device 300 via the two-wire balanced cable 30. The two-wire balanced cable 30 transmits a control signal from the control signal transmission / reception unit 107 to the monitor device 300. The audio signal input / output terminal 115 is connected to the audio signal input / output terminal 315 of the monitor device 300 via the two-wire balanced cable 40. This two-wire balanced cable 40
The audio signal after the two-wire / four-wire conversion unit 112 performs the two-wire / four-wire conversion is transmitted to the monitor device 300.
[0007]
In the case of a television interphone system, the relay amplifier 200 corresponds to a so-called video amplifier that performs relay amplification so that the FM video signal from the imaging apparatus 100 can be transmitted over a long distance. The relay amplifier 200 includes a balanced / unbalanced conversion unit 201, an input low-pass filter unit 202, a relay amplifier unit 203, an output low-pass filter unit 204, an unbalanced / balanced conversion unit 205, a video signal input terminal 206, A video signal output terminal 207 is provided.
[0008]
  The balance / unbalance conversion unit 201 is a transformer provided between the video signal input terminal 206 and the input low-pass filter unit 202, and balances the FM video signal reaching the video signal input terminal 206 through the two-wire balanced cable 10. The state is converted into an unbalanced state and transmitted to the input low-pass filter unit 202. The input low-pass filter unit 202 filters and suppresses components outside the transmission band from the FM video signal after the unbalance / balance conversion by the balance / unbalance conversion unit 201. The relay amplifier unit 203 amplifies and outputs the FM video signal whose out-of-transmission band component is filtered by the input low-pass filter unit 202. The output low-pass filter unit 204 further removes components outside the transmission band from the FM video signal amplified and output by the relay amplifier unit 203. The unbalance / balance conversion unit 205 is a transformer provided between the output low-pass filter unit 204 and the video signal output terminal 207. The FM video signal filtered by the output low-pass filter unit 204 is transferred from the unbalanced state. It is converted to an equilibrium state and transmitted to the video signal output terminal 207. The video signal output terminal 207 is connected to the monitor device 300 via the two-wire balanced cable 20.Video signal input terminal 313Connected. The two-wire balanced cable 20 transmits the FM video signal after the unbalance / balance conversion by the unbalance / balance conversion unit 205 to the monitor device 300.
[0009]
The monitor device 300 corresponds to a so-called dwelling unit monitor in the case of a television intercom system. Here, the monitor device 300 is exemplified as a dwelling unit monitor of a type that can visually check a video of a visitor at the entrance (lobby) and can talk to the visitor. The monitor device 300 includes a balanced / unbalanced conversion unit 301, a reception low-pass filter unit 302, a reception amplifier unit 303, an FM demodulation unit 304, a monitor unit 305, a CPU 306, a control signal transmission / reception unit 307, and a speaker 308. A microphone 309, a speaker amplifier 310, a microphone amplifier 311, a two-wire / four-wire converter 312, a video signal input terminal 313, a control signal input / output terminal 314, and an audio signal input / output terminal 315. Configured.
[0010]
The balance / unbalance conversion unit 301 is a transformer provided between the video signal input terminal 313 and the reception low-pass filter unit 302, and balances the FM video signal reaching the video signal input terminal 313 through the two-wire balanced cable 20. The state is converted into an unbalanced state and transmitted to the reception low-pass filter unit 302. The reception low-pass filter unit 302 filters and suppresses components outside the transmission band from the FM video signal after the unbalance / balance conversion by the balance / unbalance conversion unit 301. The reception amplifier unit 303 amplifies and outputs the FM video signal whose out-of-transmission band component is filtered by the reception low-pass filter unit 302. The FM demodulation unit 304 demodulates the FM video signal output from the reception amplifier unit 303 into a baseband video signal. The monitor unit 305 displays the baseband video signal output from the FM demodulation unit 304 as a visitor video. The CPU 306 controls an internal circuit of the monitor device 300 and inputs / outputs a control signal such as a call response with the imaging device 100. The control signal transmission / reception unit 307 is an interface that receives a command from the CPU 306 and transmits / receives a control signal to / from the imaging apparatus 100, and an external input / output terminal is connected to the control signal input / output terminal 314. The speaker 308, the microphone 309, the speaker amplifier 310, and the microphone amplifier 311 are for a person on the monitor device 300 side to talk to a visitor through this. The two-wire / four-wire converter 312 performs two-wire / four-wire conversion so that a total of four signal lines of the speaker amplifier 310 and the microphone amplifier 311 can be transmitted / received in a pair of two wires. The input / output terminal is connected to the audio signal input / output terminal 315.
[0011]
As described above, in the conventional color video monitoring system S exemplified as the entrance intercom with camera, the FM video signal does not need to be relayed and amplified when the transmission distance of the FM video signal is short or in the case of a detached house. Therefore, in such a case, the relay amplifier 200 may not be used.
[0012]
Also, the FM video signal, control signal, and baseband audio signal are transmitted through independent two-wire balanced cables 10, 20, 30, and 40, but these three types of signals are only transmitted as a pair of two-wire balanced cables. In some cases, multiplex transmission is performed by frequency multiplexing.
[0013]
[Problems to be solved by the invention]
However, the conventional color video monitoring system S as described above has the following problems.
[0014]
FIG. 11A and FIG. 11B illustrate the frequency spectrum in the above-described conventional television intercom system. The carrier frequency of FM modulation is approximately 4 MHz to 10 MHz. As shown in FIGS. 11 (a) and 11 (b), when FM modulation is performed without separating color signals from a video signal obtained by color imaging, the second state is shown in FIG. 11 (a). The folded component of the lower side wave appears, and the folded component of the third lower side wave appears in FIG. 11B. As described above, when FM modulation is performed without separating color signals from video signals obtained by color imaging, aliasing components of higher-order lower side waves are generated (particularly around 3.58 MHz).
[0015]
FIG. 12 shows the frequency spectrum of the FM video signal when waveform saturation occurs. When the relay amplifier 200 is used as in the above-described conventional example, the FM video signal is saturated as shown in FIG. 12, and the FM spectrum that appears for the second harmonic becomes the FM spectrum that appears for the main carrier. It will interfere.
[0016]
Interference between the aliasing components of the first lower side wave and the second lower side wave as shown in FIG. 11 can be avoided by appropriately selecting the carrier frequency. Since the third and more lower side wave aliasing components have a relatively low level of the third and higher lower side wave, the interference between them and the first lower side wave is usually small enough to be ignored. However, if the amplification of the FM video signal is repeated using the relay amplifier 200, the level of the third or higher lower side wave is naturally amplified, so that the interference between these and the first lower side wave can be ignored. It becomes a problem as it disappears.
[0017]
FIG. 13 shows a change in group delay (phase) characteristics in the low-pass filter. In the above-described conventional television interphone system, a filter having an amplitude characteristic as shown in FIG. 13 is used in order to suppress unnecessary radiation outside the transmission band or to remove interference noise. Due to this filter, the group delay (phase) characteristic is not flat in the FM video signal transmission band, and color phase shift occurs. That is, it is not preferable because it is difficult to see the color because a color shift has occurred even when the obtained screen is viewed.
[0018]
As described above, in the conventional color video monitoring system S, when the color video signal is handled as the FM video signal, the primary lower side wave and the high frequency are increased due to the FM modulation without separating the color signal. As a filter to suppress interference with the next lower side wave, saturation of the signal waveform of the FM video signal due to simple amplification of the FM video signal, and suppression of unwanted radiation and interference noise For this reason, the group delay (phase) characteristic is unflattened, and the color characteristic of the image after FM demodulation is deteriorated due to these factors.
[0019]
The present invention has been made to solve the above-described problems, and an object of the present invention is to monitor color video that can suppress deterioration of color characteristics when a color video signal is FM-modulated and transmitted. To provide a system.
[0020]
[Means for Solving the Problems]
  The color video monitoring system according to claim 1, wherein the video signal obtained by color imaging is FM-modulated by an FM modulator and transmitted as an FM video signal, and the FM video signal is relay-amplified. In a color video monitoring system including a relay amplifier and a monitor device that receives and visualizes the FM video signal amplified from the relay amplifier, a second lower side wave and a third lower side wave generated at the time of FM modulation A high-pass filter for removing both the second lower side wave folding component and the third lower side wave folding component is provided after the next stage of the FM modulation unit of the imaging apparatus.This prevents each of the higher-order lower side waves and their respective folded components from interfering with the first lower side wave, and more than the second harmonic generated by the limiter amplification processing during the FM modulation. A low-pass filter capable of removing the frequency band is provided after the next stage of the FM modulation unit of the imaging device.It is characterized by that.
[0021]
The color video monitoring system according to claim 2, wherein the high-pass filter is provided in the monitor device after the next stage of the FM modulation unit of the imaging device in the color video monitoring system according to claim 1. It is characterized by that.
[0023]
  Claim3In the color video surveillance system described in claim1 or 2In the described color video monitoring system, the low-pass filter is provided in the next stage of the FM modulation unit of the imaging apparatus.
[0025]
  Claim4In the color image monitoring system according to claim 1,3In the color video monitoring system described above, a delay equalization characteristic is added to at least one of the noise filter unit of the imaging device, the noise filter unit of the relay amplifier, and the noise filter unit of the monitor device, To do.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the first embodiment of the color video monitoring system according to the present invention will be described with reference to FIGS. 1 to 3, the second embodiment with reference to FIGS. 4 to 6, and the third embodiment. Based on FIG. 7, the fourth embodiment will be described with reference to FIG. 8, and the fifth embodiment will be described with reference to FIG.
[0027]
The color video monitoring system described below is the same as the conventional color video monitoring system described above unless otherwise specified.
[0028]
[First Embodiment]
FIG. 1 is a block diagram for explaining an image pickup apparatus in a television intercom system for an apartment house shown as an example of the color video monitoring system of the present invention. FIG. 2 is a block diagram for similarly explaining the monitor device. FIG. 3 is a frequency spectrum graph for explaining the removal of the second or higher side waves by the high-pass filter. This embodiment is described in order to explain claims 1 and 2 more specifically.
[0029]
As shown in FIG. 1, the imaging apparatus 100 is provided with a high-pass filter 116 at the next stage of the transmission low-pass filter unit 104. As shown in FIG. 3, the high-pass filter 116 is lower than the first lower side wave of the FM modulation so as to remove the aliasing component of the second lower side wave of the FM modulation and the lower side wave of the third and lower. It is designed to have a cutoff frequency at a nearby frequency.
[0030]
The high-pass filter 116 is not limited to the next stage of the transmission low-pass filter unit 104 as shown in FIG. 1, and may be provided after the relay amplifier unit 203 of the relay amplifier 200. In short, the FM modulation unit of the imaging apparatus 100 It may be provided after the next stage of 102.
[0031]
Accordingly, the imaging apparatus 100 that FM-modulates the video signal obtained by color imaging by the FM modulator and transmits the FM video signal as an FM video signal, the relay amplifier 200 that relays and amplifies the FM video signal, and after amplification from the relay amplifier 200 In the color video monitoring system S including the monitor device 300 that receives and visualizes the FM video signal, the second lower side wave, the third lower side wave, and the second lower side wave folding component generated at the time of FM modulation And the third lower side wave folding component are provided after the next stage of the FM modulation unit 102 of the imaging apparatus 100, so that the second lower side wave and the third and lower side waves are removed. Therefore, when the color video signal is FM-modulated and transmitted, a color video monitoring system capable of suppressing the deterioration of the color characteristics can be provided.
[0032]
In particular, when the high-pass filter 116 is provided in the monitor device 300 after the FM modulation unit 102 of the imaging device 100, a further effect can be obtained when the relay amplifier 200 is added compared to the above case. can get. That is, when the relay amplifier 200 is added, even if the high-pass filter 116 is provided after the FM modulation unit 102 in the imaging apparatus 100 to reduce the second or higher side wave of the FM modulation, Due to the amplification function of the relay amplifier 200, an unfavorable situation may occur in which the level of the second or more lower side wave increases again. In order to avoid this, it is conceivable to provide the high-pass filter 116 in the relay amplifier 200, but in that case, the high-pass filter 116 is provided in all the relay amplifiers 200, and a plurality of high-pass filters 116 are required. As a result, the system becomes expensive. Therefore, if a reception high-pass filter 316 having a function similar to that of the high-pass filter 116 is provided in the previous stage of the FM demodulator 304, the FM video signal is relay-amplified and finally received by the reception high-pass filter 316. The above lower side wave can be reduced. In other words, even if the relay amplifier 200 is added, it is possible to provide an effect that it is possible to provide a relatively low-cost system in which only one receiving high-pass filter 316 having the same function as the high-pass filter 116 is required.
[0033]
  [Second Embodiment] FIG. 4 is a block diagram for explaining a relay amplifier in a television intercom system for an apartment house shown as an example of the color video monitoring system of the present invention. FIG. 5 is a block diagram for similarly explaining the imaging apparatus. FIG. 6 is a frequency spectrum graph for explaining the removal of the second and higher harmonics by the low-pass filter. This embodiment claims1And claims3Is described in order to more specifically explain.
[0034]
The color video monitoring system according to the second embodiment is different from the color video monitoring system according to the first embodiment described above in that a frequency band higher than the second harmonic generated in FM modulation is used. In this configuration, a removable low-pass filter is provided after the next stage of the FM modulation unit of the imaging apparatus.
[0035]
As shown in FIG. 4, the relay amplifier 200 is provided with a low-pass filter 208. Unlike the output low-pass filter unit 204 shown in the conventional example, the low-pass filter 208 is a low-pass filter that is designed so as to be able to remove the frequency band of the second and higher harmonics generated during FM modulation. That is, as shown in FIG. 6, the low-pass filter 208 has a cut-off frequency in a frequency band higher than a frequency band (a frequency band of about 5 MHZ in addition to the carrier frequency) for transmitting an FM-modulated color video signal. Designed, and therefore, it is possible to remove the frequency band higher than the second harmonic generated during FM modulation.
[0036]
Such a low-pass filter 208 can be easily conceived from the function thereof, but it may be provided after the next stage of the FM modulation unit 102 of the imaging apparatus 100. The low-pass filter 208 may not be provided immediately after the relay amplifier unit 203 as illustrated in FIG. 4, for example, may be provided after the transmission amplifier unit 103 of the imaging device 100, or may not be provided in the monitor device 300. You may provide in the back | latter stage of the receiving amplifier part 303. FIG.
[0037]
Since it did in this way, it becomes easy to suppress the FM modulation | alteration second harmonic generated by the saturation output of the amplifier result in each amplifier part.
[0038]
In particular, as shown in FIG. 5, if a low-pass filter 117 corresponding to the low-pass filter 208 is provided in the next stage of the FM modulation unit 102 of the imaging apparatus 100, a so-called procedure of internal signal processing of the FM modulation unit 102 is performed. It becomes easier to more surely remove the frequency band above the FM modulated second harmonic generated by the limiter amplification process.
[0039]
  [Reference exampleFIG. 7 shows a color image monitoring system according to the present invention.referenceIt is a block diagram explaining a relay amplifier among the television intercom systems for apartment houses shown as an example..
[0040]
  thisReference exampleThe color video monitoring system of the first embodiment differs from the color video monitoring system of the first embodiment described above in that the FM video input to the relay amplifier unit is preceded by the relay amplifier unit that is a part of the relay amplifier. In this configuration, an AGC circuit unit that suppresses the signal level of the signal is provided.
[0041]
As illustrated in FIG. 7, the relay amplifier 200 includes an AGC circuit unit 209 between the input low-pass filter unit 202 and the relay amplifier unit 203. The AGC circuit unit 209 includes an attenuator unit 209a and an FM signal level detection unit 209b. The attenuator unit 209a has a function of outputting an FM video signal whose out-of-band component is filtered by the input low-pass filter unit 202 while suppressing attenuation. The FM signal level detection unit 209b detects the amplitude level of the FM video signal output of the attenuator unit 209a, and feedback-controls the attenuation level of the attenuator unit 209a so that the output level of the relay amplifier unit 203 is not saturated. In other words, the FM signal level detection unit 209b prevents the generation of the second harmonic during the FM modulation by avoiding saturation of the output level of the relay amplifier unit 203.
[0042]
As a result, it is possible to prevent generation of FM modulated second-order harmonics that are generated when the result of amplification in the relay amplifier unit 203 of the relay amplifier 200 is saturated and output.
[0043]
  [No.3Embodiment] FIG. 8 is an explanatory diagram of delay equalization characteristics provided in a noise filter section of any of the image pickup apparatus, the relay amplifier, and the monitor apparatus. This embodiment claims4Is described in order to more specifically explain. This first3The color video monitoring system according to the embodiment differs from the color video monitoring system according to the first embodiment described above in that the noise filter unit of the imaging device, the noise filter unit of the relay amplifier, and the monitor device In this configuration, a delay equalization characteristic is added to at least one of the noise filter units.
[0044]
Here, the transmission low-pass filter unit 104 (already shown in FIG. 1) corresponding to the noise filter unit of the imaging apparatus 100 is replaced with a transmission filter unit 104a having the same function as the transmission low-pass filter unit 104 as shown in FIG. In addition, a total of four phase shifters 104b are connected. The transmission filter unit 104a and the phase shifter 104b have characteristics similar to the group delay (phase) characteristics shown in the conventional example. By connecting these four transmission filter units 104a and phase shifters 104b in total, the vicinity of each peak of the characteristics is added, and even if it is narrow, it can be approximated to a substantially flat characteristic only within the FM video signal transmission band.
[0045]
By using such a transmission low-pass filter unit 104, the group delay (phase) characteristics of the FM video signal transmission band can be made flatter than before, and therefore phase distortion is prevented in the color FM video signal band. As a result, deterioration of the color characteristics of the color image can be suppressed.
[0046]
  [No.4Embodiment] FIG. 9 is a block diagram showing a television intercom system for collective housing shown as an example of a color video surveillance system of the present invention. This first4The color video monitoring system according to the embodiment has the above-described first to first aspects.3EmbodimentAnd reference examplesIt is configured to combine the features of the color video surveillance system.
[0047]
  By using one reception high-pass filter 316 described in the first embodiment, a relatively low cost system is constructed. Further, the reception high-pass filter 117 described in the second embodiment is total 1 Is used to construct a system that more reliably removes the frequency band above the FM modulation second harmonic, and moreover,referenceBy using one AGC circuit unit 209 described in the example, a system capable of preventing generation of FM modulated second-order harmonics generated by saturation output of the amplifier result in the relay amplifier unit 203, and In addition, the above3By using one total of the transmission low-pass filter unit 104 described in the embodiment, the system S that can suppress the degradation of the color characteristics of the color video as compared with the conventional group delay (phase) characteristics of the FM video signal transmission band was constructed. .
[0048]
  In this way, the first to the first mentioned above.3EmbodimentAnd reference examplesYou may comprise so that it may have the characteristics of the color video surveillance system of.
[0049]
【The invention's effect】
  In the first aspect of the present invention, an imaging device that FM-modulates a video signal obtained by imaging in color with an FM modulator and transmits it as an FM video signal, a relay amplifier that relays and amplifies the FM video signal, In a color video monitoring system including a monitor device that receives and visualizes an FM video signal after amplification from the relay amplifier, a second lower side wave, a third lower side wave, and a second lower side that are generated during FM modulation Since the high-pass filter for removing both the wave folding component and the third lower wave folding component is provided after the next stage of the FM modulation unit of the imaging device, the second lower wave and the third and lower lower side Since the aliasing component of the wave can be removed, it is possible to provide a color video monitoring system that can suppress the deterioration of the color characteristics when the color video signal is FM-modulated and transmitted.In addition, since the low-pass filter capable of removing the frequency band higher than the second harmonic generated in the FM modulation is provided after the next stage of the FM modulation unit of the image pickup apparatus, the amplifier result in each amplifier unit is saturated and output. It is easy to suppress the FM modulated second-order harmonics generated in this way.
[0050]
In the invention described in claim 2, in addition to the effect of the invention described in claim 1, since a high-pass filter is provided in the monitor device after the FM modulation section of the imaging device, a relay amplifier is added. Even so, it is possible to further provide an effect that it is possible to provide a relatively low-cost system in which only one high-pass filter is finally required, that is, only one monitor device.
[0052]
  Claim3In the described invention, the claims1 or 2In addition to the effects of the described invention, since the low-pass filter is provided in the next stage of the FM modulation unit of the imaging apparatus, the FM modulation secondary generated by the so-called limiter amplification process which is one procedure of the internal signal processing of the FM modulation unit. It becomes easier to remove the frequency band above the harmonic more reliably.
[0054]
  Claim4In the described invention, claims 1 to3In addition to the effect of the described invention, the delay equalization characteristic is added to at least one of the noise filter unit of the imaging device, the noise filter unit of the relay amplifier, and the noise filter unit of the monitor device, so that the FM video signal transmission band The group delay (phase) characteristics of the color FM video signal can be made flatter than before, and therefore phase distortion can be prevented in the band of the color FM video signal, and deterioration of the color characteristics of the color video can be suppressed.
[0055]
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a block diagram illustrating an imaging device in a television intercom system for an apartment house shown as an example of a color video monitoring system according to a first embodiment of the present invention.
FIG. 2 is a block diagram for explaining the monitor device of the above.
FIG. 3 is a frequency spectrum graph for explaining removal of second and higher harmonics by a high-pass filter.
FIG. 4 is a block diagram for explaining a relay amplifier in a television intercom system for collective housing shown as an example of a color video monitoring system according to a second embodiment of the present invention.
FIG. 5 is a block diagram illustrating the same imaging apparatus.
FIG. 6 is a frequency spectrum graph for explaining the removal of the second or higher side wave by the low-pass filter.
FIG. 7 relates to the present invention.RuOf the video surveillance systemreferenceIt is a block diagram explaining a relay amplifier among the television intercom systems for apartment houses shown as an example.
FIG. 8 is a diagram according to the present invention3It is explanatory drawing of the delay equalization characteristic provided in the noise filter part of any of an imaging device, a relay amplifier, and a monitor apparatus among the television intercom systems for apartment houses shown as an example of the color video monitoring system of embodiment of this embodiment. .
FIG. 9 is a diagram according to the invention4It is a block diagram showing the television intercom system for collective housing shown as an example of the color video surveillance system of the embodiment.
FIG. 10 is a block diagram showing a television intercom system for collective housing shown as an example of a conventional general color video monitoring system.
FIG. 11 shows a frequency spectrum obtained when an image signal obtained by color imaging is FM-modulated into an FM image signal, (a) shows an example in which the carrier frequency is about 5 MHz; (b) shows an example when the carrier frequency is about 8 MHz.
FIG. 12 shows a frequency spectrum of an FM video signal when waveform saturation occurs.
FIG. 13 is an explanatory diagram of a change in group delay (phase) characteristics in a low-pass filter.
[Explanation of symbols]
10, 20, 30, 40 2-wire balanced cable
100 Imaging device
101 Camera section
102 FM modulator
103 Transmission amplifier
104 Transmission low-pass filter (noise filter)
104a Transmission filter section
104b Phaser
105 Unbalance / balance conversion section
106 CPU
107 Control signal transmitter / receiver
108 Speaker
109 microphone
110 Speaker amplifier
111 Microphone amplifier
112 2-wire / 4-wire converter
113 Video signal output terminal
114 Control signal input / output terminal
115 Audio signal input / output terminal
116 High-pass filter
117 Low-pass filter
200 Relay amplifier
201 Balance / unbalance converter
202 Input low-pass filter
203 Relay amplifier
204 Output low-pass filter
205 Unbalance / balance conversion section
206 Video signal input terminal
207 Video signal output terminal
208 Low-pass filter
209 AGC circuit
209a Attenuator section
209b FM signal level detector
300 Monitor device
301 Balance / unbalance converter
302 Reception low-pass filter section
303 Receive amplifier section
304 FM demodulator
305 Monitor unit
306 CPU
307 Control signal transmission / reception unit
308 Speaker
309 microphone
310 Speaker amplifier
311 Microphone amplifier
312 2-wire / 4-wire converter
313 Video signal input terminal
314 Control signal input / output terminal
315 Audio signal input / output terminal
316 Receive high-pass filter
S color video surveillance system

Claims (4)

An imaging device that FM-modulates a video signal obtained by color imaging with an FM modulator and transmits it as an FM video signal, a relay amplifier that relays and amplifies the FM video signal, and the FM video amplified from the relay amplifier In a color video monitoring system including a monitor device that receives a signal and visualizes it, a second lower side wave, a third lower side wave, a second lower side wave folding component, and a third lower side generated during FM modulation the high-pass filter both removing and wave aliasing components, by Rukoto provided at the next stage after the FM modulation unit of the imaging device, the lower side band and the aliasing component and the first lower side of each higher-order A low-pass filter capable of removing a frequency band higher than the second harmonic generated by the limiter amplification process at the time of the FM modulation is provided after the next stage of the FM modulation unit of the imaging apparatus. Setting Color video monitoring system, characterized in that the.   The color video monitoring system according to claim 1, wherein the high-pass filter is provided in the monitor device after the next stage of the FM modulation unit of the imaging device. Color video monitoring system according to claim 1 or 2, characterized in that said low-pass filter, provided in the next stage of the FM modulation unit of the imaging device. A noise filter of the imaging device, a noise filter portion of the relay amplifier, at least one of a noise filter portion of the monitoring device of claims 1 to 3, wherein the obtained by adding a delay equalization characteristics Color video surveillance system.

Images