JP2010154334A - Wireless transmission device and wireless video transmission system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless transmission device which reduces an influence of a threshold value difference and a ringing and performs transmission of an accurate signal with an inexpensive and simple configuration. <P>SOLUTION: A baseband unit 51 appends a pilot signal having a known signal pattern to a baseband signal and outputs it to an H/L determination unit 61. The H/L determination unit 61 performs an H/L determination of the inputted baseband signal. A signal pattern comparison unit 64 compares the signal pattern of the pilot signal with the signal pattern of the baseband signal determined by the H/L determination unit 61. When it is determined that two signals are not identical, a threshold control unit 63 changes the threshold value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a wireless transmission apparatus capable of performing accurate signal transmission by eliminating the influence of ringing that occurs when a digital baseband signal is transmitted to a wireless transmission unit, and a wireless video transmission system using the wireless transmission apparatus. .

The wireless transmission device includes a baseband unit that outputs a digital baseband signal and a wireless transmission unit that transmits a wireless signal via an antenna. Normally, separate ICs are applied to the baseband unit and the wireless transmission unit, and both are connected to each other by a wiring pattern formed on a printed wiring board. For this reason, when a signal is transmitted from the baseband unit to the wireless transmission unit, there is a problem that the wireless transmission unit cannot read the signal accurately due to ringing.

In addition, in a CMOS input terminal of a conventional IC, a signal is judged as high (H) or low (L) (
Hereinafter, H / L determination) is performed by comparing Vdd / 2 (Vdd: power supply voltage), that is, the median value of Vdd as a threshold value, and comparing the signal voltage with the threshold value. Each manufacturer is H
In order to increase the accuracy of / L determination, the specification is such that Vdd / 3 or lower is determined as L, and 2Vdd / 3 or higher is determined as H. On the other hand, in TTL (Transistor-Transistor Logic), the threshold is set to about 1.4V regardless of the power supply voltage, and in this specification, 0.8V or less is set to L and 2.0V or more is set to H in order to improve accuracy. Yes. If such CMOS and TTL are connected as they are, there is a possibility that signals cannot be accurately transmitted due to a difference in threshold value, and in addition, when the input signal has ringing, the determination of H / L may be wrong. There is sex. In addition, in a continuous random signal such as a video signal, intersymbol interference has an effect in addition to the above-described problems, the waveform is further distorted, and H / L misjudgment increases.

The ringing will be further described. For example, when connecting two ICs (IC1 constituting the baseband part and IC2 constituting the wireless transmission part), impedance matching is achieved and the physical distance between the ICs is about several millimeters. If it is short, ringing hardly occurs, and the IC 2 can accurately determine the H / L of the input signal. However, IC1 and IC2
When there is a physically long distance on the printed circuit board due to the convenience of circuit design, or when IC1 and IC2 are mounted on different printed circuit boards and connected between them with a cable or the like, Due to parasitic components in the transmission path, ringing, overshoot / undershoot may occur in the transmitted signal waveform, and the IC 2 may not normally read the signal.
Therefore, such ringing has been dealt with by inserting a damping resistor or the like into the input terminal of the IC, and the difference in threshold has been dealt with by using a level conversion IC.

However, countermeasures against ringing due to level conversion ICs and damping resistors have been adopted in recent years.
In view of the dramatic increase in the number of input / output terminals, an increase in cost due to an increase in the number of parts is inevitable. Patent Document 1 discloses a method for binarizing an image signal such as a character pattern or a wiring pattern obtained from an imaging apparatus with high accuracy.
Japanese Unexamined Patent Publication No. 63-181521

The present invention has been made in order to solve the above-described problem, and wireless transmission capable of performing accurate signal transmission without increasing the number of mounted components and reducing the difference in threshold and the influence of ringing. An object is to provide a device and a wireless video transmission system using the same.

In order to achieve the above object, the invention according to claim 1 determines a baseband unit that outputs a digital baseband signal and a high (H) or low (L) level of the baseband signal output from the baseband unit. The baseband unit includes: an H / L determination unit that outputs a corresponding signal; and a wireless transmission unit that wirelessly transmits a signal output from the H / L determination unit via an antenna. A threshold control unit that adds a known pilot signal to the baseband signal and outputs the pilot signal to the H / L determination unit, and the H / L determination unit changes a reference threshold when performing the H / L determination; A signal pattern comparison unit that compares the known signal pattern with the signal pattern of the baseband signal that is actually output from the baseband unit and determined by the H / L determination unit; The threshold control unit automatically sets the threshold so that the signal pattern of the baseband signal determined by the H / L determination unit matches the signal pattern of the known pilot signal in the comparison result by the signal pattern comparison unit. It is characterized by changing in.

According to a second aspect of the present invention, in the wireless transmission device according to the first aspect, the threshold value control unit is configured to determine the baseband signal determined to match the signal pattern of the known pilot signal by the signal pattern comparison unit. An average value of a high value and a low value detected at a predetermined reading timing by the H / L determination unit is set as the threshold value.

According to a third aspect of the present invention, in the wireless transmission device according to the first aspect, the threshold control unit is a multi-bit baseband signal determined by the signal pattern comparison unit to match the signal pattern of the known pilot signal The high value and low value detected at a predetermined read timing for each bit by the H / L determination unit are stored, and the average value of the stored minimum value of the high value and maximum value of the low value is used as the threshold value. It is characterized by setting.

According to a fourth aspect of the present invention, in the wireless transmission device according to any one of the first to third aspects, even if the threshold control unit changes the threshold a predetermined number of times, the comparison result by the signal pattern comparison unit And a warning unit that issues a warning when the signal pattern determined by the H / L determination unit does not match the signal pattern of the known pilot signal.

According to a fifth aspect of the present invention, in the wireless transmission device according to any one of the first to fourth aspects, the signal input for transmitting the baseband signal output from the baseband unit to the H / L determination unit. A variable resistor interposed in the line and a resistance control unit for controlling the resistance value of the variable resistor are further provided.

The invention according to claim 6 is the wireless transmission device according to claim 5, wherein the resistance control unit is a value obtained by subtracting the maximum value of the low value from the minimum value of the high value stored by the threshold value control unit. The resistance value of the variable resistor is controlled so as to be maximized.

A seventh aspect of the invention is the wireless transmission device according to any one of the first to sixth aspects, further comprising a time management unit that manages a time at which the threshold control unit and / or the resistance control unit starts operating. It is further provided with a feature.

According to an eighth aspect of the present invention, in the wireless transmission device according to any one of the first to sixth aspects, the comparison result by the signal pattern comparison unit before the threshold value control unit changes the threshold value, When the signal pattern determined by the H / L determination unit matches the signal pattern of the known pilot signal, the threshold control unit and / or the resistance control unit do not start operation.

The invention according to claim 9 is the wireless transmission device according to claim 8, further comprising forcible operation starting means for forcibly starting the operation of the threshold control unit and / or the resistance control unit.

A tenth aspect of the present invention is the wireless transmission device according to any one of the first to ninth aspects,
Based on a wireless video transmission device including a camera device that outputs a video signal to the baseband unit, a wireless reception device that receives a signal transmitted from the wireless transmission device, and a video signal received by the wireless reception device A wireless video transmission system comprising a wireless video receiving device including a video playback device that plays back and displays video.

The invention of claim 11 is the wireless video transmission system according to claim 10, further comprising a storage unit for storing a video signal output from the camera device, wherein the baseband unit is stored in the storage unit. The video signal is added to the baseband signal as the known pilot signal and output to the H / L determination unit.

According to invention of Claim 1, it consists of a known signal pattern for a test from a baseband part.
A pilot signal is output, and the threshold control unit automatically changes the threshold so that the known signal pattern matches the signal pattern of the baseband signal determined by the H / L determination unit. This makes it possible to reduce the difference between the H / L threshold value of the baseband unit and the H / L threshold value of the wireless transmission unit and the ringing that occurs between the two with an inexpensive and simple configuration without using a damping resistor. The influence can be suppressed.

According to the second aspect of the present invention, the threshold control unit sets the average value of the high value and the low value detected at the predetermined reading timing by the H / L determination unit as the threshold value. It can be further suppressed.

According to the invention of claim 3, since the threshold value control unit sets the average value of the minimum value of the high value and the maximum value of the low value as the threshold value, the influence of ringing and noise can be further suppressed.

According to the invention of claim 4, if the signal pattern does not match even if the threshold value controller changes the threshold value a predetermined number of times, that is, if the response cannot be dealt with only by changing the threshold value, the warning unit issues a warning, Notify the administrator. Therefore, the administrator who receives this can quickly take another countermeasure against ringing.

According to the fifth aspect of the present invention, the amplitude of the ringing component can be suppressed by the variable resistor inserted in the signal input line, and the signal transmission between the baseband unit and the wireless transmission unit is made more accurate. be able to.

According to the invention of claim 6, since the resistance value of the variable resistor is optimized by the resistance control unit,
It is possible to prevent a signal waveform input to the H / L determination unit from being distorted due to excessive damping and adversely affecting the H / L determination.

According to the seventh aspect of the present invention, the time management unit manages the time when the threshold control unit and / or the resistance control unit starts operation. Therefore, the threshold value and the resistance value can be reset periodically. Thereby, the influence on H / L determination by the secular change of the components which comprise a circuit can be reduced.

According to the eighth aspect of the present invention, when the signal pattern matches before the threshold control unit changes the threshold, the threshold control unit and / or the resistance control unit does not start the operation. The power consumption of the wireless transmission device can be reduced.

According to the ninth aspect of the invention, since the forcible operation starting means for forcibly starting the operation of the threshold control unit and / or the resistance control unit is provided, the threshold control unit and / or the resistance is determined according to the judgment of the administrator of the apparatus. Whether or not to operate the control unit can be set.

According to the tenth aspect of the present invention, it is possible to display the video captured by the camera device on the video playback device while eliminating the influence of ringing.

According to the invention of claim 11, since the video signal actually captured by the camera device is used as the known pilot signal, the threshold value and the resistance value can be optimized according to the actual use situation.

(Embodiment 1)
A wireless video transmission system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of a wireless video transmission system. The wireless video transmission system 1 according to the present embodiment is called an interphone system. The wireless video transmission device 2 wirelessly transmits a video signal and the wireless video signal transmitted from the wireless video transmission device 2 is reproduced. It is comprised by the video receiver 3 grade | etc.,. The wireless video transmission device 2 includes a camera device 4 that captures a video, a wireless transmission device 5 that wirelessly transmits a video signal output from the camera device 4 via an antenna 6, and the like. The wireless video reception device 3 includes a wireless reception device 8 that receives a video signal wirelessly transmitted from the antenna 6 via the antenna 7, and a monitor that reproduces and displays a video based on the video signal received by the wireless reception device 8. A device (video reproduction device) 9 is provided.

The wireless transmission device 5 includes a baseband unit 51, an input interface unit 52, a wireless transmission unit 53, a memory 54, and the like. The baseband unit 51 processes the video signal output from the camera device 4 and outputs a digital baseband signal. The input interface unit 52 processes the baseband signal input from the baseband unit 51 to process the wireless transmission unit 53.
Output to. The wireless transmission unit 53 wirelessly transmits the signal input from the input interface unit 52 via the antenna 6. The baseband unit 51 and the wireless transmission unit 53 are configured by individual ICs. The baseband signal output from the baseband unit 51 is input to the input interface unit 52 via the digital input signal line 51a. Memory 54
Contains a pilot signal for testing having a known signal pattern in advance.

FIG. 2 shows the configuration of the input interface unit 52. Input interface unit 5
2 includes an H / L determination unit 61, a digital processing unit 62, a threshold control unit 63, a signal pattern comparison unit 64, a memory 74, and the like. The H / L determination unit 61 determines whether the baseband signal output from the baseband unit 51 is high (H) or low (L), and outputs the corresponding signal to the digital processing unit 62 and the signal pattern comparison unit 64. . The digital processing unit 62 is H / L
The signal output from the determination unit 61 is processed and output to the wireless transmission unit 53. The threshold control unit 63 changes a threshold that is used as a reference for the H / L determination of the baseband signal by the baseband unit 51. The memory 74 stores in advance a test pilot signal that is the same as the signal pattern stored in the memory 54.

In the present embodiment, the baseband unit 51 adds a test pilot signal having a known signal pattern stored in advance in the memory 54 to the baseband signal and outputs it to the H / L determination unit 61. The signal pattern comparison unit 64 compares the signal pattern of the pilot signal stored in the memory 74 with the signal pattern of the baseband signal determined by the H / L determination unit 61 to determine whether the threshold is appropriate. to decide.

FIG. 3 shows an example of pilot signals stored in the memories 54 and 74. In the present embodiment, an alternating signal that switches between 0 and 1 every cycle is used as the pilot signal. The baseband signal to which the pilot signal is added is subjected to H / L determination by the H / L determination unit 61, and the corresponding signal is input to the signal pattern comparison unit 64. The signal pattern comparison unit 64 includes a known pilot signal signal pattern stored in the memory 74 shown in FIG. 3 and a baseband signal that is actually output from the baseband unit 51 and determined by the H / L determination unit 61. The signal pattern is compared. When the signal pattern comparison unit 64 determines that the two signal patterns match, the H / L determination unit 61 sets the H / L at an appropriate threshold.
Assuming that the determination is made, the communication is continued without changing the threshold value. If the signal pattern comparison unit 64 determines that the two signal patterns do not match due to the influence of ringing, the threshold control unit 63 changes the threshold.

That is, when the H / L threshold value is different between the two ICs constituting the baseband unit 51 and the wireless transmission unit 53, when the data has ringing, the H / L is erroneously determined. There is a possibility. Therefore, in this embodiment, the threshold control unit 63 controls the threshold, reduces the influence of ringing, and determines H / L. The presence or absence of the influence of ringing is determined by determining a known pilot signal in advance and reading the signal.

FIG. 4 shows the relationship between the baseband signal input to the H / L determination unit 61 and the threshold value. Assuming that the threshold value is fixed, if the baseband signal affected by ringing is read at the read timing shown in FIG. 4, the read value becomes smaller than the threshold value. 61 is erroneously determined to be low. In this case, the signal pattern comparison unit 6
4, the signal pattern of the pilot signal stored in the memory 74 does not match the signal pattern of the baseband signal determined by the H / L determination unit 61, so the threshold control unit 63 changes the threshold. Thus, by dynamically changing the threshold value until the determination results in the signal pattern comparison unit 64 match, the value read from the baseband signal becomes larger than the threshold value, and the H / L determination unit 61 determines that the value is high. To do.

The initial value and the increase / decrease value of the threshold value described above can be set as appropriate. For example, when the voltage of the high signal of the baseband signal is 5V and the voltage of the low signal is 0V, the threshold control unit 63 sets the initial value of the threshold to 2
. Set to 5V, then increase or decrease by 0.5V, that is, 3V, 2V, 3.5V, and 1.5V.

FIG. 5 shows the operation of the wireless video transmission apparatus 2. When the device is turned on (# 1)
The baseband unit 51 converts the baseband signal to which the pilot signal is added into the H / L determination unit 6.
1 (# 2), the threshold control unit 63 sets the threshold value to the initial value, and the H / L determination unit 61 sets the H / L
L determination is performed (# 3). Then, the signal pattern comparison unit 64 matches the phase of the pilot signal stored in the memory 74 and the baseband signal determined by the H / L determination unit 61, and confirms whether the signal sequences match (# 4). ). As a result, when the two signals match (YES in # 5), the threshold control unit 63 determines that the signal can be read with the threshold, that is, is not affected by ringing, and the threshold is fixed with the value. End the operation (#
6). On the other hand, if the two signals do not match (NO in # 5), the baseband unit 51 again inputs the baseband signal with the pilot signal added to the H / L determination unit 61 (#
2) The threshold value control unit 63 changes the threshold value, and the H / L determination unit 61 performs H / L determination (# 3).
Until the two signals match, the processes of # 2 to # 5 are repeated to finally obtain a signal that is not affected by ringing.

According to the wireless video transmission apparatus 2 of the present embodiment, a known pilot signal for testing is output from the baseband unit 51, and the signal pattern of the known pilot signal and the baseband signal determined by the H / L determination unit 61 The threshold value control unit 63 automatically changes the threshold value so that the signal pattern matches. As a result, the difference between the H / L threshold value of the baseband unit 51 and the H / L threshold value of the wireless transmission unit 53 occurs between the two with an inexpensive and simple configuration without using a damping resistor. The influence of ringing can be suppressed. Thereby, according to the wireless video transmission system 1, it is possible to display the video captured by the camera device 4 on the monitor device 9 while eliminating the influence of ringing.

(Embodiment 2)
The wireless video transmission system according to the second embodiment is obtained by replacing the input interface unit 52 with the input interface unit 90 shown in FIG. 6 in the wireless video transmission system 1 according to the first embodiment. The input interface unit 90 includes a measurement unit (H / L determination unit) 65 that measures the high value and low value of the baseband signal, and a storage unit that stores the measured high value and low value (
(Threshold control unit) 66 and a threshold calculation unit (threshold control unit) 67 for calculating an average value of the high value and the low value.
Etc.

FIG. 7 shows the high value and low value of the baseband signal detected by the measurement unit 65 and the threshold value calculated by the threshold value calculation unit 67. The measuring unit 65 detects the high value and the low value of the baseband signal determined by the signal pattern comparing unit 64 to match the pilot signal. The measuring unit 65 detects the high value and the low value by detecting the voltage of the baseband signal at a predetermined reading timing. The threshold value calculation unit 67 calculates the average value of the high value and the low value detected by the measurement unit 65 and sets it as a threshold value. In calculating the average value of the high value and the low value, as shown in FIG. 7, the high value and the low value detected in one pulse may be used, or the high value and the low value detected in a plurality of pulses may be used. May be used.

FIG. 8 shows the operation of the wireless video transmission apparatus in the present embodiment. Since # 1 to # 5 are the same as those in FIG. If the two signals match in # 5 (YES in # 5), the measurement unit 65 measures the high value and low value of the baseband signal (# 6) and stores them in the storage unit 66 (# 7). Then, the threshold calculation unit 67 calculates the average value of the high value and the low value (# 8) and sets it as a fixed threshold (# 9).

According to the wireless video transmission apparatus in the present embodiment, the threshold value calculation unit 67 sets the average value of the high value and the low value detected by the measurement unit 65 at a predetermined reading timing as the threshold value. Can be further suppressed.

(Embodiment 3)
The wireless video transmission system according to the third embodiment has a configuration equivalent to that of the wireless video transmission system according to the second embodiment, and is different from the wireless video transmission system according to the second embodiment in the arithmetic processing of the threshold value calculation unit 67.

FIG. 9 shows the high value and low value of the baseband signal detected by the measurement unit 65 and the threshold value calculated by the threshold value calculation unit 67. The measuring unit 65 detects a high value and a low value at a predetermined reading timing over a plurality of bits with respect to the baseband signal determined to match the pilot signal by the signal pattern comparing unit 64. The storage unit 66 stores a high value and a low value detected by the measurement unit 65. The threshold calculation unit 67 calculates the average value of the stored minimum value (Hmin) of the high value and maximum value (Lmax) of the low value.

FIG. 10 shows the operation of the wireless video transmission apparatus in the present embodiment. Since # 1 to # 7 are the same as those in FIG. Measuring unit 65 measures the high value and low value of the baseband signal over a predetermined number of bits (N bits) (NO in # 11).
), # 6 and # 7 are repeated, and when the high and low values of the baseband signal are measured over a predetermined number of bits (N bits) (YES in # 11), the threshold calculation unit 67 66, referring to the high value and low value stored in 66, the minimum value of the high value and the maximum value of the low value are extracted (
# 12) The average value of the minimum value of the high value and the maximum value of the low value is calculated (# 13) and set as a fixed threshold value (# 14).

According to the wireless video transmission apparatus of the present embodiment, the threshold value calculation unit 67 sets the average value of the minimum value of the high value and the maximum value of the low value as the threshold value, so that the influence of ringing and noise can be further suppressed.

(Embodiment 4)
In the wireless video transmission system of the fourth embodiment, the input interface unit 52 is replaced with the input interface unit 91 shown in FIG. 11 in the wireless video transmission system 1 of the first embodiment. The input interface unit 91 is different from the input interface unit 52 in that it includes a determination impossible notification unit (warning unit) 68.

FIG. 12 illustrates a baseband signal input to the H / L determination unit 61 in a situation where the determination impossibility notification unit 68 operates. As shown in the figure, when the influence of ringing becomes excessively large, the high value may be detected smaller than the low value depending on the read timing. The determination failure notification unit 68 issues a warning when the signal pattern comparison unit does not match the two signal patterns even when the threshold control unit 63 changes the threshold value a predetermined number of times.
Notify the administrator that the judgment cannot be made, and clearly indicate that it is necessary to take another countermeasure against ringing. The warning can be performed by light or sound. The number of times the threshold is changed is
The administrator shall set as appropriate.

FIG. 13 shows the operation of the wireless video transmission apparatus in this embodiment. Since # 1 to # 5 are the same as those in FIG. If the two signal patterns do not match in # 5 (NO in # 5), the process proceeds to # 21. Thereafter, the processes of # 1 to # 5 are repeated, and if the two signal patterns do not match even if the threshold control unit 63 changes the threshold value a predetermined number of times (YES in # 21), the determination impossible notification unit 68 issues a warning, Encourage measures against ringing (# 22). In addition, when two signal patterns correspond in # 5 (YES in # 5), you may comprise so that the process equivalent to FIG.8 and FIG.10 may be performed.

According to the wireless video transmission apparatus of this embodiment, if the signal pattern does not match even if the threshold control unit 63 changes the threshold value a predetermined number of times, that is, if the signal pattern cannot be dealt with only by changing the threshold value, the determination impossibility notification unit 68. Issues a warning and notifies the device administrator. Therefore, the administrator who receives this can quickly take another countermeasure against ringing.

(Embodiment 5)
The wireless video transmission system of the fifth embodiment is obtained by replacing the input interface unit 52 with the input interface unit 92 shown in FIG. 14 in the wireless video transmission system 1 of the first embodiment. The input interface unit 92 is different from the input interface unit 52 in that it includes a variable resistor 69 inserted in the digital input signal line 51 a and a variable resistance control unit (resistance control unit) 70 that controls the variable resistor 69. The variable resistor 69 and the variable resistance control unit 70 are provided, for example, inside the ASIC that constitutes the H / L determination unit 61 and do not contribute to an increase in the number of parts.

FIG. 15 illustrates a baseband signal input to the H / L determination unit 61 in a situation where the variable resistor 69 operates. As shown in the figure, when the influence of ringing is excessively large and the high value is detected to be smaller than the low value, the variable resistance control unit 70 increases the resistance value of the variable resistor 69 to increase the amplitude of the ringing component. Suppress.

FIG. 16 shows the operation of the wireless video transmission apparatus in this embodiment. Since # 1 to # 5 are the same as those in FIG. If the two signal patterns do not match in # 5 (NO in # 5), the process proceeds to # 31. In # 31, when the two signal patterns are different from each other by a predetermined number of times (YES in # 31), the variable resistance control unit 70 increases the resistance value of the variable resistance 69 (# 32). As a result, the role of the variable resistor 69 as a damping resistor increases, and ringing is reduced. In # 31, the number of times is determined for each identical resistance value.

According to the wireless video transmission apparatus in the present embodiment, the amplitude of the ringing component can be suppressed by the variable resistor 69 inserted in the digital input signal line 51 a, and the signal between the baseband unit 51 and the wireless transmission unit 53 can be suppressed. Transmission can be made more accurate.

(Embodiment 6)
In the wireless video transmission system according to the sixth embodiment, the input interface unit 52 is replaced with the input interface unit 93 shown in FIG. 17 in the wireless video transmission system 1 according to the first embodiment. The input interface unit 93 includes a measurement unit 65, a storage unit 66, a threshold value calculation unit 67, a variable resistor 69, a variable resistance control unit (resistance control unit) 70, and a calculation unit that calculates the resistance value of the variable resistor 69. It differs from the input interface unit 52 in that it has 71.

FIG. 18 illustrates a baseband signal input to the H / L determination unit 61 in a situation where the variable resistor 69 operates. As shown in the upper part of the figure, the influence of ringing is excessively large.
When the high value is detected smaller than the low value, as shown in the middle stage, the variable resistance control unit 7
0 increases the resistance value of the variable resistor 69 and suppresses the amplitude of the ringing component. However, if the resistance value of the variable resistor 69 is excessively increased, the waveform of the baseband signal may be distorted as shown in the lower part, and the signal may not be read accurately.

In FIG. 18, when the resistance value of the variable resistor 69 is increased from the state shown in the upper stage to the state shown in the middle stage, a value obtained by subtracting the maximum value of the low value from the minimum value of the high value (Hmin−Lmax) increases. . Further, in FIG. 18, when the resistance value of the variable resistor 69 is increased from the state shown in the middle stage to the state shown in the lower stage, Hmin−Lmax becomes smaller. Therefore, in the present embodiment, the calculating unit 71 calculates Hmin−Lmax, and the variable resistance control unit 70 is Hmi.
The resistance value of the variable resistor 69 is controlled and optimized so that n-Lmax is maximized.

FIG. 19 shows the operation of the wireless video transmission apparatus in the present embodiment. # 1 to # 32
Since this is the same as that of FIG. If the two signal patterns match in # 5 (YES in # 5), the measuring unit 65 measures the high value and the low value of the baseband signal (# 41), and the storage unit 66 together with the resistance value of the variable resistor 69. (# 42
). The measurement unit 65 repeats the processes of # 41 and # 42 until the high value and low value of the baseband signal are measured over a predetermined number of bits (N bits) (NO in # 43).

When measurement unit 65 measures the high value and low value of the baseband signal over a predetermined number of bits (N bits) (YES in # 43), threshold calculation unit 67 uses the high value stored in storage unit 66 and With reference to the low value, the minimum value of the high value and the maximum value of the low value are extracted (# 44). Further, the threshold calculation unit 67 calculates Hmin−Lmax (# 45) and stores it in the storage unit 66 (
# 46). Until a predetermined number (M) or more of Hmin−Lmax is stored in the storage unit 66 (
In # 47, the variable resistance control unit 70 controls the resistance value of the variable resistor 69 (# 48).
), Return to # 41. When M or more Hmin−Lmax are stored in the storage unit 66 (YES in # 47), the variable resistance control unit 70 refers to the Hmin−Lmax stored in the storage unit 66 and extracts the maximum value (# 49) The resistance value of the variable resistor 69 is fixed (# 50).
Thereafter, the wireless video transmission apparatus may be configured to perform the processes of # 6 to # 14 shown in FIGS.

According to the wireless video transmission apparatus in the present embodiment, since the resistance value of the variable resistor 69 is optimized by the variable resistance control unit 70, the signal waveform input to the H / L determination unit 61 is distorted due to excessive damping, It can prevent adversely affecting the H / L determination.

(Embodiment 7)
The wireless video transmission system of the seventh embodiment is obtained by replacing the input interface unit 52 with the input interface unit 94 shown in FIG. 20 in the wireless video transmission system 1 of the first embodiment. The input interface unit 94 is different from the input interface unit 52 in that it includes a time management unit 72. The time management unit 72 manages the time when the ringing countermeasure unit such as the threshold control unit 63 starts operating. The ringing countermeasure unit managed by the time management unit 72 includes the threshold value control unit 63, the signal pattern comparison unit 64, the measurement unit 65, the storage unit 66, the threshold value calculation unit 67, the determination failure notification unit 68, and the variable resistor 69. , Variable resistance control unit 70,
The calculation unit 71 or the like may be used.

FIG. 21 shows the operation of the wireless video transmission apparatus in this embodiment. When the power of the device is turned on (# 60), the ringing countermeasure unit such as the threshold control unit 63 is operated to implement the countermeasure against ringing (# 61), and when this is completed, the time management unit 12 waits for the ringing countermeasure unit. (# 62). Thereafter, the time management unit 12 counts the time, and when a predetermined time has elapsed, outputs an operation command to the ringing countermeasure unit and implements countermeasures against ringing (# 63). Here, the countermeasure against ringing means the operation shown in FIG. 5, FIG. 8, FIG. 10, FIG. 13, FIG.

According to the wireless video transmission apparatus in the present embodiment, the time management unit 72 manages the time when the ringing countermeasure unit such as the threshold control unit 63 starts operating, so that the threshold value and the resistance value are periodically reset. Can do. Thereby, the influence on H / L determination by the secular change of the components which comprise a circuit can be reduced.

(Embodiment 8)
The wireless video transmission system of the eighth embodiment has a configuration equivalent to that of the wireless video transmission system 1 of the first embodiment, and is different from the wireless video transmission system 1 in the processing of the threshold control unit 63. In the present embodiment, when the two signal patterns match with the default threshold value of the threshold value control unit 63, the ringing countermeasure operation such as the threshold value change by the threshold value control unit 63 is not started.

FIG. 22 shows the operation of the wireless video transmission apparatus in this embodiment. Since # 1 to # 4 are the same as those in FIG. If the signal pattern comparison unit 64 determines that the two signals match with the default threshold value (YES in # 70), the operation is terminated in a standby state in which the operation of the threshold control unit 63 is stopped (# 71), and the process is terminated. (# 76).
When it is determined that the two signals do not match with the default threshold (NO in # 5), the baseband unit 51 inputs the baseband signal with the pilot signal added to the H / L determination unit 61 again. (# 72), the threshold control unit 63 changes the threshold value, and the H / L determination unit 61 performs H / L determination (# 73). Then, the signal pattern comparison unit 64 matches the phases of the pilot signal stored in the memory 74 and the baseband signal determined by the H / L determination unit 61, and confirms whether the signal sequences match (# 74). ). As a result, if the two signals match (YES in # 75), the threshold control unit 63 fixes the threshold with the value and ends the operation (# 76). On the other hand, if the two signals do not match (NO in # 75),
Returning to # 72, the processes of # 72 to # 75 are repeated until the two signals match.

According to the wireless video transmission apparatus in the present embodiment, the threshold control unit 63 does not start the operation before the threshold control unit 63 changes the threshold, that is, when the two signal patterns match at the default threshold. Therefore, the operation frequency of the threshold control unit 63 can be reduced to reduce the power consumption of the wireless transmission device.

(Embodiment 9)
The wireless video transmission system of the ninth embodiment is obtained by replacing the input interface unit 52 with the input interface unit 95 shown in FIG. 23 with respect to the wireless video transmission system 1 of the first embodiment. The input interface unit 95 is different from the input interface unit 52 in that it includes a threshold value changing operation button (forced operation starting means) 73. The threshold value changing operation button 73 is operated by the administrator. In the case where the two signal patterns match with the default threshold value and the ringing countermeasure operation such as the threshold value change by the threshold value control unit 63 is not started,
When the threshold change operation button 73 is operated, the threshold control unit 63 forcibly starts the ringing countermeasure operation. By applying this threshold value change operation button 73 to the second to seventh embodiments, the signal pattern comparison unit 64, the measurement unit 65, the storage unit 66, the threshold value calculation unit 67, the determination failure notification unit 68, and the threshold change operation button 73, You may comprise so that it may become a trigger of operation | movement start of the variable resistance 69, the variable resistance control part 70, the calculation part 71, etc.

FIG. 24 shows the operation of the wireless video transmission apparatus in the present embodiment. # 1 to # 75
Since this is the same as that of FIG. After the two signal patterns match with the default threshold value (YES in # 70), the threshold value control unit 63 enters the standby state (# 71)
) When the threshold value changing operation button 73 is operated (YES in # 80), the process returns to # 72 again, and then the threshold value is changed by the threshold value control unit 63 (# 73). Become.

According to the wireless video transmission apparatus of the present embodiment, the threshold change operation button 73 for forcibly starting the operation of the ringing countermeasure unit such as the threshold control unit 63 is provided. You can set whether or not. Therefore, when the apparatus is used for a long period of time, the supervisor appropriately operates the threshold value changing operation button 73 to influence the H / L determination due to the secular change of the parts constituting the circuit. It can reduce more effectively.

The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, the pilot signals stored in the memories 54 and 74 are not limited to simple alternating signals as shown in FIG. 3, and actual video data obtained by imaging with the camera device 4 may be used. Good. In this case, since the threshold value and the resistance value are set from the actual video data, it is possible to suppress the influence of ringing in the actual usage situation. In addition, the wireless video transmission apparatus of the present invention is not limited to an interphone system and can be widely applied to wireless communication.

1 is a block diagram showing a configuration of a wireless video transmission system and a wireless video transmission device according to Embodiment 1 of the present invention. The block diagram which shows the structure of the input interface part applied to the same radio | wireless video transmission apparatus. The figure which shows an example of the pilot signal memorize | stored in memory in the same radio | wireless video transmission apparatus. The figure which shows the relationship between the baseband signal input into the H / L determination part of the input interface part, and a threshold value. 5 is a flowchart showing the operation of the wireless video transmission apparatus according to the first embodiment. FIG. 5 is a block diagram illustrating a configuration of an input interface unit applied to the wireless video transmission apparatus according to the second embodiment. The figure which shows the threshold value calculated by the high value and low value of the baseband signal which the measurement part of the same input interface part detects, and a threshold value calculation part. 9 is a flowchart showing the operation of the wireless video transmission apparatus according to the second embodiment. The figure which shows the threshold value calculated by the high value and low value of a baseband signal in the radio | wireless video transmission apparatus of Embodiment 3, and a threshold value calculation part. 10 is a flowchart illustrating an operation of the wireless video transmission apparatus according to the third embodiment. FIG. 9 is a block diagram illustrating a configuration of an input interface unit applied to a wireless video transmission apparatus according to a fourth embodiment. The figure which shows the baseband signal input into the H / L determination part of Embodiment 4. 10 is a flowchart showing the operation of the wireless video transmission apparatus according to the fourth embodiment. FIG. 10 is a block diagram illustrating a configuration of an input interface unit applied to a wireless video transmission apparatus according to a fifth embodiment. FIG. 10 is a diagram illustrating a baseband signal input to an H / L determination unit according to the fifth embodiment. 10 is a flowchart illustrating the operation of the wireless video transmission apparatus according to the fifth embodiment. FIG. 10 is a block diagram illustrating a configuration of an input interface unit applied to a wireless video transmission apparatus according to a sixth embodiment. The figure which shows the baseband signal input into the H / L determination part of Embodiment 6. 10 is a flowchart showing the operation of the wireless video transmission apparatus according to the sixth embodiment. FIG. 10 is a block diagram illustrating a configuration of an input interface unit applied to a wireless video transmission apparatus according to a seventh embodiment. 10 is a flowchart illustrating the operation of the wireless video transmission device according to the seventh embodiment. 10 is a flowchart illustrating an operation of the wireless video transmission apparatus according to the eighth embodiment. FIG. 10 is a block diagram illustrating a configuration of an input interface unit applied to a wireless video transmission apparatus according to a ninth embodiment. 10 is a flowchart illustrating the operation of the wireless video transmission apparatus according to the ninth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless video transmission system 2 Wireless video transmitter 3 Wireless video receiver 4 Camera apparatus 5 Wireless transmitter 6 Antenna 8 Wireless receiver 9 Monitor apparatus (video reproduction part)
51 Baseband part 51a Digital input signal line (signal input line)
53 Wireless Transmission Unit 54 Memory 61 H / L Determination Unit 63 Threshold Control Unit 64 Signal Pattern Comparison Unit (Signal Pattern Comparison Unit)
65 Measurement unit (H / L determination unit)
66 Storage unit (threshold control unit)
67 Threshold calculation unit (threshold control unit)
68 Judgment impossible notification part (warning part)
69 variable resistance 70 variable resistance control unit (resistance control unit)
71 Calculation unit 72 Time management unit 73 Threshold change operation button (forced operation start means)
74 memory

Claims (11)

A baseband unit that outputs a digital baseband signal;
An H / L determination unit that determines high (H) or low (L) of a baseband signal output from the baseband unit and outputs a corresponding signal;
In a wireless transmission device including a wireless transmission unit that wirelessly transmits a signal output from the H / L determination unit via an antenna,
The baseband unit adds a known pilot signal to the baseband signal and outputs it to the H / L determination unit,
A threshold control unit that changes a threshold used as a reference when the H / L determination unit performs the H / L determination, and the known signal pattern and the actual output from the baseband unit are determined by the H / L determination unit. A signal pattern comparison unit that compares the signal pattern of the baseband signal
The threshold control unit sets the threshold so that the signal pattern of the baseband signal determined by the H / L determination unit matches the signal pattern of the known pilot signal in the comparison result by the signal pattern comparison unit. A wireless transmission device that is automatically changed. The threshold control unit, for the baseband signal determined by the signal pattern comparison unit to match the signal pattern of the known pilot signal, has a high value and a low value detected at a predetermined read timing by the H / L determination unit. The wireless transmission device according to claim 1, wherein an average value is set as the threshold value. The threshold control unit, at a predetermined read timing for each bit by the H / L determination unit, for a plurality of baseband signals determined to match the signal pattern of the known pilot signal by the signal pattern comparison unit. The wireless transmission device according to claim 1, wherein the detected high value and low value are stored, and an average value of the stored minimum value of high value and maximum value of low value is set as the threshold value. Even if the threshold control unit changes the threshold value a predetermined number of times, the signal pattern determined by the H / L determination unit does not match the signal pattern of the known pilot signal in the comparison result by the signal pattern comparison unit The wireless transmission device according to any one of claims 1 to 3, further comprising a warning unit that issues a warning. A variable resistor inserted in a signal input line for transmitting a baseband signal output from the baseband unit to the H / L determination unit, and a resistance control unit for controlling a resistance value of the variable resistor; The wireless transmission device according to any one of claims 1 to 4, wherein: The resistance control unit controls a resistance value of the variable resistor so that a value obtained by subtracting a maximum value of the low value from a minimum value of the high value stored by the threshold control unit is maximized. The wireless transmission device according to claim 5. The wireless transmission device according to claim 1, further comprising a time management unit that manages a time at which the threshold control unit and / or the resistance control unit starts an operation. When the signal pattern determined by the H / L determination unit matches the signal pattern of the known pilot signal in the comparison result by the signal pattern comparison unit before the threshold control unit changes the threshold, The wireless transmission device according to any one of claims 1 to 6, wherein the threshold control unit and / or the resistance control unit does not start an operation. 9. The wireless transmission device according to claim 8, further comprising forcible operation starting means for forcibly starting the operation of the threshold control unit and / or the resistance control unit. A wireless transmission device according to any one of claims 1 to 9, and a wireless video transmission device including a camera device that outputs a video signal to the baseband unit,
A wireless reception device that receives a signal transmitted from the wireless transmission device; and a wireless video reception device that includes a video reproduction device that reproduces and displays a video based on the video signal received by the wireless reception device. A wireless video transmission system. A storage unit for storing a video signal output from the camera device;
The baseband unit adds the video signal stored in the storage unit as the known pilot signal to the baseband signal and outputs the signal to the H / L determination unit. The wireless video transmission system described.

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