JPH1168636A - Wireless image transmission repeater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend a transmission distance by arranging a repeater having a memory between the side of transmission and the side of reception, and transmitting a received signal at the next time after storing it for a fixed time. SOLUTION: Image signals and audio signals provided by monitor cameras 1-1 to 1-n5 are sent out of transmitters TX-1 to TX-n of 2.4 GHz band spectrum spreading system, received by a receiver RX, demodulated to image signals and monitored by a monitor. In this case, repeaters RP-1 to RP-n are installed while being combined with the transmitter TX-1, and peculiar ID numbers are set. Then, these repeaters are operated to connect a line when an ID signal in a control signal from the receiver RX is coincident. Therefore, the repeaters RP-1 to RP-n are turned from continuous reception standby state to active state for repeating reception and transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repeater for extending a transmission distance of image radio transmission.

[0002]

2. Description of the Related Art Conventionally, in order to transmit an image of a surveillance camera installed at a distant place to a surveillance point on a receiving side, any of wired, wireless and optical communication methods has been used.

[0003] In the wireless system, the spread spectrum system is firstly resistant to multipath fading. Second, it is resistant to interference and noise. Third, there is little interference with other communication signals.

[0004] Although there are features such as the above, the current permission condition by the Radio Law is that the antenna output is limited to 10 mW / MHz or less in the frequency band of 2.4 GHz. For this reason, the transmission distance is limited to about 1 km (depending on the amount of data, but 30 screens / second).

[0005] Therefore, in general, retransmission is performed by changing the frequency using a repeater. However, in the spread spectrum system, the permitted bandwidth is occupied by one wave, and this method is considered impossible. Become.

Further, if there is an obstacle between the two points of transmission and reception, the distance is shortened depending on the degree of the obstacle, making it impractical.

[0007]

The above-mentioned prior art has a disadvantage that the transmission distance is limited.

[0008] It is an object of the present invention to eliminate these drawbacks and to provide a technique capable of extending the transmission distance.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention arranges a repeater having a memory between a transmitting side and a receiving side so that a transmission distance may be short, an interfering radio wave or an obstacle may be prevented. This is to solve the problem when there is something.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows an example of a remote monitoring system. Image signals and audio signals obtained by the monitoring cameras 1-1 to 1-n5 are transmitted in a 2.4 GHz band spread spectrum type transmitter T.
Transmitted from X-1 to TX-n, received by the receiver RX, demodulated into image signals, and monitored by a monitor. But,
The transmission distance is limited because the transmission power is limited due to the provisions of the Radio Law. If there is an obstacle or the like between the sending and receiving points due to the terrain such as a building such as a building or a mountain, the transmission becomes possible via the repeater (hereinafter referred to as a repeater) of the present invention.

[0012] Repeater RP-1 to transmitter TX-1
To RP-n, and a unique ID number is set. ID in control signal from receiver RX
An operation is performed so that the line is connected when the signals match.

Therefore, the repeaters RP-1 to RP-n enter an operation state of repeating reception and transmission from the continuous reception standby state.
FIG. 2 shows a block diagram of the repeater. In the figure, 2
Is a memory, 3 is a controller, 4 is a transmission circuit, 5 is an antenna,
Reference numeral 6 denotes a switch (hereinafter, referred to as SW), and reference numeral 7 denotes a receiving circuit. The control signal sent from the receiving side via the antenna 5, the image data from the transmitting side to which the monitoring camera is connected, or the status data is taken into the memory 2 for a certain period of time, and the transmission / reception switching command generated by the controller 3 is received. Receiving S
W6 is in a transmission state, and transmits the image data and status data read from the memory 2 from the antenna 5 to the receiver side.

An example of a specific data structure is shown in the data format of the image transmission apparatus in FIG. The various operations described above can be realized by the four data formats shown in FIG.

7 is a control transmission (RX → RP.T)
X), the format is set to the type code 1, and is composed of a total of 10 bytes of the ID number of the monitoring location zone, the ID number of the transmitting receiving side, the spare, and 16 bits of data.

Numeral 8 denotes a transmission request (RX → RP.TX), which is a type code 2 and has an ID number of a monitoring location zone, an ID number of a transmitting receiving side, a spare, 16 bits of data, a compression coefficient setting, and a total of 11 Consists of bytes.

9 is status data (TX / RP → R)
X), the type code 3 is composed of a receiving side ID number, an ID number of the monitored transmitting side, a spare, data bits, and a total of 7 bytes.

Reference numeral 10 denotes image data (TX / RP → RX)
The type code is 4, and the ID number of the receiving side, the ID number of the transmitting side being monitored, the spare, the data of 4 bits, the compression coefficient,
It consists of a total of 8 bytes of image data plus image data.

[0019]

As described above, the combined use of the repeaters can increase the distance between transmission and reception.
In the description so far, an example in which one repeater is used per line has been described. However, by using a plurality of repeaters in a series, the transmission distance can be further increased.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a remote monitoring system according to the present invention.

FIG. 2 is a block diagram of a repeater showing an embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating a specific example of a data format of an image transmission device according to an embodiment of the present invention.

[Explanation of symbols]

TX-1 to TX-n: transmitter, RX: receiver, RP-1
ＲＰRP-n: repeater (repeater).

Claims (2)

[Claims] A system for wirelessly transmitting a single signal or a combination of a plurality of transmission signals such as an image signal, an audio signal, and a control signal. A wireless transmission repeater that operates so as to be in a transmission state, stores a received signal for a predetermined time, and transmits the signal at the next time. 2. The repeater according to claim 1, wherein the repeater operates by receiving a designation from among a plurality of repeaters under the control of the receiving side, and outputs and transmits at the same frequency as the transmitter.