JPH0865194A - Receiver - Google Patents

Abstract

PURPOSE: To protect the power supply circuit of a GPS receiver. CONSTITUTION: A current sensor 31 and a power switch 30 are provided between a power supply circuit 10 of a receiver body 23 and a connector 7 connecting to an antenna cable 5 and when a microcomputer 26 detects it that a current I is excessive, the power switch 30 is open to stop supply of power supply E to a preamplifier 3. Furthermore, a speaker 28 is used to output an alarm tone and an alarm voice signal. Thus, destruction of the power supply circuit 10 of the receiver body 23 is avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver suitable for application to, for example, a GPS receiver that receives radio waves from GPS satellites and specifies the reception position.

[0002]

2. Description of the Related Art FIG. 2 shows a configuration of a receiving device according to a conventional technique.

A receiving device 1 for receiving a weak electric wave transmitted from an artificial satellite such as a GPS satellite and demodulating the signal has an antenna 2, and a preamplifier 3 having a small noise figure is arranged directly below the antenna 2. Has been done. The preamplifier 3 actually has a module structure integrated with the antenna 2.

After the weak signal received by the antenna 2 is low-noise amplified by the preamplifier 3, it is, for example, 50Ω.
The down converter 8 via the system connector 4, the core wire of the antenna cable 5, and the 50Ω system connector 7 of the receiving device body 6.
Is supplied to the input side of. The output signal of the down converter 8 is supplied to the demodulation circuit 9, and the demodulation circuit 9 demodulates the signal.

On the other hand, the power supply circuit 1 is provided on the receiving device body 6 side.
0 is provided, and the power supply E (for example, +5 V DC) from the power supply circuit 10 is used as the down converter 8 and the demodulation circuit 9.
To the power supply terminal of the preamplifier 3 through the protective resistor 11, the high frequency cut-off impedance 12, the core wire of the antenna cable 5 and the high frequency cut-off impedance 13. It has become.

Coupling capacitors 14 and 15 for blocking direct current are inserted at the output side of the preamplifier 3 and the input side of the down converter 8, respectively.

As described above, the signal and the power source E are superimposed on the antenna cable 5 constituting the receiving device 1 in order to reduce the number of connecting lines connecting the receiving device main body 6 side and the antenna 2 side. Has been done.

[0008]

By the way, the antenna cable 5 which is a coaxial cable of 50Ω or the like is generally provided with a high frequency connector such as a BNC connector or an N type connector integrally at both ends thereof. There is. Therefore, for example, there is a possibility that the core wire of the antenna cable 5 and the ground wire (braided wire) are short-circuited at the connector portions.

Further, if the connector is not used, there is a possibility that the core wire side of the antenna cable 5 may be short-circuited to the ground side due to a connection mistake of the antenna cable 5 itself.

Furthermore, when an abnormality occurs in the preamplifier 3,
The resistance value between the power supply terminal and the ground terminal may become extremely small.

When such a short circuit between the core side of the antenna cable 5 and the ground side or an abnormality of the preamplifier 3 occurs, if the protective resistor 11 is not inserted, the power supply circuit 10 There is a risk that an excessive current will flow from the terminal to the ground side, reception will be interrupted, and in the worst case, the power supply circuit 10 will be destroyed and the receiving device body 6 will also fail.

However, as the protection resistor 11, for example, a power resistor of about several tens of Ω and about 2 W is used, and this power resistor has a larger volume than other circuit elements, and Since the weight is heavy, the receiving device main body 6
There was a problem that it became large and heavy.

Therefore, a small fuse is also inserted in place of the protection resistor 11. However, when the fuse is inserted, the preamplifier 3 is used after the fuse is blown.
Since the blown fuse must be replaced with a normal fuse when the normal condition is restored, the receiving device main body 6
There was a problem that the maintainability of was worse.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a receiving apparatus having a compact and lightweight protection circuit and having good maintainability.

[0015]

According to the present invention, for example, as shown in FIG. 1, a preamplifier 3 is connected to the output side of an antenna 2 for receiving radio waves, and the output side of the preamplifier 3 is received via a cable 5. In the receiving device which is connected to the down converter 8 of the device body 23 so that the power E is supplied from the power supply source 10 of the receiving device body 23 to the preamplifier 3 via the cable 5, the power supply source 10 and the cable 5 A current detection circuit 31 is provided between the power supply circuit and the power supply circuit, and the supply of the power supply E to the preamplifier 3 is stopped when an excessive current is detected.

Further, the present invention is characterized in that when the current detection circuit 31 detects an excessive current, the power supply E to the preamplifier 3 is stopped and the power supply to the down converter 8 is also stopped. .

Further, according to the present invention, the current detection circuit 31 is provided.
Temporarily stops the supply of the power source E, and then the current I
Is detected, and when the current I returns to the normal value, the supply of the power source E to the preamplifier 3 is restarted.

[0018]

According to the present invention, the current detection circuit is provided between the power supply source on the main body side of the receiver and the cable, and when an excessive current is detected, the supply of power to the preamplifier is stopped.

Further, according to the present invention, when the current detection circuit detects an excessive current, the power supply to the preamplifier is stopped and the power supply to the down converter is also stopped.

Furthermore, according to the present invention, the current detection circuit detects the current periodically after the power supply is once stopped, and when the current returns to the normal value, the current is automatically supplied to the preamplifier. The power supply is restarted.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the drawings referred to below,
Components corresponding to those shown in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows the configuration of the receiver 21 of this embodiment.

The receiving device 21 is a GPS receiving device,
Basically, the antenna module 22 and the receiver main body 23
And an antenna cable 5 for connecting them.
BNCP connectors are connected to both ends of the antenna cable 5, while the corresponding antenna module 22
Since the BNCJ connector is provided on the side of the receiving device main body 23 and the side of the receiving device main body 23, the antenna cable 5 is configured to be attachable to and detachable from the antenna module 22 and the receiving device main body 23. The BNCP connector and the B
The connectors to which the NCJ connectors are connected are referred to as connectors 4 and 7, respectively.

The power supply circuit 10 is arranged in the receiving device main body 23, and the input side of the power supply circuit 10 is supplied with + 12V power from a vehicle-mounted + 12V battery 25, for example.

The power supply circuit 10 supplies this + 12V voltage to +
The down converter 8 which forms the receiving device main body 23 by lowering it to a stabilized voltage of 5 V and using it as a power source E,
The signal is supplied to the demodulation circuit 9, the microcomputer 26 also serving as the power supply monitoring control means, and the display unit 27 including a liquid crystal display device or the like. The microcomputer 26 includes a CPU, a ROM in which a system program and an application program are stored, a work RAM, and other input / output interfaces such as an A / D converter. The RAM is backed up by the battery 29. A speaker 28 is connected to the microcomputer 26.

The power E supplied from the power circuit 10 is also supplied to the fixed contact 30b side of the power switch 30,
It is supplied to the input side of the current detection sensor 31 via the common contact 30a side of the power switch 30. The control contact 30c of the power switch 30 has a microcomputer 26
Is supplied with the switching signal S of the power switch 30.

The current detection sensor 31 may be, for example, a single low-power resistor having a small resistance value, and the voltage D across the resistor is an A / D (not shown) of the microcomputer 26.
By being converted into a digital signal by the converter, the value of the current I flowing through the current detection sensor 31 can be detected by the microcomputer 26.

When the preamplifier 3 is operating normally, the value of the current I supplied to the preamplifier 3 is about several mA to several tens mA, so that the current detection sensor 31 is used, for example.
2 to 20 times that, for example, a current I of 100 mA
The power switch 30 is immediately opened by the switching signal S when the microcomputer 26 detects that the current flows. In this case, when the resistance value of the current detection sensor 31 is selected to be 2.2Ω, for example, a 1 / 4W resistor is sufficient.

The power source E is a high frequency cutoff impedance 1
2. The signal is supplied to the power supply terminal of the preamplifier 3 through the signal terminal of the connector 7, the core wire of the antenna cable 5, the signal terminal of the connector 4 and the high frequency cutoff impedance 13. It should be noted that the high frequency cut-off impedances 12, 13
Is represented by a symbol of inductance, but it is sufficient if it is an element whose impedance is larger than the output impedance of the preamplifier 3 and the input impedance of the down converter 8 in the frequency band of the received signal. A resonant element or a band elimination filter may be used.

In the receiving device 21 configured as shown in FIG. 1, signals from GPS satellites are received by the antenna 2,
It is amplified by the preamplifier 3. The amplified signal is supplied to the down converter 8 through the coupling capacitor 14, the signal terminal of the connector 4, the core wire of the antenna cable 5, the signal terminal of the connector 7, and the coupling capacitor 15.

After the signal is further amplified by the down converter 8, it is frequency-converted and supplied to the demodulation circuit 9. The demodulation circuit 9 is a signal processing ASIC (application-specific IC).
The ASIC for signal processing is controlled by the microcomputer 26, and the latitude / longitude /
The altitude is displayed on the display unit 27 as needed.

While the main power switch (not shown) of the receiver main body 23 is turned on, the microcomputer 26 constantly monitors the value of the current I supplied to the antenna module 22 side through the current detection sensor 31. ing.

Therefore, if an abnormality occurs in the preamplifier 3, a short circuit occurs between the power supply path to the preamplifier 3 and the ground, or an erroneous connection occurs when the antenna cable 5 is connected, Current detection sensor 3
An overcurrent flows to the microcomputer 1, which is the microcomputer 26.
At the voltage D. When the overcurrent is detected, the microcomputer 26 opens the power switch 30 by the switching signal S to stop the supply of the power E to the preamplifier 3. As a result, the preamplifier 3, the current detection sensor 31, and the power supply circuit 10 are protected.

When the overcurrent is detected, the microcomputer 26 outputs a voice or an alarm sound through the speaker 28 and also displays on the display unit 27 that the overcurrent has occurred.

When an overcurrent is detected, the function of the receiving apparatus 23 relating to the receiving process is stopped. Therefore, a power switch is also inserted at the portion indicated by the symbol x in FIG. It is possible to switch by the control of 26. When an overcurrent is detected, the power switch, which is inserted together with the power switch 30 at the position indicated by the symbol x, is also opened so that useless power consumption of the battery 25 can be suppressed.

When the power switch 30 is open, the microcomputer 26 periodically closes the power switch 30 and the current detection sensor 31 detects the value of the current I. When the value of the current I has returned to the normal value, the power switch 30 is held in the closed state. At this time, if the power switch is inserted at the location indicated by the symbol x, the power switch is also switched to the closed state. As a result, the supply of the power E to the preamplifier 3 is restarted, the supply of the power E to the down converter 8 and the like is restarted, and the reception process of the reception device 21 is automatically restarted.

As described above, according to the above-described embodiment, the current detection sensor 31 as the current detection circuit is provided between the power supply circuit 10 which is the power supply source on the receiving device main body 23 side and the connector 7 connected to the antenna cable 5. The power switch 30 is provided, and when the microcomputer 26 detects an excessive current, the power switch 30 is opened to stop the supply of the power E to the preamplifier 3. Therefore, the power supply circuit 10 on the receiving device body 23 side is not destroyed. Since the current detection sensor 31 is smaller and lighter than the power resistor described in the section of the related art, the receiver main body 23 can be made smaller and lighter.

Although one small resistor is used as the current detection sensor 31 in the above-mentioned embodiment, for example, the current detection sensor 31 and the power switch 30 are replaced with a known current limit protection circuit. Good. As the current limit protection circuit, for example, one having a configuration in which a current sink transistor and a current detection resistor connected between the base and emitter of this transistor are provided on the input / output side of the power supply circuit 10 can be used. With this configuration, when the load of the new power supply circuit with current limiting protection circuit is short-circuited, a limited current flows, but the power switch 30 can be omitted. In this case, the value of the current I may or may not be detected by the microcomputer 26. This is because, if the short circuit of the load is resolved, the power supply circuit with the current limit protection circuit automatically recovers.

Further, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various configurations can be adopted without departing from the gist of the present invention.

[0040]

As described above, according to the present invention, the current detection circuit is provided between the power supply source on the main body side of the receiver and the cable, and when an excessive current is detected, the power is supplied to the preamplifier. I'm trying to stop. Therefore, the effect that the current supply source on the main body of the receiving device is not destroyed is achieved. In other words, it is possible to prevent damage to the receiving device itself. Further, since the current detection circuit is generally smaller and lighter than the power resistor, it is possible to achieve the effect of reducing the size and weight of the receiving device body.

Further, according to the present invention, when the current detection circuit detects an excessive current, the power supply to the preamplifier is stopped and the power supply to the down converter is stopped. The effect of saving the consumption of is achieved.

Further, according to the present invention, the current detection circuit detects the current periodically after the power supply is once stopped, and when the current returns to the normal value, the power is supplied to the preamplifier. Since the operation is restarted, it is possible to shorten the time from the failure to the recovery and to achieve the effect of improving the maintainability.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a receiving device according to a conventional technique.

[Explanation of symbols]

2 ... Antenna 3 ... Preamplifier 4, 7 ... Connector 5 ... Antenna cable 8 ... Down converter 21 ... Receiving device 23 ... Receiving device main body 26 ... Microcomputer 30 ... Power switch 31 ... Current detection sensor D ... Voltage E ... Power supply S ... Switching signal

Claims (3)

[Claims] 1. A preamplifier is connected to an output side of an antenna for receiving radio waves, an output side of the preamplifier is connected to a down converter of a receiving apparatus main body via a cable, and the cable is connected from a power supply source of the receiving apparatus main body. In the receiving device in which power is supplied to the preamplifier through, a current detection circuit is provided between the power supply source and the cable, and when an excessive current is detected, power is supplied to the preamplifier. A receiving device characterized by being stopped. 2. The supply of power to the preamplifier and the supply of power to the down converter are stopped when the current detection circuit detects an excessive current. Receiver. 3. The current detection circuit, after temporarily stopping the power supply, periodically detects the current, and when the current returns to a normal value, restarts the power supply to the preamplifier. The receiving device according to claim 1 or 2, characterized in that: