CN202210157U - GPS (Global Position System) receiving circuit - Google Patents
GPS (Global Position System) receiving circuit Download PDFInfo
- Publication number
- CN202210157U CN202210157U CN2011203481043U CN201120348104U CN202210157U CN 202210157 U CN202210157 U CN 202210157U CN 2011203481043 U CN2011203481043 U CN 2011203481043U CN 201120348104 U CN201120348104 U CN 201120348104U CN 202210157 U CN202210157 U CN 202210157U
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- gps
- signal
- optocoupler
- receiving circuit
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Abstract
The utility model discloses a GPS (Global Position System) receiving circuit. The GPS receiving circuit is characterized in that a GPS+ signal is connected with a pin 1 of the input end of an optical coupler D1 through a serial limiting resistor and a serial voltage-regulator tube V1, wherein the limiting resistor comprises a resistor R1 and a resistor R2 which are in parallel connection with each other; a GPS- signal is connected with a pin 2 of the input end of the optical coupler D1; a jumper X1 is in parallel connection with the voltage regulator tube V1; a bidirectional transient suppression diode T1 is connected between the GPS+ signal and the GPS- signal; and a diode V2 is in parallel connection between the pin 1 and the pin 2 of the optical coupler D1; an electrode A of the diode V2 is connected with the pin 2 of the optical coupler D1, and an electrode K of the diode V2 is connected with the pin 1 of the optical coupler D1. The GPS receiving circuit can receive a dead contact signal or an RS485 signal of a GPS time synchronization device, can convert the dead contact signal or the RS485 signal into a CMOS (Complementary Metal-Oxide-Semiconductor Transistor) level accepted by a CPU (Central Processing Unit), therefore, an RS485 interface chip and an isolation DC (direct current)-DC chip are not needed, so that the cost is saved, and the GPS receiving circuit is novel.
Description
Technical field
The utility model relate to GPS to the time technical field, relate in particular to a kind of GPS receiving circuit.
Background technology
GPS to the time device to the time interface mainly contain two kinds of RS485 mode and idle contact (active 24V) modes by Physical layer.
The RS485 mode is that all devices are hung on the RS485 bus, the GPS device regularly (when generally being whole second) level change pulse through differential lines A (+) and B (-) to device send to the time signal.
The idle contact mode is the contact point signal that is similar to relay, the GPS device to the time contact output and every table apparatus to the time input connect one to one.The idle contact mode can not be born high voltage, general require be 24V open into.
Usually, the input circuit of GPS for adapt to above-mentioned two kinds to the time mode need design two kinds of circuit, a kind of 24V of being opens into circuit, another kind is to isolate 485 circuit.Not only need take circuit board than large space, and circuit cost is higher.
The utility model content
For addressing the above problem, the utility model aim to provide a kind of can adapt to two kinds to the time mode the Novel GPS receiving circuit.
For realizing above-mentioned purpose, the utility model has adopted following technical scheme:
A kind of GPS receiving circuit; The GPS+ signal is received optocoupler D1 input end 1 pin through series limiting resistor and series connection stabilivolt V1; Said current-limiting resistance comprises the resistance R 1 and resistance R 2 that is in parallel, and the GPS-signal is received optocoupler D1 input end 2 pin, and wire jumper X1 is parallelly connected with stabilivolt V1.For improving antijamming capability; Between GPS+ and GPS-, be connected a two-way Transient Suppression Diode T1, damage optocoupler D1 for preventing reverse voltage, between 1,2 pin of optocoupler D1 and a diode V2; The A utmost point of diode V2 connects 2 pin of optocoupler D1, and the K utmost point of diode V2 connects 1 pin of optocoupler D1.
3 pin of said optocoupler D1 meet GND, and 4 pin of optocoupler D1 are received 5V through pull-up resistor R3.In order to improve antijamming capability; 4 pin of said optocoupler D1 are received 2 pin of Schmidt trigger D2 (5V power supply); Output pin 4 pin of Schmidt trigger one D2 are received 2 pin of Schmidt trigger two D3, and convert the 3.3V level signal to and give CPU through series termination resistance R 4 through 4 pin of Schmidt trigger two D3.
In the foregoing circuit, supply pin 5 pin of Schmidt trigger D2 meet 5V, and meet GND through decoupling capacitor C1, and 3 pin of Schmidt trigger one D2 meet GND.
In the foregoing circuit, supply pin 5 pin of Schmidt trigger two D3 meet 3.3V, and meet GND through decoupling capacitor C2, and 3 pin of Schmidt trigger two D3 meet GND.
The beneficial effect of the utility model is: adopt optocoupler to receive the RS485 differential signal, can adapt to different to the time mode, saved isolation DC-DC, 485 interface chips etc., make circuit simplify more, improved reliability, saved plate area and cost.
Description of drawings
Fig. 1 is the schematic diagram of the GPS receiving circuit of the utility model;
Fig. 2 is the differential output voltage of RS485 interface chip SN75LBC184 and the graph of a relation of output current;
Fig. 3 is the LED side voltage of optocoupler TLP114A, the graph of a relation of electric current;
Fig. 4 is the graph of a relation of optocoupler TLP114A forward current and current transfer ratio.
Embodiment
Below in conjunction with accompanying drawing the embodiment of the utility model is done further explain.
Shown in accompanying drawing 1, be to adopt optocoupler to receive the RS485 differential signal in essence.Common 24V opens the RS485 differential signal that can not be used for receiving 5V into circuit, because in order to improve antijamming capability, generally can go here and there the stabilivolt of a 12V.This programme is employed in the method for stabilivolt two ends parallel connection wire jumper X1, when need receive 485 signals, with wire jumper X1 short circuit.Two important performances are arranged during signal when adopting this circuit to receive the RS485 differential pair: 1) to the time precision; 2) what devices GPS device RS485 interface can connect.Wherein, The 1st performance (to the time precision) depend on that adopting high speed photo coupling still is common optocoupler; And only depend on negative edge, high speed photo coupling (like TLP114) the signal negative edge time is less than 0.3 μ S, and the negative edge time of common optocoupler (like TLP127) is less than 20 μ S; But, the 2nd performance had certain influence because the current delivery of high speed photo coupling is smaller.The 2nd performance depends on the resistance of driving force, optocoupler parameter and the series limiting resistor of GPS device RS485 interface.
Explain with instance how the 2nd performance derives at present.For example, series limiting resistor R1, R2 all get 2K, ± 5%, 2010 packaged resistances, and GPS device RS485 interface uses SN75LBC184, and optocoupler uses TLP114A.Accompanying drawing 2 is the relation of SN75LBC184 differential output voltage and output current.Existing derate is used, and VCC gets 4.5V, and output current is got 20mA, and then differential output voltage is about 2.3V.Accompanying drawing 3 is the LED side voltage of TLP114A, the relation of electric current, I
FWhen electric current is 1mA, V
FWorst case is 1.3V, then I
F=2.3-1.3/1000=0.001 (A).
When getting 20mA, the RS485 output current can drive 20 such receiving circuits.
Accompanying drawing 4 is the graph of a relation of TLP114A forward current and current transfer ratio, I
FWhen electric current was 1mA, current transfer ratio was greater than 20%, and derate 50% is calculated I by 10%
0=0.1mA, then resistance R 3 ≈ 5/0.0001=50000 Ω=50K Ω.
Optocoupler output signal is in order to improve noise margin, to strengthen antijamming capability, through giving CPU again after the simple gate Schmidt trigger SN74LVC1G17 shaping.
The foregoing description is technical conceive and the characteristics for the utility model is described just, and its purpose is the content that lets the one of ordinary skilled in the art can understand the utility model and implements according to this, can not limit the protection domain of the utility model with this.The variation or the modification of every equivalence of having done according to the essence of the utility model content all should be encompassed in the protection domain of the utility model.
Claims (4)
1. GPS receiving circuit; It is characterized in that: the GPS+ signal is received optocoupler D1 input end 1 pin through series limiting resistor and series connection stabilivolt V1; Said current-limiting resistance comprises the resistance R 1 and resistance R 2 that is in parallel, and the GPS-signal is received optocoupler D1 input end 2 pin, and wire jumper X1 is parallelly connected with stabilivolt V1; Between GPS+ and GPS-, be connected a two-way Transient Suppression Diode T1; Diode V2 of parallel connection between 1,2 pin of optocoupler D1, the A utmost point of diode V2 connects 2 pin of optocoupler D1, and the K utmost point of diode V2 connects 1 pin of optocoupler D1.
2. GPS receiving circuit according to claim 1; It is characterized in that: 3 pin of said optocoupler D1 meet GND; 4 pin of optocoupler D1 are received 5V through pull-up resistor R3; 4 pin of said optocoupler D1 are received 2 pin of Schmidt trigger one D2, and output pin 4 pin of Schmidt trigger one D2 are received 2 pin of Schmidt trigger two D3, and convert the 3.3V level signal to and give CPU through series termination resistance R 4 through 4 pin of Schmidt trigger two D3.
3. GPS receiving circuit according to claim 1 is characterized in that: supply pin 5 pin of Schmidt trigger one D2 meet 5V, and meet GND through decoupling capacitor C1, and 3 pin of Schmidt trigger one D2 meet GND.
4. GPS receiving circuit according to claim 1 is characterized in that: supply pin 5 pin of Schmidt trigger two D3 meet 3.3V, and meet GND through decoupling capacitor C2, and 3 pin of Schmidt trigger two D3 meet GND.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011203481043U CN202210157U (en) | 2011-09-16 | 2011-09-16 | GPS (Global Position System) receiving circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011203481043U CN202210157U (en) | 2011-09-16 | 2011-09-16 | GPS (Global Position System) receiving circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202210157U true CN202210157U (en) | 2012-05-02 |
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ID=45989701
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011203481043U Expired - Lifetime CN202210157U (en) | 2011-09-16 | 2011-09-16 | GPS (Global Position System) receiving circuit |
Country Status (1)
| Country | Link |
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| CN (1) | CN202210157U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102680757A (en) * | 2012-05-11 | 2012-09-19 | 蔡远文 | Multi-channel digital signal isolation, conditioning and acquisition device |
| CN107765754A (en) * | 2017-09-29 | 2018-03-06 | 南京国电南自电网自动化有限公司 | A kind of adaptive time setting circuit of incoming level |
-
2011
- 2011-09-16 CN CN2011203481043U patent/CN202210157U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102680757A (en) * | 2012-05-11 | 2012-09-19 | 蔡远文 | Multi-channel digital signal isolation, conditioning and acquisition device |
| CN107765754A (en) * | 2017-09-29 | 2018-03-06 | 南京国电南自电网自动化有限公司 | A kind of adaptive time setting circuit of incoming level |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term |
Granted publication date: 20120502 |
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| CX01 | Expiry of patent term |