Key Feature:
- Output 10MHz accuracy sine wave or square wave,low noise
- Output 1pps second pulse,sync with UTC time,can keep time.
- High sensitive GPS receive,small sky can lock.
- With lock inductor,red led off,equipment lock.
- Power is 12V/1.5A,simple easy,can used switch power
- Unexpensive,small valume,used convenient
- The unique removal of GPS signal jitter algorithm,higher accuracy
- LCD display GPS strength,time,output frequency

Overview: GPSDO name GPS disciplined oscillator,used GPS output accuracy time signal to control clock equipment.This equipment used GPS output 1 pps,control on board OCXO,used special algorithm to filter the GPS time jitter.make the OCXO output accuracy clock. always amend.board with LCD display gps strength,time and frequency deviation.

Parameter:
- NAME:LCD-GPS DISCIPLINED OSCILLATOR
- POWER:DC11.7-12.9V<=15W
- GPS ANT POWER:DC3.3V/50mA
- 1PPS OUTPUT:SQUARE WAVE,3.3Vpp
- 10M OUTPUT :SINE WAVE,1Vrms (10-15dBm),square wave,3.3/4.7Vpp
- RS232 OUTPUT:GPS NMEA SIGNAL
- ACCURACY: above than OCXO 2 order of magnitude
- SIZE:W*H*D=107*55*172mm(INCLUDE BNC CONNECT)

1.Work state led
ALM : warning,on,output frequency accuracy is low.
GPS LOCK:GPS lock inductor,while GPS lock,led on.
RUN: run indicator led,led flash,equipment is normal,If not flash,fault in equipment.
2.DB9 connect,output NMEA GPS flow.output 1PPS signal,RS232 level.
3.One pulse per second,BNC connected.from GPS module.rising edge is valid,
4.10MHz output,BNC connected,output sine wave or square wave.
5.Connect active GPS antenna,SMA connected.
6.External power connect,used 5.5mm/2.1mm DC plus.inside is positive,outside is negative,11.7-12.9V max 15W
6.Accessory is 5m active GPS antenna,DC12V/1.5A nnect GPS antenna,connect DC12V power supply.can output 10MHz standard frequency.

ATTENTION: must be used 5.5/2.1 DC plus,if used 5.5/2.5 will poor contact.

Front is a LCD,display machine state.
4.3 Connect PC
GPSDO-DB9        PC-DB9
PIN2--------------------PIN2
PIN3--------------------PIN3
PIN5--------------------PIN5
PIN8--------------------PIN8
GPSDO-DB9 PIN2,PIN5,PIN8 is connect to PC-DB9 PIN2,PIN5,PIN8,
Baud rate is  9600BPS,Baud rate is fixed.

4.4 Rear panel work state:
Power up : three led all on,all off,then RUN flash,GPS LOCK led off,WARN led on.
Power up current: less than 1.5 A.
Preheat: on board there is a OCXO,OCXO preheat need 30 minute.After a period of time,the current will slowly become small.Until GPS LOCK led on,WARN led off,means the equipment is normal
Normal: RUN led flash,GPS LOCK led on.WARN led off,means GPSDO running normal.When WARN led off,the accuracy is less than 0.05Hz@10MHz,keep GPS lock for 5 hours,the accuracy is less than 0.005Hz@10MHz.

4.5 Front panel LCD state:
Used 1602 LCD, display area there is two line,every line there is 16 character.
GPS signal strength display,First line 1,2 character,display GPS signal strength,first character is antenna mark,all display,second character is GPS signal strength,there is 6 step.from strength weak to strong is empty,1dot,2dots,2+3dots,2+3+4dots,2+3+4+5dots.
Character display area,6character,can via command to setting.
time display area, 8 characters,can via command setting
Disciplined state display,1 character,when system is accuary,display L,else not display.
Referenec output frequency display area,15 character.
Power up,LCD dots all on,then all off,check lcd is good or bad.
then display
GPSDO UTC +/- XX:XX display UTC offset
BG7TBL V20171210 display author and version
complete,enter normal display mode
If GPS not fix,LCD bottom will display GPS NO FIX

4.6 Display mode setting command
Setting display frequency mode,6 character,UTC offset,need short inside PCB jump.

Baud rate is 9600BPS,data bit 8,stop bit 1,Check bit NONE,flow control NONE.
Command is star with $GPGTC,end with T*,middle is 12 byte command.
 $GPGTC,X1  X2 X3 X4 X5 X6 X7 X8 X9 X10  X11 X12  T*
X1,setting display frequency mode,10000000.0000Hz,1,10M +/-0.0000Hz,2,10M +/-000.00ppb 3,10M +/-0.00000ppm
X2 X3 X4 X5 X6 X7 display 6 character.
X8 time offset,+/-
X9 X10 hour offset,max 23
X11 X12 minute offset,max 59

Example 1:display BJT,UTC+8,ppb,command is $GPGTC,2  BJT +0800T*
Example 2:display GMT UTC+0,display 10000000.0000Hz,command is $GPGTC,0, GMT +0000T*
Example 3,display EST-5,PPM,command is $GPGTC,3  EST +05:00T*
Command is OK,machine return OK.
connect db9,connect jumper.
com port setting,input command

4.7 Use notes:
LCD display frequency is reference only,there is deviation with actual output.
Gpsdo long time on line,the surface of the machine is warn, This kind of phenomenon is normal.
GPS antenna avoid interference,avoid high voltage,avoid lighting.put antenna to open sky.one line sky can lock,but the accuracy and jitter is worse.

Signal flow:1575M signal come from GPS antenna,input the GPS module,GPS output 1PPS and NMEA GPS lock signal.Used 1PPS for gate via CPLD and MCU output EFC signal,correct the OCXO output frequency.

FAQ:
1.Q : how can I know the machine is good.
  A : power on times,red led off,machine is good.

2. Q : how can I know MCU is good.
   A : when power on,all LED will on,then RUN led flash,red LED on,means MCU is good.

3. Q:5m GPS active antenna is short,how to do.can not connect GPS antenna?
   A : Used GPS extended line,such as 5m,10m,15m,20m extended line.can not used GPS antenna,it is a OCXO.

4. Q: i used frequency counter test frequency is difference with LCD display frequency,what can i do?
   A:LCD display frequency is reference only,actual test there is deviation.when LCD display L10000000.000xHz or other L frequency,frequency is accuary.Make sure test frequency standard is less than 0.001Hz accuary else is the frequency standard deviation.
   Q: GPS strength is change some time is high some time is low
   A:that is right,Because the signal intensity is affected by the satellite position,the weather and the Algorithm.

Package List:
- 1 x GPS disciplined clock
- 1 x AC110-220-DC12V ADAPTER
- 1 x 5 m GPS ANT