From the shipping on Dec. 1st, GPS module will be NEO-7M, one after generation to NEO-6M.

Note for this item: In the image, you can see U4 (down from u-blox module) is vacant and you may think this board is without non-volatile memory (or I've forgot to put one), but it is not true. IC3 is EEPROM and indeed I prepare two types EEPROM wiring pattern for different EEPROM shape. Also the backup battery holds the setting inside u-blox module, not external setting. Please don't worry about it...

Another note: On PCB, two thin wire jumper can be seen, but the PCB of this image is not for sale but my initial prototype. The item for sale (shipped one) is carefully cared by epoxy and from the shipping on Oct 15, PCB is jumper-wireless. (made by second revision PCB). Please don't worry about it...

If have some difficulty, please contact me with tindie's messaging system. I've guided to make it work 100% customer.

What is it?

Super high precision GPS trained frequency standard (signal generator), which can provide arbitral frequency from 1 MHz to 200 MHz with 4-output. This is the most practical item I've ever made. Any 70's 80's 90's and up-to-date time domain related instrument (VNA, SPA, oscilloscope, SG) with 10 MHz input will get the atomic clock precision from GPS by ultra low cost!

Why did you make it?

My previous item is quite handy and portable and reliable for frequency measurement less than 4 MHz. But you may already have frequency counter, spectrum analyzer, vector network analyzer, oscilloscope, or something which has 10 MHz input on the back panel. Each of professional measurement instrument has TCXO but they has "aging" and it may be unreliable after 30 years from production. This item will refresh your instrument with "atomic clock precision" given by GPS signal!

What makes it special?

• Four output signals are independently programmable. The frequency is generated by PLL IC (Silicon Labs Si5356 with GPS trained 8 MHz clock), and its output is programmable from 1 MHz to 200 MHz. Programming details is available from Application note of Si5356 Silicon labs's software Clock Builder Pro will automatically generate register values for your frequency configuration and copying them to Arduino source will provide the signal of your demand!

• Default firmware supports 10, 20, 30, 40 MHz high precision signal output. The firmware is written in onboard ATmega88PA with Arduino sketch released in my GitHub account

• Onboard Lipo battery charger enables portable application. USB-bus power operation is also supported.

• Output waveform is 3.3 V square wave (mainly good for digital clock). If sine-wave preferred for analogue application, harmonics suppression required.

Phase noise is around -75dBc/Hz at 10MHz. More details are available at my Hackaday log.

What is included in this item

• Fully tested and initial firmware (10, 20, 100, 200 MHz output) loaded GPS trained signal generator board.

• Two stage LNA embedded active GPS antenna (3m cable, IP67, embedded amplifier: MAX2659 two stage, Gain 28dB / NF <1.5dB)

What is NOT included in this item

• Lipo battery. It is not essential for operation for USB bus power mode but you may need it for portable application

Precaution of the operation NEO6M (GPS module) generate 8MHz even before GPS locking (with low precision) and after GPS clock capturing, it goes to atomic clock precision!. Please wait for a while for getting locked to atomic clock precision for your operation. (If the attached GPS antenna is put on the windows side, it will lock in a few minutes.)

u-blox's NEO6M utility "u-center" is available at https://www.u-blox.com/en/product/u-center By which 8MHz 50% duty ratio clock generation setting can be done at TP5 register of NEO6M.

If have some difficulty, please contact me with tindie's messaging system. I've guided to make it work 100% customer.