Hi Today I did the same test without these 2 oscillators. The stddev on 20141228 data is 149ps. The stddev of today is 97ps. According to the new datasheet, stddev will be lower if set to 45ps resolution mode. I did that and got 76ps stddev. The datasheet does not lie to me :).
Data is uploaded to http://www.qsl.net/b/bi7lnq//freqcntv4/test/20150108/tdc_stddev.xls The configuration of tdc-gp22 is now: Register_0 = 0x00c42700, //Register_1 = 0x19498000, //stop2-stop1 Register_1 = 0x01418000,//0x01418000, //stop1-start, Register_2 = 0xe0000000, Register_3 = 0x00000000, Register_4 = 0x20000000, Register_5 = 0 << 27, Register_6 = 1 << 12; 2015-01-06 7:33 GMT+08:00 Li Ang <lll...@gmail.com>: > Hi Bob, > There are 2 oscillator on board, one 8MHz for MCU one 125MHz for FPGA. > I've took it down from the board, and changed MCU to use internal RC > oscillator for MCU and PLL to mutilply refclk to 200MHz for FPGA. > I will try do the same test tonight thanks. > > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.