[time-nuts] Fw: Homebrew frequency counter, need help

[Li Ang]

Thanks Tom,

The "front end" is still 75ALS176, but I put another simple transistor
circuit from wenzel to to compare the performance.
http://www.wenzel.com/wp-content/uploads/diffsqr.gif



2014-12-12 17:04 GMT+08:00, Tom Van Baak <tvb at leapsecond.com>:
> This large posting is from Li Ang.
> /tvb
>
> ----- Original Message -----
> From: Li Ang
> To: Discussion of precise time and frequency measurement
> Sent: Thursday, December 11, 2014 7:37 AM
> Subject: Re: [time-nuts] Homebrew frequency counter, need help
>
>
> Hi Bob,
>    I've sent the PCB to the factory and I am waiting for the new board. This
> time, it's a 4-layer borad and changed from CPLD to FPGA. This is the first
> time of FPGA & 4-layer project. Hope everthing be OK.
>    TPS79333 as the LDO for TDC. Better PSRR and noise spec than before
> (XC6206). Analog and digital parts have their dedicated LDO.
>
>
>    While I'm waiting the the new board. I did a test with PRS10 & FE5650
> with current board. It's strange that the 20s adev of "without linear
> regression" is better than "with linear regression".