I test a counter usually against my 10 Mhz rubidium source.
Neither a cheap 1 Ghz counter from China nor a self built counter built around pic micro controller produced good results. They were way of,...
This new project which I found on the Elektor homepage raised my curiosity.
Usually I don't like Eektor projects that much, they tend to use the most expensive components but then deliver a mediocre circuit that does not make use of all the bells and whistles this components could deliver. On the other hand I like the magazine and always hope this time they hit gold.
First for pre scaling (dividing the input signal down) it uses a cheap pll chip instead of an expensive dedicated pre scaler. (nice!)
Second as counter it uses a CPLD device and provides the VHDL (Verilog hardware description language) sources.
Third it uses a 0.5 ppm crystal oscillator as reference.
Forth it can measure the power level but unfortunately only within an accuracy of 4 db (if the frequency is modulated). I can live with that, power meters almost always have trouble with modulated sigbak sources .
I ordered an empty pcb, luckily I already ad most of the needed parts in my lab.
In the build process I first populated the most difficult parts like the qfn power detector, the input amplifier and than the rest of the integrated circuits.
Then I soldered the passive components.
Afterwards the big components like the display were soldered.
Before power up I checked for short circuits.
Next step is programming the Cpld and the Dsp about which I will tell you in another blog post.
|Counter function blocks|
2) Dc input
3) Battery input
4) Input splitter (Log detector, Counter)
5) Log Detctor
7) Pll (prescaler)
9,10) Linear regulators
12) Polyfuse circuit protection
13) Jtag disable
14) Jtag (Busblaster programmer input)
15) Icd (Dsp programmer input)