ATV 10GHz FREQUENCY COUNTER USING AN LNB
Some of the LNB we can get hold of at Car Boots have a more chance of working than ones bought at Radio Rallies from my experience. And you can put these to good use as a very simple frequency counter. By changing the Puck in the LNB to a 9.1GHz one you then get out a freq IF of about 900 to 1400MHz at a level of 1m/W for an RF input of 10,000 to 10,500MHz and at u/W sensitivity. You only need to sniff the RF at 10GHz and off you go....Some of the Frequency Synth chips have an input counter some times Div by 256 and you can get at the output if you program them correctly. So if you divide down the IF you get a frequency of ,over the range above, 3.515625Mhz to 5.468750MHz .....So all I had to do was to feed this into a device that would work all the calculations and Display it..... And I like PIC16F84's and Serial LED Displays so it was just that but some wise guy may say a PIC cannot go that fast even with 10MHz Xtal its internally divided by 4 so the software cannot cope with this speed....If you take the "T" off "CANT" you "CAN" and here is how use the internal pre-scalar and let that interrupt the u/P its got nothing else to do!..... So its let it do just that for say a one second period then you have a RESULT value that is related to frequency at 10GHz..... This RESULT is then Converted and Shown on the 8 DIGIT LED Display..... Sounds simple but it took a few days overcoming software problems... The hardest thing for me was making small PCB with my then Pen Plotter and fitting the surface mount chips I am 55 years old and my eyes are not as good as when I was 20 years old..... A good magnifying Lamp was the answer and a tinny soldering iron... There is drift on switch on of the LNB but for ATV use that's nothing because we only need to know to within say 100KHz anyway......
Just two chips MC145190/1 and the usual PIC16C84.............. G3RFL