PLL VCO
 

hi
can anyone help me. I am using a crystal control PLL. The PLL chip
contains Phase detector, charg pump loop filter, and VCO and divider
feedback to phase detector. Now I would like to use another signal
(audio) and modulate the two and transmite. my only problem is cannot
figure out what to use to modulate the two signals. Please if you have
any suggestion help.

PLL VCO
 

veck wrote:
hi
can anyone help me. I am using a crystal control PLL. The PLL chip
contains Phase detector, charg pump loop filter, and VCO and divider
feedback to phase detector. Now I would like to use another signal
(audio) and modulate the two and transmite. my only problem is cannot
figure out what to use to modulate the two signals. Please if you have
any suggestion help.



You need to decide if you want AM, FM or PM.

PLL VCO
 

On 16 Mar 2007 18:19:26 -0700, "veck" wrote
in .com:

hi
can anyone help me. I am using a crystal control PLL. The PLL chip
contains Phase detector, charg pump loop filter, and VCO and divider
feedback to phase detector. Now I would like to use another signal
(audio) and modulate the two and transmite. my only problem is cannot
figure out what to use to modulate the two signals. Please if you have
any suggestion help.


The Philips datasheet for the 4046 includes a really good primer on
PLL circuits. I suggest you start there.

PLL VCO
 

On Mar 16, 8:19 pm, "veck" wrote:
hi
can anyone help me. I am using a crystal control PLL. The PLL chip
contains Phase detector, charg pump loop filter, and VCO and divider
feedback to phase detector. Now I would like to use another signal
(audio) and modulate the two and transmite. my only problem is cannot
figure out what to use to modulate the two signals. Please if you have
any suggestion help.

The simple method is to use a high-level modulation scheme... probably
with a transformer. This is commonly done in CB radios. Try Googling
"high level modulation". This should put you on the right track.

www.telstar-electronics.com