# Hi, Does know anybody how to make FM modulated signal in SIEMTRIX

#### michael1978

Joined Jun 29, 2014
309
Hello, can somebody help me how to make a fm modulated signal circuit in simetrix /simplis simulation

#### michael1978

Joined Jun 29, 2014
309
Hello can somebody help me, i search on the intnernet, there is a signal frequency and you need to define SFFM, but i dont know

#### Audioguru

Joined Dec 20, 2007
11,249
You will not see the tiny amount of FM modulation in a simulation or on an oscilloscope.
The maximum North American frequency deviation is only 75kHz which is less than 1 millionth of the 100MHz radio frequency.

#### michael1978

Joined Jun 29, 2014
309
You will not see the tiny amount of FM modulation in a simulation or on an oscilloscope.
The maximum North American frequency deviation is only 75kHz which is less than 1 millionth of the 100MHz radio frequency.
Hi Audioguru, do you see i ltspice you have a component am fm modulation, here i dont have, i have to select frequency modualtion index and some other frequency

#### michael1978

Joined Jun 29, 2014
309
THIS IS, i dont know how to put the right values….
An single frequency FM source may be entered in the Text Sheet of the Universal source using the syntax described below
This applies to both voltage and current sources

sffm ( VO VA [FC [MDI [FS ]]] )

VO Offset (Volts or amps) Compulsory
VA Amplitude (Volts or amps) Compulsory
FC Carrier frequency (Hz) Default if omitted or zero = 1/Stop time*
MDI Modulation index Default if omitted = 0
FS Signal frequency (Hz) Default if omitted or zero = 1/Stop time*
* Stop time is the time at which a transient analysis finishes. It is specified in the second argument of the .tran simulator control.

Defined by:
V(t) = VO + VA.sin[2.p.FC.t+MDI.sin(2.p.FS.t)]

#### michael1978

Joined Jun 29, 2014
309
You will not see the tiny amount of FM modulation in a simulation or on an oscilloscope.
The maximum North American frequency deviation is only 75kHz which is less than 1 millionth of the 100MHz radio frequency.
BUT how to do it, i gonna make amplifier

#### Audioguru

Joined Dec 20, 2007
11,249
I do not know what you are doing, and I do not know why you are doing it.
If it is for school work then ask your teacher to teach you how to do it.

#### michael1978

Joined Jun 29, 2014
309
I do not know what you are doing, and I do not know why you are doing it.
If it is for school work then ask your teacher to teach you how to do it.
is for my self, i dont go in school, please audioguru

#### michael1978

Joined Jun 29, 2014
309
aiiiii Man why you make so difficult, if you know let me know, o told you i am 40year, is my hobby

#### michael1978

Joined Jun 29, 2014
309
I do not know what you are doing, and I do not know why you are doing it.
If it is for school work then ask your teacher to teach you how to do it.

#### Audioguru

Joined Dec 20, 2007
11,249
I do not know anything about the SIEMTRIX simulation program and I do not know why you are trying to simulate an FM receiver circuit on it.

#### michael1978

Joined Jun 29, 2014
309
I do not know anything about the SIEMTRIX simulation program and I do not know why you are trying to simulate an FM receiver circuit on it.
I make if amplifer and local oscillator and i need to make rf amplifier, demudulation stage, and some tuned circuit,
but you know sffm is the same like other simulator, you need offset input v or a, carrier frequency index and signal stop,

#### Bordodynov

Joined May 20, 2015
2,642
See Simetrix:

See LTspice:

#### Bordodynov

Joined May 20, 2015
2,642
Unfortunately I could not get a good picture in SIMetrix. I have little experience in using SIMetrix. In LTspice it turned out all by itself.