Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Is audio FM transmitter different from normal FM transmitter?

Status
Not open for further replies.
S

SeungminLee

Junior Member level 2
Joined
Jun 14, 2010
Messages
21
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,281
Location
Seoul
Activity points
1,447
Hi,

While finding FM module, I found audio FM transmitter which fits my demand.

however, that module is designed for audio use.

is it differnet from normal FM transmitter?

i'm trying to transmit 16bit AD-converted signal.

thank you in advance.
 

An audio FM transmitter will use linear modulation, in other words, the frequency is shifted according to the amplitude of an analog signal fed into it.
For digital use the transmitter may be still be frequency modulated but it is only necessary to have one frequency for binary '0' and one frequency for binary '1'.
As with any modulated transmission, other frequencies are generated as the carrier moves.
For your digital transmission, a digital input transmitter module is what you need, not an analog one.

Brian.
 

Audio FM transmitter for mono signal normally has 15kHz lowpass filter on audio input and 100kHz for stereo. For digital signal if you want FM you can use FSK modulation what betwixt described. FSK modules RX and TX or transceivers are cheap and available on market.
 

A stereo FM transmitter would have the same audio bandwidth as mono - around 15kHz, not 100kHz. The difference with stereo is that the left-right channels would be modulated on to a 38kHz subcarrier with the subcarrier suppressed and a 19kHz tone transmitted .

Keith

---------- Post added at 22:36 ---------- Previous post was at 22:35 ----------

en.m.wikipedia.org/wiki/FM_broadcasting?wasRedirected=true
 

FM transmitter for stereo MPX must have 100kHz modulation bandwidth and 0.1db gain flatness to assure -40dB crosstalk between audio channels etc. That is what I am talking about and not about audio channel bandwidth which is 15kHz for L and R.
Sorry but you are both ignorants. Look at composite baseband spectrum on above wiki link.
 
Last edited:

You said audio bandwidth is filtered to 15kHz for mono and 100kHz for stereo. That is incorrect. The transmitted bandwidth is a different matter, but that isn't what you said. Being abusive doesn't correct your mistake.

Keith
 

Audio FM transmitter for mono signal normally has 15kHz lowpass filter on audio input and 100kHz for stereo. For digital signal if you want FM you can use FSK modulation what betwixt described. FSK modules RX and TX or transceivers are cheap and available on market.
I meant FM transmitter modulation bandwidth and calling it audio input is wrong. Actually it is modulation imput whose parameters are different for mono and stereo transmission. When in mono mode it has 15kHz filter and in stereo mode it is flat up to 100kHz.
 
Last edited:

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top