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Topic: FM modulation device (Read 1 time) previous topic - next topic

charlieamer

Nov 03, 2013, 06:47 pm Last Edit: Nov 03, 2013, 06:50 pm by charlieamer Reason: 1
Hi. I would like to have a device that would modulate analog signal by Frequency Modulation. I know there are a lot of devices like this, but, I need to make it so that you can switch between 333MHz and 433MHz programatically/electronically, during runtime, without a need to rewire something, etc. Is there such a device ? And how hard is it to make one myself ? Thank you for your help.

EDIT: Perhaps the best would be a device in which you put ANY clock source as carrier wave, and analog value, and it magically spits out modulated signal.

LMI

I am not sure what it is you want to do. 434MHz is part of the ISM band (and HAM band too). ISM transceivers let you choose either 433-434MHz band or 968 band. And maybe some other bands too.
But what about the FM modulator? This large change of frequency is not usually called modulation. With ISM transceivers you don't have care about modulation, and you really should not, because you may cause interference to others.

This is best I can do without a crystal ball and some magic.

charlieamer

Maybe u didn't understand me very well. I wanted to have fm modulator that will be able to send voice sometimes on 333MHz center frequency, and sometimes on 433MHz.

LMI

Last time I checked, it was illegal to transmit voice on ISM band. Radio amateurs have a permission to do it on their bands or frequencies. You should check your local authorities what is possible and what not. Or became a radio amateur, a Ham.

TransWarp

Ham I am.

Keep away from 333 MHz or you may get shot by Anti-Terror Forces if you harm or jam Avionic Radio Signals !
("There must be a Terrorist who attacks an Airplane"...)

It's a hard project, and for what distance and bandwidth? (Quality of voice)

May an Radio- or Bluetooth Headset do the Job ?

charlieamer


Ham I am.

Keep away from 333 MHz or you may get shot by Anti-Terror Forces if you harm or jam Avionic Radio Signals !
("There must be a Terrorist who attacks an Airplane"...)

It's a hard project, and for what distance and bandwidth? (Quality of voice)

May an Radio- or Bluetooth Headset do the Job ?

Well ... I wanted to communicate directly 2km away (1.5mile). I thought if I use satellite dish, I will not bother anyone, just to pick a right frequency. I thought 333MHz and 433MHz were radio amateurs' frequency. What are your thoughs ?

LMI

#6
Nov 05, 2013, 08:43 pm Last Edit: Nov 05, 2013, 08:48 pm by LMI Reason: 1
I think there are some approved/legal modules for long distance data transfer. They work around 2,4GHz I think. But 1.5km is a long distance.

By the way, this is an Arduino forum. This has had very little to do with Arduinos so far. You could check other Arduino forums too, like Project Guidance and so on. And try Googling with some magic words like "long distance radio module" or something similar.

Edit: And how about starting a new thread with subject "long distance communication? Your current subject has nothing to do with what you actually wish to do.

TransWarp

Well just buy two CB-Radios, they can also transmit Data (Packet Radio).
If you can see the antenna, even PMR-Walky Talkies will work.
(If legal in your country)

Maybe there are other ways to do this ? GSM-Shield, Voice over Infrared, Internet, etc. ?

jomac_uk

As far as im aware, voice IS allowed on certain channels on the 433Mhz band, certainly in Europe

cjdelphi

http://m.ebay.com.au/itm/201002484579?nav=SEARCH&sbk=1

One day I'm going to use one of these on an  antenna  and drive off seeing how far it will go ..

jomac_uk

With the correct antenna, many kilometres, the world record for distance between 2 standard wifi units and high gain antenna's is over 300Kms. Ive built many systems using standard but modified 100mw wifi dongles built into high gain antenna's and had reliable wifi links in excess of 10Kms

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