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Forum Index : Microcontroller and PC projects : Decoding FSK on MM

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OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 982
Posted: 12:18am 11 Apr 2012
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Do you think that it is possible to decode 75 bps FSK with a mite? My initial investigations show that the frequency measurement takes a long time and may not be responsive enough to grab each frequency change even at 75 bps.
 
vk4tec

Senior Member

Joined: 24/03/2012
Location: Australia
Posts: 239
Posted: 09:07am 11 Apr 2012
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It might be ok with an extrenal PLL ? I know a simple cct can be used to do RTTY like my grandad did.

You lock onto a tone and then the PLL gives a zero or a one for FSK.

75 bps should be easy as with the PIC32

Andrew Rich VK4TEC

NE567 ?
Andrew Rich VK4TEC
www.tech-software.net
 
djuqa

Guru

Joined: 23/11/2011
Location: Australia
Posts: 447
Posted: 09:21am 11 Apr 2012
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MM-FSK sounds like a Great project
Let's start looking at the options
VK4MU MicroController Units
 
OA47

Guru

Joined: 11/04/2012
Location: Australia
Posts: 982
Posted: 09:33am 11 Apr 2012
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Djuqa, I am currently producing the FSK using one mite by tying the RS232 TX to 2 digital I/p and sensing the pulse rise or fall and producing the appropriate frequency.

Best Regards
 
vk4tec

Senior Member

Joined: 24/03/2012
Location: Australia
Posts: 239
Posted: 09:38am 11 Apr 2012
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I can think of many ways to interface with external pll circuit

You could use mixw32 to make rtty or psk signals

I have some easyradio modules I need to integrate as well

434 MHz 100 mw

Andrew
Andrew Rich VK4TEC
www.tech-software.net
 
ThierryP
Newbie

Joined: 12/04/2012
Location: Netherlands
Posts: 12
Posted: 06:39am 12 Apr 2012
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Graeme,
Some simple external circuitry would certainly do it (2xNE567 or 1xPicaxe 08M2), but I also did provide a possible way forward in MM-Basic that could just about be able to do this, here: Link
Thierry
 
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