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Need help building Intelligent Signal Router

Question asked by mtbrider405 on Jan 25, 2011
Latest reply on Mar 29, 2011 by mtbrider405

Ok guys I am new around here.  I searched for a similar situation and could not find one so I'm asking for help. 


I am new to SigmaStudio and to Sigma DSP's.  I bought the 1442 EVAL board.  My goal is to use the board to prototype my system design then design my own board using the same components.


First I will do my best to describe the system as a whole.  I am working with a team of 4 people to design a redundant communication system.  At one end and FSK modem will output a signal (alternating frequency sine wave) to card 1. Card 1 will mix an out of band tone with the incoming signal and output the new mixed signal on two outputs. These two outputs are sent to two independent fiber optic lines and transmitted to the remote end. 


At the remote end, the two analog signals are sent into card 2.  Card 2 will separate (using filters) the FSK signal and the out of band signal.  The RMS of the out of band signal will be checked against a threshold value to determine if the line is healthy and if one of the out of band signal's RMS falls below the threshold the other FSK signal will be sent to the output of card 2. 


This is were I am having the problem.  The mixing of the FSK signal and the out of band tone in card 1 seems like it should be a no brainer and the filtering of the two signals in card 2 is easy as well.


I cannot figure out how to build this intelligent signal switcher in card 2.  The key is, if the system switches the output from say channel A to channel B, it must stay on channel B until channel B goes down even if channel A comes back up in the mean time.  Then it would switch back to channel A if B were to go down and stay on channel A even if B were to come back up. An so on. 



I can't get myself to believe I can't do it in SigmaStudio, but I can't figure out even how to start going about this.  I have tried using a multiplexor to control switching between the two incoming channels and I still feel like that's the way to go, but I cannot figure out how to drive the multiplexor based on the switching characteristics described above.


Any help would be much appreciated!  I have attached the SigmaStudio file I have been working on for Card 2 but it has no switching logic included. 

If any of this is unclear please let me know and I will do my best to help you understand it.


Thank you very much,