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Clarification on DTMF

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prasannabalaji

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hi,

i am using MT8880 which is a DTMF transceiver..after initialisation of control reg i am giving the input of 7 i want to know, how to check that wheather this IC is txansmitting DTMF signal or not

thank u in advance
 

Prabakaran

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Hi
Prasannabalaji,
check the MT8880 by using the CRO , check the output of DTMF and u can see there is some frequency comming out from that.

Can u send the details of MT8880 , its cost and circuit diagram of this , because i too using the same module , i couldn get the IC in the Market. so can u send the details regarding the cost of the IC and place where u got the Ic , and send me the Application circuit.
 

vinunandakumar

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prasannabalaji said:
hi,

i am using MT8880 which is a DTMF transceiver..after initialisation of control reg i am giving the input of 7 i want to know, how to check that wheather this IC is txansmitting DTMF signal or not

thank u in advance
try using a dtmf decoder like 8870
 

saubhik

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A question which made me mad on my college days when I was doing the project on DTMF receiver.
After that what idea we have used I can explain it to u , I think it will help u to find out the answer very easily .

In a DTMF transmitter for any key press it generates two frequency signals (in Rake Receiver concept those signals are orthogonal to each other ) - one is of high frequency and another is of low frequency . Then if you know the frequecy range and what frequency the TX should generate then easily using filters u can separate the frequency signals and check in a CRO at the output of the filters ,. This method will help u to get the exact frequencies generated by the Tx.



Any how for ur help I am sending u the DTMF decoder IC details also which is preferred by Mr. vinunandakumar .....u can find it in the following link




I hope u can right now easily solve the problem ......




Ok and Bye ......
 

nandhu015

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prasannabalaji said:
hi,

i am using MT8880 which is a DTMF transceiver..after initialisation of control reg i am giving the input of 7 i want to know, how to check that wheather this IC is txansmitting DTMF signal or not

thank u in advance

just connect the output to a working telephone line. You can hear the tone

simple

Nandhu
 

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