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#1
October 19th 03, 01:15 AM
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NRZI coding
Hi,
I'm looking for some info on NRZI coding. google gives me useless links... nothing special. I am about to write someting that uses NRZI but i can not find any specification. I appreciate any input on this. Regards, Mariusz SP3FXC |
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#2
October 20th 03, 03:39 AM
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Mariusz SP3FXC wrote:
I'm looking for some info on NRZI coding. google gives me useless links... nothing special. I am about to write someting that uses NRZI but i can not find any specification. If you look at this with a monospaced font (Courier for example) it should make sense: __ ________ _____ __ __| |__| |__| |________| 0 0 0 1 1 0 0 1 0 1 1 0 Non-Return Zero Inverting means (1) the signal does not return to a resting state after a bit, and (2) a zero is indicated by a change of state, and a one by no change. Clock is extracted from the data, which means there must be a limit to the number of consecutive 1's, and the "zero stuffing" technique leads to a bigger discussion. HTH |
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#3
October 20th 03, 03:39 AM
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Mariusz SP3FXC wrote:
I'm looking for some info on NRZI coding. google gives me useless links... nothing special. I am about to write someting that uses NRZI but i can not find any specification. If you look at this with a monospaced font (Courier for example) it should make sense: __ ________ _____ __ __| |__| |__| |________| 0 0 0 1 1 0 0 1 0 1 1 0 Non-Return Zero Inverting means (1) the signal does not return to a resting state after a bit, and (2) a zero is indicated by a change of state, and a one by no change. Clock is extracted from the data, which means there must be a limit to the number of consecutive 1's, and the "zero stuffing" technique leads to a bigger discussion. HTH |
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#4
October 20th 03, 04:06 AM
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NRZI encoder:
Invert the NRZ data, then apply to both the J and K inputs of a J-K flipflop; clock to the clk input of the FF. Q output of the FF is the encoded NRZI data. NRZI decoder: Encoded NRZI data to both the input of a D flipflop and one input of an XOR gate. Q* (Q-not) output of the D-FF to the other input of the XOR gate. Clk to the clk input of the FF. XOR output is the decoded NRZ data. -- Tom, N5EG "Mariusz SP3FXC" wrote in message ... Hi, I'm looking for some info on NRZI coding. google gives me useless links... nothing special. I am about to write someting that uses NRZI but i can not find any specification. I appreciate any input on this. Regards, Mariusz SP3FXC |
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#5
October 20th 03, 04:06 AM
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NRZI encoder:
Invert the NRZ data, then apply to both the J and K inputs of a J-K flipflop; clock to the clk input of the FF. Q output of the FF is the encoded NRZI data. NRZI decoder: Encoded NRZI data to both the input of a D flipflop and one input of an XOR gate. Q* (Q-not) output of the D-FF to the other input of the XOR gate. Clk to the clk input of the FF. XOR output is the decoded NRZ data. -- Tom, N5EG "Mariusz SP3FXC" wrote in message ... Hi, I'm looking for some info on NRZI coding. google gives me useless links... nothing special. I am about to write someting that uses NRZI but i can not find any specification. I appreciate any input on this. Regards, Mariusz SP3FXC |
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#6
October 20th 03, 09:51 PM
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Moebius Velcro wrote:
Mariusz SP3FXC wrote: I'm looking for some info on NRZI coding. google gives me useless links... nothing special. I am about to write someting that uses NRZI but i can not find any specification. If you look at this with a monospaced font (Courier for example) it should make sense: __ ________ _____ __ __| |__| |__| |________| 0 0 0 1 1 0 0 1 0 1 1 0 Non-Return Zero Inverting means (1) the signal does not return to a resting state after a bit, and (2) a zero is indicated by a change of state, and a one by no change. Clock is extracted from the data, which means there must be a limit to the number of consecutive 1's, and the "zero stuffing" technique leads to a bigger discussion. HTH Very good  One more question. Is it "level-sensitive" coding? I mean if wechange the phase (by 180deg.) of NRZI coded signal would it be still readable when it hits decoder? I need to verify this because it is essential for my project. Mariusz |
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#7
October 20th 03, 09:51 PM
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Moebius Velcro wrote:
Mariusz SP3FXC wrote: I'm looking for some info on NRZI coding. google gives me useless links... nothing special. I am about to write someting that uses NRZI but i can not find any specification. If you look at this with a monospaced font (Courier for example) it should make sense: __ ________ _____ __ __| |__| |__| |________| 0 0 0 1 1 0 0 1 0 1 1 0 Non-Return Zero Inverting means (1) the signal does not return to a resting state after a bit, and (2) a zero is indicated by a change of state, and a one by no change. Clock is extracted from the data, which means there must be a limit to the number of consecutive 1's, and the "zero stuffing" technique leads to a bigger discussion. HTH Very good One more question. Is it "level-sensitive" coding? I mean if wechange the phase (by 180deg.) of NRZI coded signal would it be still readable when it hits decoder? I need to verify this because it is essential for my project. Mariusz |
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#8
October 21st 03, 02:55 AM
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Mariusz SP3FXC writes:
__ ________ _____ __ __| |__| |__| |________| 0 0 0 1 1 0 0 1 0 1 1 0 Very good One more question. Is it "level-sensitive" coding? I mean if wechange the phase (by 180deg.) of NRZI coded signal would it be still readable when it hits decoder? I need to verify this because it is essential for my project. Look at the diagram. A zero is a change in state; doesn't matter in which direction it changes. If you invert the input signal the output is still the same: __ ________ _____ __ __| |__| |__| |________| -- -- -- -------- |__| |________| |_____| |__ 0 0 0 1 1 0 0 1 0 1 1 0 Same output. // marc |
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#9
October 21st 03, 02:55 AM
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Mariusz SP3FXC writes:
__ ________ _____ __ __| |__| |__| |________| 0 0 0 1 1 0 0 1 0 1 1 0 Very good One more question. Is it "level-sensitive" coding? I mean if wechange the phase (by 180deg.) of NRZI coded signal would it be still readable when it hits decoder? I need to verify this because it is essential for my project. Look at the diagram. A zero is a change in state; doesn't matter in which direction it changes. If you invert the input signal the output is still the same: __ ________ _____ __ __| |__| |__| |________| -- -- -- -------- |__| |________| |_____| |__ 0 0 0 1 1 0 0 1 0 1 1 0 Same output. // marc |
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#10
October 21st 03, 04:10 AM
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Mariusz SP3FXC wrote:
Moebius Velcro wrote: Mariusz SP3FXC wrote: I'm looking for some info on NRZI coding. google gives me useless links... nothing special. I am about to write someting that uses NRZI but i can not find any specification. If you look at this with a monospaced font (Courier for example) it should make sense: __ ________ _____ __ __| |__| |__| |________| 0 0 0 1 1 0 0 1 0 1 1 0 Non-Return Zero Inverting means (1) the signal does not return to a resting state after a bit, and (2) a zero is indicated by a change of state, and a one by no change. Clock is extracted from the data, which means there must be a limit to the number of consecutive 1's, and the "zero stuffing" technique leads to a bigger discussion. HTH Very good One more question. Is it "level-sensitive" coding? I mean if wechange the phase (by 180deg.) of NRZI coded signal would it be still readable when it hits decoder? I need to verify this because it is essential for my project. No. __ ________ _____ __ __| |__| |__| |________| means the same as __ __ __ ________ |__| |________| |_____| |__ in that a zero is represented by a change, in either direction, and a one is no change. ;B |
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