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#1 2015-01-24 21:53:57
- marshmellow
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- From: US
- Registered: 2013-06-10
- Posts: 2,302
PSK3 demod questions
Does anyone know how to manually demod psk3 from the graph? i cannot seem to detect multiple 1 bits in a row. i can successfully demod psk1 and 2.
it makes me wonder if some filter in the fpga is obscuring the data.
or we might not be sampling accurate enough?
Last edited by marshmellow (2015-01-24 21:55:02)
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#2 2015-01-25 14:19:33
- app_o1
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- Registered: 2013-06-22
- Posts: 247
Re: PSK3 demod questions
Do you have some traces I can play with ?
What bit rate do you use ?
Should I try some random ones with : 0x00003040 ?
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#3 2015-01-25 15:14:33
- marshmellow
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- From: US
- Registered: 2013-06-10
- Posts: 2,302
Re: PSK3 demod questions
I used the modulation one in the traces folder. The readme.txt says what value it should be. I also tried a few others I made. I used 64 and 32 bit rates. Carrier RF/2.
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#4 2015-01-29 07:03:06
- marshmellow
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- From: US
- Registered: 2013-06-10
- Posts: 2,302
Re: PSK3 demod questions
So I guess I'm not the only one that hasn't figured it out... 
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#5 2015-02-07 00:33:22
- marshmellow
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- From: US
- Registered: 2013-06-10
- Posts: 2,302
Re: PSK3 demod questions
it appears to me that the encoding/modulation is flawed, or intended to never need to detect multiple 1 bits in a row.
By definition, the phase changes only on the rising input edge, or when the input (binary data) goes from 0 to 1. the phase doesn't change again until it goes from 0 to 1 again. so there is nothing to indicate when it went from 1 to 0. ...
so you could demod 01010101010101001000001000001000010101010001
but not 0110
or two(or more) 1 bits in a row...
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#6 2015-02-07 00:34:59
- marshmellow
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- From: US
- Registered: 2013-06-10
- Posts: 2,302
Re: PSK3 demod questions
anyway, it appears to me psk2 could be used to demod psk3 if there are never two 1 bits in a row.
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