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jhenderson
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Joined: 07 Mar 2006
Posts: 2254
Location: So. Cal. USA
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 Posted: Fri Jun 04, 2010 9:01 am Post subject: 8-ch DDC |
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| Quote: | I am using an X5-210M in conjunction with the 8-ch DDC core. You said previously that as stated in the DDC datasheet, I and Q are 16-bit encoded. I have made the following measurement:
1- sinus at 14.50 MHZ on ADC0. Clock 50 MHz. decimation rate 128 (no modification of the test.ini file); DDC tuning freq is 14.48MHz. The sinus on ADC0 has a power of 10 dBm, which means 1Vpp (verified on an oscilloscope 50Ohm input), so that 1Vpp covers the full range of the ADC.
When I look at the data recorded with Matlab, the I (or Q) channel at the output of the DDC covers only the range 1072 to -1074. That makes around 11 bits for encoding, and not 16 as stated in the datasheet. It’s even less than the input of the ADC which is 14 bits. Consequently the minimum input level on ADC0 is around -50 dBm. That is normal as the max is encoded on 11 bits wich makes 11bits*6dB =66dB; so +10dBm-66dB = -50dBm.
Could you explain why the I (or Q) are not encoded on 16 bits?
Could you confirm that the powermeter does not influence the scaling of the data, that powermeter is just for information?
And what is the range of the decimation? When I look at the test.ini file, I can see the CIC decimation rate (which 128 by now). When it is 128 for the CIC, what is the total decimation rate (I think I have seen somewhere in the documentation that the 2 FIR filters also decimate). And what is the range of the CIC decimation, and the step between 2 values?
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X5-210M has 14 bits A/Ds.
The ini file shows the basic setup for the configuration of the DDC.
The output of the DDC is 16 bits max.
This however is dependent on the selection of gain at each stage in the DDC.
DDC has CIC, CFIR and PFIR stage.
The gain at CIC can be up to 2 bits (12 dB).
The gain at CFIR and PFIR can be upto 6 bits (72 dB)
The reason for this user defined gain setting is the flexibility of
adjusting the sensitivity of receiver depending on the application.
You can select optimum values for CIC, CFIR and PFIR bits to get a full
scale 16 bit output.
This can be done by changing the test.ini file.
e.g. if you select Bstart = 1 instead of 2 for [CIC], you can get 6 dB
gain in the output. Care should be taken while choosing these values to
avoid overflow in the DDC output. |
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ARNAUD
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Joined: 23 Jan 2009
Posts: 235
Location: FRANCE
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| Posted: Tue Jun 08, 2010 5:54 am Post subject: |
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Dear Support,
I ask again for the last two questions, because DDC’s documentation is very very light:
Could you confirm that the powermeter does not influence the scaling of the data, that powermeter is just for information?
And what is the range of the decimation? When I look at the test.ini file, I can see the CIC decimation rate (which 128 by now). When it is 128 for the CIC, what is the total decimation rate (I think I have seen somewhere in the documentation that the 2 FIR filters also decimate). And what is the range of the CIC decimation, and the step between 2 values?
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Best Regards,
Arnaud |
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amane
Joined: 17 Apr 2006
Posts: 118
Location: Simi Valley
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| Posted: Tue Jun 08, 2010 7:22 am Post subject: |
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Hi,
The powermeter is only for testing purposes.
The overall decimation of the DDC is as follows
1. CIC decimation ...
VARIES FROM 8 to 1024
2. CFIR decimation
fixed at 2
3. PFIR decimation
fixed at 2.
This gives overall decimation of
mininum = CICxCFIRxPFIR = 8x2x2 = 32
maximum = 1024x2x2 = 4096
Sincerely,
Amit Mane |
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ARNAUD
Distributor
Joined: 23 Jan 2009
Posts: 235
Location: FRANCE
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| Posted: Tue Jun 08, 2010 8:11 am Post subject: |
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Hi Amit,
And do you have a matlab simulation for the DDC? I have seen in the documentation that you provide it.
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Best Regards,
Arnaud |
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amane
Joined: 17 Apr 2006
Posts: 118
Location: Simi Valley
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| Posted: Tue Jun 08, 2010 3:31 pm Post subject: |
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Hi Arnaud,
The simulation library is for 4 channel DDC.
Two 4 Channel DDCs were joined together to make a 8 channel DDC.
In the received CD or DVD you should have a IP core library.
IF there is no Library present in the CD or if you are unable to locate it, please email me asap.
Sincerely,
Amit Mane |
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ARNAUD
Distributor
Joined: 23 Jan 2009
Posts: 235
Location: FRANCE
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| Posted: Mon Jun 21, 2010 8:28 am Post subject: |
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Dear Support,
We tried to recompile DDC project with VC9 and we have error:
Erreur 1 error C2039: 'GetHwConfig' : n'est pas membre de 'Innovative::DdcCollective<T>'
c:\Innovative\X5-210M\Projects\Examples\DDC\Common\ApplicationIo.cpp 404 Snap
Use attached file.
I downloaded the last X5-210M version but the problem still here
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Best Regards,
Arnaud |
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jhenderson
Site Admin
Joined: 07 Mar 2006
Posts: 2254
Location: So. Cal. USA
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| Posted: Thu Jun 24, 2010 4:06 pm Post subject: |
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| Ollie emailed the updated project. Please retest and advise if the problem is resolved. |
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Aedan
Joined: 21 Mar 2012
Posts: 1
Location: USA
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| Posted: Wed Mar 21, 2012 10:42 pm Post subject: |
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| I am also facing the same problem, would you like to tell me how can i get rid from it. Thanks |
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jhenderson
Site Admin
Joined: 07 Mar 2006
Posts: 2254
Location: So. Cal. USA
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| Posted: Tue Mar 27, 2012 3:09 pm Post subject: |
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| We believe this problem is resolved in the latest beta version of the Malibu libraries. |
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