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| DDS Help | ||
| Author bubulu Views 15 Posted at 2008/8/28 06:14 [View In Forum] | ||
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anyone please help . vlzp vlzp vlzp tell me the step to come out with DDS vlzp vlzp vlzp 120 MHZ vlzp vlzp vlzp 8 bit vlzp vlzp vlzp vlzp vlzp vlzp please help |
| Reply No. | Replier | Total Replies 30 [View All Replies] [New Reply] | Replied at |
| 21 | dongyea | err we know that The vertical scale on the "sine" signal is from -128 to 127: is there a way that i change shift the whole sine signal like 128 to 255 |
2008/8/28 06:14 |
| 22 | booksir | My ModelSim display has a vertical scale of -128 to 127 because I configured ModelSim that way. It wasn't that way by default. If you want to change your vertical scale to something else, use the radix/offset/scale/height settings that I mentioned earlier. | 2008/8/28 06:14 |
| 23 | z4120356 | see this | 2008/8/28 06:14 |
| 24 | netlgc | Do you want to modify the signal in your HDL code (instead of modifying ModelSim's display)? You can do that by multiplying the signal by a scaling factor and than adding an offset constant. For example, to convert from range -128 to 127, to range 128 to 255, you could multiply by 0.5 and then add 192. | 2008/8/28 06:14 |
| 25 | z315 | err i try already but errr offset everything just change the size of the wave but still i see - and on my wave |
2008/8/28 06:14 |
| 26 | z4120356 | Did you remember to change the data bus type or width to accommodate the larger values? Values from 128 to 255 will overflow an 8-bit signed data bus, and cause false negative values. |
2008/8/28 06:14 |
| 27 | naoge | Hi hope this pdf file which deals with the complete technical details of DDS can help you with your queries.You can find all the relevant terchnical details. | 2008/8/28 06:14 |
| 28 | ken7976 | Hi this is another pdf file that deals about reconfigurable quadrature oscillator based on direct digital synthesis.This can give u some more insight about scaling the frequency and adjustment of the various quadrature parameters. | 2008/8/28 06:14 |
| 29 | wyslnhhh56 | This is a direcr digital synthesis primer ,a technical overview by analog devices. | 2008/8/28 06:14 |
| 30 | pdang | Thanks a lot | 2010/8/30 07:26 |
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