Aug 3, 2008 #1 7 7rots51 Advanced Member level 4 Joined May 17, 2002 Messages 1,183 Helped 25 Reputation 50 Reaction score 12 Trophy points 1,318 Activity points 9,636 ad9954 fm Is this possible to voice fm modulation using ad9954 and micro and adc at 157MHZ ? Is there any spur and interference with other channels ?(ch BW=25khz) if yes,how to remove interference ?
ad9954 fm Is this possible to voice fm modulation using ad9954 and micro and adc at 157MHZ ? Is there any spur and interference with other channels ?(ch BW=25khz) if yes,how to remove interference ?
Aug 3, 2008 #2 FvM Super Moderator Staff member Joined Jan 22, 2008 Messages 52,478 Helped 14,756 Reputation 29,794 Reaction score 14,120 Trophy points 1,393 Location Bochum, Germany Activity points 298,338 You get some spurs of the modulation sampling frequency, that can't be filtered, cause you get a stepped frequency variation. It could be at best reduced by using Linear Sweep rather than Single-Tone Mode or increasing the sampling frequency.
You get some spurs of the modulation sampling frequency, that can't be filtered, cause you get a stepped frequency variation. It could be at best reduced by using Linear Sweep rather than Single-Tone Mode or increasing the sampling frequency.
Aug 4, 2008 #3 7 7rots51 Advanced Member level 4 Joined May 17, 2002 Messages 1,183 Helped 25 Reputation 50 Reaction score 12 Trophy points 1,318 Activity points 9,636 how much sampling rate is enough? Is there any other method for FM digital mod of voice?
Aug 4, 2008 #4 FvM Super Moderator Staff member Joined Jan 22, 2008 Messages 52,478 Helped 14,756 Reputation 29,794 Reaction score 14,120 Trophy points 1,393 Location Bochum, Germany Activity points 298,338 how much sampling rate is enough? Click to expand... I don't know. You can do a numerical simulation of the sampled voice signal and FM and determine the resulting spectrum.
how much sampling rate is enough? Click to expand... I don't know. You can do a numerical simulation of the sampled voice signal and FM and determine the resulting spectrum.
Aug 5, 2008 #5 7 7rots51 Advanced Member level 4 Joined May 17, 2002 Messages 1,183 Helped 25 Reputation 50 Reaction score 12 Trophy points 1,318 Activity points 9,636 You can do a numerical simulation Click to expand... In what softwares I can do the simulation?
Aug 7, 2008 #6 7 7rots51 Advanced Member level 4 Joined May 17, 2002 Messages 1,183 Helped 25 Reputation 50 Reaction score 12 Trophy points 1,318 Activity points 9,636 I fm modulated a 1KHZ sound with 8khz deviation at ad9957 ,in that freq,I saw spurs at 3MHZ space relative to carrier and -60dbc. this spur have no problem for me.what is your idea? is another problem?
I fm modulated a 1KHZ sound with 8khz deviation at ad9957 ,in that freq,I saw spurs at 3MHZ space relative to carrier and -60dbc. this spur have no problem for me.what is your idea? is another problem?
Aug 7, 2008 #7 FvM Super Moderator Staff member Joined Jan 22, 2008 Messages 52,478 Helped 14,756 Reputation 29,794 Reaction score 14,120 Trophy points 1,393 Location Bochum, Germany Activity points 298,338 I think, it should work this way.