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From: | Robert McGwier |
Subject: | Re: [Discuss-gnuradio] Need some answers about FM TX |
Date: | Sat, 01 Oct 2005 23:43:44 +0000 |
User-agent: | Mozilla Thunderbird 1.0.2 (Windows/20050317) |
The pico-board looks great. I recently acquired the AD9954 eval board (two 9954's sync'd for I/Q) and a AD9958 eval board to learn what was going on. AD is a serious believer these days in DAC nonlinearities and clock leakage causing all sorts of issues that are mistaken for other things and as such they are truly seriously pushing the 9958 with its 10 bit DAC and smaller accumulator and phase word which seems so counterintuitive but as you all say, measurements will tell the tale. Their app engineers are all over you when you talk to them at length about the problems attributed to phase truncations which mathematically cannot be and which they have tracked down to DAC/clock leak issues.
I will post a note here with some results. Bob address@hidden wrote:
The same does apply to a DAC as well as an ADC. They are both sampling systems. A DAC typically has a low pass filter to cut all the alias images. But you can also bandpass filter those images to produce the desired signal. The system is very linear and isn't a mixer.Here is my original post:
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