Re: [Freetel-codec2] FYI: mode 2400B handheld
probably not HARD amplitude limited. sign bit would still rule though... but band limited of course. and if in linear mode, AGCed so there would be a reasonably consistent level there, FM or SSB probably 10-16dB max dynamic range. (guess) still worthwhile doign your numbers to see where all the sampling products land, and also, where the aliases of the harmonics present on the fitler output (non zero) and 2f of the created ADC distortion land. the 2f and 3f can get very bad with under specified sample AND holds when operating super nyquist. On 2/05/2018 9:51 AM, David Rowe wrote: I like it. good use of undersampling. Although the SFDR of the microcontroller at 4x undersampling is probably in the toilet, since it is band limited, that does not matter of course. very good. Glen - would the FM be limited by that stage? That would mean a simple ADC would suffice, we're just looking for the sign bit. - David -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2 -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
Re: [Freetel-codec2] FYI: mode 2400B handheld
I like it. good use of undersampling. Although the SFDR of the microcontroller at 4x undersampling is probably in the toilet, since it is band limited, that does not matter of course. very good. Glen - would the FM be limited by that stage? That would mean a simple ADC would suffice, we're just looking for the sign bit. - David -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
Re: [Freetel-codec2] FYI: mode 2400B handheld
Great work Jereon ! I like it. good use of undersampling. Although the SFDR of the microcontroller at 4x undersampling is probably in the toilet, since it is band limited, that does not matter of course. very good. glen VK1XX On 2/05/2018 8:00 AM, Jeroen Vreeken wrote: Hi all, A small update: the dra818 module is a bit dissapointing. The worst problem: it takes almost a second before it modulates after switching to TX. So I went for a different approach: A while back I modified my FT817 a bit to make the 455kHz IF available on the back. This is done by using the c -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
