Exactly: this prevented me to buy the ESI Juli@ sound card. It was suggested by a fellow time-nut and this card is indeed very interesting but in my opinion sound cards are not well defined about the sampling process. I need more details. The Juli@ has the greater than usual bandwidth, not limited to the audio spectrum but up to 90KHz, so it is perfect as a general digitizer for the VLF radio spectrum (DCF77, WWWB and others).
On Fri, Jul 6, 2012 at 11:15 PM, Azelio Boriani <azelio.bori...@screen.it>wrote: > The trick here is the 50% divide-by-5, as you can see rather strange but > needed for the XOR. > > On Fri, Jul 6, 2012 at 11:14 PM, Azelio Boriani > <azelio.bori...@screen.it>wrote: > >> OK, here the VHDL of the 24.576MHz synchronizer: >> >> >> LIBRARY IEEE; >> USE IEEE.std_logic_1164.ALL; >> USE IEEE.std_logic_unsigned.ALL; >> ENTITY FRSync IS >> PORT (ClkIN, RefIN: IN std_logic; -- ClkIN is 24.576MHz/1536->16KHz, >> RefIN is 10MHz/625->16KHz >> PWMOut: OUT std_logic); >> END ENTITY FRSync; >> ARCHITECTURE Proc4 OF FRsync IS >> SIGNAL Cnt5A: std_logic_vector (2 downto 0); >> SIGNAL Cnt125 std_logic_vector (6 downto 0); >> SIGNAL Cnt768 std_logic_vector (9 downto 0); >> SIGNAL Cnt2, Cnt5B, Cnt125N, Fr625: std_logic; >> BEGIN >> -- Dividers section >> Div125: PROCESS -- Divide the 10MHz first by 125 then by 5 >> BEGIN >> WAIT UNTIL RefIN'EVENT AND RefIN='1'; >> IF Cnt125="1111100" THEN >> Cnt125<= (OTHERS=> '0'); >> ELSE >> Cnt125<= Cnt125+1; >> END IF; >> END PROCESS Div125; >> Div5A: PROCESS >> BEGIN >> WAIT UNTIL Cnt125(6)'EVENT AND Cnt125(6)='1'; >> IF Cnt5A="100" THEN >> Cnt5A<= (OTHERS=> '0'); >> ELSE >> Cnt5A<= Cnt5A+1; >> END IF; >> END PROCESS Div5A; >> Div5B: PROCESS >> BEGIN >> WAIT UNTIL Cnt125N'EVENT AND Cnt125N='1'; >> Cnt5B<= Cnt5A(1); >> END PROCESS Div5B; >> Div768: PROCESS -- Divide the 24.576MHz first by 768 >> BEGIN >> WAIT UNTIL ClkIN'EVENT AND ClkIN='1'; >> IF Cnt768="1011111111" THEN >> Cnt768<= (OTHERS=> '0'); >> ELSE >> Cnt768<= Cnt768+1; >> END IF; >> END PROCESS Div768; >> Div2: PROCESS -- Then by 2 for a total of 768*2 -> 1536 >> BEGIN >> WAIT UNTIL Cnt768(9)'EVENT AND Cnt768(9)='1'; >> Cnt2<= NOT Cnt2; >> END PROCESS Div2; >> -- Combinational section >> Cnt125N<= NOT Cnt125(6); >> Fr625<= '1' WHEN Div5A (1)='1' OR Div5B='1' ELSE '0'; -- 50% divide-by-5 >> PWMOut<= Fr625 XOR Cnt2; -- The XOR needs exactly a 50% duty cycle >> END ARCHITECTURE Proc4; >> >> >> On Fri, Jul 6, 2012 at 9:40 PM, Tristan Steele >> <tristan.ste...@gmail.com>wrote: >> >>> Another option is to do it yourself, it is one of my projects that is >>> currently in progress. I have some early information at: >>> >>> http://electronics.ozonejunkie.com/category/electronics/time/10mhzaudio/ >>> >>> I am aware that the jitter will not be all that low, but I was more >>> interested in longer term stability. I have since made a smaller, neater >>> board that just needs to go through some testing. If there is interest, I >>> can post schematics up in the next few days. >>> >>> Tristan >>> >>> On 06/07/2012, at 20:13, li...@lazygranch.com wrote: >>> >>> > I'd suggest hacking USB type soundcards. It is certainly easier to get >>> at the guts. >>> > >>> > There is a Chinese card peddled by a few vendors on ebay that comes in >>> a blue metal case. You can slip out the PCB. The card uses CMedia chips. >>> > >>> > This is the first one I spotted on ebay: >>> > >>> http://item.mobileweb.ebay.com/viewitem?itemId=280506784055&cmd=VIDESC&index=19&nav=SEARCH&nid=33879388392 >>> > >>> > I have an older version. These CMedia based cards work well under ALSA. >>> > >>> > >>> > _______________________________________________ >>> > time-nuts mailing list -- time-nuts@febo.com >>> > To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> > and follow the instructions there. >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> >> > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.