Cecil No you didn't miss. This was just for the Time Nuts! I punned it "It's about time"... Most of the Time Nuts didn't attend. I am going to make it much later Eastern time next time so Jim can get home in time to spend some time on Teamspeak. I think that would be his first time. I didn't realize it but we had a time conflict last night since the Rose Bowl committee picked our time to have the game.
Flex-Radio-Friends weekly teamspeak forum is same time same station on Friday at 0100. See you next time. Eric2 -----Original Message----- From: KD5NWA [mailto:[EMAIL PROTECTED] Sent: Thursday, January 05, 2006 10:47 PM To: Eric Ellison Cc: FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR I must have missed the change in schedule of the Teamspeak meeting, is this change permanent? At 06:14 PM 1/5/2006, Eric Ellison wrote: >Folks > >Missed you on our Teamspeak session last night "It's about time"! > >Had a good discussion amongst a few people working on both the projects >(Xylo) and Flex. Guess the fantastic Texas - USC entertainment got most >others! > >Bob K5KDN is working on a Timebase board, chassis etc and has a Jupiter and >nice 10 mhz Ovenized VCXO interfaced and building a board which will squat >down on the DIP connector on the Jupiter. > >On the Xylo side Bill - KD5TFD published a picture of his breadboard of the >Jupiter interfacing to the Xylo board, which will eventually pass >frequency/phase information back to the PowerSDR software. > >I am looking for more information on anyone who has produced a complete >circuit design published here several months ago by Tom Clark. Based on an >original design by Tom van Baak and enhanced by Tom Clark. > >This is really an inspired design! > >PIC header is published here without permission, however, I did not note a >copyright, and Tom made it available on the Forum several months ago. > >If it uses 10 MHZ this is the way to go! > >; ---------------------------------------------------------------------- >; >; Title: >; >; 10 MHz frequency divider >; >; Function: >; >; This PIC 16c84 program is designed to divide a 10 MHz frequency >; source down to 1 Hz (1 PPS). >; >; Since several extra output pins are available the program creates >; a total of 9 square wave outputs -- one for each frequency decade >; from 100 kHz to 0.001 Hz (1000 s). >; >; A STOP input and a 1 PPS synchronization input are also provided. >; Raising the STOP input high stops and resets the divider. The >; divider resumes on the leading edge of the 1 PPS SYNC input. The >; 1 PPS output will be synchronized to the 1 PPS SYNC input to less >; than 1.2 us (three PIC instructions at 10 MHz). >; >; The following chip schematic shows the assignment of each pin. >; >; ------ ------ >; 100 kHz <- RA2 |1 --- 18| RA1 -> Red LED >; Green LED <- RA3 |2 17| RA0 <= Stop input >; 1PPS SYNC => T0CKI/RA4 |3 16| OSC1/CLKIN <= 10 MHz input >; +5 VDC -> /MCLR |4 15| OSC2/CLKOUT -- N/C >; GND -> Vss |5 16C84 14| Vdd <- +5 VDC >; 10 kHz <- INT/RB0 |6 13| RB7 -> 1000 s >; 1 kHz <- RB1 |7 12| RB6 -> 100 s >; 100 Hz <- RB2 |8 11| RB5 -> 10 s >; 10 Hz <- RB3 |9 10| RB4 -> 1 Hz / 1 PPS >; --------------- >; >; Implementation: >; >; To generate a 10 kHz square wave at 50% duty cycle an output pin >; must be flipped every 50 us (125 instructions at 10 MHz clock). >; This program does not use TMR0, the pre-scaler, or interrupts. >; Instead it relies on the fact that given an accurate 10 MHz clock >; each PIC instruction takes precisely 400 ns and the main loop has >; been designed to use exactly 125 instructions. >; >; The 100 kHz frequency (10 us period) is generated by setting an >; output pin on and off every 25 cycles. Since 25 is an odd number >; it is not possible for the PIC to generate this square wave with >; a 50% duty cycle. Instead a 20% duty cycle (5 cylcles on and 20 >; cycles off) was chosen for this frequency output. A total of 5 >; pairs of 100 kHz bit set/clear code are carefully interspersed >; within the 50 us main loop. >; >; Pins RA0 and RA4 are not used to drive a LED. RA4 is a Schmidt >; trigger input and O.C. output. It is used as the SYNC input. >; The data sheet says not to toggle RA0 under some conditions so >; it is used as the STOP input. >; >; Version: >; >; 1998-Aug-05, Version 4, tvb >; >; ---------------------------------------------------------------------- > >; Using Microhip assembler. > > > > > > > >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] On Behalf Of John Ackermann N8UR >Sent: Thursday, January 05, 2006 1:49 PM >To: [EMAIL PROTECTED] >Cc: FlexRadio@flex-radio.biz >Subject: Re: [Flexradio] DIP OCXO for SDR > >Great plan, John. I only had access to the 5052A for a day, so was >pretty limited in what I could do; it's great that you'll be able to >carry things forward. > >The one addition I would suggest is that you duplicate the DDS output >measurements using the 10MHz source as well as the VF oscillator. That >would add to my sketchy info about the effect of the multiplier on phase >noise. > >I was not happy with the results I got, I think due to the way I was >coupling out of the DDS, which was essentially a x1 scope probe with >less-than-perfect grounding. After the fact, I redid the connection >with a 50 ohm series resistor at U1 pin 6 (actually, mounted into a via >on that line) and a short piece of RG-174 feeding a buffer amplifier. I >think something like that will give better results. > >By the way -- I looked at the AD9854 data sheet and it includes several >phase noise plots. From those, you would gather that there is a cost in >using the internal multiplier, but that it doesn't scale with DDS output >frequency. Also, from a quick read you could get the impression that >the phase noise of the reference clock doesn't really matter (within >reason, of course); they show the output phase noise plot without any >reference to the noise of the clock. > >73, >John >---- > >[EMAIL PROTECTED] wrote: > > This is cool. It's great to be able to discuss the nuances of what > > really goes on within our radios. Spreading the word is a very good > > thing. I checked out John's(N8UR) web site and I'm inspired. I have > > an E5052A Signal Source Analyzer setting here and plan to make a few > > measurements. > > > > Here's the plan so far: > > > > i. measure phase noise of a 10MHz crystal > > (it will probably be limited by the E5052A) > > ii. the 200MHz VF1611 > > iii. DDS output with VF1611 as the clock at: > > 1MHz > > 5MHz > > 10MHz > > 50MHz > > > > Anyone have any additional ideas? I'm all ears. > > > > 73, > > k2ox > > > > > > -----Original Message----- > > From: richard allen [mailto:[EMAIL PROTECTED] > > Sent: Wednesday, January 04, 2006 5:39 PM > > To: John Ackermann N8UR > > Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz > > Subject: Re: [Flexradio] DIP OCXO for SDR > > > > Gentlemen, > > > > The DDS does Direct Digital Synthesis hence the name. It does not > > divide > > back to anything but runs an phase accumulation engine at 200 MHz (or > > whatever > > the clock rate) that produces output values to the dac at that rate. > > > > No division is performed. > > > > Richard W5SXD > > > > John Ackermann N8UR <[EMAIL PROTECTED]> wrote: > > (01/04/2006 16:09) > > > > > >>[EMAIL PROTECTED] wrote: > >> > >>>First of all, any osc multiplied up widens its sidebands > >>>(phase noise) by the multiplication factor and the inverse is > >>>also true. The DDS does a 20X to 200MHz and a divide by 20 to > >>>get back to 10MHz. I guess it's academic at this point how > >>>much jitter is added by the DDS until someone measures it. > >> > >>You're only dividing back to 10MHz if that's the operating frequency. > >>At higher operating frequencies, the division doesn't equal the > >>multiplication (and of course, at lower ones it exceeds it). Measuring > >>the DDS output lets us see the phase noise where it counts, taking into > >>account both multiplication and division, rather than just at the > >>fundamental frequency of the reference. > >> > >> > >>>Second, Rubidium standards are not intended to be used as local > >>>oscillators. They have terrible phase noise. They are intended > >>>to be used in timekeeping. It is their long term drift that > >>>excels, not short term phase noise. > >> > >>Agreed in general -- though there's a wide difference in performance > >>between different types of Rb; some use FM modulation of the xtal, which > >>results in horrible phase noise, while others, like the 5065A, don't. > >>My post wasn't suggesting that you use an Rb as the primary reference. > >>However, the DDS output when driven by 10MHz shows the effect of the > >>multiplication, which is all I was trying to do. My web page also has a > >>plot of the HP 5065A phase noise at 10MHz, so you can see the difference > >>in noise between the raw and multiplied frequencies. > >> > >>John > >> > >> > >>>http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has > >>>screenshots that show the phase noise at the output of the DDS for the > >>>standard 200MHz oscillator, and an HP Rubidium frequency standard at > >>>10MHz multiplied by 20 in the DDS. You can clearly see the phase-noise > >>>hit caused by the multiplication. > >>> > >>>John > >>> > >>>_______________________________________________ > >>>FlexRadio mailing list > >>>FlexRadio@flex-radio.biz > >>>http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > >>> > >>> > >> > >> > >>_______________________________________________ > >>FlexRadio mailing list > >>FlexRadio@flex-radio.biz > >>http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > > > > > > > > > > >_______________________________________________ >FlexRadio mailing list >FlexRadio@flex-radio.biz >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > > >_______________________________________________ >FlexRadio mailing list >FlexRadio@flex-radio.biz >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Cecil Bayona KD5NWA www.qrpradio.com "I fail to see why doing the same thing over and over and getting the same results every time is insanity: I've almost proved it isn't; only a few more tests now and I'm sure results will differ this time ... 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