The DS4000 does temperature compensation digitally and this graph may show the resolution. The accuracy is 1 PPM so I suppose that the oscillator can hunt around within that range. We can use an analog TCXO in rev. B.
73,
John KD6OZH ----- Original Message ----- From: Juan Rivera To: 'Jim Sanford' Cc: eagle@amsat.org Sent: Wednesday, July 04, 2007 03:29 UTC Subject: [eagle] Re: The DS4000 Digital Controlled TCXO
Jim and group,
I can't either, but here's another area where we need requirements. How stable does this receiver need to be to satisfy the needs of the users? Is it driven by the human ear or the ability of a data decoder to stay locked up? - We need long term / short term requirements?
I'm getting set up to do a temperature run tomorrow. I just ran the radio from +26C to +50C to get an idea what to expect. Here's what I found:
That missing chunk in the middle is me re-patching my test equipment. When I saw those saw-tooth's I wanted to hook the TS-2000 up so I could listen again. Sure enough they are jumps in frequency just as the chart shows. Each "tooth" is made of multiple data points so this is not the +/- 1 digit LSB frequency counter error I mentioned earlier.
For this preliminary test I didn't have a temperature probe inside the radio so I don't know how close to +50 it actually got. Tomorrow I'll do a much more thorough job and take it down to about -30C. I'm thinking -30C to +50C. Any other suggestions as to temp extremes?
Juan
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From: Jim Sanford [mailto:wb4gcs@amsat.org] Sent: Tuesday, July 03, 2007 8:08 PM To: juan-rivera@sbcglobal.net Cc: 'Bill Ress'; eagle@amsat.org Subject: Re: [eagle] Re: The DS4000 Digital Controlled TCXO
Juan: I can't imagine it NOT being a problem.
For the sake of completeness, let's assume that it IS, and solve it.
Thanks for all your hard work.
73, Jim wb4gcs@amsat.org
Juan Rivera wrote:
Hi Bill, Aren't all these tools neat? I though you'd like the audio! I'm thinking that the uplink guys are going to have to weigh in and tell usif these jumps are a problem or not for data. I'd think that they would befor demodulating data and a major annoyance for SSB. It's the sort ifsubtle stuff that I didn't notice at first. I'm sure there are a few moresurprises waiting to be discovered. I'm curious about the beat since the two oscillators produced IF outputsthat were fairly far apart and yet the beat seems to be around 1 Hz. Iguess I could try to sniff the internal oscillator to see exactly where itreally is. 73, Juan -----Original Message-----From: Bill Ress [mailto:bill@hsmicrowave.com] Sent: Tuesday, July 03, 2007 6:49 PMTo: juan-rivera@sbcglobal.netCc: eagle@amsat.orgSubject: The DS4000 Digital Controlled TCXO Hi Juan, The audio is a fantastic addition to your super analysis regime. Just really fine work!! I've already addressed the issue of the two 10 MHz oscillators beating as heard in clip #1. Now what you hear in the second audio clip doesn't surprise me. Just another reason why I remain digitally challenged and analog biased. The DS4000 is a "digitally" corrected voltage controlled oscillator. I believe what you are hearing is the frequency being corrected in finite digital steps. An analog temperature corrected VCO will not do this. The correction will be continuous and smooth. The key advantage of the "digitally" corrected VCO is the ability to "remotely" correct the frequency with a digital input. I would submit, that feature is not needed for our application. The "analog" TCVCXO used in the S2 concept converter uses a low cost device (available from several suppliers) and offers +/- 1 PPM stability over temperature (-40 to 85 C). Regards...Bill - N6GHz Juan Rivera wrote: All, I should have gone to work today but I ended up working on the 70 cm Receiver all day instead. Today marks a milestone for me -- my first use of audio files. You'll find two in my write up if you click HERE http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Stability.htm. I think they work much better than descriptions and graphs. Now you can hear what I'm talking about... Have a great 4th! I plan to do a temperature run on the receiver tomorrow to celebrate! Let's see what that internal oscillator does when it's not at room temperature! P.S. to OSCAR guys... If you have time come on over and help me run this test. I'll probably start early to beat the heat. If you've never been gassed by CO2 before, now is your chance! 73, Juan - WA6HTP _______________________________________________Via the Eagle mailing list courtesy of AMSAT-NAEagle@amsat.orghttp://amsat.org/mailman/listinfo/eagle
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