[eagle] Re: The DS4000 Digital Controlled TCXO
bill at hsmicrowave.com
Tue Jul 3 21:23:32 PDT 2007
Yes indeed, Jim.- a happy and safe Independence Day to you all.
The BBQ's cleaned (well sorta) and ready for tomorrow's hot dogs and
Regards...Bill - N6GHz
Jim Sanford wrote:
> Based on what I REMEMBER (I'm senile, so take it with a pound of salt)
> -30 to +50C is plenty at this point.
> Thanks for all you're doing. You are producing good data and
> articulating valid concerns, which I'd rather deal with NOW than ON ORBIT.
> Happy Independence Day to all. Please take some time out to enjoy
> family, celebrate our Nation, honor our Veterans, and spend some time
> in what my wife calls, "Norman Rockwell America."
> Thanks & very 73,
> wb4gcs at amsat.org
> Juan Rivera wrote:
>> 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
>> 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?
>> *From:* Jim Sanford [mailto:wb4gcs at amsat.org]
>> *Sent:* Tuesday, July 03, 2007 8:08 PM
>> *To:* juan-rivera at sbcglobal.net
>> *Cc:* 'Bill Ress'; eagle at amsat.org
>> *Subject:* Re: [eagle] Re: The DS4000 Digital Controlled TCXO
>> 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.
>> wb4gcs at amsat.org <mailto:wb4gcs at 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 us
>> if these jumps are a problem or not for data. I'd think that they would be
>> for demodulating data and a major annoyance for SSB. It's the sort if
>> subtle stuff that I didn't notice at first. I'm sure there are a few more
>> surprises waiting to be discovered.
>> I'm curious about the beat since the two oscillators produced IF outputs
>> that were fairly far apart and yet the beat seems to be around 1 Hz. I
>> guess I could try to sniff the internal oscillator to see exactly where it
>> really is.
>> -----Original Message-----
>> From: Bill Ress [mailto:bill at hsmicrowave.com]
>> Sent: Tuesday, July 03, 2007 6:49 PM
>> To: juan-rivera at sbcglobal.net <mailto:juan-rivera at sbcglobal.net>
>> Cc: eagle at amsat.org <mailto:eagle at amsat.org>
>> Subject: 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:
>>> 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!
>>> Juan - WA6HTP
>> Via the Eagle mailing list courtesy of AMSAT-NA
>> Eagle at amsat.org <mailto:Eagle at amsat.org>
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