[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

RE: Alive SEDSAT




Dennis et. al,

 The component that was damaged during assembly was replaced roughly a month
before the shock test disaster, with much assistance from the Cyanetics
engineer who designed the circuit. All of our final communications testing
was done with the new component in place and the receiver re-tuned.

 All of this was covered extensively in the weekly SEDSAT mailing list
updates written by Dr. Maier. An archive of the updates will be available
sometime in the Fall.

 The long and the short of it is we have not managed to test the uplink. The
two tests that were done in the past were done incorrectly, the first with
the wrong uplink frequency, the second with the wrong reset code.

 This of course begs the question "What is preventing another test from
happening?"

 The answer is a combination of things. First, UAH does not have the
capability of transmitting at 1200mhz at 9600 baud. (To our shame, we
launched a satellite without a compete groundstation). All of our attempts
have been provided by the very generous Jim White (Thanks Jim!). They
currently receive telemetry daily from extremely generous HAMs (N8DEU,
GW6KZZ, VK2XGJ, and JE9PEL primarily. Others, on occasion)

 Second, because this was a student project, and students inevitably
graduate and move on, there has been some loss of knowledge. The original
team (including myself) contributes as we can, but between my job and my
marriage in 26 days I have had very little time of late.

 Finally, a lot of things have to fall into place for a test to happen.
Everyone has to be available, SEDSAT has to be "awake" and broadcasting, and
AOS above the uplinking station has to occur at a reasonable time of day.

 There will be another uplink attempt soon. I don't want to waste anyone's
time with another flawed test that proves nothing. On the other hand SEDSAT
was never designed to "deeply discharge" so often - roughly every 38 hours!
The fact that she still transmits in a predictable manner is a testament to
everyone who helped to design and build her.

 A lot of things could and should have been done differently. On the other
hand, SEDSAT was (and continues to be!) a tremendous learning experiance for
many lucky students, of which I am proud to be one.

 For information on "working" (such as is available) SEDSAT, please see
www.seds.org/sedsat or email christopherbond@email.com for details.

-Chris Bond

> -----Original Message-----
> From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
> Behalf Of Dennis Ray Wingo
> Sent: Monday, August 23, 1999 9:22 AM
> To: amsat-bb@AMSAT.Org; Mineo Wakita
> Subject: Re: [amsat-bb] Alive SEDSAT
>
>
>
> Thanks Mineo!
>
> We have been getting data here in Huntsville, curtesy of Tim
> N8deu as well.  The batteries are starting to degrade due to
> the continuous deep discharge cycles but we are nearing a
> year in orbit now. Cry. I wish we could talk to the bird!
>
> On that note an RF engineer friend of mine said that if a
> componet was broke by the students on the main receiver
> instead of the secondary one as reported then we should be
> able to possibly transmit on one of the receiver spurs and
> possibly talk to the bird. My RF engineer friend thinks that
> this is what they were actually doing in the final days of
> testing after the component broke.
>
> Keep your fingers crossed!
>
> Dennis
> KD4ETA
>
>
> Get your FREE Email at http://mailcity.lycos.com
> Get your PERSONALIZED START PAGE at http://my.lycos.com
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home