[amsat-bb] Re: AO-7 Record
w7lrd at comcast.net
Sat Jul 17 17:14:55 PDT 2010
When there is vhf/uhf contest going on I occasionally hear a contester on the AO-7 downlink. However due to fact that AO-7 has an inverting band pass the UHF uplink which is USB comes down LSB. This of course is unknown to the contester. Whereas everyone using AO-7 uplinks in LSB so that we receive in USB on the 145mhz downlink. This way I can tell who is the unintentional satellite operator. I think I got that right.
73 Bob W7LRD
----- Original Message -----
From: "James Duffey" <jamesduffey at comcast.net>
To: "Andrew Glasbrenner" <glasbrenner at mindspring.com>
Cc: "James Duffey" <jamesduffey at comcast.net>, "Amsat-bb BB" <amsAT-BB at amsat.org>
Sent: Saturday, July 17, 2010 4:20:45 PM
Subject: [amsat-bb] Re: AO-7 Record
Drew - Thanks for the comments and shedding light on this topic.
On Jul 17, 2010, at 3:55 PM, Andrew Glasbrenner wrote:
> Let me clarify something here for the record, especially since it keeps coming up. We absolutely DO have the ability to command AO-7, including a command set that will result in the satellite being silenced permanently. There simply is not much operational advantage to it, even when in continuous illumination. The ability to ceaase transmissions is all that is required of us by the FCC; I just hope we never have to do it. You do not have to look to hard to find other amateur satellites that are derelicts though...
I did not know this. Thanks for the clarification. Sorry for stating that we were flying a satellite we cannot control and I am sorry for adding to the confusion on this issue. It will not happen again.
> Additionally, although not stated in this discussion, there is much misconception about the legality of Mode B with the 432 uplink. AMSAT has an FCC waiver that is still in effect, so using the 432 is completely legal for US operators, at least.
As you say, I did not say that Mode B was illegal and did not mean to imply that it was illegal. But it does fall outside the general guidelines for amateur satellite operations today and we should consider that issue when we use it on Mode B.
I based my comments on the AMSAT Satellite Summary of AMSAT Oscar AO-7 located on the AMSAT website. See:
< http://www.amsat.org/amsat/sats/n7hpr/ao7.html >
Which contains the following two paragraphs:
"*Note: Due to changes in Amateur Service and Amateur Satellite Service there are questions as to legality of Amateurs transmitting to AO-7. The uplink frequency predates the WARC '79 allocation of 435-438 MHz by the ITU for the Amateur Satellite Service and places the uplink in 70cm weak signal segment.'
"Potential users should realize that when they are uplinking to a satellite, they are no longer operating in the Amateur Service but instead operating in the Amateur Satellite Service. Thus they are subject to Amateur Satellite Service rules. Therefore uplinking to AO-7 is possibly illegal since the Amateur Satellite Service is not permitted at 432.1 MHz. Also, since the IARU bandplan has the 432.1 MHz range earmarked as "weak signal" in all three Regions, it would appear that all users trying to access the uplink are also outside the Amateur Satellite Service rules and regulations."
The AMSAT web page is a prominent return when one searches for Oscar 7 on Google. Thanks for pointing out that these statements are incorrect, or at the very least, overcautious.
> As it is an uplink, there is absolutely no ill effect AO-7 can have on terrestrial 432 operations.
I agree for the most part, AO-7 uplink on 70cm will in general have little effect on 432 operations. But to say it has absolutely no ill effect is hyperbole. Consider this situation. A multi contest station is looking for QSOs on 70 cm Sunday evening and tunes across someone calling CQ in the uplink passband. The contest station thinks it is a terrestrial station in the contest and calls him. The station calling in the uplink hears the contest station on the satellite downlink and they have a QSO, exchanging signal strengths and grid squares. The contest station logs the contact and moves on. The multistation owner later gets a QSL from the station in the uplink claiming a satellite contact since he copied the contest station on the downlink. THe multistation owner realizes that his multistation has violated the contest rule that prohibits satellite operation in contests. Respecting the rules, he withdraws his submission and asks that it be considered a check log and is out !
of the competition with a very good score. This is an unusual case, I grant you, but I have been "distracted," for want of a better word, a time or two by satellite users in the OSCAR 7 uplink during a contest until I realize that they are not terrestrial stations in the contest, but trying to uplink to Oscar 7. Usually it is obvious, occasionally it is not. No harm done, other than the waste of a few minutes. I suspect that a few others may have had similar experiences.
If satellite operators on the 70 cm uplink are aware of their proximity to the 70cm calling frequency, particularly during contests, and call CQ Satellite, and mention that they are on the satellite during the QSO, then the impact of having the AO-7 uplink close to the 432.1 weak signal calling frequency can be minimized.
> I just noticed a few days ago that the AO-7 entry on wikipedia is 100% wrong on this and needs to be corrected. Maybe someone more familiar with wikipedia than I will do so after seeing this email.
The Wikipedia entry is pretty much a verbatim quote of the AMSAT satellite summary on the AMSAT page and cites it as a source, which makes sense, so changing the information I quoted above on the AMSAT summary is a good start on getting it changed on Wikipedia. When the citation goes away the Wikipedia entry will have less value. I don't contribute to Wikipedia, but I can learn how to change this if that is what is warranted. It won't help much to change the secondary source, Wikipedia, when the primary source, AMSAT, remains unchanged though.
Again Drew, thanks for your comments on this issue. I have revised my thinking on Oscar 7 control. - Duffey
Cedar Crest NM
Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
More information about the AMSAT-BB