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

RE: Orbit 250 apogee

At 01:44 17-05-2001, you wrote:
>Lee wrote:
>         ...100w EIRP should provide a 23db SNR at the AO40 U-rx.
>Wayne replies:
>100W ERP may give 23dB SNR at the AO40 receiver, but the corresponding
>downlink doesn't give most of us any where near 23 dB SNR on the S2
>downlink.  For me, the average SNR with SSB signals is in the 0-10 dB range.
>Most of us need more than 100W uplink ERP to get a readable SSB downlink.

It's that kind of alligator-mentality that must be fought at all cost, with 
all available means, if the hambans are not to be a waste of tile :-((

>Ideally we would all get 0.5 dB NF downconverters and 24+ dBi antennas, plus
>precision rotors to handle such a narrow antenna beamwidth.  But most of us
>don't have all that, and should we really need that with a 50W transponder
>and high gain antennas?

Do your math, Wayne!

>  Maybe the current LEILA-controlled "power per user"
>is appropriate for some time in the distant future when there are 100+
>signals on the transponder.  But it doesn't seem reasonable now when there
>are few users and most of us are struggling to hear the satellite.

That is the most infantile argument i have heard so far!!!!

Exactly WHEN is this graceperiod going to end, with all the crocs hogging 
the transponder?


Next week?

Next month?

When wayne gets tired of (ab)using the sat because there is so few people 
to talk to, since he is pumping up the AGC, not allowing anyone throug than 
the big-boomers?
Or maybe these are the only people wayne wants to talk to?

 >Wayne replies:

>Telemetry watchers say that 23cm uplink signals hardly budge the AGC even
>when the downlink signal is strong.  In comparison, 70cm uplinks affect the
>AGC a LOT even when the downlink signal is weak.  To me, the telemetry
>suggests that something is wrong with at least one of the AGC's.

Why not try to find all the flaws in YOUR setup, Wayne, rather than PRETEND 
that there is something wrong with bird, simply because your stonedeaf 
setup is unable to hear most of what goes on. Grrrr!

As i said before, read some of JRM's articles, it did open MY eyes!

>Lee wrote:
>         Driving AO40's ul AGC
>         primarily acts to keep the offending downlink signal from getting
>         stronger.  It does this by reducing the effective sensitivity of the
>         rcvr.  As a result, the aligators aren't really that much stronger,

My point exactly, Lee.

>but they
>         prevent the lower powered stations from accessing the satelllite.

And that's what p***** me off about Wayne's selfish attitude.

>Wayne replies:
>I know the theory, but that is NOT what I observe.  I observe a linear
more beating around the bush....

>I'm curious to hear from former AO13 mode-S users.  How does the signal
>strength from AO40's LEILA-controlled 50-watt U/S2 transponder compare to
>signals from the tiny 1W U/S transponder on AO13?

The Squint, Wayne, remember the Squint and try again!

>I don't want to advocate an ERP arms race,

So why do you!

>  but I do want to advocate making
>the U/S2 transponder "usable" with commonly available equipment.

Like the one you just happen to have already?
LNA's are HIGLY available, believe me.

>  In my
>opinion that requires a slightly higher LEILA setpoint.

Nope, it requires more $ spent on the receiver, and less on the Linear!

>The S1 antenna with minimal squint would provide a much stronger downlink,
>but I fear that off-pointing requirements for solar illumination will force
>us to use the wider-beamwidth S2 antenna most or all of the time.

Wayne, there are people out there who have worked the sat QRP with usable 
signals, but you are having trouble hearing yourself with much more power.

What does that reveal about your RX-setup?

73 de OZ1LRG

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