[amsat-bb] Lower your power!!!

[Hasan al-Basri]

Excellent follow up, James, just super.!
73, N0AN
Hasan


On Sat, Mar 7, 2020 at 9:22 AM JamesDuffey <jamesduffey at comcast.net> wrote:

> Hasan-This is a good post. I would add a couple of small points:
>
> 1. Use full duplex. it is easier to tell how loud one is on full duplex
> and if you are running so much power as to modulate the passband. I think
> it good practice to use duplex all the time on the satellites, FM or
> linear, but that is a topic for another time.
>
> 2. Use a gain antenna, like a Yagi. Even a two or three element Yagi will
> help a lot to bring the satellite received signal and satellite noise floor
> above your local noise floor.  I think an antenna with the elements for
> both bands all in a plane, like the cheap Yagis, the DK7ZB duoband
> antennas. or a log periodic like the Elk is better than an antenna where
> the elements for the two bands are orthogonal. Again, antennas are a topic
> for another time, but they are the easiest and cheapest way to improve your
> signal. Some may say only way.
>
> 3. If you are new to linear satellites, tell those who you contact you are
> new to the linear satellites and ask how your signal compares to the beacon
> or to other responsible ops.
>
> 4. If you are reluctant to tell someone they are running too much power or
> don‘t think you can do so tactfully, give reports relative to the beacon
> strength and hope that the op who receives a report that their signal is
> 10dB over the beacon will take the hint and reduce their power. Best case,
> they will ask what that means and why it is important.
>
> 5. Realize that the satellite passband is a shared resource. It is not
> always easy to share. Recognize that and try to behave in the passband the
> way that you would like others to behave in the passband. Although we tend
> to think of sharing in terms of who gets the kindergarten and preschool
> toys, or who gets the last piece of cake or pie, or who gets to ride
> shotgun, it is more like the “Tragedy of the Commons” that you learned
> about in freshman econ. To refresh your memory read:
> < https://en.wikipedia.org/wiki/Tragedy_of_the_commons > and act
> accordingly.
>
> 6. If someone consistently runs too much power on the satellites, it is
> often out of ignorance rather than malicious intent. Mentoring locals that
> are operating with poor receive capability or poor antennas, and offering
> help, can go a long ways towards helping reduce alligators. When someone
> moves up from the FM birds and wants to improve their station, they are
> often amazed that replacing that run of RG58 with LMR400 or even RG213 and
> putting up a cheap Yagi makes a big difference. And if they operate duplex
> they can hear the difference.
>
> I hope this helps.  The problem is an electro-psychological one, where
> attitude is as important to the solution as is technology. Few of us
> readily change our behavior without a wake up call.  - Duffey
>
> James Duffey KK6MC
> Cedar Crest NM
>
> On Mar 7, 2020, at 04:23, Hasan al-Basri via AMSAT-BB <amsat-bb at amsat.org>
> wrote:
>
> Joe, (and other inexperienced sat operators). When I use the term 'you'
> in
> this post it is not to be taken personally. If the shoe fits...well, then
> yes, take it personally, otherwise just take it as a way to describe an
> operating guide.
>
> 1. Yes running too much EIRP aka Effective Radiated Power, (power plus
> antenna gain - feedline loss) ruins operations for other operators. It may
> also cause a malfunction of AO-7, to include FM'ing on SSB or shutting down
> the xponder entirely.
>
> AO-7 is a particularly sensitive case. So, let's set it to the side for the
> moment.
>
> On the other linear (SSB/CW) birds like CAS-4A, 4B, XW-2A, 2B, 2D (again),
> and 2F here are the issues:
>
> The downlink power (the sat's transmitter) is shared. It is shared in
> proportion to the strength of the uplink signal from each individual
> station. So, if a station is running *excessive EIRP,* they capture the
> vast majority of the available downlink power and everyone else's signal is
> driven into the noise floor. This happens at a syllabic rate on voices
> (heard by others running proper power levels as a pumping up and down of
> their signal at the speech rate of the offending signal). On cw, it is even
> worse, with each keyed character driving all the other signals into the
> noise floor at the keying rate.
>
> Saying, "I'm only running 5 watts" is NOT an acceptable answer. It also
> demonstrates that those saying it have no idea how to considerately operate
> on a satellite.
>
> *There is one simple rule: You should never be louder on the downlink than
> the strength of the CW beacon, period.*
>
> It is the ops responsibility to stay within this limit. No excuses, no
> explanations, just do it.
>
> Unfortunately, this pumping/power robbing happens frequently on all birds,
> because operators either:
>
> 1. Have no idea what they are doing....or
> 2. Don't care that they are ruining the operation for others.
>
> I have many hours of 15 minute pass MP4 recordings of these situations and
> have been tempted to publish them. I have resisted publishing them because
> so many of them seem to be the result of "innocent" mistakes.
>
> So, what is excessive EIRP and how do we avoid it? For simplicity's sake,
> I'm going to refer to EIRP as power.
>
> You should adjust your uplink power so that it *NEVER *exceeds the strength
> of the CW beacon you are hearing *AT THAT TIME*. Simply looking at the
> beacon once in an entire 15 minute pass does not reflect what is happening
> throughout the pass. The beacon reference needs to be repeatedly checked
> during the pass to see if you need to power down. It's a LOT easier to tell
> if  you have enough power (you can hear yourself), but a lot harder to pay
> attention to the fact you are too loud.
>
> I cannot tell you how many times I have witnessed a QSO where one op tells
> the other, "*You have a great signal*"....yeah, 8 dB above the beacon,
> stealing the downlink power from the considerate operators who have kept
> their uplink power low enough to stay no stronger than the beacon. Yes,
> they are loud. But on this shared resource we call a satellite downlink
> passband, being an Alligator (big mouth, poor ears) is not something to be
> proud of, nor should we be complimenting operators for this lack of either
> 1) awareness; or 2) consideration, for the other operators.
>
> Also, you may sound weak because of poor receiver performance on your end,
> so you are tempted to turn up your transmit power to make up for your poor
> ears. *This is a constant problem on the birds as they are being used
> lately. *Many ops seem unaware of how poorly they are hearing and it has
> little or nothing to do with their bright and shiny new rig. :-)
>
> Someone else mentioned, that if you can't hear the beacon, don't
> transmit. *Truer
> words were never spoken*. If your rx performance is so bad that you cannot
> hear a signal that is easily 15 to 25 dB above the noise, then don't
> transmit, all you are going to do is power rob others.
>
> The truth is, all of the linear birds on mode B (2m downlink), have beacons
> that  consistently run 15 to 25 dB above the noise floor. If  you don't
> hear them that strong, fix your receiver setup. Add a preamp, use better
> coax, increase your receiver antenna gain. etc.
>
> Another simple test: do you hear passband noise from the satellite? When it
> comes into view, you should be able to hear a marked increase in your
> receive noise. At the peak of the pass you should be able to hear it
> easily. If you don't, your rx performance is poor. 9700 and SDR users will
> see a marked 'hump' shape of the passband if they are set to a wide
> panoramic view.
>
> Turning up your transmit power is not the solution and you will, indeed,
> ruin other people's qsos.
>
> In another post, I mentioned a simple and dirty way to tell if you have
> adequate receiver performance. It requires no test equipment.
>
> 1. Disconnect your antenna.
> 2. Connect a 50 ohm dummy load (a simple 47 Ohm resistor works fine) to the
> antenna input of your radio. You will not be transmitting.
> 3. If you can turn the agc off in your rx, do so. If not, set it to Fast.
> 4. Noise Blanker or Noise Reduction OFF
> 5. Now....turn up the volume so the noise coming out of the speaker is
> quite obvious, but not ear splitting.
>
> Remember how loud it sounds.
>
> 6. Quickly disconnect the resistor and replace it with your satellite
> antenna.
>
> Did the noise jump up considerably compared to the noise caused by the 50
> ohm resistor?
>
> If not, your rx performance is poor. You need to fix it, as above.
>
> If it did jump up, at least a bit, you are probably in a relatively quiet
> RF location for noise and that is really good...and the fact that you can
> hear environmental noise above your receiver's internally generated noise
> is very good.
>
> If it jumped up a very large amount, then your locally generated
> environmental noise is high, which is NOT good, because you will end up
> turning up your transmit power (uplink) to the birds to overcome it...and
> of course, the rest of the people using the satellite will be driven down
> into the noise floor, or power modulated by your speech rate or cw keying.
>
> So, what do we do about all of this?
>
> 1. Exercise some real care about your operating practices. Take time to
> learn how your station performance varies by the nature of a pass (shallow,
> moderate, very high) and during a pass ((current elevation and polarization
> fading).
>
> Using linear birds considerately requires skill and operator attentiveness.
> This is completely different than FM birds and is much more demanding of
> operator intervention.
>
> *Most importantly, during the pass itself check the beacon strength several
> times and adjust your uplink power such that your received signal does not
> exceed the strength of the CW beacon.*
>
> Those with the nice shiny new Icom 9700 have no excuse for ever being
> stronger than the beacon. They can simultaneously monitor the beacon level
> and their own signal (as well as others in the passband) with the
> panadapter feature of the 9700. Set your rx width on the panadaptor to +/-
> 25 kHz and center it so the PSK beacon is at the left edge of the display
> and the right edge is above the op of the satellite passband (and  you will
> see the CW beacon just above (to the right) of the PSK beacon and the
> normal passband just above (further to the right) of the CW beacon). This
> should be on your display all the time. Then you can always see if  you are
> too strong. It will be obvious.
>
> 2. If you have access to an SDR dongle like the FunCube Pro +, run software
> like SDR Console v3 (free). You will be able to see every signal in the
> passband in real time from the PSKBeacon to the CW Beacon to your signal
> and all the others.
>
> When you can see what poor operating practices do to the satellite passband
> and everyone trying use it, you will be amazed.
>
> Since more and more of the serious satellite ops are getting 9700s and
> SDRs, I find that the first thing I tell someone when I'm working them is
> how strong their signal is (in relative dBm) and how strong the beacon is
> (in relative dBm) . If they are exceeding he beacon, I ask them to reduce
> power. It's that simple.
>
> I'd really like to not have to:
>
> 1. Chase people all over the birds asking them to reduce their signal
> because they are 6 to 10 dB over the beacon and are "power modulating"
> every signal on the satellite.
>
> 2. Get on their freq and politely call them....only to have to chase them
> all over the passband because they can't hear themselves and they continue
> to transmit anyway.
>
> As the popularity of satellites, especially the linear birds, has
> increased, we are coming under more and more pressure to clean up our
> operating habits. These are NOT FM birds. *Getting on one freq and
> capturing the downlink with one signal with all the juice you can put out
> is not an acceptable operating technique on the linear birds*.
>
> It is inconsiderate and destructive.
>
> Hopefully, the directness of these explanations will help and not offend
> new satellite ops. It has gotten bad enough, that something needed to be
> said. We want all of you on the birds,  just play nicely.
>
> 73, N0AN
> Hasan
>
>
> On Fri, Mar 6, 2020 at 3:19 PM Joe KD2NFC via AMSAT-BB <amsat-bb at amsat.org
> >
> wrote:
>
> I was just on AO-7 and was told to lower my power from more then one
>
> person. Sorry about that folks, just getting adjusted here, please be
>
> patient with a satellite beginner.
>
>
> Now that we are here I was curious what a lot of power in does to the
>
> linear birds, does it ruin the passband for others? Also how much is a good
>
> amount of power to start with or one shouldn’t exceed?
>
>
> FM birds probably have similar operating rules as well right.  I’m here to
>
> learn :)
>
>
> Joe
>
> KD2NFC
>
>
>
> Sent from my iPhone
>
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>
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>
> _______________________________________________
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> to all interested persons worldwide without requiring membership. Opinions
> expressed
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> AMSAT-NA.
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