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Author Topic: i'm glad someone finally told me  (Read 6331 times)
KM4IY
Member

Posts: 31




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« on: April 06, 2013, 04:52:19 AM »

that my PSK signal was all over the place!  my only excuse is ignorance, not stupidity.  As a novice in the mode, I tried to follow suit and adjust my station like I saw others.  i'd reduced power to about 40 watts like a lot of other stations I listened to.  I was unaware of how much impact my audio would have...

its difficult to ascertain the signal strength/quality from my end of the antenna, but the reports i'd received had been excellent and even comments about how "clean" my signal was had been made, so I went happily on, warbling along.

then I guess, a frustrated station made a remark that left me wondering how to interpret it, being a worrier, it interpreted it to mean the worst and began investigations.

to my embarrassment, I found I was guilty of doing what i'd fussed about so many times, splattering all around me.  with the help of several very patient and kindly stations that took screen shots and videos, I believe I have contained my beastly audio and will be easier to listen to and not take so much space on the falls.  I've found that my 20/25 watts and abt half the audio i was using, amazingly to me, does as well.

From the comments i received, i assume the impact of my signal is relative to the distance the receiving station is from me.  the guys in the surrounding states were most bothered when asked while the guys on the coasts and the overseas stations didn't seem to see as much.

I am appreciative of the help I've received and the manner in which it was given.  there was no swearing or angry words, only diplomacy and tactfulness.  i believe if this technique was used on others who are probably unknowingly doing what as i was, it would help us all... i don't mean to advocate "policemen" on the falls, but don't assume that the person's overdriven audio is purposeful.  i think most of us are concerned with being good neighbors and would take kindly to some well meaning, tactful, constructive criticism.

Yet, i guarantee there are those that will take offense and "go off" on anyone that offers help...

i'd like to make my apologies to those who's PSK life's I've made miserable the past 6 weeks, and thank those that took time to educate me.  Please, if you hear me doing that again... kick me!  i get excited when i'm trying to nail a "new one" and in my enthusiasm get too loud, but a good boot in the rear will wake me up.  :-)

73
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AD9DX
Member

Posts: 1481




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« Reply #1 on: April 07, 2013, 05:14:58 PM »

I am fairly new to digi-modes. I am always grateful to hear good or bad how my signal looks on the other end.  I hate it when a OP runs full bore on PSK and wipes out the whole spectrum and no one tells him about it. 
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EX, KC9TRM, KB9IRZ
AJ4RW
Member

Posts: 568




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« Reply #2 on: April 07, 2013, 06:14:24 PM »

What was wrong with the audio to cause your splattering?  Mic gain set too high?

Thanks Randy
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AA4PB
Member

Posts: 12837




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« Reply #3 on: April 08, 2013, 05:23:44 AM »

A PSK meter will let you monitor the quality (IMD) of your own PSK31 signal.
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AJ4RW
Member

Posts: 568




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« Reply #4 on: April 08, 2013, 01:39:50 PM »

Quote
A PSK meter will let you monitor the quality (IMD) of your own PSK31 signal.

Thanks for the info.  I've been using PSK31 for a couple of years but only minimally until recently.  I googled it and found some informative articles plus the website for the PSK meter.  I've really started using PSK31 while exercising on the treadmill, I noticed that PSK 31 is well used and it's easier to make QSO's thus time blows on by.  I use the DATA port on the back of the radio and adjust the signalink according to manufacturers recommendations.  My audio must not be distorted because I usually seek a frequency that's at least 200 Hz away from everyone else and within about 5 minutes I'll have a couple of stations within about 5 Hz from my signal.  I don't like prducing a distorted signal so as long as they don't cause too much distortion with me I'm a happy camper.
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W6UV
Member

Posts: 538




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« Reply #5 on: April 09, 2013, 12:24:32 PM »

I am fairly new to digi-modes. I am always grateful to hear good or bad how my signal looks on the other end.  I hate it when a OP runs full bore on PSK and wipes out the whole spectrum and no one tells him about it. 

Note, however, that there's a difference between "wiping out the whole spectrum" by over driving your transmitter and doing the same with a big (but clean) signal.

The first is a problem and should be corrected by setting the audio output of your sound card and the mic gain of your rig to appropriate levels. The usual criteria is that you don't want to see any ALC indication. If you do, turn down the audio until you don't.

The second is completely different (and controversial). A strong (but clean) signal anywhere in the IF passband will cause your rig's ALC circuit to reduce receiver gain. This makes it appear that the waterfall goes blank. This is normal and the expected action when encountering a strong signal. The solution is to use a narrow filter to reduce the size of the IF passband to exclude the strong signal. A PSK31 signal has a bandwidth of around 31 Hz. Using a 3 kHz filter to receive a 31 Hz signal is equivalent to using a 300 kHz filter to receive a 3 kHz SSB signal -- roughly the equivalent of a filter as wide as the entire 20m band.

Some say that one shouldn't use more than 20 watts or so on PSK31. I disagree. The difference between 20 watts and (for example) 100 watts is only 7 dB. Propagation can easily cause a 30 db (or more) difference in signal strengths. There's really no way to tell that the strong signal you see wiping out the waterfall is from someone running 100-200 watts or someone running 5 watts, but with favorable propagation.
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AC4BB
Member

Posts: 46




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« Reply #6 on: April 16, 2013, 07:26:50 PM »

  It's been my experience in my13 years on digital that most are delighted to get the reports good or bad. You'll find a very few that will get their drawers in a wad when you point it out.
 GL and I hope to see you on the waterfall.
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AE5J
Member

Posts: 27




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« Reply #7 on: April 17, 2013, 06:03:35 AM »

Not wishing to get into the discussion of the need or desirability of using large amounts of power on modes that require very little, there is, as has been pointed out, the need for more careful monitoring of operating technique on digital modes.

I consult the technical specifications for my rigs to determine what maximum level of power my rig is capable of producing in AM mode. That number becomes my upper limit - a never exceed power output level.

Using Signalink USB interfaces, I set the rig power at maximum output. I then carefully monitor the ALC level during transmit and use the output level on the Signalink to keep the ALC completely off and power at or below the upper power limit - for me usually quite a bit below.

If I cannot reduce the output power enough with the Signalink control, I reduce the output level on the computer. Tigertronics has an excellent guide for steps to accomplish this on their website. I always double-check myself to be certain I am adjusting levels for the Signalink sound card, and not the computer sound card.

I then EXPECT other hams to let me know if I am not transmitting a clean signal and I let others know when they need to adjust settings.

I used to think today's modern transceivers made operation much simpler. Certainly CW and SSB are. However digital operation takes skills (I have found) that rival the days of old - tuning tube equipment and controlling modulation - albeit lacking the old time glow. Good luck, tune carefully, and 73.

Pete
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K9MHZ
Member

Posts: 406




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« Reply #8 on: May 05, 2013, 05:55:09 AM »

  It's been my experience in my13 years on digital that most are delighted to get the reports good or bad. You'll find a very few that will get their drawers in a wad when you point it out.
 GL and I hope to see you on the waterfall.


Excellent point, I totally agree.  Probably has something to do with a waterfall not telling any lies.  In SSB, "you sound tinny, you sound overdriven", etc are qualitative, but a wide PSK signal is there for the whole world to see.

 
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AA4PB
Member

Posts: 12837




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« Reply #9 on: May 05, 2013, 01:40:26 PM »

The waterfall tells you the condition of the signal being processed at your sound card but distortion can be injected anywhere in the signal chain between the transmit sound card and the receive sound card. It doesn't necessarily always prove that the transmit signal is defective. I've personally seen an AGC setting on a receiver make a significant difference in the waterfall and the displayed IMD. If everyone has a bad signal then you might want to check out the receiver  Cool
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K5TED
Member

Posts: 728




Ignore
« Reply #10 on: May 06, 2013, 07:54:50 PM »

On some radios, leaving the NB on will cause ringing across the waterfall on strong signals. While the NB may appear to "clean up" the waterfall in certain instances where there is a high impulse noise floor and weak signals, leaving it OFF will rarely affect decoding.

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