Posted: 12/10/2011 3:22:27 PM EDT
There's a guy on 14.070@1500 who's just blowing all of the other signals out. When he transmits, I go from s2 up to s6. Good clear signal, but his text is all crap. I can read most of the other signals. Audie is around 50%, so not overloaded. Do I have something set wrong? Is that not a PSK31 signal? Or is he transmitting something encrypted? New to this digital thing, so trying to figure this one out. Thanks, -Slice |
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His spectrum looks fairly good, but he's slightly over driven (you can see the "ghost" traces above and below the main trace).
PSK depends on phase (hence the name) so you need the signal to stay linear, it looks like his may be slightly non-linear, so it's losing phase info and turning to crap. You might try turning on your attenuator or dialing down on the RX gain or audio gain into your interface, to see if it helps, you can overdrive on the receive end as well, and your traces are pure white. Odd are it's him, especially given that he's blowing out everyone else. He probably has the rig turned up on max and/or is using an amp outside of the linear mode. The key with PSK is if the AGC is activating on transmit at all, that the signal is overdriven and that will screw up the phase and thus information content. Some people really overdo it, and you see 20 sideband traces fading away from the main signal, and that's totally useless. Other modes can handle non-linear CW, pretty much all the FSK-based modes (RTTY, MFSK, Olivia/Contestia) can handle this, but it's still good practice to stay linear so your signal is as clean as possible. |
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That isn't a slightly overdriven signal. It's seriously overdriven signal. I see at least a pair of sidebands on either side of the main signal. Bad news all around. And once it gets this bad the decode quality starts going away.
Another thing is that I'm seeing more and more of on 20m is lids running 100w and just blowing away the waterfall. DON"T BE A LID! 50w max if you're chasing DX and 35w is plenty enough to work W, VE and XE with a dipole. If you're running a Yagi or other gain antenna turn it down even further. This ain't RTTY where more is better. The mode was designed around 40 to 50w and experiments have shown running more gains you nothing except the ire of other ops. |
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You can talk around the world on 20-25 watts PSK-31. Any more and you just interfere with everyone else. Anyone that uses more power than that should be beaten with a 6 meter dipole. This is where CB equipment works well in ham. Should be beaten with a 102" stainless whip. |
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You can talk around the world on 20-25 watts PSK-31. Any more and you just interfere with everyone else. Anyone that uses more power than that should be beaten with a 6 meter dipole. Sorry AFM, but this is flat wrong. You can use as much power as you want or need and still put out a perfectly clean signal. I do it all the time. The entire "don't use more than XX Watts" myth probably came from the fact that most hams these days are just knob twisters and have no theoretical understanding of what they are doing and it was a fairly simple and reliable way of keeping people from transmitting crappy signals. It is by no means the way to get the most performance from a radio. Of course the only true way to judge the ones signal for lack of distortion, intermodulation products and spurious outputs is to use a reference receiver and a spectrum analyzer. Unfortunately that is more than most of us can afford. A second best way is to set the radio to the power level you want and then adjust the audio drive level until the ALC indicator on the radio just barely starts to indicate some ALC action. However on some radios this is useless as the ALC doesn't provide a good indication of signal distortion. The IC7000 is a case in point. The guys on the IC7000 list found, using the aforementioned expensive test equipment, that the IC7000 ALC indicator could be driven to ridiculous levels and there would still be no distortion. A third way is to set the radio for a given power level and then adjust audio drive until either an average reading power meter is showing about 60% of the commanded power level or a peak reading power meter shows about 80% of the commanded power level. This is the method I use (I have an IC7000) and I consistently get excellent signal reports and compliments on my signals. To double check that one of the above methods worked properly, simply ask the person you are QSO'ing with how your signal looks on the waterfall. Finally, remember that drive levels will need to be adjusted when you change modes, antennas, bands and radios. |
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Quoted: You can talk around the world on 20-25 watts PSK-31. Any more and you just interfere with everyone else. Anyone that uses more power than that should be beaten with a 6 meter dipole Rettysnitch. Fixed it for ya.   http://rettysnitch.org/ |
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That's why whenever I set up PSK on a new radio, I ask for a signal report immediately. If the guy you're having a QSO with knows what he's looking for, it's a great opportunity to made adjustments to your signal (in short transmissions) to get an idea of what you can do and still be linear. I could drive my TS-940s to about 90 watts before the signal got nasty. My 897 would go to about 45 watts.
When my 480HX arrives I'll be finding out how much I can push too.... 200 watts on mobile PSK  
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Quoted:
Quoted:
You can talk around the world on 20-25 watts PSK-31. Any more and you just interfere with everyone else. Anyone that uses more power than that should be beaten with a 6 meter dipole. Sorry AFM, but this is flat wrong. You can use as much power as you want or need and still put out a perfectly clean signal. I do it all the time. The entire "don't use more than XX Watts" myth probably came from the fact that most hams these days are just knob twisters and have no theoretical understanding of what they are doing and it was a fairly simple and reliable way of keeping people from transmitting crappy signals. It is by no means the way to get the most performance from a radio. Of course the only true way to judge the ones signal for lack of distortion, intermodulation products and spurious outputs is to use a reference receiver and a spectrum analyzer. Unfortunately that is more than most of us can afford. A second best way is to set the radio to the power level you want and then adjust the audio drive level until the ALC indicator on the radio just barely starts to indicate some ALC action. However on some radios this is useless as the ALC doesn't provide a good indication of signal distortion. The IC7000 is a case in point. The guys on the IC7000 list found, using the aforementioned expensive test equipment, that the IC7000 ALC indicator could be driven to ridiculous levels and there would still be no distortion. A third way is to set the radio for a given power level and then adjust audio drive until either an average reading power meter is showing about 60% of the commanded power level or a peak reading power meter shows about 80% of the commanded power level. This is the method I use (I have an IC7000) and I consistently get excellent signal reports and compliments on my signals. To double check that one of the above methods worked properly, simply ask the person you are QSO'ing with how your signal looks on the waterfall. Finally, remember that drive levels will need to be adjusted when you change modes, antennas, bands and radios. I'm not talking about putting out a clean signal, which is, of course, the goal. It's about blanking out everyone else in the vicinity. If you are putting out PSK signals at 75 watts, the guys on the receiving end won't see anyone but you. The automatic gain in their receiver will make that happen. It is not a matter of turning down the gain, everyone else will drop down with it. |
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I'm not talking about putting out a clean signal, which is, of course, the goal. It's about blanking out everyone else in the vicinity. If you are putting out PSK signals at 75 watts, the guys on the receiving end won't see anyone but you. The automatic gain in their receiver will make that happen. It is not a matter of turning down the gain, everyone else will drop down with it. Agreed! 
But this assumes that I want them to see anyone but me!
More seriously, this is one of the classic conundrums of HF amateur radio, along with code/no-code, contesting, automated stations, ALE, spread spectrum, USB/LSB, and a bunch of other stuff. Of the following three characteristics: legal, effective and polite, operating techniques may or may not encompass all of those characteristics (although one hopes "legal" is always covered). That said I've never been accused of running too much power or asked to "turn it down". But you might be the first to do so! I suppose someday, if I ever have an uber-loop or some sort of serious antenna or a 1KW amp that might happen. Until then I'm giving her all she's got, captain (but without intermod's!) |
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If it's REALLY over-modulated.....I'll take a screenshot (ALT+PRINT SCREEN, ...paste) and email it to the offender.
I try not to be a dick about it, ...just say..."here's a screenshot of your signal, 73" most guys will reply with "OMG, I had no idea, thanks for letting me know." Some of the worst are the fucking CUBANS ( but I don't bother emailing them) |
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If it's REALLY over-modulated.....I'll take a screenshot (ALT+PRINT SCREEN, ...paste) and email it to the offender. I try not to be a dick about it, ...just say..."here's a screenshot of your signal, 73" most guys will reply with "OMG, I had no idea, thanks for letting me know." Some of the worst are the fucking CUBANS ( but I don't bother emailing them) I did that for the special event station k3fbi
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If it's REALLY over-modulated.....I'll take a screenshot (ALT+PRINT SCREEN, ...paste) and email it to the offender. I try not to be a dick about it, ...just say..."here's a screenshot of your signal, 73" most guys will reply with "OMG, I had no idea, thanks for letting me know." Some of the worst are the fucking CUBANS ( but I don't bother emailing them) Same Here, the cubans have wiped me out here more than once. ETA: Just want to add it sucks when you are working some weak signal station and some ass wipes out the waterfall running 90-200 watts, I have sent emails to people on that also. I start with low power and work up, only found the need to go above 20 watts one time. |
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Quoted: Quoted: If it's REALLY over-modulated.....I'll take a screenshot (ALT+PRINT SCREEN, ...paste) and email it to the offender. I try not to be a dick about it, ...just say..."here's a screenshot of your signal, 73" most guys will reply with "OMG, I had no idea, thanks for letting me know." Some of the worst are the fucking CUBANS ( but I don't bother emailing them) Same Here, the cubans have wiped me out here more than once. Would one of you guys mind posting one of those pics here, of what over-modulated looks like? |
Not the best example Only one I can find at the moment
You can see the "Ghost" image just up the waterfall, the superbrowser does not do it justice. You will see a lot of verticle lines on the standard waterfall, and the signal will approach 200+ Khz where it turns white, when they are really bad you will see a ghost image. By the way my RX audio was turned down on that screen capture to make sure it was not an artifact of my receiver, it was still over driving the line in, and several others commented in later QSO about the offending signal. ETA: The super browser still showed a couple of traces that were not visible on the other waterfall, but obviously the program would not be able to decode. |
Here are three different signals PSK31. Each is nice and tight. I could read all three clearly, though they are very closely spaced.
Here is an overdriven signal. You can see the ghosting on each side. 
But a signal can be nice and tight, no overmodulation, but driven at a high level. When that happens you see only that one signal, and everything else on the waterfall is blacked out. The signal in that case is so strong that the automatic gain in your radio cuts way back, which means the radio is only listening to the strong signal. Nothing else can be heard. There is usually no need to use more than 20 - 25 watts for PSK31. I have made QSOs 5000-6000 miles away on 20 watts. But a guy in the next state running 100 watts will ruin that. (These are screen shots from my own computer, not something I found on the net.) Take a look at that second picture. See at the bottom? There was a signal to the left of the overmodulated signal (centered at about 14.069.87 mHz) that disappeared when he began to transmit. Also, further over to the left, centered on 14.069.67 mHz, see what happened to his signal way over there? When Mr. Overmod's too strong signal came in, it blanked that other signal out to where it was barely visible on the waterfall, and not readable. That will happen over the entire waterfall with such a signal. It is not just the overmod, it is the signal strength, too. |
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Quoted:
Quoted:
You can talk around the world on 20-25 watts PSK-31. Any more and you just interfere with everyone else. Anyone that uses more power than that should be beaten with a 6 meter dipole Rettysnitch. Fixed it for ya.
http://rettysnitch.org/ PC, I just don't want to know... 
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Quoted: Quoted: Quoted: You can talk around the world on 20-25 watts PSK-31. Any more and you just interfere with everyone else. Anyone that uses more power than that should be beaten with a 6 meter dipole Rettysnitch. Fixed it for ya. http://www.arrl.org/images/view/Group/Sections/sec-1316.jpg http://rettysnitch.org/ PC, I just don't want to know... My 2nd line manager at the office had one of those... |
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Yeah the Cubans have done the same to me. However when you let them know most of them will make adjustments immediately. Got to give them a bit of a pass. Here we have the luxury of whipping out the credit card and the brown truck drops off a finished box ready to plug in. There they pretty much have to homebrew the interfaces using audio coupling rather than electrical coupling.
Same Here, the cubans have wiped me out here more than once. ETA: Just want to add it sucks when you are working some weak signal station and some ass wipes out the waterfall running 90-200 watts, I have sent emails to people on that also. I start with low power and work up, only found the need to go above 20 watts one time.
Lost one new DX when some jackass popped up and totally wiped out the waterfall. The DX was weak and 559 at best. Had a hard time with the decode missing quite a number of characters but was about to make a go of it. Then the lid started one of those forever and a day CQs and then on the exchange told his life story and down to the smallest detail his station. Spun the dial in disgust.
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