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Author Topic: New CW patterns in 160m contest  (Read 4025 times)
NO9E
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Posts: 416




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« on: January 29, 2013, 07:37:00 AM »

In 160 m contests, there were usually two type of CW signals: with wide clicks and with narrow clicks. When seen on a panadapter, these signals had a distinct narrow peak.

In the last 160 m contests there were a few extra patterns:
1. Like with wide clicks but cut neatly about +-200Hz from carrier
2. Noisy (less distinct peak)
3. Noisy and wide with streaks every 100 Hz.

Clicks come mostly from too rapid rise/decline, as shown on W8Ji pages. Where would teh other types come from?

Ignacy, NO9E
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N3QE
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Posts: 2284




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« Reply #1 on: January 29, 2013, 10:39:04 AM »

I don't have a panadaptor, but I definitely heard something like strong synthesizer/phase noise on one signal, and several signals had a lot of 120Hz power supply ripple. Is it possible your 100Hz streaks were really 120Hz streaks? (Of course a EU would have 100Hz power supply ripple).

And as Saturday night turned into morning, I think the high A and K indices were causing some near-local signals to have weird wobbly sounds. Not too different than the "backscatter" sound on 10M locals, or "interstellar" sound on locals on 40M in late night early AM, but not the same either. Interestingly enough, if I pointed my K9AY receive loop in a different direction, this did clear it up.
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NO9E
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« Reply #2 on: January 29, 2013, 01:47:29 PM »

Quote
I don't have a panadaptor, but I definitely heard something like strong synthesizer/phase noise on one signal, and several signals had a lot of 120Hz power supply ripple. Is it possible your 100Hz streaks were really 120Hz streaks? (Of course a EU would have 100Hz power supply ripple).

The streaks in one signal were not quite stable and the signal was noisy and wide: > 1 KHz.    I did not hear a distinct AC modulation but perhaps my radio was set at too narrow bandwidth to hear it.
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W5LZ
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« Reply #3 on: January 29, 2013, 03:54:11 PM »

Or, were those sounds possibly 'ringing' from too sharp a skirt on those filters?  Been a while since I was very familiar with sharp skirts but then, what I'd say a noise sounded like is probably different from what your ears tell you.  'Skirts' can be too sharp.
 - 'Doc

(and on some, skirts can also be too short! Wink)
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GW3OQK
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Posts: 153




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« Reply #4 on: January 30, 2013, 02:18:41 AM »

N3QE, condx were extrordinary at at the time you mention, dawn in UK 0600-0730 27th, and I worked 40 NA stations including Arizona and Mexico with my modest set up. At one time I thought I heard a weak echo of my own signal.

I often hear 100 Hz ripply on VERY strong EU signals and always think they dont have enough smoothing on their illegal level amps. And they usually have click either side too.
Andrew
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N3QE
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« Reply #5 on: January 30, 2013, 06:34:03 AM »

N3QE, condx were extrordinary at at the time you mention, dawn in UK 0600-0730 27th, and I worked 40 NA stations including Arizona and Mexico with my modest set up. At one time I thought I heard a weak echo of my own signal.
Oh, yes, without a doubt. At the time you mention, several G's were coming in super duper loud here in the mid-atlantic, louder than many of the NE US stations. Later near US dawn, I swear I was hearing backscatter from the stronger US NE stations.
Quote
I often hear 100 Hz ripply on VERY strong EU signals and always think they dont have enough smoothing on their illegal level amps. And they usually have click either side too.
I think 100/120Hz ripple can be there for a number of reasons, not just poor design, but old filter caps too.

I find it interesting that some of us think in terms of signal cleanliness as it looks on a panadaptor (original poster), and others of us are quite willing to diagnose the cause by ear (you and me). Mostly because you and I know what 100 or 120 Hz ripple sounds like. In contests on the HF bands, I listen for tell-tale 100Hz ripple (as opposed to 120Hz ripple) to identify real quick whether the signal is DX or NA. I'm sure same could be done with a panadaptor but... I guess I think about that with my ears, not my eyes. Interesting, as others would do it with their eyes.
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ZENKI
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Posts: 956




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« Reply #6 on: February 01, 2013, 03:31:41 AM »

The wide clicks  that I have noticed come from a lot of the autotune and solid state amplifiers. Many owners of these amplifiers use ALC for protection. When the amp is not tuned correctly or the VSWR is slightly off
these combinations of amplifiers and certain radios cause wideband broad keyclicks.  These clicks can go very wide, far wider than just ordinary keying sidebands.  You also get problems when  switching between the amp and the radio is not perfect.

 When you watch these stations on a SDR or Panadapter its like watching   wave in the ocean, as it rolls toward the shore. In this case wide clicks or sidebands roll away from the signal and then settles down. You however still hear the keyclicks. With the wide spread availability of SDR radios and pan adapters everyone should really be monitoring their signal quality and the SDR is perfect tool for doing so. With the peak hold turned you can see the signature of the destructive keying spikes and how it takes out several KHZ causing QRM. This  problem seems to very prevalent with Acom 2000 amplifiers and certain radios.

It seems clicks during CW contests have become the norm, its really hard to believe we have gone backwards in regards to total keying bandwidth in this day and age. Today we should have  radios producing perfect narrow band CW keying but this is not the case today.

Ideally if someone produced a piece of software for a SDR receiver it should have a narrow band occupied bandwidth MASK which quickly give a pass or fail on your signal. Its just very hard to convince manufacturers and authors
of the SDR software too implement such features. All they concerned about is useless features and coarse resolution bandwidths. LINRAD by SM5BSZ has got the best set of tools for determining occupied bandwidth of SSB and CW signals. There is no piece of SDR software or pan-adapter that  has the same ability to determine and monitor occupied bandwidth, they all just eye candy monitors  when they could be good spectrum analyzers.



In 160 m contests, there were usually two type of CW signals: with wide clicks and with narrow clicks. When seen on a panadapter, these signals had a distinct narrow peak.

In the last 160 m contests there were a few extra patterns:
1. Like with wide clicks but cut neatly about +-200Hz from carrier
2. Noisy (less distinct peak)
3. Noisy and wide with streaks every 100 Hz.

Clicks come mostly from too rapid rise/decline, as shown on W8Ji pages. Where would teh other types come from?

Ignacy, NO9E
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K8AC
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Posts: 1477




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« Reply #7 on: February 08, 2013, 05:56:43 AM »

Quote
In 160 m contests, there were usually two type of CW signals: with wide clicks and with narrow clicks. When seen on a panadapter, these signals had a distinct narrow peak.

It's rather easy to misinterpret what you see on the panadaptor.  The narrowness of the peak has nothing to do with clicks you're hearing - a perfect CW signal will be very narrow with steep skirts.  If a signal has clicks, it will usually show distinct sidebands which are the clicks that you can hear.  It's difficult to see these click sidebands on the panadaptor and almost impossible to pick them out in a contest situation on 160M.  The shape of the skirts you see will also be determined by some of the parameters you set in the software being used to display the panadaptor image and you can often be misled by that. 

73, K8AC

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NO9E
Member

Posts: 416




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« Reply #8 on: February 27, 2013, 01:16:43 PM »

Quote
It's rather easy to misinterpret what you see on the panadaptor.  The narrowness of the peak has nothing to do with clicks you're hearing - a perfect CW signal will be very narrow with steep skirts.  If a signal has clicks, it will usually show distinct sidebands which are the clicks that you can hear.  It's difficult to see these click sidebands on the panadaptor and almost impossible to pick them out in a contest situation on 160M.  The shape of the skirts you see will also be determined by some of the parameters you set in the software being used to display the panadaptor image and you can often be misled by that. 

Truue taht with wide panadapter settings it is hard to see details. I observed signals with P3 set to 2 Khz wide. Visual and aural experiences are in full agreement.
Ignacy
 
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