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Author Topic: cw interfering with digital on 40 meters  (Read 3331 times)
WB5NHH
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Posts: 14




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« on: February 19, 2010, 12:42:55 AM »

I am a licensed amateur radio operator.  I operate only cw and mainly on 40 meters  of which i am allowed to do according to my station license. I am very aware of band conditions and interference on 40 and all amateur bands and gosh knows we know there is interference. Operating  is on a shared basis and I understand that. Before operating on a given frequency  I listen and then transmit qrl several times listening in between to make sure I dont interfere with another station that i might not here or is not transmitting at the time but from time to time things do happen and I feel bad about that when it does. On February 7, 2010 AT 0255 utc on 7.076mhz  I sent qrl several times listening in between calls to make sure  i am not interfering with anyone. Hearing nothing I transmitted a cq and was answered by a WA6 station and we carried on a cw qso. A few days later I now have received from a OO that I was interfering with a NON FREQUENCY AGILE DIGITAL SYSTEM  that was already transmitting on that frequency. I never heard that station at all at any time before, during and after my qso. And if I cant hear the digital station then how do i know i am interfering with them. According to my license i can operate on 40 meters from 7025 to 7125 and i am going to continue to operate cw in the 40 meter band allocated for cw.. If however there has been a rule change from the FCC that I am not aware of  that I cant operate there then i will gladly qsy to a different frequency but for the time being  i am going to continue to work  in the frequncy  spectrun on 40 meters allocated to cw and  for those people who operate non frquency agile digital systems you are going to have to just get over it.  And the radio observer  who sent me the report if you were listeng to me send then why didnt you get on the air and tell me i was interfering with this non frequncy agile digital system or you just taking these peoples word for it.  It appears these people want a perfect operating scenario and they want their cake and coffee and what ever else they want.For me to stop sending and operating cw then some one is going to have to try and pry my hand off that cw key and it wont be someone who operates non frequncy agile digital systems for darn sure.
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N2EY
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Posts: 3913




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« Reply #1 on: February 19, 2010, 01:57:23 AM »

Write back to the OO and explain that at no time did you hear the digital station.

Ask for more details, such as the digital station's exact frequency, the exact time, etc. Also ask why the digital station could not QSY.

73 de Jim, N2EY
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WW5AA
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Posts: 2086




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« Reply #2 on: February 19, 2010, 04:37:23 AM »

The OO is a very good program but as in all parts of our hobby, some turn it into a job. Due to propagation and other variables it is very easy to have a conflict with an unheard station. I most certainly would continue to operate your station within good operating practices as you see fit.

73 de Lindy
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N7DM
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Posts: 671




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« Reply #3 on: February 19, 2010, 07:09:52 AM »

OO's are volunteers, not the Funny Candy Company. Nobody can hear everything on a frequency, when the primary mode of propagation is 'skip'. You seem to have done YOUR best, the rest is 'tough'. The other day I suspected 12 meters to be open. I heard NOTHING across the band. AS CW IS A LEGAL MODE OF OPERATION ON ANY FREQUENCY IN ANY HAM BAND, I went right up into the middle of the Phone Sub-Band, 24.950, and called a 'slower' CQ. The second time I did, a very weak SSB station said, "Station calling CQ...the frequency is in use". To which I replied "DIT-DIT". I was able to hear him say, "Thanks".

Un-intentional QRM in this hobby is a given. We just hope for minimal.  I *will* say, from 30 meter experience, the Screamers of packet are hard to recognize as anything worthy of 'respect'. If you can't hear 'em OR know what the heck they are...Too Bad.

dm
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W5ESE
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Posts: 550


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« Reply #4 on: February 19, 2010, 08:41:11 AM »

On February 7, 2010 AT 0255 utc on 7.076mhz I sent qrl several times listening in between calls to make sure  i am not interfering with anyone. Hearing nothing I transmitted a cq and was answered by a WA6 station and we carried on a cw qso. A few days later I now have received from a OO that I was interfering with a NON FREQUENCY AGILE DIGITAL SYSTEM that was already transmitting on that frequency. I never heard that station at all at any time before, during and after my qso. And if I cant hear the digital station then how do i know i am interfering with them.

From the 'Hidden Transmitter Effect', it's possible that you were in the "skip
zone" of the digital system.

I would look at it from another angle, though.

Here's the ARRL band plan for 40 meters
(from http://www.arrl.org/FandES/field/regulations/bandplan.html )

40 Meters (7.0-7.3 MHz):
7.040 RTTY/Data DX
7.080-7.125 RTTY/Data
7.171 SSTV
7.290 AM calling frequency

Other than the DX window at 7040 KHz, the 40 meter data mode activity
is expected to inhabit 7080-7125 KHz. What the heck is someone doing
setting up a non-frequency agile, semipermanent system on 7076 KHz?

I assume this is a Winlink PMBO system, which are listed at:

http://www.winlink.org/webfm_send/88

You could have been interfering with one of these two:

N1ICS.WINLINK  [EN70SU: Van Wert, OH] 7076.9
WD8DHF.WINLINK [EM11DB: Harker Heights, TX] 7075.4

There are several US-based Winlink PMBO stations on 40 meters that are
more or less permanently parked on frequencies that are not in compliance
with the ARRL band plan.  Huh

I suggest you bring that to the attention of the OO and ask him to send
an OO notice to those WinLink operators that are ignoring the ARRL
band plan!

Of what use are band plans if everyone ignores them?

73
Scott W5ESE
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WX7G
Member

Posts: 6214




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« Reply #5 on: February 19, 2010, 09:06:54 AM »

If you could not hear the digital station then he could not have heard you, given the same transmit power. Therefore you could not have interferred with his reception. How about the station he was in contact with? If you could not hear him, he could not hear you, given the same transmit power. Therefore you did not interfere with anyone (except for the OO).

The OO was most likely at a location where he could hear both you and the digital station. His complaint is without merit.
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W7ETA
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Posts: 2527




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« Reply #6 on: February 19, 2010, 05:48:16 PM »

OOs observe--they aren't traffic cops.

The OO sent information to you.

You read the note.

You reviewed your operating habits; can't avoid sigs you can't hear.

You can go back to having FUN.

73
Bob
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N1UK
Member

Posts: 1572




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« Reply #7 on: February 20, 2010, 03:46:18 PM »

Since you couldn't hear the digital station it is unlikely that the digital station could hear you either. So you probably wouldn't have been interfering with the digital station's reception at all.

The OO could hear both you and the digital station and yes you interfered with the OO's reception of the digital station but that is the nature of the beast on HF and NO offense has been committed by you. You aren't responsible for interference caused to the reception of other stations who are listening to stations that you can't even hear, especially since the aggrieved station couldn't even be bother to tell you of the interference that he was suffering.

Mark N1UK
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NN4RH
Member

Posts: 330




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« Reply #8 on: February 21, 2010, 02:30:39 AM »

>>According to my license i can operate on 40 meters from 7025 to 7125 and i am going to continue to operate cw in the 40 meter band allocated for cw..<<


Pay attention to the Band Plan. http://www.arrl.org/FandES/field/regulations/bandplan.html  and you'll reduce your chances of interfering with other modes.
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KE4ILG
Member

Posts: 151




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« Reply #9 on: February 21, 2010, 08:27:17 AM »

Perhaps I don't comprehend what the band plan states but it is my understanding that data also means cw.  Since data is specifically allowed between 7.000 thru 7.125 how does the band plan suggest that this ham was operating in a way that would invite conflict with other modes? Please explain what adhering to the band plan differently than was done would have changed the manner in which this incident happened.  It is not my intent to be snotty but to understand these recommendations as I am primarily a cw and wish to operate properly.  73, Mike ke4ilg
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N2EY
Member

Posts: 3913




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« Reply #10 on: February 21, 2010, 09:24:05 AM »

KE4ILG: "Perhaps I don't comprehend what the band plan states but it is my understanding that data also means cw. Since data is specifically allowed between 7.000 thru 7.125 how does the band plan suggest that this ham was operating in a way that would invite conflict with other modes?"

Band plans are gentleman's agreements, not FCC regulations. They exist so that we can all get more out of limited bandspace. By following their recommendations, we have less congestion and inter-mode QRM.

The alternative is a free-for-all of modes from bandedge to bandedge. Nobody wins in that scenario.

73 de Jim, N2EY
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KE4ILG
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Posts: 151




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« Reply #11 on: February 21, 2010, 09:43:27 AM »

I understand that the band plan is not a law. If I choose to operate on any unoccupied frequency between 7.025 and 7.125 (I am a licensed General)where am I stepping on any other mode according to the band plan?  

I stay out of the areas normally populated by the other digital modes but I don't see where in the band plan it suggests that I am "unwelcome" to  operate anywhere using cw.  

I get the feeling that those suggesting to read the band plan are suggesting that the ham was operating in conflict of the band plan.  Please explain how operating cw anywhere between 7.000 and 7.125 is against the band plan.  Thank you all I really am trying to learn from this.  73 Mike.
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N2EY
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Posts: 3913




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« Reply #12 on: February 21, 2010, 10:30:14 AM »

KE4ILG writes: "If I choose to operate on any unoccupied frequency between 7.025 and 7.125 (I am a licensed General)where am I stepping on any other mode according to the band plan?

I stay out of the areas normally populated by the other digital modes but I don't see where in the band plan it suggests that I am "unwelcome" to operate anywhere using cw."

The bandplan says 7.080 to 7.125 is "RTTY/data". CW is not data.

What it means is that it is *recommended* that RTTY/data stations congregate there, and that CW stations work lower down in the band (7.000 to 7.080). Not by law but out of courtesy, and good amateur practice.

If I take the position that it's perfectly OK for me to operate CW anywhere CW is allowed by FCC rules, and that nobody should complain, then I can't complain when somebody decides to run RTTY on 7.005, because FCC rules allow it.  

KE4ILG: "I get the feeling that those suggesting to read the band plan are suggesting that the ham was operating in conflict of the band plan."

He wasn't. The band plan suggests RTTY/data starts at 7.080, and he was on 7.076.

The real issue is: what was a non-frequency-agile data system doing on 7.076? That's not in agreement with the band plan!

As W7ETA points out, an OO is an observer, not a cop. He heard what sounded like QRM, but it's clear that the CW station couldn't hear the data station, so it could not be intentional. It's also not clear if the data station actually experienced interference.

Skip zone and all that. Some hams don't understand the concept; the OO may be one of them.

KE4ILG: "Please explain how operating cw anywhere between 7.000 and 7.125 is against the band plan."

CW isn't a data mode in that context.

Here's an analogy:

On 75 meters, 3885 is considered an AM watering hole. It's where most AM folks hang out, to the point that some have crystal-controlled rigs there.

It's not illegal to operate SSB, NFM, SSTV or even CW on 3885. But it's good amateur practice and courtesy not to, and to leave that QRG for the AM folks.

By the same, it's not illegal to operate CW on 7.080 to 7.125. But it's good amateur practice and courtesy not to, and to leave that part of the band for the RTTY/data folks.

All IMHO.

73 de Jim N2EY
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KE4ILG
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Posts: 151




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« Reply #13 on: February 21, 2010, 11:48:58 AM »

After re-reading the ARRL band plan I accept your interpretation that data does not refer to cw.  By my reading of the band plan cw is authorized everywhere except the 60 meter band.  So for those suggesting a op should look at the band plan seems they believe that certain areas are not for cw.   Your contention that cw ops should stay away from the 7.080-7.125 is interesting.  Just to let you know there many slow code ops hanging out between 7.100 and 7.125 and I have to believe you know that. So if the frequency is not in use I can operate there.  

The original post stated the interference with a "non frequency agile digital station".  I don't know for certain what a "non frequency agile digital station" is.  Sounds like a beacon station but I guess not since it would be far easier just to say beacon station.  

In the end non interference requires effort that the originator exercised.  I asked questions that I truly didn't understand.  I think I am done now, best to all, Mike ke4ilg.
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AE4RV
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« Reply #14 on: February 21, 2010, 03:06:58 PM »

Agreed that the OO heard both stations and (incorrectly) assumed that they could hear each other.

But, regarding band plans, why are there so many digital stations (far) below 7.080?
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