Re: [digitalradio] An open letter: W1AW and 80m psk31 interference(A dissent)

2009-09-22 Thread Cortland Richmond 
Hi, Rik.

Then use a 250 or 500 Hz BW pass band filter. Engage the notch filter. Get
an MFJ 1026 and null him out.  Use a separately rotatable loop antenna for
receive. There are a number of things which will work, either by
themselves, or together.   

We have or can get filters and other tools.  That is a good thing, since no
law of physics confers immunity from strong stations a KHz away, either
down the block or across the ocean.   Imagine, if you will, someone trying
to work 3 KHz wide narrow-band FM at 3975 KHz; the SSB signals would render
his receiver useless.  That's our situation, unless we improve our
receivers and do what it takes to live in a crowded band where different
modes must coexist with each other.


Cortland
KA5S


> [Original Message]
> From: Rik van Riel 

>
> Cortland Richmond wrote:
> > Sound card users' preference for bandwidth wide enough to receive fifty
or
> > more signals is what makes us vulnerable.   W1AW does NOT wipe out the
"80m
> > psk31 sub-band;"  its CW signal occupies perhaps 50-100 Hz.  Use a
narrow
> > filter, and a front-end able to handle nearby strong signals, and the
> > problem goes away.   Use PBT,even and put W1AW off the filter skirts. 
>
> Here in southern New Hampshire, W1AW is S9+40.
>
> Typical psk31 signals are anywhere between S2 and S8 here.
>
> To get W1AW suppressed by >50dB means moving the filter far
> enough away that only a small part of the psk sub band
> remains.

Re: [digitalradio] An open letter: W1AW and 80m psk31 interference (A dissent)

2009-09-22 Thread Rik van Riel 
Cortland Richmond wrote:
> Sound card users' preference for bandwidth wide enough to receive fifty or
> more signals is what makes us vulnerable.   W1AW does NOT wipe out the "80m
> psk31 sub-band;"  its CW signal occupies perhaps 50-100 Hz.  Use a narrow
> filter, and a front-end able to handle nearby strong signals, and the
> problem goes away.   Use PBT,even and put W1AW off the filter skirts. 

Here in southern New Hampshire, W1AW is S9+40.

Typical psk31 signals are anywhere between S2 and S8 here.

To get W1AW suppressed by >50dB means moving the filter far
enough away that only a small part of the psk sub band
remains.

-- 
All rights reversed.

RE: [digitalradio] An open letter: W1AW and 80m psk31 interference (A dissent)

2009-09-22 Thread Cortland Richmond 
Sound card users' preference for bandwidth wide enough to receive fifty or
more signals is what makes us vulnerable.   W1AW does NOT wipe out the "80m
psk31 sub-band;"  its CW signal occupies perhaps 50-100 Hz.  Use a narrow
filter, and a front-end able to handle nearby strong signals, and the
problem goes away.   Use PBT,even and put W1AW off the filter skirts. 


Cortland
KA5S


> [Original Message]
> From: Rik van Riel 
> To: ; 
> Date: 9/22/2009 12:08:22 AM
> Subject: [digitalradio] An open letter: W1AW and 80m psk31 interference
>
> Due to an unfortunate coincidence, W1AW's CW broadcasts pretty
> much wipe out the 80m psk31 sub-band for a significant fraction
> of the time.  To try and address this, I have sent the following
> open letter to W1AW at the ARRL, and also published it on my web
> site:  http://surriel.com/radio/w1aw-psk-interference
>
>  Original Message 
> Subject: W1AW and 80m psk31 interference
> Date: Tue, 22 Sep 2009 00:04:58 -0400
> From: Rik van Riel
> To: w1aw
>
> To whom it may concern,
>
> The W1AW broadcasts are a great tradition and a help to some
> amateur radio operators, and do not seem to be in the way on
> most of the amateur radio bands.
>
> However, the W1AW CW broadcast on the 80 meter band, on 3581.5
> kHz, is right in the middle of the psk31 sub band.  Needless to
> say, a high power CW station pretty much wipes out the nearby
> psk31 signals, which are typically transmitted at low power.
>
> While strictly speaking it is legal to transmit CW anywhere
> on the band (I will not go into the legality of broadcasting
> on the ham bands), I believe we can agree that putting a strong
> signal right in the middle of a band segment dedicated to lower
> power operation is not what the ARRL's "Considerate Operator's
> Frequency Guide"[1] would call considerate.
>
> Because putting a high power CW broadcast in the middle of the psk31
> sub band (which sees activity whenever there is propagation) is
> guaranteed to cause interference to active operators, I hope you
> would consider moving the W1AW CW broadcast to a frequency where
> interference is merely a possibility and not a guaranteed issue.
>
> The interference issue is especially severe due to the fact that
> the W1AW transmissions are scheduled on an almost daily basis,
> several times a day[2], wiping out the 80m psk31 subband for a
> significant fraction of the time.
>
> Since the W1AW CW broadcast is an automatically controlled
> transmission, maybe it would be better in the band segment assigned
> to automatically controlled data stations (3585-3590). Another good
> choice could be 3579.5 kHz, which would put the W1AW broadcast
> 500 Hz below the psk31 segment, just like it is on the 17 and
> 15 meter bands.
>
> kind regards,
>
> Rik van Riel, AB1KW
>
> [1] http://www.arrl.org/FandES/field/regulations/conop.html
> [2] http://www.arrl.org/w1aw.html#w1awsked
>
>
> 
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