K3 RTTY bandwidth already too narrow?

[RLVZ]

I understand the desirable effects of  reducing bandwidth... but sometimes
I wonder if the K3's transmit bandwidth  on RTTY is already too narrow.  
Case in point: I enjoy operating a lot of  RTTY contests, but even when I'm
running 1,500 watts... I continually have  stations that move in real close to
me and cause me a  tremendous amount of received interference.  (I often
have to QSY  which is frustrating when I've got a nice run taking place)  And  
that's when I'm running my receive filters tight, such as: 250hz roofing  
filter with DSP filter set at 350hz.  (though I prefer to use my 400hz  
roofing filter with a 400hz DSP setting as it copies signals better)  So it seems
to me that: 1) either their receiver selectivity  is better then that of my
K3... which is unlikely, or 2) my K3 is already  transmitting a much cleaner
signal then theirs.  If my K3 transmit signal  is already much cleaner then
theirs, then I'm going to receive even greater QRM  if I narrow my K3
transmit bandwidth further.  Which is why  I sometimes wonder if my K3 transmit b
andwidth isn't already too narrow.   Again, I appreciate the effort to
reduce bandwidth as it's a good  thing, but more effort needs to be made for this
to happen on a  global scale.  
 
I like the idea of stations with BIG bandwidths and  Key Clixs to be
penalized or disqualified.  But that's unlikely to happen  with any regularity.
 
73,
Dick- K9OM
 
 
 
 
In a message dated 3/23/2013 12:01:41 P.M. Eastern Daylight Time,  
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Today's Topics:

1. Re: K3  reduced-bandwidth RTTY analysis (Jay WS7I)
2. Re: K3  reduced-bandwidth RTTY analysis (Kok Chen)
3. Re: K3  reduced-bandwidth RTTY analysis (Robert Chudek - K0RC)
4. Re:  K3 reduced-bandwidth RTTY analysis (Lee Roberts)
5. My  thoughts on RTTY analysis (Phil Sussman)
6. Re: My thoughts on  RTTY analysis (Bill Turner)
7. Re: K3 reduced-bandwidth RTTY  analysis (Jim W7RY)
8. First RTTY QRP Contest (Walter  Dallmeier)
9. Re: First RTTY QRP Contest (Elmar  PD3EM)


----------------------------------------------------------------------

Message:  1
Date: Fri, 22 Mar 2013 14:25:20 -0700
From: Jay WS7I  <[hidden email]>
To: W8AEF <[hidden email]>
Cc:  [hidden email]
Subject: Re: [RTTY] K3 reduced-bandwidth RTTY  analysis
Message-ID: <[hidden email]>
Content-Type:  text/plain; charset=ISO-8859-1; format=flowed

Yeah but they don't mix  the processor with it nor does the Mic Gain
usually have a lot of  difference, which is of course why they do it that
way and why most of us  contest guys and gals use FSK not that it is
better but its easier.   They also don't shape the FSK or AFSK if you
would rather either.   But they could.

On 3/22/2013 12:33 PM, W8AEF wrote:

> Most, maybe  all, Yaesu rigs run AFSK.  They call it FSK but when you
> look at  the schematic you find the AFSK integrated circuit.
>
> de Paul,  W8AEF
>
> -----Original Message----- From: Jay WS7I
> Sent:  Friday, March 22, 2013 10:07 AM
> To: [hidden email]
>  Subject: Re: [RTTY] K3 reduced-bandwidth RTTY analysis
>
> Guess  you missed the point.  Andy's work was with the K3 which he no
>  doubt owns and likes.  FLdigi no doubt has facilities to do testing  for
> their software and I have major doubts that their are thousands of  folks
> running AFSK RTTY on anything in any  case.
>

------------------------------

Message:  2
Date: Fri, 22 Mar 2013 14:36:49 -0700
From: Kok Chen  <[hidden email]>
To: RTTY Reflector <[hidden email]>
Cc:  "Joe Subich, W4TV" <[hidden email]>
Subject: Re: [RTTY] K3  reduced-bandwidth RTTY analysis
Message-ID:  <[hidden email]>
Content-Type:  text/plain; charset=us-ascii

On Mar 22, 2013, at 1:31 PM, Joe Subich,  W4TV wrote:

> Similarly, even ARRL (most specifically W3IZ's review  in the current
> issue of QST) do not make the slightest mention of  signal purity issues
> like the absolutely horrible transmit phase noise  spectrum of the new
> FT-3000.

As bad as the FT-dx3000, its  transmit phase noise (about -100 dBc at a 1
kHz offset) is still nowhere close  to the interference from an (continuous
phase) FSK signal, whose keying  sidebands are in the region of -60 dBc at
the same 1 kHz offset from one of  the FSK tones.

You might be confusing the transmit phase noise with the  poor reciprocal
mixing (-82 dBc at 2 kHz offset) in the FT-dx3000.  The  latter only affects
the owner, not the other occupants of the band.  But  even that number is
still dominated by FSK keyclicks from a signal that is 2  kHz offset away
(although not by much).

One way to look at it is that  if you receive with an FT-dx3000, you
probably won't be able to tell if the  other people are filtering their RTTY
signals :-).

73
Chen,  W7AY



------------------------------

Message: 3
Date:  Fri, 22 Mar 2013 17:42:33 -0500
From: Robert Chudek - K0RC  <[hidden email]>
To: [hidden email]
Subject: Re: [RTTY] K3  reduced-bandwidth RTTY analysis
Message-ID:  <[hidden email]>
Content-Type: text/plain;  charset=ISO-8859-1; format=flowed

The only way we're going to clean up  the bands quickly is to pass
legislation equivalent to the "Cash for  Clunkers" program. You know,
something like "Your old rig plus $100 for a  brand new K3".

We could then be entertained watching videos on YouTube  of Icom 7800's,
Kenwood 990's, Yaesu 5000's, and Swan 350's being fed into  scrap metal
crushers.

...well, it was just a thought.

73 de  Bob - K?RC in  MN

------------------------------------------------------------------------
On  3/22/2013 4:36 PM, Kok Chen wrote:
> On Mar 22, 2013, at 1:31 PM, Joe  Subich, W4TV wrote:
>
>> Similarly, even ARRL (most  specifically W3IZ's review in the current
>> issue of QST) do not  make the slightest mention of signal purity issues
>> like the  absolutely horrible transmit phase noise spectrum of the new
>>  FT-3000.
> As bad as the FT-dx3000, its transmit phase noise (about -100  dBc at a 1
kHz offset) is still nowhere close to the interference from an  (continuous
phase) FSK signal, whose keying sidebands are in the region of -60  dBc at
the same 1 kHz offset from one of the FSK tones.
>
> You  might be confusing the transmit phase noise with the poor reciprocal
mixing  (-82 dBc at 2 kHz offset) in the FT-dx3000.  The latter only
affects the  owner, not the other occupants of the band.  But even that number is  
still dominated by FSK keyclicks from a signal that is 2 kHz offset away  
(although not by much).
>
> One way to look at it is that if you  receive with an FT-dx3000, you
probably won't be able to tell if the other  people are filtering their RTTY
signals :-).
>
> 73
> Chen,  W7AY
>
> _______________________________________________
>  RTTY mailing list
> [hidden email]
>  http://lists.contesting.com/mailman/listinfo/rtty
>



------------------------------

Message:  4
Date: Fri, 22 Mar 2013 17:31:12 -0600
From: Lee Roberts  <[hidden email]>
To: [hidden email]
Subject: Re: [RTTY] K3  reduced-bandwidth RTTY analysis
Message-ID:  <8371099.NJzMKdWmWH@server1>
Content-Type: text/plain;  charset="us-ascii"

Too bad I don't have narrower transmit filters in my  TS2000 for FSK. I
guess if
I want to minimize my bandwidth I'll have to go  AFSK with waveshaping or
get a
rig with transmit waveshaping for  FSK.


------------------------------

Message: 5
Date: Fri,  22 Mar 2013 19:37:50 -0400
From: Phil Sussman  <[hidden email]>
To: [hidden email]
Subject: [RTTY] My  thoughts on RTTY analysis
Message-ID:  <[hidden email]>
Content-Type:  text/plain; charset=ISO-8859-1; DelSp="Yes";
format="flowed"

I've been following the thread and now I'm tempted to  step gingerly into
the lion's den. From a practical point of view, yes the  RTTY analysis is
interesting. However, I've got a point of  view.

First, I'll admit that no signal is absolutely perfect. So, in  real life
it is a matter of degree. We can approach a 'perfect' signal or  can head
to the other end. My ideal is to transmit a 'clean' signal or as  clean as
I can make it. It doesn't have to be perfect, it has to be set  correctly
and not overdriven. Propagation will twist whatever goes out and  I rely
on the ability of a good decoder. Note: I did not say 'perfect' or  'wave
shaped' or 'reconstructed' or 'sampled' or 'filtered' -- I said  'good.'

That's why I personally prefer a piece of professionally  designed hardware
to the 'engineered' computer sound card. That's not to  say the computer
card can't deliver performance -- of course it can. Yet, a  separate stand
alone modem is my preference. It's not perfect, but it works  better than
most for me.

Chasing a weak signal in the midst of a  plethora of RF is not my style. I
prefer WARC bands or other places of  'quiet.' We ought to assist others by
helping them achieve a good settings  and cleaning up the band, not trying
to eke out that last db.

I  think of RTTY as a hobby not as an obsession of a perfect RTTY  signal.

End of soap box,

Thanks for reading,

de Phil -  N8PS




------------------------------

Message:  6
Date: Fri, 22 Mar 2013 17:52:28 -0700
From: Bill Turner  <[hidden email]>
To: RTTY Reflector  <[hidden email]>
Subject: Re: [RTTY] My thoughts on RTTY  analysis
Message-ID:  <[hidden email]>
Content-Type:  text/plain; charset=us-ascii

ORIGINAL MESSAGE:
On Fri, 22 Mar 2013  19:37:50 -0400, Phil wrote:

>I think of RTTY as a hobby not as an  obsession of a perfect RTTY signal.

REPLY:
Obsessions found all  over the ham spectrum.

There are a couple of subscribers to the Amps  reflector who are obsessed
with IMD performance. Meeting the FCC specs is  not nearly good enough, they
want way more than that.

It takes all  kinds.

73, Bill  W6WRT


------------------------------

Message: 7
Date:  Fri, 22 Mar 2013 21:06:26 -0700
From: "Jim W7RY"  <[hidden email]>
To: <[hidden email]>,  <[hidden email]>
Subject: Re: [RTTY] K3 reduced-bandwidth RTTY  analysis
Message-ID:  <E57A8A28482A41C78C2661FC197253B4@JimsLaptop>
Content-Type:  text/plain; format=flowed; charset="iso-8859-1";
reply-type=response

Oh please!

73
Jim W7RY


The  only way we're going to clean up the bands quickly is to pass
legislation  equivalent to the "Cash for Clunkers" program. You know,
something like  "Your old rig plus $100 for a brand new K3".

73 de Bob - K?RC in  MN



------------------------------

Message: 8
Date:  Sat, 23 Mar 2013 08:08:11 +0100
From: Walter Dallmeier  <[hidden email]>
To: Contesting RTTY  <[hidden email]>
Subject: [RTTY] First RTTY QRP  Contest
Message-ID:  <[hidden email]>
Content-Type:  text/plain;    charset=us-ascii

Hello,

A very  interesting QRP RTTY contest is starting tomorrow.
See  http://wwqrprtty.jimdo.com/ 

vy 73 de Walter,  DL4RCK




------------------------------

Message:  9
Date: Sat, 23 Mar 2013 10:36:00 +0100
From: Elmar PD3EM  <[hidden email]>
To: Contesting RTTY  <[hidden email]>
Subject: Re: [RTTY] First RTTY QRP  Contest
Message-ID:  <[hidden email]>
Content-Type:  text/plain; charset=us-ascii

Hi,

Looks indeed very interesting  to do a QRP RTTY Contest!
I didn't knew about this contest but I'll  join.

Hope to see a lot of you on the screen tomorrow!

73, Elmar  PD3EM

On Mar 23, 2013, at 8:08 AM, Walter Dallmeier wrote:

>  Hello,
>
> A very interesting QRP RTTY contest is starting  tomorrow.
> See http://wwqrprtty.jimdo.com/ 
>
> vy 73 de  Walter, DL4RCK
>
>
>  _______________________________________________
> RTTY mailing  list
> [hidden email]
>  http://lists.contesting.com/mailman/listinfo/rtty

------------------------------

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------------------------------

End  of RTTY Digest, Vol 123, Issue  35
*************************************

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[Ed Muns, W0YK]

Comments below, in line...

K9OM wrote:
> I understand the desirable effects of  reducing bandwidth...
> but sometimes I wonder if the K3's transmit bandwidth  on
> RTTY is already too narrow.

The K3's bandwidth (prior to the DSP-281 firmware, about to be released to
Beta) is on a par with all other radios' internally generated FSK.  And,
this bandwidth is significantly wider than it needs to be.  The wave-shaped
or filtered FSK signal in DSP-281 is an optimum balance between bandwidth
and intelligibility.  In other words, it is possible to be too narrow.
Thus, the new K3 FSK bandwidth occupies only enough bandwidth as needed for
reliable communication.  Hopefully, other manufacturers will follow suit.

> Case in point: I enjoy operating a lot of  RTTY contests, but
> even when I'm running 1,500 watts... I continually have  
> stations that move in real close to me and cause me a  
> tremendous amount of received interference.

I suspect this is not due to the (current) K3 FSK signal being inherently
narrower than the other station's radio, but more likely due to improperly
adjusted AFSK or an improperly-driven linear amplifier.  If the other
station properly adjusted his transmitting system I think you'd find about
the same bandwidth in your signals.  And, perhaps the other station chooses
to tolerate your QRM more than you choose to tolerate his!

> (I often have to
> QSY  which is frustrating when I've got a nice run taking
> place)  And that's when I'm running my receive filters tight,
> such as: 250hz roofing filter with DSP filter set at 350hz.  
> (though I prefer to use my 400hz roofing filter with a 400hz
> DSP setting as it copies signals better)

Two points here:

1.  The K3 KFL250A is actually 370 Hz wide at the -6 dB points.  The KFL400A
is 435 Hz.  There is no reason to have both filters in the same receiver.

2.  The IF bandwidth is a function of the cascaded bandwidths of the crystal
and DSP filters.  For example, the resulting bandwidth of the KFLA250
(actually 370 Hz) and a DSP of 350 Hz, will be something less than 300 Hz.
The KFLA400 (really 435 Hz) and DSP of 400 will be nearly 300 Hz.

> So it seems to me
> that: 1) either their receiver selectivity  is better then
> that of my K3... which is unlikely,

They may also be using a K3.  There are more than 7000 out there!

> or 2) my K3 is already  
> transmitting a much cleaner signal then theirs.

Not yet, unless the other station is mis-adjusted or defective, at least for
the vast majority of RTTY radios in use.

> If my K3
> transmit signal  is already much cleaner then theirs, then
> I'm going to receive even greater QRM  if I narrow my K3
> transmit bandwidth further.  Which is why  I sometimes wonder
> if my K3 transmit b
> andwidth isn't already too narrow.

Yes, it is true that if you transmit a substantially narrower signal than
your neighbors on the band, that you are subject to more QRM from them than
they are from you.  This puts pressure on other manufacturers to follow suit
and narrow their transmitted signals down to the optimum needed for reliable
communication.  This is better than allowing the K3 to be adjusted wider so
as to "defend" your  run frequency.  ;>)

> Again, I appreciate the
> effort to
> reduce bandwidth as it's a good  thing, but more effort needs
> to be made for this to happen on a  global scale.

Absolutely.  A parallel history exists with CW bandwidth (key clicks) across
various manufacturers' radios.  Elecraft rightly chose not to allow user
adjustment of keying rise/fall times such that key clicks can be created.
They are about to do the same for FSK bandwidth by narrowing the K3 FSK
bandwidth to only what is needed.

Viewing K0SM's excellent work, it is easy to see that higher power FSK
signals are disproportionally worse than low power.  This is because the
skirts of the unfiltered FSK transmissions are not linear, but flare out
considerably.  Properly filtered FSK bandwidths are similar to good, and
properly adjusted, AFSK bandwidths.

Ed W0YK

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