[CQ-Contest] Skimmer ultimate setup?

[Pete Smith]

Hi Dave - I think you are very close.  A few comments below.

At 03:57 PM 3/20/2008, Dave Hachadorian wrote:
>I'm trying to figure out how CW Skimmer will ultimately
>physically tie in to an so2r contest setup. Let me propose a
>straw man, and then you smart guys can whip it into shape.
>
>1. We use the IF output of the so2r S&P receiver as the
>source of wideband RF.

Yes


>2. Using an Elecraft K3 as an example, the IF output is at
>8.215 Mhz. I hear you need a buffer amp on that output.
>Somebody makes a "Z10000" that fills the bill.
>
>3. The output of the Z10000 goes to a "Softrock Lite"
>receiver tuned for 8.215 Mhz. Maybe that frequency needs to
>be offset from the 8.215 IF to prevent the softrock Lite
>oscillator from getting into the K3 IF?

You may not feel the need of the buffer amp (Clifton Laboratories, K8ZOA, 
www.cliftonlaboratories.com) if you offset the Softrock local oscillator so 
that it falls outside the roofing filter bandwidth, but it would be a good 
precaution.  On the radio to which my SoftRock is connected, the local 
oscillator is S9+40.


>4. The stereo audio output of the Softrock Lite goes into a
>good quality soundcard with a high sampling rate, since we
>will be dealing with up to 50(?) KHz audio? This soundcard
>can be the one in the contest computer, since the soundcard
>is not normally used in CW contesting. If you want to do an
>audio recording of the entire contest, maybe you need
>another computer networked to the logging program and do the
>recording there?

The soundcard I am currently using is a M-Audio Revolution 5.1 PCU, which 
cost me about $50.  It records 96 KHz stereo audio, which translates into I 
and Q channels that the Skimmer software will display as a 96-khz swath of 
IF bandwidth centered around the center frequency of your SoftRock.  You 
can get sound cards that go up to 192 KHz, for quite a bit more 
money.  Look out, though, for cards that have shared mic and line input.

I use the audio CODEC in my MK2R+ to record contests.  Depending on the 
BIOS in your computer, you may be able to run both a PCI sound card and 
your original on-board sound.  I can't, but that's Dell for you...


>5. Whichever computer gets the audio, it needs to be running
>the $70 version of CW Skimmer, and that computer also needs
>to be running the logging program.

Yes, although the spots can be passed to the logging program over a local 
area network, so in theory you could have Skimmer on one PC and the logger 
on another.  It is worth mentioning here that the CPU demands of the 
Skimmer, especially in contest circumstances are quite high; this could be 
disruptive to LPT or COM port CW, depending on your computer and logging 
software.  I run N1MM and Winkey CW, and experienced absolutely no 
disruption with Skimmer running on a 2.2 GHz Celeron, even though CPU 
utilization occasionally hit 100 percent.


>6. CW Skimmer outputs spots to the logging program and puts
>them on the bandmap. I'm a little fuzzy on how CW Skimmer
>knows the frequency of these spots. Does it look at the rig
>control frequency of the S&P Radio, or is some other
>connection required for Skimmer to know the frequency?


Ah, here's the rub -- Skimmer needs to know what frequency your radio is 
tuned to, so that it can display the waterfall with real frequencies rather 
than frequencies relative to the Softrock local oscillator; that, in turn, 
means that Skimmer needs to be communicating with your radio.  The only 
means Skimmer currently has for doing this is through VE3NEA's OmniRig 
interface, which works with many of his programs.

Unfortunately, Omnirig is not compatible with the rig control used by any 
of the leading contest logging programs.  I have heard rumors that Writelog 
can be adapted to permit exchanging frequency data with Skimmer - it may 
well be that other logging programs can be readily modified to supply radio 
frequency data through UDP or other means, and that Skimmer will evolve to 
support such adaptations as they develop - but all of this depends on the 
software authors.

I'd suggest reading the section of the Skimmer help file that deals with 
the "SoftRock with IF" option for further details.


>7. Since Skimmer will be connected to the S&P Radio, that
>radio pretty much has to be dedicated for S&P for the
>duration of the contest, otherwise Skimmer won't get much
>listening time because of all the cq-ing if it's connected
>to the run radio radio?

Probably right, though I used Skimmer briefly during the Russian DX contest 
on my run radio - it would simply stop while I was CQing, and then resume 
copying calls as soon as I started to listen for callers.

The way I visualize using Skimmer on Sunday in SS is that you would switch 
the S&P radio to a new band, pause a minute or so while Skimmer works, and 
then look on your S&P bandmap for Skimmer spots to call.  At that point you 
would just run up or down the band picking off any fresh meat, and then go 
on to another band and repeat the process.

73, Pete N4ZR