[Skimmertalk] RBN and busted calls was:Re: Skimmer Server & CQWW: one year late

k3mm at verizon.net k3mm at verizon.net
Tue Nov 30 12:58:46 PST 2010


Ahh yes, I remember seeing something like that where someone was skimmed on multiple frequencies at once.  However, this wasnt that and I've seen the problem before.   It was definitely an S&P station getting spotted as he moved around answering CQs.  I've seen this before where Skimmer hears the CQ of the runner, but then grabs the call of the answerer instead. I'll bet it wont happen in Aggressive mode ;)

Ty K3MM
Nov 30, 2010 01:25:41 PM, n4zr at contesting.com wrote:

One of our RBN Skimmers has had recurrent problems with I/Q images. 
He's running some sort of receiver that feeds I/Q audio to a sound card, 
and it is always necessary to adjust the phase and amplitude balance or 
you get images on either side of the center frequency. For example, if 
his center frequency is 14050, and he spots somebody at 14035, there is 
a good chance he will spot the same guy on 14065 in a minute or two. 
When the balance is properly adjusted, the images go way down.

73, Pete N4ZR

The World Contest Station Database, updated daily at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000


On 11/30/2010 12:31 PM, k3mm at verizon.net wrote:
> The problem is on the second day at a multi, at least 90 percent of the skims are going to be busted calls. On 20 meters they were coming in so fast that I couldnt keep up with them as the pouncer. Yeah, some of them you can look at and ignore, but many times it's not so clear. What's the harm of running in Aggressive mode if it eliminates 95 percent of the busted calls from Normal and takes an extra 15-30 seconds to generate the good spots? I just think the AI can probably be improved to do a more accurate job.
>
> The other thing that was happening and I'm not sure it was a skimmer, but lots of S&P guys were getting spotted on multiple frequencies, so something they were doing (probably sending their call many times) was confusing a skimmer into thinking it was their frequency.
>
> 73, Ty K3MM
>
> Nov 30, 2010 12:19:01 PM, k1ttt at arrl.net wrote:
>
> i agree, aggressive was being way to restrictive in my skimmer server. i went back to normal and it looked 'normal'... there were some busted calls but not too objectionable.
>
> i run mine on a quad core 64bit box and cut it back to 6 bands at 96khz from my normal 7 bands at 192khz and it seemed happier. i did see a high of 20 users connected to mine, i think that was affecting performance also... hopefully the rbn or ve7cc or other nodes will become more reliable so in the future users don't have to connect to individual skimmers.
>
>
> Nov 30, 2010 11:14:48 AM, km3t at km3t.org wrote:
>
> I ran in Normal mode because it seemed like Aggressive was being way
> too restrictive. In retrospect I should have left it in Aggressive.
> I am still getting up to speed on evaluating Skimmer performance.
>
> I ran a QS1R in 96kHz mode hooked to two antennas:
> 1) A DX Engineering active receive vertical out in the woods.
> 2) An 80m OCF dipole up around 50-60 feet out in the woods.
>
> I was running a temporary machine, 2GB RAM, Windows XP Home Media
> Edition. I forget what CPU it had - it was a Dell desktop, several
> years old. I was getting 100% decoding and I wasn't there so I didn't
> get a chance to get any data on how many decoders were running.
>
> Thanks for the .ini file tips - when I get a permanent machine I will
> look more closely.
>
> I am also trying to figure out how to spec a machine so I can run a
> node more permanently.
>
> 73,
> Dave KM3T
>
>
> Ty K3MM wrote:
> "I started out running aggressive the first night, but then switched
> to Normal and I discovered that greatly increased the busted calls
> coming from my node. I was elsewhere operating the contest, so I
> couldnt switch it back easily. I noticed that KM3T also seemed to be
> supplying a lot of busted calls."
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