2365Re: [dxatlas] Skim Server and Master.dta?
- Feb 1, 2011Hi Pete,
As I have already written, a program that receives spots from multiple
Skimmers can radically reduce the number of errors simply by showing only
the spots received from two or more Skimmers. This is the same principle
that is used for Aggressive filtering in CW Skimmer, except that instead of
waiting for more copies of the callsign decoded by the same Skimmer, we
would get those copies instantly from other Skimmers. In other words,
instead of time diversity we would use spatial diversity.
73 Alex VE3NEA
----- Original Message -----
From: "Pete Smith" <n4zr@...>
Cc: "Alex, VE3NEA" <alshovk@...>
Sent: Tuesday, February 01, 2011 11:44 AM
Subject: Re: [dxatlas] Skim Server and Master.dta?
> Ah, I'm glad to see this topic surfacing. Working with multiple Skimmers
> feeding the RBN, we've encountered a rather different problem.
> Here's a summary from the N1MM developers group, in response to a
> complaint from N2IC about the plethora of bad spots he encountered over
> the weekend in the CQ 160 CW test:
> "[4:07:09 PM | Edited 4:07:49 PM] Pete Smith: I think I see the problem
> now, and as Steve says, it depends on your definition of error rate. If I
> watch the output of one skimmer, I see lots of spots and a very low error
> rate. But if you watch the whole RBN or even a sub-set (like the
> half-dozen Skimmers in PA, MD, VA, and WV) then the effective error rate
> is much higher, because the errors make it through while the good spots
> either come up gray (if already worked) or are duped out before they ever
> make it to the bandmap. This makes it a particularly bad problem late in
> a contest, when most of the legitimate stations have been worked but the
> op must still look at every spot to make sure it is a miscopy.
> [6:17:55 AM] Pete Smith: I will bring this to the people involved who
> actually know something (Felipe, Nick and Dave) and see if we can come up
> with a filter for the RBN that attempts to identify these situations and
> filter out the junk. It'll take some doing, but should be do-able. One
> simple-minded way would be to look at spots coming through within a short
> time window on the same frequency, and if there are spots that differ
> from the callsign that the majority are spotting correctly on that
> frequency, don't send them out."
> Kind of a voting system, I guess. Anyhow, the RBN solution aside. might
> it be possible to do the same thing in Skimmer so that folks like Lee who
> prefer to collect their Skimmer spots themselves. Or do you have a better
> idea, Alex?
> 73, Pete N4ZR
> The World Contest Station Database, updated daily at
> The Reverse Beacon Network at http://reversebeacon.net, blog at
> spots at telnet.reversebeacon.net, port 7000
> On 2/1/2011 9:43 AM, Alex, VE3NEA wrote:
>> Hi Lee,
>> I thought about this but could not find an acceptable solution. If
>> Validation is set to Normal, almost every call is posted on the network
>> it first meets the Normal validation criteria. A few seconds later, when
>> more data are received, the call may meet a higher validation level, but
>> since it has already been posted, is will not be posted again. I have
>> received tons of complaints about the same callsign posted multiple
>> and had to enforce the 10-minute rule. The net result is, all spots, with
>> few exceptions, will have the Normal validation level.
>> If your goal is to filter out possible errors after the aggregation of
>> spots from multiple Skimmers, then one simple solution is to publish only
>> the callsigns reported by two or more Skimmers.
>> 73 Alex VE3NEA
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