In order to correctly evaluate the accuracy of the RBN versus
traditional spotting, I think you need to start with the idea that
the RBN is not a traditional spotting network. Here's what I
mean.
Accuracy of a properly set up CW Skimmer in copying callsigns runs
right around 99 percent. There is an as-yet-unresolved problem
with copying callers as if they were runners - more on that
below. But let's assume the 99 percent is right for an individual
Skimmer, one not assailed by local RFI.
If you consider the RBN, on an open band, with no spot filtering
by spotter location, then the picture changes. Suppose you have
30 Skimmers in zones 4 and 5, all copying an open band. Each
running station will be spotted every 10 minutes by each RBN
station, so long as the station remains on its run frequency. You
could, theoretically, have as many as 180 spots of each running
station every hour. In that case, simple probability says there
will be roughly 1.8 busted spots per hour of each one.
If you are sitting at a big multi-op, receiving spots from all over the
world, or just all over the US, then it is almost inevitable that
you will see busted spots a lot more often than from the Cluster
network. Not only are there 10-15 times as many spots, but there
will be busts of many running stations, just by the math. On
Sunday, you will see tons of busts, because by that time you will
have worked most of the good callsigns, leaving only the busts on
your bandmaps.
There are several partial solutions, not all of which will be
implementable at a big multi, but let me mention a
few:
* Filter by spotter location, so that you only get spots from
stations who are probably hearing the same things as you can. For
example, I filter by spotterstate = MD or PA or VA or NC or WV
(have to get my own spots too). That cuts down the number of
Skimmers feeding my bandmap to 7-8, sharply reducing the
probability of busts.
* Use the "Unique > x" filter in AR Cluster version 6. That
filter only passes a spot if at least x+1 Skimmers worldwide have
copied the same spot the same way in a relatively short period of
time. This helps a lot to winnow out busts, as you can imagine.
The RBN has a very robust ARC6 node at
arcluster.reversebeacon.net, port 7000.
* Use a logging program that permits displaying unworkable spots
(already worked, or not workable in a given contest) on the
bandmap. For example, N1MM Logger displays such spots in gray.
The advantage of doing this is that if LZ9W is running, but you
worked him 30 hours ago, and LZ9WL suddenly shows up on the same
run frequency, you can see that it's pretty likely to be a bust.
This also helps with callers mistakenly identified as runners; if
you see calls appearing one after another on the same frequency as
one of the big runners, you're probably safe in skipping past
them.
We hope this is helpful.
73, The RBN Team
Wednesday, April 25, 2012
Saturday, March 24, 2012
Aggregator 2.1 - new insight for Skimmer ops
The newest Aggregator, Version 2.1, is now available, after extensive
beta testing. This post explains the new features of this release, tab
by tab.
First of all, there is an entirely new tab titled "Skimmer Traffic." Here's what it looks like:
Overwhelming, right? What this does is to keep track of what happens to every spot made by your Skimmer.
The left-hand side of each row is exactly the same as you are used to seeing in the Aggregator, except for the color coding. Only the green spots are actually sent along to the RBN.
The right-hand side is where the fun stuff is.
For example, take a look at the first green timestamp. The rest of that line (the brown part) tells you how Aggregator decided to send the spot on to the RBN, and what it sent. The first brown entry is the frequency sent to the RBN. This will be different from the spot frequency on the left if you are using a transverter in front of your SDR and have entered a base frequency to be added to each spot.
Then Skimmer decided that first green spot was a "CQ" spot. If it had been a VHF spot, Aggregator would have sent it on anyway, but NVHF means it was not. NExcl means that the spot's frequency was not within the excluded frequencies controlled by the server (more on that below), and NBcn means it was not a regular, listed beacon. Either VHF or Bcn would have over-ridden an NCQ determination, while Excl would have blocked a spot that otherwise seemd to qualify (see below). NInMaster didn't matter, because I had not selected the option to spot only those stations in the master.,scp file, and finally, NInBadCall meant that I had not identified this call as a "badcall", one of those produced by local RFI.
Why bother? Some RBN Skimmer Ops wanted to be able to see why a given spot was or was not sent to the RBN, or whether their BadCall list was working properly. This should give them all the information they need.
Reminders about the color-coding and symbols are at the top of the Skimmer Traffic tab.
Some users had expressed a need for a way to notch out specific frequencies, typically on 60 meters, because digital signals on those frequencies were being mis-decoded. This capability has now been added to the Spot Filters tab.
On the .ini files tab, Edit buttons have been added for each of the files listed in the two .ini rotations.
There is a new feature in the middle panel of the Connections tab.
The last check-box allows you to accept or reject a list of excluded frequencies downloaded from the RBN. Typically, the purpose is to block "spots" of RTTY stations, where Skimmer will attempt to decode Baudot as if it were Morse. However, during contests you would want to un-check this option, because CW contest activity typically runs into the normal RTTY frequencies and beyond.
In addition, in the Local User area at the bottom, Dick has added two new features on the right side. Port 7550 is now capable of accepting more than one logon at a time, in case several of your friends want to connect locally.
The SETT response is what Aggregator uses to tell the RBN server periodically what bands you are listening on. We thought any local users might want the same information periodically.
That's all for this release. What would you like to see in the next one?
73, Pete N4ZR
First of all, there is an entirely new tab titled "Skimmer Traffic." Here's what it looks like:
Overwhelming, right? What this does is to keep track of what happens to every spot made by your Skimmer.
The left-hand side of each row is exactly the same as you are used to seeing in the Aggregator, except for the color coding. Only the green spots are actually sent along to the RBN.
The right-hand side is where the fun stuff is.
For example, take a look at the first green timestamp. The rest of that line (the brown part) tells you how Aggregator decided to send the spot on to the RBN, and what it sent. The first brown entry is the frequency sent to the RBN. This will be different from the spot frequency on the left if you are using a transverter in front of your SDR and have entered a base frequency to be added to each spot.
Then Skimmer decided that first green spot was a "CQ" spot. If it had been a VHF spot, Aggregator would have sent it on anyway, but NVHF means it was not. NExcl means that the spot's frequency was not within the excluded frequencies controlled by the server (more on that below), and NBcn means it was not a regular, listed beacon. Either VHF or Bcn would have over-ridden an NCQ determination, while Excl would have blocked a spot that otherwise seemd to qualify (see below). NInMaster didn't matter, because I had not selected the option to spot only those stations in the master.,scp file, and finally, NInBadCall meant that I had not identified this call as a "badcall", one of those produced by local RFI.
Why bother? Some RBN Skimmer Ops wanted to be able to see why a given spot was or was not sent to the RBN, or whether their BadCall list was working properly. This should give them all the information they need.
Reminders about the color-coding and symbols are at the top of the Skimmer Traffic tab.
Some users had expressed a need for a way to notch out specific frequencies, typically on 60 meters, because digital signals on those frequencies were being mis-decoded. This capability has now been added to the Spot Filters tab.
On the .ini files tab, Edit buttons have been added for each of the files listed in the two .ini rotations.
There is a new feature in the middle panel of the Connections tab.
The last check-box allows you to accept or reject a list of excluded frequencies downloaded from the RBN. Typically, the purpose is to block "spots" of RTTY stations, where Skimmer will attempt to decode Baudot as if it were Morse. However, during contests you would want to un-check this option, because CW contest activity typically runs into the normal RTTY frequencies and beyond.
In addition, in the Local User area at the bottom, Dick has added two new features on the right side. Port 7550 is now capable of accepting more than one logon at a time, in case several of your friends want to connect locally.
The SETT response is what Aggregator uses to tell the RBN server periodically what bands you are listening on. We thought any local users might want the same information periodically.
That's all for this release. What would you like to see in the next one?
73, Pete N4ZR
Wednesday, March 7, 2012
What Does a Flare Look Like?
Amazing screenshot from the RBN taken during today's flare. Questions, anyone?
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