This is less of an actual "update" than it is an in-depth look at the current metro APRS infrastructure. Still, a new TX gateway has popped up inside the freeway loop. More on that later.
First, we should take a look at the current messaging-capable stations in town:
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| metro messageable 4/19/23 |
As always, and for all of the images on this blog, you can click on the picture to enlarge it.
My last update looked at digipeaters, and the unique potential of "small digipeaters" (5-10W) to change the urban APRS landscape. In this update, I'll take a (less intensive) look at I-Gates.
Why all of the gateways?
I was once asked this question on-air when I was talking about new gateways appearing in the metro. The point was that all we really need is one gateway, and the digipeaters can feed that one gateway.
The answer comes down to three factors: size, siting, and activity.
First, the metro area is large. Just the freeway loop is 25 miles wide. Even a well-positioned I-Gate such as W0YC-5 can't reliably cover the entire area directly. Additional gateways are needed to provide reliable coverage across the entire area.
Next, the metro infrastructure is not ideally distributed. There is no central authority guiding the development of APRS in Minnesota; it's basically anarchy. This is the "siting" factor. Amateur operators put up gateways and digipeaters wherever they choose. And, in most cases, those sites are their own homes. Yes, there are cases such as W0PZT-1 on the county tower in Medina, or K0YTH-13 on the hospital tower in Robbinsdale, or W0YC-5 at the University. But these are the exception, not the rule. And you will notice that all three of those are in the northern half of the metro. Ideal public sites themselves are not ideally distributed.
Virtually all of the metro's digipeater capacity is located in the northern half of the metro. The exceptions are the KF0ZH digi in Shakopee, and the N0NGK digi in Burnsville. Certainly, some of the northern digipeaters reach into the south metro quite well. But the point is that local digipeaters are not placed in ideal and strategic positions to effectively cover the metro. And, when new digipeaters go up, the operators usually are not trying to fill some strategic gap in coverage.
Last is the activity factor. Traffic in the metro is close to continuous. The metro is also a regional hub for distant traffic; not just rural digipeaters to the west and north, but also a massive digipeater network in Wisconsin. Add in Faribault and Rochester, too. And the new Askov digipeater should be included.
This is, of course, pretty great for local operators to be at the crossroads of so much activity. In the past couple of years, developments in the west have taken some of that load off, and the new gateway in Barron, WI has also helped with that somewhat. But it's still quite clear that there is a lot of digipeated traffic, whether local or DX, coming across a shared simplex frequency in the Twin Cities. And, due to packet collisions, one gateway can't handle all of that traffic.
All but the most modest I-Gates in the metro handle hundreds of digipeated packets every month, often from stations far outside of the metro. Truth be told, we could still use a few more just to handle digipeated traffic arriving here.
Local updates
Another new TX gateway has appeared on the scene. K9GCC near Falcon Heights went on-air around Monday (4/17), and it's already filling in the St. Paul area nicely. It seems to need a tweak of its RX audio levels, however.
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| K9GCC coverage |
N9MEC-8 is also new. This is a TX gateway in the same spot as the long-standing N9MEC I-Gate, and it seems to have nearly the same coverage. It's especially nice to see this new gateway reaching into the south-east corner of the metro, helping to fill that void.
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| N9MEC-8 coverage |
I had a brief exchange with N0KGK (Jim) over the last week concerning his Burnsville digipeater. While N0KGK has been up for over a year now, I knew nothing about it. The digipeater has really boosted the south metro coverage nicely, and I've always wondered if he was using some fancy hardware to accomplish that. As it turns out, it's a fairly modest station -- almost "retro", actually. The RF side is a 25W commercial Kenwood rig running into a dual-band Comet antenna about 30 feet high. The TNC is a Kantronics KPC-3 that's "at least 35 years old". Jim said the biggest challenge he had setting up the digipeater was trying to remember how to program the KPC-3. For those who don't know, the KPC-3 TNC was the standard workhorse TNC for both "straight packet" and APRS stations alike back in the "early days". It's still available, too, after all of these years.
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| N0KGK coverage |
K0BEN-10, the relatively new TX gateway in South Minneapolis, covers a pernicious dead zone in the metro's APRS coverage. Per K0BEN (Ben), it's operating out of a garage using an indoor antenna. For those of you that think it takes mega-stations with an antenna hundreds of feet in the air to make a difference, this I-Gate proves that's a fallacy. It covers the low-elevation Lynnhurst neighborhood, Linden Hills, Lake Harriet, up to Powderhorn and even Uptown. This unassuming gateway also handles digipeated packets across the wider metro area, and gates RF messages from APRS Thursday.
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| K0BEN-10 coverage |
Only a couple of miles away is the WG0A-2 TX gateway. It's a nice addition to the south metro, as well. WG0A (Brent) is a long-time local packet aficionado, running BBS, WinLink, straight packet and HF APRS services. Aside from providing fill-in coverage to the southern exurbs, this gateway is also helping to fill that void in the south-east fringes of the metro. While we still need a digipeater in Cottage Grove to fill that area out properly, there's at least some direct coverage there.
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| WG0A-2 coverage |
KF0ZH has existed as a digipeater longer than I've been a licensed ham. It anchors the APRS coverage for the south-west metro, benefitting from close proximity to the RX-only AE0RF-10 gateway. But its RX has always reached into Minneapolis proper, a and even into St. Paul. Lately, however, that reception coverage has begun to decline.
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| KF0ZH coverage 12/10/22 |
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| Current KF0ZH coverage |
I can only speculate as to the cause. Maybe other new stations are handling the packets KF0ZH once digipeated. It could be antenna issues. Whatever the cause, this station still needs support to the west. Another gateway (or even digi) in Waconia would add some continuity of coverage with the N0DP-10 TX gateway in Minnetonka.
Summary
We've looked at several of the metro's infrastructure elements and the role they play in the network. This is just a fraction of what comprises the entire network, however. But it does cover some of the lesser-known stations that make APRS operation work so well here. If you are new to APRS, you may be unaware of most of them. In future updates, I'll cover more of the infrastructure, and explain how each of these stations adds to the 'synergy' of our local scene.
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