Fall 2018 6m APRS and Misc Update

November 2, 2018

Figured I’d take this “downtime” evening in 4-land and toss together a quick update on the 6m APRS system and a status report. Note that I have several draft blog postings that I’ll try to finalize in the coming weeks. Sorry for the lack of posts, but get used to that being the new normal on here due to other priorities. Hey, you get what you pay for 😉

Well hopefully everyone had a good summer. I wound up being back-n-forth bi-coastal more than originally planned but it’s all good. It stresses the XYL at times, but like I remind her “we’re healthy, we have a roof over our heads, clothes on our backs, we can pay our bills, job security is not a concern, and we’re ahead of the game on retirement plans so let us realize just how blessed we are.” We recently got in from a nice Fall trip up in New England. We were a bit late for peak Fall foliage color in the inland areas, but there was some spectacular color along the coastal areas.

We stopped in 4-land for a quick work project and I needed to absentee vote this year. A longtime friend and former co-worker is running for Judge Exec and his Chief Deputy is running to fill his shoes as Sheriff. We also have a somewhat interesting statehouse race.

So I just cast what may be my last vote as a Kentuckian. The other half is an official Wyomingite so we’re heading back west this week so she can vote there. Plus we both need to get a pile of work done before holiday hustle and bustle arrives.

Hey where the heck did 2018 go to? Current plans are Thanksgiving in 4-land, then another extended family Christmas in the Idaho mountains, followed by New Years Eve in Wyoming. Hey the snow is piling up on the mountains so holiday mountain grandeur and fresh powder to play in = yes please!

Hopefully during some of the holiday downtime I can get the blog and some other ham radio documentation projects caught up for the locals. No guarantees though LOL.

Okay, moving on to some status reports….

6m APRS:

K4KPN-6/-4 was moved from the Jonesville tower site to the Jonesville “East” tower site (my personal tower) in early September after some coverage testing. The east site has a lower noise floor (better receive performance) and still meets coverage needs into the three tough to cover EMCOMM relevant locations we keep that port around for.

The K4KPN-6 6m APRS Digi/I-gate remains on the air 24×7 on 50.6200 MHz using 1200 baud AFSK and no changes are currently planned.

KI4WEF recently got his home Outpost PMM terminal on the air again from the new home he is building. He’s on a temporary 6m antenna till he finalizes how he’s going to setup his new station. His station is also beaconing an APRS compatible beacon so we have another 6m APRS station on the air.

I haven’t had time to confirm the details but scuttlebutt is 6m APRS is being used in some of the Marine Corps Marathon events. Cool eh?

 

Packet and Repeaters:

Most all the packet gear has been shifted over to the club callsign.  I just got the coordination for 444.4250+ repeater switched over to the club callsign and will reprogram it’s ID when time allows. This is all part of an evolving plan to move things over to the JFD tower site and let Greg, Lonnie, and Mark manage it once we fully retire out west.

There has been some talk about making 425 dual-mode analog/FUSION or analog/P25. The reasoning will be explained later on. It’s currently on the air from Williamstown in low profile test mode as I need to finish tweaking it. Current plans are to relocate it back to its primary site at JFD once some antenna and feedline repairs are completed there. ETA on that move = good question, probably going to be next Spring.

 

Node/BBS/RMS Shutdown plans:

Several have understandably asked if these systems will still be around in a few years. First off I’m not going to guarantee anything. I have plans but I can’t predict the future. It is just just a hobby, we don’t charge a dime in dues, we do what we do for the love of packet radio. Several silent keys and folks moving off for work/retirement reasons have left KYPN and packet activity in N. Kentucky at a fraction of what it used to be. It is what it is.

Actual local utilization will drive choices on what remains. Rack space and site integration issues at the future site will also play a role. There’s not going to be room for everything there so if I was to hazard a guess? The 10m RP, 220 1.2k, and 441 9.6k ports will be what remains. For those wondering what packet gear to invest in? There’s your answer 😉

 

2m APRS:

The K4KPN-15 2m APRS Digi/I-Gate is scheduled to be turned off January 2020. It is at a location where I lease space for my day job. I’m slowly extricating myself from my KY obligations and will not need that space come 2020.

I don’t have any free site that would accommodate K4KPN-15. Hopefully some others will step up and run some of the local 2m APRS infrastructure.

K4KPN-15’s days are numbered. Plenty of notice has been provided.

 

30m RP APRS / K4KPN-10:

While there are no current plans to shut down K4KPN-10 I am looking at moving it to a site near the VA/KY border. This is where one of my day job clients has a spare HF antenna and some rack space.

I’ve had the VA site patched into the WAN loop since July. I’ve been playing with both IP and stream feeding a spare modem on the remote radio there into K4KPN-10. Results show very little difference in NOAM and S. EU coverage and a slight improvement on the N. EU path. So that’s looking like an option I may explore further when time allows for me to run more tests from out west.

 

Well I’m beat and we want to hit the road early so that’s enough for now.

WA4ZKO


K4KPN-10 Storm Damage

July 3, 2018

Update July 4th . K4KPN-10 is back in service.

So far the damage sounds like a power supply (likely repairable), a few fuses/tripped breakers, and unfortunately the tragic sacrifice of a kind gentle soul of a Rev 1 SCS Tracker TNC to the thunder gods. Thankfully there were spares nearby and we were able to get things back online last night.

There may be some brief outages later in the week due to electrical work/repairs at the site.

73 de WA4ZKO

Apparently around noon eastern time the Dry Ridge site took a major lightning hit. Mike ran by and his quick assessment is the site is dark and the transfer switch got smoked pretty good. Judging by telemetry things ran till the UPS systems told things to shut down.He did a cold start and it looks like at least a PSU and the Tracker modem on K4KPN-10 is dead…radio came on but may well be damaged.

He’s heading back out there this evening to get the tower lights back on and start checking and bringing the commercial gear online. Once the commercial gear is back up he’s going to call me and we’ll start doing further damage assessment on the ham gear. I have some spares on hand, but depending on how bad things are K4KPN-10 may be down for the count.

WA4ZKO /7


K4KPN-10 Robust Packet I-Gate / Digipeater Update and APRS-IS Gotchas

May 26, 2018

K4KPN-10 has clearly benefited from the combination of antenna system repairs and noise floor (NF) reduction work at the site last Fall. Performance is back to what one would expect from it.

For those that ask why Robust Packet? One word….performance. Below is a screencap of what the 30m RP APRS world looks like from the Kentucky gate’s perspective over a few days.

RPR_K4KPN-10_20180519

K4KPN-10’s view of the 30m Robust Packet APRS world. Why RP? One word….Performance.

Around 25 to 30 of those stations on there have been heard direct on RF at some point. Single hop stateside coverage is easy. Europe is in to some degree nearly every evening and EU mobiles are often heard. Even the challenging polar path over to RT9K-15 is in there at times.

I’m hesitant to use APRS-IS for serious coverage analysis since it doesn’t begin to reflect everything heard on RF, especially on HF. Regardless K4KPN-10’s “heard” and “heard by” data is interesting:

RPR_K4KPN-10_heard_201805

APRS-IS perspective on RP HF APRS stations heard by K4KPN-10 so far this month.

RPR_K4KPN-10_heard_by_201805

APRS-IS perspective on RP HF APRS stations that have heard K4KPN-10 direct so far this month.

Yes some of the soundcard modems will do good work on 300 baud AFSK for single hop HF APRS and some occasional DX can get through. Some can do even better with bit fixing. The problem with bit fixing (guessing) is it breaks spec and can easily cause corruption if done too aggressively even on APRS. Thus why we so often trace corruption on the VHF APRS feeds back to soundcard modem equipped gates. Even with bit fixing the limitations of 300 baud AFSK become apparent over long haul DX paths.

Where Robust Packet shines is it uses Pactor-III like modulation that allows error correction without breaking spec. RP offers good noise immunity and deals with the multi-path on long haul DX packets better than a typical AFSK modem can.  Since RP uses space and power efficient dedicated hardware it is also well suited to stand-alone portable/mobile tracker uses without the need for a PC/laptop.

Robust packet is a mode and hardware built from the ground up for improved performance on HF and well suited to HF APRS. DX reception is not occasional, it is commonplace. I admit to sort of taking 4,000+ mile APRS DX as NBD till one of the HF AFSK guys sent me a “holy $#@$ what are you using that hears across the pond nightly” email LOL.

For those asking “where is K4KPN-10 hearing RT9K-15? Oh it is in there on RF, but due to his gate configuration it’s going to be difficult for stations other than a few lucky EU gates to ever get credit (APRS-IS perspective) for hearing him.

RT9K-15_at_K4KPN-10

RT9K-15 being heard direct at K4KPN-10.

Well here is an opportunity for a good lesson on the flaws of assuming APRS-IS gives a complete picture of what is going on at the RF level.

It is important to realize that APRS-IS does dupe checking. If I-Gate A and I-Gate B hear the same packet only one of them can get credit for it from the APRS-IS perspective. Which one gets credit? The first one that gets that packet to APRS-IS. The one with the lowest latency to the APRS-IS system.

If you run an I-Gate or home APRS system on both IP and RF you can easily screw yourself with bad timing values. The RT9K-15 I-gate is doing something that will make it very hard for coverage analysis via APRS-IS. It appears to be aggressively beaconing to APRS-IS every few minutes? I’m told that it is heard often in EU, but rarely does an EU gate get credit for it in the eyes of APRS-IS. This tells me it is probably making the 2nd mistake of beaconing to APRS-IS and RF at the same time. This means even if another gate hears his packet on RF then it’s unlikely outside of internet congestion on his link that another gate can decode that packet off RF and inject it into APRS-IS before his internet beacon gets into APRS-IS.

Another problem this creates for APRS-IS analysis is it throws the packet counts off on the above pages. A good example is it shows a monthly total of 5 packets for DF1CHB /AM.  He was in direct on the eastern USA I-gates for hours earlier this morning, but also hitting EU gates so NOAM will only get occasional credit for gating him even after dozens of packets gated in. Tonight he is airborne over Serbia and K4KPN-10 is hearing him direct like clockwork on 30 meters:

DF1CHB_30m_rpr_aprs_20180526

DF1CHB /AM over Serbia and coming in on 30m robust packet almost as if he’s a local on VHF LOL.

Don’t get me wrong, this is not a complaint towards APRS-IS. It’s just how the system works and how it has to work. It’s just important for APRS operators to understand that APRS-IS doesn’t give you the full RF picture due to the necessary dupe checking going on. This is especially true on HF where the same packet can easily be heard by multiple I-Gates hundreds or thousands of miles apart.

Also noteworthy that some stations run beacons marked “RFONLY” or “NOGATE” paths. A properly configured I-Gate will not gate those beacons into APRS-IS. This is another gotcha if you’re trying to get a full picture of RF level activity via APRS-IS based systems and apps.

Recommendations based upon lessons learned here if you are interested in getting decent coverage analysis via APRS-IS?

  1. There is normally no need for an APRS station to position beacon on their internet port (APRS-IS) more than once or twice an hour unless it is moving. Serves no useful purpose for fixed stations and it only adds to the cumulative load on the APRS-IS system.
  2.  I-gates should consider beaconing on their internet port at a rate of just under 60 minutes.
  3.  Avoid beaconing via RF and internet ports at the same time.
  4.  If you are not moving, then you don’t need to be pounding the heck out of the RF side either. 2-3 RF beacons an hour from a fixed station is more than enough to keep you on most maps and fresh in APRS-IS for messaging/gating purposes if you are in range of an I-Gate.

WA4ZKO