Category Archives: Packet Radio

APRS SATCOM base antennas

Years ago, Bob Bruninga, WB4APR, talked about a “good” antenna for APRS SATCOM applications.  It was a 19-inch vertical antenna that would function on both the 2m and 70cm bands, and had lobes that were up around the 30-degree mark.  Looking for information on that antenna last night I found a page Bob had written expanding on the idea.  This page provides designs for i-gate antennas on 2m and includes the 19-inch antenna as well as a new design, a 3/4-wave 2m antenna.

I’m seriously considering building one or both of these antennas this weekend to test out these antenna designs.

Apple Orchard Mountain in July 2017

Success! That’s the word I’m using to describe my latest battle up a summit. It wasn’t easy and it wasn’t without some failure, but I’m willing to give this trip a grade of B. Luckily I had some help…

Stats

  • When: 2017-07-15 from 14:00Z to 20:00Z
  • Where: Apple Orchard Mountain – W4V/RA-001
  • Who: Dave KB3RAN, Ed KC3EN, Steve N3IPN, and myself
  • Ascent: 280ft in .58mi (3928ft to 4208ft)
  • Equipment: Lots (See below)
  • APRS Coverage: Excellent with nearby I-Gate
  • T-Mobile Coverage: Poor.  Could receive text messages and voicemail notifications but couldn’t make calls or send messages.  Seemed common among all carriers.  There is one spot at the northwest corner of the FAA fence that seems to get okay coverage that may work.

Getting There and Staying There

Picture of Ed KC3EN, Steve N3IPN, and Eric WG3K.

Ed KC3EN, Steve N3IPN, and Eric WG3K. – Photo by Dave KB3RAN.

This is a fun event made even more enjoyable by the addition of a few friends. This year, like last year, I was joined by Dave KB3RAN and Steve N3IPN. A new member of the group, Ed KC3EN, also joined us this year, and I hope will continue to be part of the team.

Since we’re so far away (about a 5 hour drive) we camped at the Peaks of the Otter Campground, the night before, which is a few miles south of Apple Orchard Mountain.  The campground is nice and wasn’t crowded.  We were able to get two sites that were adjacent allowing us to put up two tents and have the RV all together.

Steve, and his excellent fire-building skills, had a roaring fire going in no time, and pork chops were our first meal of the trip.

Overnight rain kept me in a tent and out of my hammock that I’ve been sleeping in as of late, so that was kind of a bummer.  At least we missed the torrential rainfall that hit the area earlier in the day.

Up the mountain we go

Ed, Eric, and Steve arriving at the summit with wagon #2 loaded with radio equipment.

Final push for wagon #2 as we arrive at the summit. – Photo by Dave KB3RAN

I don’t think I touched on this subject last year, probably because I was still sore (physically and emotionally) about the situation.  For this year’s readers I’ll do a recap.

Last year was our first year supporting the APRS Golden Packet event.  It was also our first time ever going atop Apple Orchard Mountain.  While we had looked at maps and measured distances and altitude changes we really hadn’t grasped the energy it would take to get two overloaded wagons up the mountain.  For the record, the distance up the road is .6 mi and the elevation change is just over 300 feet.  But last year the two wagons of gear were likely weighing in excess of 2 tons each (metric, imperial, royal… your pick).

This year we scaled back enormously.  Batteries and antenna masts were reduced and lightened.  Radio and antennas were lessened.  Oh, and we added another mule to the team (thanks Ed!).  This year we made it up to the summit much faster than last year.

The Primary Mission

Image of Eric WG3K setting up the APRS digipeater on a boulder.

Eric WG3K setting up the APRS digipeater. – Photo by Dave KB3RAN

The primary mission of this trip was to activate an APRS digipeater on Apple Orchard Mountain in support of the APRS Golden Packet event. The event takes place annually and takes fifteen teams from Springer Mountain in Georgia to Katahdyn in Maine to build and maintain a network of VHF digipeaters so that a golden packet may be passed from Georgia to Maine and back.

Last year we completed our portion of the mission but there were problems along the link (equipment and personnel) that caused a failure.  What parts we did get active worked well and we tested both 1200 and 9600 baud links.

This year we decided to do only 9600 baud links.  Unfortunately I didn’t realize that the link between us (AOMTN-5) and Hawksbill (HAWKBL-6) is quite fragile and a change in antenna made the path between us unusable for 9600 baud.  Even 2m FM voice was tough going.  Fortunately 1200 baud packet was able to get through, and everyone switching to 1200 baud allowed the entire network to connect and function.  It wasn’t too long after everyone switched to 1200 baud that news went out that the Golden Packet had been passed from Maine to Georgia and back so we were successful!  Mission complete.

Hind sight

In hind sight I should have probably walked our antenna around a bit to see if I could have found a better location while I had Hawksbill on VHF voice.  Next year I want to bring a 2m/70cm yagi to direct my power to where I want it to go instead of just having it fly all over the place.

I’m also hoping to venture back out to Apple Orchard Mountain, before next July, and test comms with Hawksbill if I can get time and another team on the distant end.

Other Activities (SOTA)

Image of the SOTA flag flying from an antenna mast.It’s a haul to get up to the top of Apple Orchard Mountain. At least the road is paved, though. Of course we’re not going to go up there with only a TM-D700 and call it a day; no, we brought stuff! I believe there were five HF/VHF+ transceivers that made the trip with several antennas, batteries, poles, tents, and other accouterments. Like last year, we also decided to activate the summit for SOTA!

We were much more successful this year than last. We did have some failures, but overall I think everyone enjoyed themselves. Last year Dave had issues with his portable HF digital station but had this to say this year:

I had 15 contacts, 13 states, have 4 eQsl confirmations already and maybe picked up VT as my 49th state. Dang, could have had DE and had a WAS but couldn’t hear Bob Balint [KF3AA].

Steve also had problems last year but was busy scratching contacts onto his log while working a pile-up on 40m. He wanted to work 2m SSB but heard no one, which is unfortunate.

Image of Steve N3IPN with his 2m loop antenna in the air.

Steve N3IPN with his 2m loop antenna.

I, too, tried listening on the lower portion of 2m and didn’t hear squat which I found amazing from ~4200 feet. No beacons or chit chat of any kind. What was worse was the neighborhood RF seemed to be overloading the front end of my K1 making my Plan A QRP station completely inoperable. Thankfully I was able to borrow a 40m dipole for a few minutes and put a few contacts in the log using my FT-857D.

I was actually talking with W2SE on 40m when I had a duh moment and grabbed the microphone on the D700 and called Comers Mountain and worked their crew for summit-to-summit (S2S) credit. Hawksbill had already closed down so I missed my opportunity there, unfortunately. In the end I managed 10 SOTA contacts which isn’t too shabby.

What worked well

APRS worked really well from up on the summit.  There was plenty of digipeater coverage below and that allowed us to send spots and communicate with others well.

Dave KB3RAN sitting on a up-turned milk crate working PSK31 using a tablet.

Dave KB3RAN sitting on a up-turned milk crate working PSK31 using a tablet.

APRS2SOTA worked spectacularly!  Being able to let the chasers know what frequencies were were operating on in real time via RF was priceless.  It’s easy to use, and I was able to interact with the service using only my D72 portable radio.

PSK31.  Dave left his tablet and phone home last year but was ready this year and boy did he put some contacts in the log.  Of course you never really knew when he was working stations or just goofing off because he was always just sitting on the up-turned milk crate with the tablet in his hand looking around and chatting.

LifePo4 batteries. I purchased one of these batteries days before the expedition so I hadn’t had a chance to do anything except rig it with Anderson Power Poles and charge it up.  Turns out, the battery lasted for around five or so hours being hooked to the D700 being run on high power for the digipeater, high power on UHF for coordination with Comers, and on the FT-857D running 25-watts on HF.  When it stopped working (and boy did it stop) the voltage was a little over 8V.  It had recovered a bit by the time I had gotten home but I’ll call it a good day.

What didn’t work well

K1.  The K1’s front end seemed to be overloaded from the high-RF environment that is Apple Orchard Mountain.  Unfortunately, I had planned on this being my primary operating radio and so the antenna I had brought was specifically for this transceiver.

Cellular phones. Up on top of the summit there is either too much competition for cellular signals or weird multipath happening.  Sitting in one spot I could watch my phone go from no signal to get a 3G signal to a 4G signal to nothing all within the time-span of a minute or two.  Walking to one specific location on the summit would yield a usable signal for text messaging and maybe a phone call where the rest of the summit was useless.  This problem seemed to be common to all carriers.

2m weak signal. Not sure what was going on as last year that’s pretty much all I worked.

Ideas for next year

I’ve got a couple of ideas for next year including a better antenna to point at Hawksbill.

One thought is to attempt a microwave link to Comers (2.4GHz, 3GHz, or 5GHz).  We’ll have to coordinate some on this one.

Speaking of coordinating, others were apparently active on HF from their summits.  It would have been nice to know what summits were active and coordinate with them (maybe using our freshly-built APRS network) to make some SOTA contacts.

Anyway, I’m excited about what 2018 will bring.

What's that noise on 20m?

Yesterday I was tuning around 20 meters and heard packet!  Wow, it’s been years since I’ve used packet (outside of APRS which is a different animal when compared to this).  Turns out I stumbled onto the Net105 frequency with all of their users.  It’s quite busy there and I’ve seen stations from Florida and Colorado and everywhere in between.

I still enjoy packet radio and even worked two stations, keyboard to keyboard, this morning.  I may try to put up something more permanent up for the network.  If I can find a KAM+ I should be able to hook an HF radio and a VHF/UHF radio together and provide a gateway for myself and anyone else that wants to join in.

We’ll see what happens in the future.

Automatically Controlled Digital Stations on HF

According to Part 97 of the FCC rules (specifically §97.221 Automatically controlled digital station) automatically controlled digital stations have 134.5kHz of space to work in on the the HF bands (10 meters through 80 meters).  Breaking this bandwidth up into 500 Hz channels* we see that we have 269 spaces for digital stations to work.  The breakdown is as follows:

Frequency               | Bandwidth | Channels
------------------------|-----------|-------------
28.120 MHz - 28.189 MHz | 69 kHz    | 138 channels (57 channels @ 1200 baud)
24.925 MHz - 24.930 MHz | 5 kHz     | 10 channels
21.090 MHz - 21.100 MHz | 10 kHz    | 20 channels
18.105 MHz - 18.110 MHz | 5 kHz     | 10 channels
14.095 MHz - 14.0995 MHz| 4.5 kHz   | 9 channels
14.1005 MHz - 14.112 MHz| 11 kHz    | 21 channels
10.140 MHz - 10.150 MHz | 10 kHz    | 20 channels
7.100 MHz - 7.105 MHz   | 5 kHz     | 10 channels
3.585 MHz - 3.600 MHz   | 15 kHz    | 30 channels

So we can easily see where we have the most areas to play.  Ten meters may be a bit misleading as you can run 1200 baud packet there.  So who is operating on all these frequencies?  Looking backwards (longest wavelength first) we see the following channel users:

3.5850 MHz - WL2K
3.5859 MHz - NTSD
...
3.5870 MHz - WL2K, NTSD
3.5872 MHz - WL2K
...
3.5890 MHz - WL2K
...
3.5900 MHz - WL2K
...
3.5909 MHz - NTSD
3.5910 MHz - WL2K
3.5919 MHz - NTSD
...
3.5930 MHz - WL2K
3.5935 MHz - NTSD
...
3.5950 MHz - WL2K
...
3.5970 MHz - NTSD
3.5979 MHz - NTSD
...
7.1004 MHz - NTSD
...
7.1011 MHz - NTSD
7.1012 MHz - WL2K
7.1014 MHz - NTSD
7.1015 MHz - WL2K
7.1017 MHz - WL2K
7.1019 MHz - WL2K
7.1024 MHz - WL2K, NTSD
7.1029 MHz - NTSD
7.1030 MHz - WL2K
7.1034 MHz - WL2K, NTSD
7.1035 MHz - WL2K, US Packet
7.1037 MHz - WL2K
7.1039 MHz - NTSD
...
7.1044 MHz - WL2K
10.1409 MHz - NTSD
10.1412 MHz - WL2K
10.1419 MHz - NTSD
10.1420 MHz - WL2K
10.1429 MHz - NTSD
10.1434 MHz - WL2K
10.1437 MHz - WL2K
...
10.1449 MHz - NTSD
10.1450 MHz - WL2K
10.1455 MHz - WL2K
10.1459 MHz - NTSD
10.1462 MHz - WL2K
10.1465 MHz - WL2K
10.1467 MHz - US Packet
10.1470 MHz - WL2K
10.1477 MHz - WL2K
...
14.0959 MHz - NTSD
14.0962 MHz - WL2K
...
14.0974 MHz - NTSD
14.0978 MHz - US Packet
14.0979 MHz - NTSD
14.0980 MHz - WL2K
14.0985 MHz - WL2K
14.0987 MHz - WL2K
...
14.1027 MHz - WL2K
...
14.1042 MHz - WL2K
...
14.1067 MHz - WL2K
...
14.1080 MHz - WL2K
14.1085 MHz - WL2K
14.1089 MHz - WL2K
...
14.1099 MHz - WL2K
14.1100 MHz - WL2K
...
14.1120 MHz - WL2K
...
18.1062 MHz - WL2K
18.1069 MHz - WL2K
...
21.0934 MHz - NTSD
21.0987 MHz - WL2K
(All frequencies are center.  WL2K and NTSD station frequency list pulled on 19 October 2011.  Incomplete listing of US Packet SKIPNETs.  Only US stations included in the listing.)

So are we using our frequencies in a channelized fashion?  No we are not.  What does that mean?  That means that the overall efficiency of our spectrum is reduced.  If you have a station between two channels transmitting they are basically occupying two channels instead of one.  Is this a problem?  Maybe.  I’ve heard several times two stations transmitting where they were clearly overlapping causing neither station to communicate with who they were attempting to talk with.  But from where I’m listening  (40 meters) it’s rare.  The use of PACTOR-III makes things worse, however, as these stations transmit 2kHz-wide signals taking up four channels.  These stations also get on and off the frequencies faster as well so they aren’t taking up any channels as long as a regular 500 Hz station would.  (Yes, we are TDMA.)  You can tell by the ellipses I’ve included in the chart where there are gaps in known usage.  That means that there is still room for new stations to come up on HF and utilize the spectrum.

Would it be better to have a “frequency coordinator” of sorts working with all HF networks to spread stations out and make better use of the spectrum we have?  Probably wouldn’t hurt.  Is it necessary?  Probably not; at least not now.

And remember that band that has 69kHz of available spectrum?  No one claims to be there…

* There is nothing that says we have to channelize our spectrum here but to not do so would be incredibly wasteful and could lead to interference.

XFBB and NTS Message Routing

NTS traffic is addressed very simply:@NTS.  So if I was going to send an NTS message to the ARRL I would use 06111@NTSCT.  Simple, right?  And I’m assuming that most BBSs would allow you to route traffic based on the @NTSportion of the address but not FBB.  FBB routes traffic based on the zipcode *only*.  While this does allow a more fine tuning this also means that your forward.sys file will be quite long for routing NTS traffic all over the US and Canada and you’ll also have to figure out the zip code schema.  Not to worry as I’ve already done that last part for you.  Below is the complete list of zip codes per state.  Simply copy and paste which zip codes a forwarding BBS will handle into their portion of the forward.sys file and off you go.

  Z NTSAL
  Z 35*
  Z 36*
  Z NTSAK
  Z 99*
  Z NTSAZ
  Z 85*
  Z 86*
  Z NTSAR
  Z 71*
  Z 72*
  Z NTSCA
  Z 90*
  Z 91*
  Z 92*
  Z 93*
  Z 94*
  Z 95*
  Z 96*
  Z NTSCO
  Z 80*
  Z 81*
  Z NTSCT
  Z 06*
  Z NTSDE
  Z 197*
  Z 198*
  Z 199*
  Z NTSDC
  Z 20*
  Z NTSFL
  Z 32*
  Z 33*
  Z 34*
  Z NTSGA
  Z 30*
  Z 31*
  Z 39901
  Z NTSHI
  Z 96*
  Z NTSID
  Z 83*
  Z NTSIL
  Z 60*
  Z 61*
  Z 62*
  Z NTSIN
  Z 46*
  Z 47*
  Z NTSIA
  Z 50*
  Z 51*
  Z 52*
  Z NTSKS
  Z 66*
  Z 67*
  Z NTSKY
  Z 40*
  Z 41*
  Z 42*
  Z NTSLA
  Z 70*
  Z 71*
  Z NTSME
  Z 039*
  Z 04*
  Z NTSMD
  Z 20*
  Z 21*
  Z NTSMA
  Z 01*
  Z 02*
  Z 05501
  Z 05544
  Z NTSMI
  Z 48*
  Z 49*
  Z NTSMN
  Z 55*
  Z 56*
  Z NTSMS
  Z 386*
  Z 387*
  Z 388*
  Z 389*
  Z 39*
  Z NTSMO
  Z 63*
  Z 64*
  Z 65*
  Z NTSMT
  Z 59*
  Z NTSNE
  Z 68*
  Z 69*
  Z NTSNV
  Z 88901
  Z 88905
  Z 89*
  Z NTSNH
  Z 03*
  Z NTSNJ
  Z 07*
  Z 08*
  Z NTSNM
  Z 87*
  Z 88*
  Z NTSNY
  Z 06390
  Z 10*
  Z 11*
  Z 12*
  Z 13*
  Z 14*
  Z NTSNC
  Z 27*
  Z 28*
  Z NTSND
  Z 58*
  Z NTSOH
  Z 43*
  Z 44*
  Z 45*
  Z NTSOK
  Z 73*
  Z 74*
  Z NTSOR
  Z 97*
  Z NTSPA
  Z 15*
  Z 16*
  Z 17*
  Z 18*
  Z 19*
  Z NTSRI
  Z 028*
  Z 029*
  Z NTSSC
  Z 29*
  Z NTSSD
  Z 57*
  Z NTSTN
  Z 37*
  Z 38*
  Z NTSTX
  Z 73301
  Z 73344
  Z 75*
  Z 76*
  Z 77*
  Z 78*
  Z 79*
  Z 885*
  Z NTSUT
  Z 84*
  Z NTSVT
  Z 05*
  Z NTSVA
  Z 201*
  Z 22*
  Z 23*
  Z 24*
  Z NTSWA
  Z 98*
  Z 99*
  Z NTSWV
  Z 247*
  Z 248*
  Z 249*
  Z 25*
  Z 26*
  Z NTSWI
  Z 53*
  Z 54*
  Z NTSWY
  Z 82*
  Z 830*
  Z 831*
# CANADIAN PROVINCES
  Z A*
  Z B*
  Z C*
  Z E*
  Z G*
  Z H*
  Z J*
  Z K*
  Z L*
  Z M*
  Z N*
  Z P*
  Z R*
  Z S*
  Z T*
  Z V*
  Z X*
  Z Y*

Creative Commons License
Radio W4OTN by Eric H Christensen W4OTN is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

BBS Forwarding over HF

After months of gathering pieces and trying to get time to tinker I think I’ve finally got everything figured out with connecting my PTC-II modem to my XFBB BBS so I can communicate over HF to distant lands.  Right now I’m only setup to guard and call on a single frequency.  I need to figure out the cabling to link my PTC-II modem to my Kenwood TS-480SAT for frequency control.  Once that happens I will be able to have the modem to tell the radio to scan several frequencies and to call stations on particular frequencies.

For now I’m just trying to get my connections to the NTSD established so I can send and receive NTS traffic.  I have plans, though, for future connections.

Creative Commons License
Radio W4OTN by Eric H Christensen W4OTN is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

Things to do: NTS and NTSd list

There needs to be a comprehensive list of all NTS nets and NTSD stations. This list needs to be in text format and a “pretty” graphical format and should be available on the ARRL website under NTS.

This would make it easier for those of us on the road to be able to utilize the NTS system to send messages back home or to friends.

Notification to ARES groups

I’ve been thinking a lot about volunteer responders in the scheme of emergency management. Many of these groups lack a robust communications system without which you are going to be stuck in the mud.

So what about ARES groups. From the emergency managers point of view ARES is a communications powerhouse. Give them a message and the message comes out wherever it is supposed to. Or at least that’s how it should work. But how does ARES get notified of a communications emergency? If the emergency is a phone outage then your phone tree won’t work. And calling on the repeater? How many people actually monitor the repeater all the time?

So I have two proposals to help remedy this:

Proposal One: Voice Pagers
Give your ARES members voice pagers like firefighters and EMTs carry. They are small and can be kept quiet so members might not mind carrying them. That way they are always a couple of button presses away.

Of course here is where you might run into problems. Do you page them from governmental systems or amateur systems? It is always better to have ARES notified via amateur radio so that if they are being called to help out with your fire paging system being down the message will still get out. Don’t rely on a resource that you may need help with to notify your communications contingency.

Of course if you page them from your local ARES repeater (many repeater controllers can do this for you) how does the city/county make that happen? Unless someone is a ham that works for emergency management or your 911 center then someone else outside emergency management’s control will have to initiate the notification. Also not a good option.

Another problem I can foresee is the cost of a voice pager. These things can run into the hundreds of dollars a piece. This is not to say that you can’t find them cheaper on eBay.

Proposal Two: Digital Pagers
Remember back in the nineties when it was cool to have a pager? It still can be! Pick up some Motorola Bravo pagers and a Kantronics KPC-9612+ and you can have your very own paging system. Of course you’ll have to get it up high and I don’t have a clue at how far away those pagers can be activated from but it is a cheap option. I recently found Bravo Plus pagers on eBay for around $15 a piece. That’s not bad at all. Of course you’ll still have the same problems with it being on an amateur band. How does emergency management interface with the system if he/she’s not a ham?

Anyone have any other thoughts/ideas?

Humor Posts via Packet

Every day or so my local packet BBS receives a humor post from W1GMF in Massachusetts. I really enjoy the jokes but I’m really impressed by the path the message has to take to make it to Yorktown, Virginia. The path looks like: KR4MA N9NDS KB0OFD N0KFQ KB8DM N4JOA N9ZZK ON0AR F4BWT VE2PKT N1UAN W1GMF W1GMF. Wow, lets see where all these stations are.

  1. W1GMF – Abington, MA
  2. N1UAN – Kingsport, TN
  3. VE2PKT – Sainte-Catherine-de-la-Jacques-Cartier, Quebec, Canada
  4. F4BWT – Chartainvilliers, France
  5. ON0AR – ?, Belgium
  6. N9ZZK – Diamond, IL
  7. N4JOA – Boynton Beach, FL
  8. KB8DM – Aurora, CO
  9. N0KFQ – Branson, MO
  10. KB0OFD – Forsyth, MO
  11. N9NDS – Cloverdale, IN
  12. KR4MA – Yorktown, VA

Wow, now that’s a lot of hops across a couple of continents to get my daily joke! Thanks for being there guys!