HF APRS

[at_olw]

Anyone have experience with HF APRS?

A little background:
I've been running a mobilinkd + kenwood v71a + roof mounted NMO sti-co flexi-whip (1/4 wave) + windows 8 tablet, and have begun to notice the limitations of this system in the backcountry. I am still on the newer end of the HAM spectrum, and APRS. I have only taken this setup on a couple trips so far. For the most part I had pretty good coverage throughout utah, zero in death valley (which I expected), very few successful sent packets (3 made it on aprs.fi from just north of cima) in general mojave national preserve area (we ran mojave road and went all over the park). I did receive a number of other stations throughout the park, though. I heard of other folks successfully using APRS out there, so I was a little disappointed by that. I do have a larson 2/70b I may try swap with the flexi-whip to see if that improves coverage. Using that makes me nervous though - the roof in my truck (tacoma) is extremely thin, and the antenna flexes the roof considerably, which is why I'm running the flexi-whip. In any rate...

I'm very interested in a HF system to improve the coverage and allow those at home to track me while on trips. I know I could do some sort of satellite thing, but that's no fun

Can anyone point me to a system that will stand up to the rigors of wheeling?

 

[Frdmskr]

There are systems for HF. Expensive approach uses the SCS Tracker and a mode called Robust Packet. Not a huge following in the US but you have enough coverage to do what you want. The plus is this system also can do Winlink. Also there are folks using PSK63. This is more common in North America but again, not nearly as common as VHF APRS. Both systems have high activity around 30m so you need a General Class ticket or higher.




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[unseenone]

Good information there, thanks. It is an interesting topic for the reasons the OP pointed out.

 

[at_olw]

There are systems for HF. Expensive approach uses the SCS Tracker and a mode called Robust Packet. Not a huge following in the US but you have enough coverage to do what you want. The plus is this system also can do Winlink. Also there are folks using PSK63. This is more common in North America but again, not nearly as common as VHF APRS. Both systems have high activity around 30m so you need a General Class ticket or higher.




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Thanks for the response. I very much plan to upgrade to general the next time the test is offered, so no issue there (I was only two shy of passing with never seeing a "general" test question before trying the test :Wow1. Unfortunately I live in a sleepy town and it's only offered every couple of months. Although realistically it'll take me at least that long to figure out the next system configuration. Thanks for the tip on PSK63. Using that as a search key, I've found that a number of folks are using the APRS Messenger program (which can then be interfaced with APRSISCE [currently using] or etc for map display). On a related note, this site has proven very informative:
http://wa8lmf.net/APRS_PSK63/

I clearly have a lot more research to do. Especially in regards to a HF transceiver. Although, realistically I'm most interested in 10.149 700 MHz for APRS. Antenna-wise I'm thinking something like a hamstick would work well and be durable enough for offroad use.

Good information there, thanks. It is an interesting topic for the reasons the OP pointed out.

It's definitely interesting! I think it'll be a great upgrade to my rig when I get it all figured out.

 

[mm58]

Until reading this thread, I did not know APRS could be done via HF. Is there a standard HF band/freq that is used like 144.390 is on VHF?
And is the HF APRS digipeated?

Mike

 

[at_olw]

Check out that link in my previous post, lots of info

But to answer your question - from my research thus far (I am no expert and have a LOT to learn) it's generally done on 30m, with 10.151 500 MHz being the primary HF frequency. This wiki suggests there are a couple others, as well as 6m, which I wasn't aware of.

I'm fairly certain digipeating HF APRS is frowned upon, given how many folks share the same frequency.

I'm pretty set on getting this up and running in the rig. Have a big multi-week trip planned in august, part of which I'll be solo. I was hoping to find a single band 30m radio, but that doesn't seem to exist outside of qrp stuff. Leaning towards selling the v71a to a friend, and picking up a 857d. Probably just use a 30m hamstick and leave the flexiwhip up for 2m, or find a place to put the larson 2/70b. I was hoping there was a cheaper way to get HF APRS than getting an all-mode radio but c'est la vie.

 

[at_olw]

Bumping this up - if anyone on here is running HF APRS, which antenna are you using? The options I've seen for 30m include:
1. atas 120a (seems expensive and I'd probably break it)
2. hamstick (cheap, wouldn't cry if it broke, but struggling with where to mount)
3. whip + tuner

1. I'm not terribly interested in this, as I have a feeling I'd whack the antenna on a tree branch, and be pretty sad. k0bg calls it "the least efficient, remotely controllable, HF mobile antenna, money can buy!"
2. Seems like a decent way to go, as I wouldn't cry if it broke, and seem reasonably well regarded. Some reports are that it doesn't work so great at 30m+, which would defeat the purpose as I'd need 30m. Monoband would work fine in general.
3. Don't know enough about this approach yet, but it seems pricy.

In a general sense, I'm also struggling with where / how to mount a 7ft + antenna. I already hit my 4' firestick (CB I know ) on everything and that's mounted at bed-red height, although it's probably getting moved this weekend when I make a rtt bedrack.

A primary impetus to all of this is a long trip in august through oregon, washington and part of canada, and will be wooded. So something that will withstand tree abuse would be ideal. Am I hoping for too much? I haven't been able to find a lot of info about setups that withstand offroad abuse.

 

[unseenone]

I have made contacts in Japan, Serbia, all over with the ATAS 120.. It seems fine to me, but you wouldn't want to hit anything but the whip with a tree branch. The upside is you can use it on many bands, the down side is the mounting concerns. I haven't had any problems or broke mine yet, but you have to think ahead so you don't damage it.

I have a roof rack fold over mount, so when it is down, the rack rails protect it from hitting anything. It is a hassle. A front bumper or hood mount is nice, but you will take a huge hit in performance.

 

[at_olw]

Nice. I'm assuming the convenience factor is why you picked the atas 120 ("A" I'm assuming?) over say... a little tarheel II?

My situation is somewhat unique in that I don't entirely care if I can make contacts halfway across the world. I just want to make sure my APRS packets can generally reach the nearest 30m igate. At this point, I am not as concerned with HF voice outside of backcountry emergencies. Although who knows. Maybe when I get a 857d I'll think differently.

 

[AlbanyTom]

I wasn't going to jump in, because I don't want to discourage you, but change my mind because of a couple of phrases you used - 'outside of emergencies' and 'make sure'. I absolutely think that this is a great project, fun and practical. And I wish you the best. I just want to insert a little level set, so you don't expect too much too soon, and don't have your reliability expectations too high.

I'm going on the assumption that you're an experienced 2m operator, and also familiar with packet. My background is 2m and HF, digital HF, and some mobile HF. No APRS.

2m FM is, pretty much, plug and play, especially with repeaters. APRS is a bit more complicated, but very predictable. Propagation, as you know, is mostly line of sight for mobile. Every once in a while you get ducting, depending on where you are, but you know you can't count on it.

HF is a whole different animal. Outside of ground wave, which is very nearly limited to line of site in most cases, propagation is much, much less predictable. It depends on the ionosphere, which changes very much by time of day and location. Sometimes talking to someone 1000 miles away is possible on a particular band, while talking to someone 100 miles away is not. Sometimes talking to someone 25 miles away is a challenge on ANY band. My point is, it's a lot of fun, but it's not plug and play or always working.

Taking HF mobile adds another set of problems. Except for 10m, mobile antennas are lousy on HF. You've done your homework, and you know that screwdrivers are generally considered the best HF mobile antenna, by most hams. And from there, a whip with tuner, and far down on the list is a hamstick type. But there is a lot to getting an HF antenna installed and grounded right. Oh, and length matters.

Next, HF digital is also tricky. Now, APRS, which I believe 300 baud, probably isn't as tricky as PSK, but on the other hand...and you found this info on another site and it's correct - 300 baud FSK is a lousy mode for HF, compared to PSK31. Meaning it won't work as well with a poor antenna, which is any antenna HF mobile.

So if you combine being new to HF, and HF mobile, and HF digital, all at once, you've got a LOT to get up to speed on. And even for someone that was used to that, I wouldn't count on HF APRS as being 90+% reliable. On this last part I am making a guess...but I have to wonder if one of the reasons you don't hear much about HF APRS is that it doesn't work all that well. The other thing I bet is that if it were BPSK31, and on 20m instead of 30, it would work a whole lot better, but that's just my guess again.

I'm saying this because I don't want to see you try this and give up, or worse, try it, and find it reliable at home, and then go out and have one of two bad things happen. 1 - have some sort of accident, and have no way to communicate because you were counting on this. or 2 - have the wife not hear from you, like she was sure she would, and have a giant air/land search launched to find you when you're really fine.

summary - I think this sounds like fun, but absolutely don't count on it working when you need it to.

Final thought - consider packing a 40m and or 80m dipole with you, and playing HF radio, either digital or voice, when you're camped for the night. Will work way better than any mobile antenna, and you might have some fun, too.

 

[unseenone]

I think this is a fun thing to experiment with. Where it may be used more, from what I have seen is on boats who go far off shore. These are situations where, a single position update every couple of days are acceptable, so it isn't an issue. I have no idea how it will work mobile, but to be practical it I think it needs to work without a lot of extra hardware, like a computer. That being said, it might be fun to experiment with..

As far as HF on a mobile Vehicle platform, it can be done and done reliably, you just need to take the time to do the research and installation correctly. I have just as good luck on DX while mobile as the base station. It is just a lot of fun. There are limitations, like with anything.. Most of all, commit to the work, research and have some fun with either if you go that direction.

 

[at_olw]

I wasn't going to jump in, because I don't want to discourage you, but change my mind because of a couple of phrases you used - 'outside of emergencies' and 'make sure'. I absolutely think that this is a great project, fun and practical. And I wish you the best. I just want to insert a little level set, so you don't expect too much too soon, and don't have your reliability expectations too high.

I'm going on the assumption that you're an experienced 2m operator, and also familiar with packet. My background is 2m and HF, digital HF, and some mobile HF. No APRS.

2m FM is, pretty much, plug and play, especially with repeaters. APRS is a bit more complicated, but very predictable. Propagation, as you know, is mostly line of sight for mobile. Every once in a while you get ducting, depending on where you are, but you know you can't count on it.

HF is a whole different animal. Outside of ground wave, which is very nearly limited to line of site in most cases, propagation is much, much less predictable. It depends on the ionosphere, which changes very much by time of day and location. Sometimes talking to someone 1000 miles away is possible on a particular band, while talking to someone 100 miles away is not. Sometimes talking to someone 25 miles away is a challenge on ANY band. My point is, it's a lot of fun, but it's not plug and play or always working.

Taking HF mobile adds another set of problems. Except for 10m, mobile antennas are lousy on HF. You've done your homework, and you know that screwdrivers are generally considered the best HF mobile antenna, by most hams. And from there, a whip with tuner, and far down on the list is a hamstick type. But there is a lot to getting an HF antenna installed and grounded right. Oh, and length matters.

Next, HF digital is also tricky. Now, APRS, which I believe 300 baud, probably isn't as tricky as PSK, but on the other hand...and you found this info on another site and it's correct - 300 baud FSK is a lousy mode for HF, compared to PSK31. Meaning it won't work as well with a poor antenna, which is any antenna HF mobile.

So if you combine being new to HF, and HF mobile, and HF digital, all at once, you've got a LOT to get up to speed on. And even for someone that was used to that, I wouldn't count on HF APRS as being 90+% reliable. On this last part I am making a guess...but I have to wonder if one of the reasons you don't hear much about HF APRS is that it doesn't work all that well. The other thing I bet is that if it were BPSK31, and on 20m instead of 30, it would work a whole lot better, but that's just my guess again.

I'm saying this because I don't want to see you try this and give up, or worse, try it, and find it reliable at home, and then go out and have one of two bad things happen. 1 - have some sort of accident, and have no way to communicate because you were counting on this. or 2 - have the wife not hear from you, like she was sure she would, and have a giant air/land search launched to find you when you're really fine.

summary - I think this sounds like fun, but absolutely don't count on it working when you need it to.

Final thought - consider packing a 40m and or 80m dipole with you, and playing HF radio, either digital or voice, when you're camped for the night. Will work way better than any mobile antenna, and you might have some fun, too.

Thank you for the thoughtful response!

You are correct - I should have worded things better. I am aware that there are a multitude of environmental conditions that effect radio waves and effective range, and HF in general requires more finesse than 2m/70cm does. My thinking is that this is just one more tool to have available for safety purposes.

I have a pesky habit of trying to run before learning to walk, which may very well be exemplified here. I don't entirely expect it to be easy, but hope my determination will help to get me there for this endeavor. You may be right that HF APRS doesn't work very well, but I'm not ready to give up hope, without giving it a serious go. If you are right, then I have other digital modes to explore as well, that may de facto accomplish my project objectives.

My beloved v71a will be finding a new home with a friend next week, which should coincide with when my new 857d is anticipated to arrive on my doorstep, as well as a signalinked usb.

I very likely will be packing some sort of portable antenna (probably a dipole), but still intend to install something mobile. If you have suggestions on specific routes to go, I am all ears, especially considering this is going on a vehicle that sees regular offroad use. I was fairly set on a little tarheel II for a while, but was recently pointed to a silver bullet 1000. Seems like a interesting way to go. Simple, and cheap. Probably more durable? All sounds like good things to me...

 

[at_olw]

I think this is a fun thing to experiment with. Where it may be used more, from what I have seen is on boats who go far off shore. These are situations where, a single position update every couple of days are acceptable, so it isn't an issue. I have no idea how it will work mobile, but to be practical it I think it needs to work without a lot of extra hardware, like a computer. That being said, it might be fun to experiment with..

As far as HF on a mobile Vehicle platform, it can be done and done reliably, you just need to take the time to do the research and installation correction. I have just as good luck on DX while mobile as the base station. It is just a lot of fun. There are limitations, like with anything.. Most of all, commit to the work, research and have some fun with either if you go that direction.

I have seen it done for watercraft, but haven't found as much supporting information about it. One more niche within a niche to research! You touched on something I think is very true - I'm not trying to update my position every 5 min or even hour. If one packet gets gated a day, I'll have met my project goals. I have a windows 8 2 in 1 already installed in the truck, so no worries there. Although I have seen development on the cellphone platform. Androidpsk/etc. Outside what I'm trying to do, though.

I am moving ahead and know that I have a lot more to learn / research. Thank you.

 

[AlbanyTom]

I think you're going to have a fun trip. Pushing to do things you haven't done before is a great way to go, as long as you're going in aware of the issues, it sounds like you have that covered.

 

[Frdmskr]

I had/will be reinstalling a Tarheel Model 75. Runs 10-80. Worked fantastic with the 480. Going to be eventually putting it on my new 01 4Runner someday. (Need to not work 80 hr weeks). Used it for years and loved it.

Weld/drill holes but physically connect it to the rig. On my Escape I had a riveted and welded bracket that was fantastic. For the 4Runner I will be doing it with a Breedlove mount.

All that being said I also have run ham sticks and hustlers. Ham sticks are good down to 40. Not great but good. Cheap and disposable. Hustlers are a bit heavier and pricier but always gives you 6m.


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