[hfsig] HF performance under 1000 miles?

Mitch Winkle mitchwinkle at gmail.com
Tue Oct 11 15:06:43 CDT 2016


Bob,

More info makes for a better discussion.

30m mobile isn't all that hard to do.  40m mobile with verticals has always
been fraught with resonance issues, but the smaller cars may have mitigated
that somewhat. ;)

For ships/boats it's a might easier and more useful I would imagine than
cars.  At SHORTER distances, say NVIS, most will need be horizontally
polarized, while a bit more skywave allows for mixed polarization.  Thus
30m might play well.

Have you considered 6 or 7 character MGRS for locations?  That's pretty
tight and no repeats.  It defines the SW corner of the grid roughly 6 miles
square (10km).

--
Mitch Winkle
http://ewamjlu.blogspot.com
...How long will you go limping between two different opinions? If the LORD
is God, follow him...
1 Kings 18 ESV

On Tue, Oct 11, 2016 at 2:29 PM, Robert Bruninga <bruninga at usna.edu> wrote:

> The tradeoff I’m working with here is position resolution for an APRS
> mobile.  Right now Grid squares are worldwide unique.  This requires a lot
> of bits that never change unless the DX is huge.  I took another look at it
> and if we organize the same grids into groups that are 9x9, instead of the
> current 180x180, then we can get a position down to about 0.2x0.3 miles
> instead of the current 7x10 mile resolution in the same number of bits.
>
>
>
> But the positions are not unique worldwide but repeat every 1800 miles in
> latitude and every 2500 miles in longitude.  But this pretty well covers a
> continent.  SO, we can use this if we chose a band that hardly ever goes
> beyond 1800 miles…
>
>
>
> What do you think about 30 meters?  I guess it can still do that far?  OK,
> then what about 40m?
>
>
>
> And again, I am only talking about the transmitter end being a mobile with
> a vertical antenna.
>
> I appreciate your input.
>
>
>
> Bob
>
> WB4aPR
>
>
>
> *From:* hfsig [mailto:hfsig-bounces at tapr.org] *On Behalf Of *Mitch Winkle
> *Sent:* Tuesday, October 11, 2016 9:21 AM
> *To:* TAPR HF Modes SIG Mailing List
> *Subject:* Re: [hfsig] HF performance under 200 miles?
>
>
>
> DX is hardly evil as long as the results are achieved.  Your project, your
> decision...my 2 cents.
>
> Mitch
>
>
>
> On Oct 10, 2016 9:37 PM, "Robert Bruninga" <bruninga at usna.edu> wrote:
>
> But I dont want DX ever in this app..  I want HF that works out to 250
> miles during the day and not much beyond 500 miles at night.  Then, just
> like WIDE1-1 on VHF, we can keep things HF local, re-use the freuqncy and
> also gain 100 to one precision by not having to transmit worl-wide unique
> posits, but just say 1000 mile unique.  That's the idea anyway.
>
> I climbed up the roof to inspect my multi-band dipole and to my amazement,
> all 8 legs were intact, and just drooping down in the shrubery on all
> sides, so it looks like aI can gt back on HF by just a lot of rock throwing
> and string...
>
> bob, WB4APR
>
>
>
> On Mon, Oct 10, 2016 at 11:36 AM, Mitch Winkle <mitchwinkle at gmail.com>
> wrote:
>
> That's not always valid reasoning when it comes to HF actually, and here's
> why.
>
>
>
> Just because the "nearest" HF gate is 200 - 300 miles away doesn't mean
> that's the best one to use all the time.  NVIS communications make sense if
> you are networking around that model (such as MARS does in regional
> comms).  If you are involving alternate connectivity such as internet, RF
> distance is rather inconsequential.
>
>
>
> Case in point:  Using WINMOR for Winlink connectivity for the recent
> Virginia ARES SET, it was necessary for me to use a station in North Miami,
> FL, over 1000 miles away in order to gain access to the network reliably on
> HF.  Now the same could be said for HF APRS as well.  Why worry about the
> distance at all?  Designate a frequency on each band and be happy.
> Scanning is commonplace for many types of networking tools such as packet,
> ALE and Winlink systems.
>
>
>
> To try to provide a direct answer to your question though, an overall high
> availability data only band like 30m (which is already the target for many
> using APRS) makes a lot of sense.  It's long-regional flavor spans not only
> NVIS on it's edge days of propagation, but good sky wave as well, and solid
> overnight performance for many hundreds of miles.  It is common to have
> trans-Atlantic QSO's in the dark also.
>
>
>
> "What frequency should I use on HF?" is one of the most asked questions in
> all of Amateur Radio.  The answer is almost always the same.  "The one that
> works today."
>
>
> --
> Mitch Winkle
> http://ewamjlu.blogspot.com
> ...How long will you go limping between two different opinions? If the
> LORD is God, follow him...
> 1 Kings 18 ESV
>
>
>
> On Mon, Oct 10, 2016 at 9:44 AM, Robert Bruninga <bruninga at usna.edu>
> wrote:
>
> For under say 200 miles, what is the best band round the clock?
>
> Given that a 1 Watt WSPR transmitter performs as if it was 1000W due to
> processing gain, couldn't it punch through the day time noise?
>
> And APRS only has to go say 200 miles to the nearest HFgate to provide
> almost total coverage of the USA because every where is within 200 miles of
> a city where maybe a ham will be running an HF gate?
>
> So that is the question.  Forget the high noise levels... WSPR can work
> through that.  what band will provide the connectivity 24/7/364 over that
> 200 to 300 mile range?
>
> Bob
>
>
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