[hfsig] HF performance under 1000 miles?

Fri Oct 14 08:36:21 EDT 2016

Good Morning,

       Throwing an edge case out there... If the grid squares are repeated
within groups around the globe, what if I'm between these groups? Say there
is a cluster that covers the continental US and another that covers the
Atlantic ocean. If I transmit from Bermuda and my signal is received by two
stations, one in the center of each group, the station in Ohio, for
example, will locate me in Bermuda, but another might think I'm on the
Canary Islands.  I'm curious how this overlap will be handled.

Thank you and best wishes,
Mike Coles
WB2B

--
Mike

On Tue, Oct 11, 2016 at 4:06 PM, Mitch Winkle <mitchwinkle at gmail.com> wrote:

> 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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