[aprssig] APRS on HF
julian.g4ilo at gmail.com
Sun Feb 20 08:54:27 EST 2011
A 300-baud capable TNC (or the AGW Packet Engine and a sound card
interface) and APRS client software such as APRSIS32.
G4ILO's Shack: www.g4ilo.com
On 20 February 2011 12:51, Ramakrishnan K.A. <vu2kuc2 at gmail.com> wrote:
> To get start of APRS on HF what are basic requirements can anyone guide me
> other than HF equipment and antina.
> On 2/20/11, Stephen H. Smith <wa8lmf2 at aol.com> wrote:
>> On 2/20/2011 12:50 AM, Julian, G4ILO wrote:
>>> Having run a 30m IGate (G4ILO-1) for several months now I have often
>>> been the station that gates European HF mobiles to APRS-IS. I
>>> understand that in areas where there is little VHF coverage (which
>>> includes much of the UK) a mobile has a better chance of being gated
>>> if they use HF, even though they will be gated by someone 1,000 miles
>>> away. So is that the only real purpose of APRS on HF, to gate HF
>>> mobiles? And if so, why do HF IGates need to transmit?
>>> Julian, G4ILO
>>> G4ILO's Shack: www.g4ilo.com
>> Support of mobiles in remote locations has been the main use of HF APRS in
>> North America.
>> In the American west (and all of Canada more than 100 miles/160KM north of
>> US border), the population density is EXTREMELY LOW and VHF infrastructure
>> sparse. In the US alone, this is an area approximately ONE THOUSAND MILES
>> SQUARE (1600 KM square) in the western one-third of the country. (Once
>> go more than about 100 miles east in from the Pacific coast, coverage
>> to almost nothing, except along the major Interstate highways and islands of
>> coverage in cities that are hundreds of miles apart.)
>> Turn off the Interstates onto the secondary roads and scenic byways in the
>> west, especially in mountainous terrain, and you drive off the edge of the
>> world APRS-wise on VHF. HF coverage covers this mountainous Great Basin
>> area (the interior west between the Sierra Nevadas in California and the
>> Mountains of Colorado) very well. Depending on the time of day, you are
>> either propagating eastward to igates in the MidWest and/or the East Coast,
>> westwards to igates on the populous Pacific Coast, or both.
>> HF APRS is also widely used by pleasure boats in the Caribbean, and off the
>> west coast of the US and Mexico, once you get more than about 30 miles from
>> shore. Given the very limited capacity of a 300 baud (or slower) channel,
>> the fact that every transmission occupies the channel for a radius of
>> miles, depending on propagation, absolutely the last thing thing you want
>> do is gate VHF traffic onto HF.
>> About twice a year I drive from Los Angeles, CA to East Lansing, MIchigan
>> home town where my sister and mother still live) --- a trip of about 2200
>> miles/3500 KM each way. For about 600 miles of this trip there is just NO
>> coverage at all.
>> One-way igates break a major feature of APRS operation: two-way messaging.
>> I have carried on extensive two-way messaging from my mobile with the HF
>> Messenger application on the last three or four cross-country trips. Most
>> contacts have been RF<-->RF, but I have had exchanges with a station in Los
>> Angeles coming out of an igate on the East Coast while I was mobile in the
>> southern Utah desert -- an RF haul of over 2000 miles. The
>> of PSK63 over weak signal paths is dramatic when working from a mobile in
>> boondocks of the Great Basin.
>> Stephen H. Smith wa8lmf (at) aol.com
>> EchoLink Node: WA8LMF or 14400 [Think bottom of the 2M band]
>> Skype: WA8LMF
>> Home Page: http://wa8lmf.net
>> ===== Vista & Win7 Install Issues for UI-View and Precision Mapping =====
>> *** HF APRS over PSK63 ***
>> "APRS 101" Explanation of APRS Path Selection & Digipeating
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