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APRS: SSIDs, Paths, and Beacons – Ham Radio Q&A


tell your packets where to go we’re
going to do that with APRS path settings so please keep watching for
more hi I’m Michael KB9VBR, your
host for ham-radio Q&A I’m on a mission to inspire and educate the amateur radio
community so if this is your first time watching please consider hitting that
subscribe button While APRS the Automated Packet
Reporting System is a tactical communications tool intended to share
real time information and short messages I say it’s a tactical communication
system because really its purpose is for local communications for tracking
resources such as vehicles and sending telemetry information from maybe weather
balloons or weather stations and also sharing objects local objects like
repeaters or other informations on a map although there’s an opportunity for
distance communication with APRS DX work is really not the intended purpose of
the automated packet reporting system so in this video we’re going to talk about
three important concepts in APRS first your call sign and SSIDs next APRS path
protocols and finally your APRS beacon rate this is if you’re new to APRS and
you’re just picked up this video first you may want to check out my
introduction to APRS video there’s a link in the video description below and
that’ll kind of give you an overview of the automated packet reporting system
otherwise if you’re interested in moving on to some of the more technical
features of APRS we’re going to take a look at first your callsign and what
an SSID is. Of course you’re going to need to use your call sign with your
APRS activities but if you’re running multiple devices say a home station on
mobile trackers or a handheld if any number of those devices are running at
the same time you’re gonna run into potential conflicts within the APRS
network so to the rescue our SSIDs or secondary station identification what
the SSID is is it’s a numbered suffix that you put attached to your callsign
to help differentiate between the different types of APRS assets you’ve
got running on the network so to break things down on the SSID is gopher
zero to 15 a first one SSID of dashes zero or actually no SSID at all would be
just your plane callsign and that’s what we typically use for a home station an
SSID of zero is going to be your home station next up are your SSID of one
two three and four these are reserved for digipeaters. if
you’re using one of the smartphone apps you might want to use an SSID of dash
five. SSID – seven is reserved for hand held radios – nine is reserved for
mobiles, say if you’ve got one of the Kenwood mobile radios or one of the Yaesu
mobile radios. 14 is for truckers that may be using APRS on their over the
road travels and 15 is reserved for any other station or any other activity so
that’s sort of a catch-all any other any other thing so if you wanted to add
another digit Peter or maybe a second weather station or another I gate or
something like that you could use the dash 15 for any of these numbers any of
these stations now the thing with SS IDs is there are no hard and fast rules
these are only guidelines and we use them to really give the the user the
viewer of the map sort of quick and easy identification of what kind of station
and what kind of you know abilities that the station has so you can you know look
at a map and you can see a dash seven hope that must be a handheld radio or a
dash nine he’s a mobile really so what things boil down to it’s like I said
these are guidelines so if you need additional SSIDs if you’re putting a
whole bunch of digit Peters on the air and I know a guy that’s done it you can
use those numbers for all of those Digitas so the path is our route or
Direction distance an APRS packet takes within the network before it expires. Iin my introduction APRS I talked a little bit about how APRS is not a
long-distance communication method so you don’t want your packets to light up
every man and digipeater within a 500-mile radius
you really want to try to keep them relatively confined to a local area
where an igate will pick them up and then allow people to interact with you
via the internet APRS data stream so in talking about paths we use a definition
called the wide n – n designator where n is the number of hops that we want the
packet to travel a path of wide one – one will go one hop and wide two – two
will go two hops and in in in the n – n definition the first n is the total
number of hops we’re defining and then the second end or number is sort of like
a counter that the digipeater will count down or decrement as it passes
through the system so when a digit Peter receives a APRs packet it’s going to
look at the wide – – – and then it’s going to take that second – and it’s
going to change it to a one through the the callsign substitution process and
then send it along its merry way a second digipeater will receive that
packet it’s going to see the wide 2-1 it’s gonna change that one to a zero
it’s going to send it along its way and then when a third digipeater hears that
packet it says wide 2-0 it knows not to send the packet out and the packets
going to expire on its own limiting it’s over the air travel. remember when we send out an APRs packet it’s going to go out in all directions
so on its first hop it might hit one or two wide digipeater then on a second
hop it could hit four or more digits and by the time it gets to its third hop you
could be lighting up eight to sixteen digipeater within the network so we
really want to be cognizant of that and and you pick a path that’s going to sort
of control our packets try to keep them within about about a hundred twenty mile
radius and in today’s dnase you really don’t need to go further than that
so when we set up our APRs path we want to decide how far our station our
packets are going to go for a home station we may only want to go out two
or three hops we really don’t need to go more than three hops so in our path
designator we all may only use a watt a generic path of wide 2-2 if we want to
further limit things a little bit more we may use a named station like in my
area I’ve got a digipeater I’ll use W9SM-1 and then a comma and then a
wide 2 – 2 to go out an extra two hops that’ll be three hops total if I only
wanted my home station and go out two hops I’ll use a W9SM-1 – one to hit the
wide digi and then a wide two – one so it goes up one hop after that so for
mobile stations the we’re going to want to use a path of say wide one – one and
then a comma and then a wide two – two that will get us out three hops the wide
one – one as the first hop in our in our digi path we’ll try to activate either a
low level and or a wide active digi once it does that then it’s got two hops with
the wide – – – to further propagate through the system ensuring us a better
chance of hitting an eye gate with trackers and mobile stations you know we
want at least two or three but no more than three hops to get the signal out
because depending on its location and where it’s going it may not be within
easy reach of in I gate so three hops is perfectly acceptable for our mobile
stations so to summarize home stations should
either use a specific digi callsign and then wide 2 – 2 or 2 – 1 and then mobile stations should use the total generic
path of wide 1 – 1 wide 2 – 2 giving us either two or three hops
anything more is overkill within the APRS system since APRS is an automatic
protocol you’re going to need to set a beacon rate or how often your station
transfer it’s for a given period of time mobile
or tracker stations are gonna want to beacon more often than a home or fixed
or stationary stations and now the reason is is that a track or a mobile
stations location is going to change more often so you’re going to want more
frequent updates of their current location there’s a general expectation
that you should be able to turn on the APRs map and get a general overview of
all of the stations within the local network within about 10 minutes so with
that being said a lot of people recommend a beacon rate of 10 minutes or
faster you know I think that for home stations and stationary objects a beacon
rate of 10 minutes is plenty fast and may recommend 20 or 30 minute beacon
rates depending on the on the type of object I think it’s it’s you you know
within a 60 minute time period your station should be Canali snobol stations
are trackers on the other hand are going to want to have a much faster beacon
rate so if you’re moving at highway speeds of beaconing once every minute is
not out of the question if for slower moving stations say when I’m on my
bicycle I’m going to set the beacon rate of about once every 2 minutes
that’s plenty plenty fine for the speed I’m going also want to conserve my
battery life a little bit too with the handheld radio pedestrians probably
beacon once every five minutes considering how fast they are moving of
course this is a generalized rule and you might want to make exceptions to
that at any time for instance we’ve put trackers on vehicles for parade and
we’ve had them beacon at every 30 seconds even though they were quite
slow-moving I wanted to be able to see a very precise location of where they were
on the route so that high beacon rate was perfectly acceptable for this short
term duration trackers like the tiny track the open track and
and the newer Kenwood radios have a feature in them called smart beaconing
and they will dynamically adjust their beacon rate depending on how fast you’re
moving and also if there’s direction changes in your in your location so at
highway speeds they may beacon more quickly they may beacon if you turn a
corner and also they will slow their beaconing down if you stop in our idled
or got the vehicle turned off for a longer period of time this is a really
nice feature of the tracker devices so if you’re in if you’re using them in
moving vehicles consider activating the smart beaconing feature but if you’re
using the these type of trackers and say like a bicycle or a pedestrian you might
be wiser to turn the smart beaconing off and then have a manually set of beacon
rate because they tend not work too well when you’re slower than say five or ten
miles per hour and you might be in an area that may be tough to get out of
mate it may be it’s it’s difficult terrain or there’s something that’s you
know blocking you know where the digipeater just can’t reach you. Second
digipeating is kind of like a battle of the bands
so the loudest signal is always going to win and be digipeated by the wide area
digipeaters. So low-power stations and moving stations have a more
difficult time getting into the to the wide digi. Low-level Digis help fill
in those areas and give those on low powered stations kind of a boost to get
them reliably and more consistently into the network. What I’ve done is when
I’m used my portable sometimes is to use what I call my beacon box so the beacon
box is just a two meter mobile radio I’ve got it cooked up to an egm battery
and then I’ve got an older T and C in there
I’ve programmed that’ll listen for just my callsign
and then did you repeat that packet on so it’s only digipeating my packets on
into the into the APRS Network and if I found this really useful one winner when
I was out volunteering for a cross-country ski race the terrain
wasn’t the best and I just had my little handheld radio but with the beacon box
in my car and an antenna on the roof of the car I was able to consistently get
into the APRs Network even though I was in kind of a not so not so good location
and that’s the really nice thing about APRS. It’s a disconnected system so you can add any number of resources or other
temporary items in order to boost the the network for a specific purpose or
short-term need do you have questions or comments what’s your experience with
APRs please leave them in the comments below i do comb through the comments and
answer them and also your comment may end up in the in a future video on APRs
for more articles and information be sure to check out my blog at wwe.com and
also if you enjoyed this video please give me that big thumbs up I really
appreciate that I check out some of the other videos
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produced and with that hi I’m Michael KB9VBR thanks for watching
have a great day and 73

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