today we're talking about APRS or the automated packet reporting system so
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hi I'm Michael KB9VBR your host for ham-radio Q&A I'm on an mission to
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Well today I'm going to talk about APRS or the automated packet reporting system
in fact I'm going to do a few different videos on APRS, we're gonna go into some
of the more technical details in one of the later ones but on the first one I
just really want to give you sort of that overhead view of what the automated
packet reporting system is, give you a brief history, and also some of the ways
in which you can get started in APRS. so this video is really not going to be
overly technical we're going to save that for a future video. but the
automated packet reporting system is a digital real-time communication system
to share tactical information and messages the most common activity for
APRS is going to be to plot local locations of moving objects on a map
using GPS technology so but APRS can also be used for short messaging weather
telemetry the power of APRS is its ability to geocode moving or stationary
objects and display them in real time on a map so excellent uses for APRS would
include say like tracking static locations or moving objects on a
marathon or other type of large distributed event or maybe tracking
Skywarn spotters during a severe weather storm net. A little bit about the history
of APRS, you know the end of the originators and the innovators of the
mode are still around but its history tends to be a little bit on the fuzzy
side so I've been involved with APRS since about 2000 so 17 18 years ago,
and so what I'm gonna say he might be colored a little bit by my own personal
experience but basically APRS are the automatic packet reporting system or
automated position reporting system as it was first called way back in the
early 80s was developed by Bob Bruninga WB4APR and he's generally considered
the father of APRS. Back in the early 80s he was working on
object positioning systems to track items during a marathon or a very long
distance race. He used it in some boating events at
the time. And that early work developed in the early 1990s into a more early form
of a geo coded mapping system and then with the introduction of consumer grade
GPS tracking systems global positioning satellite tracking systems that
technology was married to what he was working with and by the mid 90s we had a
more robust APRs framework but a few things really needed to happen for APRs
to make it in ready for the primetime you know number one by the early 2000s a
formalized single VHF frequency was introduced for APRs Internet gateway was
created so that a period so that the tracking information could be shared
with disconnected stations and the big thing is is that a formal diging
protocol was established in order to prevent some of a lot of the collisions
and network congestion that was happening with with the protocol but the
APRS system really hit its stride, you know, was ready for primetime when the
major amateur radio manufacturers started to pick it up
Kenwood developed a couple models of handheld and a mobile radio with
integrated APRs and Yaesu soon followed with an integrated handheld and also a
mobile radio. So those Wild West days of APRS may be long gone but you know it's
still a APRS is a viable mode and it's an excellent tool for emergency
communications use so APRS works by transmitting unconnected packets
containing a callsign path information location and other information APRS is
built on the packet radio technology so it uses the ax dot twenty five format
and it's transmitted at 1200 baud you're going to need a device called a TNC or a
terminal node controller in order to take the digital
data from the computer and encode it into audio tones to be transmitted over
a standard 2 meter FM radio in today's world you know this sounds kind of
outdated or antiquated but really the genius of the system is its is its
robust nature so when I say unconnected, I mean APRSpackets are transmitted with
the expectation that they're not going to be received by another station back
in the olden days when you were a using packet radio you would actually
physically connect to over the airwaves to another another station or computer
via your TNCs much like with computers and modems
connecting to each other via the telephone lines so with the unconnected
nature of APRs any other station or digit potentially pick up the packet and
retransmit it and this had the potential for collisions and conflicts within the
network so a method of filtering and packet the deprecation was built into
the digital air in order to reduce or eliminate this this problem of duplicate
packets the way APRS packets distance is controlled by their path information so
if you ever looked at an APRS packet you probably saw things like wide or wide
1-1 or etc. these are your path protocol. the purpose of a digit peter is to
listen to four packets and to retransmit them since the digipeaters cover a wide
area they were automatically retransmit up acket that has that wide designator
so when a digi receives a packet labeled wide it's gonna it's going to
take that packet it's going to substitute its own callsign for the wide
designator and then it's going to retransmit it that callsign substitution
is the digipeaters way in which preventing the packet of being
retransmitted by itself or another digipeater thereby reducing the chance for
collisions of course multiple digits can receive this packet
and they can also digipeat it in due course but with that
callsign substitution it will all it'll it'll reduce that that potential
conflict or ping-pongs between two or more digipeaters so passed like wide
one - one and two - to work in the same way except those are like counters
that'll help extend the packet for multiple hops on multiple digis so a
wide one - one designator will let the packet go out one hop a wide2-2
designator will let the packet go out two hops when the digipeater hears the
2-2 packet it's going to change the packet so that wide 2-2 becomes a 2-1
and retransmit it and then the next digit Peter will hear that wide 2-1 and
it's gonna take it's going to take that 2-1 and since that's the last hop it's
going to substitute its callsign and retransmit it thereby eliminating
collisions and keeping your packet range manageable so really the key purpose of
APRS isn't to light up as many maps and Digis as you can along the entire
network but it's to give your packet enough hops so that they can find an
igate and get injected into the APRS internet data stream so an igate
listens to data over the air and takes those packets and injects them into the
internet stream and igate also can take information from the internet stream and
if it's heard a station locally it will retransmit the packet intended for that
station over-the-air one of the nice things about a gates is they let you
send and receive messages over-the-air picked up to the internet stream and
then retransmitted over-the-air to another unconnected station literally
anywhere over the world so you can use APRs as a short messaging system
one of the other nice advantages of AI gates is they also let you view the
local APRS traffic anywhere anywhere in the world so how do we view the APRS
information well the easiest way is to get online and use the website APRS.fi
APRS.FI transposes APRS packets from the
internet stream and geocodes them onto a into a google map so the user interface
is very familiar and easy to use some of the features like messaging aren't
available on APRS.fi but there's a lot of stuff you can do with this site into
an monitor or viewing the APRs data for any any local area so the easiest way to
really get started with APRS is with a handheld radio the BTech APRS cable and
your smartphone the BTech cable you will attach to the two pin connector on just
about any baofeng type handheld radio and then it's got an audio plug that'll
go into your iPhone or Android type device there's software that's available
apps that are available to view the APRS data APRS droid for Android devices
and APRS pro deluxe if you've got an iPhone the GPS in your phone will
provide the positioning data that you need and and then the smart phone will
emulate a terminal node controller to transcode that data into audio tones
necessary for the radio this setup lets you view and transmit APRS location
data on the channel that lets you send and receive messages and also you can
connect to the APRS data stream and view location information anywhere in
the world so when I first got started with APRS I built trackers using mobile
radios and GPS bricks and TV TNCs that I picked up at ham fest you know the
downfall I found with APRS is it's got a lot of cables and connections between
all of these devices and sometimes something always tends to go wrong or
get disconnected so when I really started to get into
bicycling I wanted to take APRS with me and that's when I invested in an
all-in-one APRS radio such as the a Yaesu VX-8R
the this rear little radios got the built-in GPS TNC and of course the
transceiver so it's it's integrated all-in-one APRS
tracker box that's very rugged and reliable downside is you know because
it's a handheld it's only five watts but other radios like the Kenwood D 710
offers the same functionality you know you know mobile radio uses got similar
models and so you can have an integrated all-in-one tracker system if you don't
want to go with another route such as a tiny track APRs tracker module or the
argent data systems tracker but the common thread here in in APRS is that
you're going to need a TNC or a terminal node controller smartphone apps like
APRs droid they emulate the TNC tracker boxes like the tiny track or the argent
data systems have the TNC built into them a radios like the Kenwood d710 or
the Yaesu VX-8R are have TNCs integrated into them also or you can buy a
standalone TNC like the Kantronics KPC3 plus. the KPC3 plus it's been around
for a long time and it's it's become a little bit esoteric because packet radio
isn't what it used to be and it tends to be quite an expensive investment frankly
even on the used market KPC3 pluses are garnering prices of what they
were used maybe five or ten years ago so searching for a used deal in us in us
you know at a ham fest or swap fests might be a viable option and maybe you
know if you're looking for a simple TNC there's models that are available that
will fit your needs well maybe like the AEA pk-12 or MFJ made their twelve
seventy series of TNCs that'll all work quite well with APRS as a simple
tracker or as a home station with a keen eye you
should be able to scour the ham fests and you might be able to pick one up for
under $50. they've definitely have increased in price a little bit what
that what they once were but keep it up for them and if you see a TNC feel free
you know think about grabbing it for APRs use but once you have your TNC
you're ready to get rolling with an APRs home station and we're going to talk
about how to set up your own APRs home station in a future video
so did I pick your interest do you have questions or comments about APRs or the
automated packet reporting system I'd love to hear them so please leave a
comment down below I'll answer your questions and we'll follow them up in a
future video for more articles and information please check out my blog at
www.jpole-antenna.com give me a big thumbs up if you enjoyed this video I really
appreciate that check out some of these other videos that are suggested right
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released well that's it for this episode i'm
michael KB9VBR have a great day in 73