11 votes
Accepted

How to do APRS in real wilderness?

So you want to broadcast your location using backpack-portable equipment from deep in a narrow valley hundreds of miles from civilization. I'll assume that you would also like the ability to get a ...
rclocher3's user avatar
  • 9,212
9 votes
Accepted

Use amateur radio frequencies for commercial purpose

This is answered somewhat in this question already, and the answer is no. And I will add some passages about the broadcasting part. To quote the relevant rule §97.113: §97.113 Prohibited ...
PhilippNagel's user avatar
9 votes
Accepted

What's the difference between an APRS "item" and an APRS "object"?

Per the spec, which unsurprisingly is found at aprs.org, objects are intended for moving or animate objects of the same nature as a station beacon (people, vehicles, storms, etc.) while items are ...
hobbs - KC2G's user avatar
  • 12.4k
7 votes
Accepted

Help understanding path taken by APRS packet

According to the way things work for simple AX.25 packets, the part after ">" is the destination address. However, the APRS specification commonly repurposes fields, with the goal being to keep the ...
rclocher3's user avatar
  • 9,212
7 votes
Accepted

Can I use APRS over TCPIP without ham license?

I don't know Europe's regulations, but in the US under the FCC's jurisdiction, the onus is on the station operator to prevent unauthorized transmissions. An unlicensed individual using APRS on the ...
Phil Frost - W8II's user avatar
6 votes
Accepted

Is there a difference between AFSK and FSK for AX.25/APRS USE?

My reading suggests that the advantage of AFSK is that the audio signal can be fed to any radio mike input. But if we ignore that, and assume a transmitter where the frequency can be controlled ...
Kevin Reid AG6YO's user avatar
  • 24.5k
6 votes

RTL-SDR dongle - what antenna should I use for APRS receive only?

Here are the fundamentals of improving VHF antennas from what you've got: "Rubber ducky" (loading coil shortened) antennas are less efficient and more frequency-selective than un-shortened antennas. ...
Kevin Reid AG6YO's user avatar
  • 24.5k
5 votes

AX.25 on macOS (aside from APRS)

Xastir isn't bad at all but I recently encountered something called YAAC (Yet Another APRS Client). On it's site it states the following: YAAC can be used as a stand-alone APRS client, an APRS RF-...
Tmanok's user avatar
  • 161
5 votes

APRS: what is with stations clustered in the middle of a lake?

Two relevant facts about APRS: APRS stations are not obligated to get their location from GPS. And in practice, many fixed stations have manually entered locations. It is possible to transmit an ...
Kevin Reid AG6YO's user avatar
  • 24.5k
5 votes

Is there a difference between AFSK and FSK for AX.25/APRS USE?

AFSK sent over a FM radio is very different to FSK, as explained in my blog post FM over FSK: FSK over FM is not FSK when you look at the over the air waveform. The spectrum is no longer two tones ...
David Rowe's user avatar
5 votes
Accepted

Should I have a license for APRS on my company car fleet

If the devices are fixed to transmit on amateur APRS frequencies, then you most likely cannot legally use them for business purposes, because that type of use is not allowed on the amateur bands — ...
Kevin Reid AG6YO's user avatar
  • 24.5k
5 votes
Accepted

Can APRS and other AX.25 packet-based systems (ie. a BBS) use the same frequency?

APRS typically uses a fixed frequency (e.g. 144.39MHz in the US), and shared by all APRS users. So yes, it would be frowned upon to also run a BBS on that frequency as it would interfere with everyone ...
User5754448's user avatar
4 votes

Can I use APRS over TCPIP without ham license?

Contrary to other answers, there are ARPS networks out there that can be used without a Ham license. The key, as @PhilFrost points out, is that your original packet must not make it out to RF. The ...
penguin359's user avatar
4 votes

Can I use APRS over TCPIP without ham license?

When you send something to APRS, even via Internet, it eventually may end up retransmitted on ham radio frequencies. Thus, you are not allowed to use the system if you do not have valid amateur radio ...
Pedja YT9TP's user avatar
4 votes

How to do APRS in real wilderness?

Apart from matured and highly reliable commercial satellite-based services, WSPR can be another 'DIY/experimental' alternative for broadcasting your location from wilderness. See examples for balloon, ...
EEd's user avatar
  • 562
4 votes

What is the legality of data modes over UHF/VHF in the US?

You may be able to operate the device without consideration of your amateur radio status. CFR 47 Part 15.231 permits the low power use of 433 MHz without a license provided certain transmission ...
Glenn W9IQ's user avatar
  • 18.6k
4 votes

RTL-SDR dongle - what antenna should I use for APRS receive only?

Rubber ducky antennas are not very efficient indeed. Also for best performance they may require a ground plane or radials, which I guess you could omit. Personally I used RTL-SDR Blog Multipurpose ...
Aleksander Alekseev - R2AUK's user avatar
4 votes

Why does the APRS specification suggest to use 7-bit ASCII for user-defined data formats?

So far as I know, nobody here is on the APRS Working Group, so it's difficult to say exactly what their motivations were, but I'll make a few guesses. First, Unicode was still fairly young in 2000, ...
rclocher3's user avatar
  • 9,212
4 votes
Accepted

String in APRS report

You're looking at a Mic-E packet. The Mic-E format uses the TOCALL to encode part of the position data (the entire latitude and two bits of the longitude) and a three-bit "message ID". This ...
hobbs - KC2G's user avatar
  • 12.4k
4 votes

Can you receive GPS coordinates from a Garmin Astro dog collar on a handheld ham radio that has APRS?

I don't know what protocol the Garmin 320 and 430 dog tracking collars use, but it is highly unlikely that they use AX.25 packet as their protocol, because that protocol is old and slow, and therefore ...
rclocher3's user avatar
  • 9,212
4 votes

Can you receive GPS coordinates from a Garmin Astro dog collar on a handheld ham radio that has APRS?

No. These collars do not transmit in the ham bands nor do they use APRS. While many ham receivers can receive outside the ham bands, the protocol used by the Astro is proprietary, best I can tell. So ...
Phil Frost - W8II's user avatar
4 votes
Accepted

Lack of understanding in the APRS specification for LoRa

Why do I have to send these characters at the beginning of the message? It's just an arbitrary header that this group of people used to identify APRS messages, and distinguish them from other packets ...
hobbs - KC2G's user avatar
  • 12.4k
3 votes
Accepted

What is the legality of data modes over UHF/VHF in the US?

Telemetry is explicitly allowed in §97.111. You must use an authorized "digital code", which probably means ASCII. And you must use a publicly documented technique. I don't see any ...
Phil Frost - W8II's user avatar
3 votes
Accepted

Can I use my call sign in APRS tracker abroad?

The actual answer is a bit complicated and depends on a lot of things. In general, the answer is no, with exceptions, but the number of exceptions can be large, due to bilateral or multilateral ...
AndrejaKo's user avatar
  • 2,893
3 votes
Accepted

What does the APRS 'to'/destination address mean?

The Txxxxx labels are the Mic-E encoded Destination field. Let's take the first example, TU3RTW. If we look up the latitude digits from the table, we get 453247. Then there is the other information ...
rclocher3's user avatar
  • 9,212
3 votes

Help understanding the information field in an APRS-IS message

Everything after the : is the payload that the station is sending out. While there are conventions so that the data is meaningful, I don't believe there are any standards. For example, the first ...
Duston's user avatar
  • 939
3 votes
Accepted

Direwolf sends APRS transmission but it isn't being picked up by local digipeaters

Yes, the lack of WIDE1-1 and WIDE2-1 is why no other stations are picking up your beacon. For example a station (mine is n9ds) listens for a packet with "WIDE1-1" in the routing. Since it's still "...
Duston's user avatar
  • 939
3 votes
Accepted

APRS: What's the `n` in WIDEn-N?

Ultimately, it's just a name, but you're right, the convention is 2 is "bigger" than 1. Let me explain. WIDE2 stations tend to cover a wide area and often have Internet connections to send the ...
Duston's user avatar
  • 939
3 votes
Accepted

Resources and guidance regarding APRS

As you already know, amateur radio is an excellent resource for emergency communications, and APRS is a fine tool for it. However, APRS is not the only tool, and I would caution you to not obsess ...
rclocher3's user avatar
  • 9,212
2 votes

How do I connect a GPS receiver to a radio for APRS?

Forget Baofeng. Buy an old Kenwood THD7 for little more. I have one for 18 years and is rock solid still. It has APRS built-in and many other useful things. You can ...
q74's user avatar
  • 59

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