APRS questions - Page 1
Forum section: electronics / rf-microwave

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 06, 2017, 05:05:52 am
content: Been reading up a bit on APRS, it sounds really interesting. I don't have a ham license, so I know I can't transmit or even submit data as an igate, but I'd like to setup a local receiver station that has a local map. Something that runs on Linux and has a web based map. Is there such software?Also, since the frequencies are different based on continent, how does it work for stuff like weather balloons? Do they need to switch frequencies based on their location?I know there is the odd balloon that gets sent up and it would be pretty cool if I could pick them up. Do I need to listen on all APRS frequencies or just the one for North America where I am?I may actually look into getting my license at some point too so I can play with this stuff further, but just want to play around with receiving for now.

author: AG6QR
author_rank: Frequent Contributor
timestamp: January 06, 2017, 05:56:29 am
content: Not sure about software for Linux, but for Android, there is APRSDroid. It may be configured in many ways, but one way to make a recieve-only station is to configure it to use AFSK, and connect a reciever's audio output to the Android's audio input.But I'd recommend getting licenced so that you can transmit, for many reasons besides APRS. If you know basic electronics, you've got the hardest part of the license covered. There are some rules to learn, but they're not hard.

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 06, 2017, 06:25:09 am
content: Yeah I actually did a mock exam on the Industry Canada site for fun, actually got 50%, which is not bad considering I don't really know much about it, or even electronics. My goal is to learn more though, so I might get my license as the process will help me learn more about electronics too. Actually I might start a separate thread for that... as I do want to pickup some books or some other resource so I can study properly. ( I want to actually understand, not just memorize the questions)

author: Lord of nothing
author_rank: Super Contributor
timestamp: January 06, 2017, 02:38:13 pm
content: HiNormally in the most Country its not illegal or a gray scale receiving Amateur Radio data w/o a Licence.But there is nothing special with with APRS.QuoteDepend on the country. Here the use old and outdated and some wrong therms for thinks who could be named right.At the other Hand you have might hight cost for the License. Here we have to pay a hight fee for the Call sign.

author: LaserSteve
author_rank: Super Contributor
timestamp: January 06, 2017, 02:51:46 pm
content: He's in Canada. No rules ban him from monitoring any ham radio signal as long as it never leaves the wet space between his ears....Steve

author: JimRemington
author_rank: Regular Contributor
timestamp: January 20, 2017, 07:45:04 pm
content: QuoteYou don't have to be able to "pick them up".Any balloons transmitting near a suitable receiving station will have the data posted onhttp://aprs.fiBut, check out the APRS micromodem (TX/RX software and hardware interface for Arduino) athttp://unsigned.io/microaprs-jun-18th-2014/All you need in addition is a suitable receiver.

author: dr.diesel
author_rank: Super Contributor
timestamp: January 20, 2017, 07:50:56 pm
content: xastir is native on Linux.http://xastir.org/index.php/Main_Page

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 21, 2017, 07:21:26 am
content: Quote from: JimRemington on January 20, 2017, 07:45:04 pmMaybe I was not clear, I'm inquiring about actually picking up the signal. If I got my license I would create an actual feeder site for that website. That website relies on feeder stations that pickup the actual signal. What shows up on that site is what was picked up by stations.Xastir looks interesting will check that out.

author: TheDane
author_rank: Regular Contributor
timestamp: January 21, 2017, 12:47:43 pm
content: I have received and decoded APRS traffic using a cheap SDR dongle and Qtmm (windows, if linux isn't your thing).SDR# has/had some AFSK decode plug-ins I think, but I can't tell which versions work as it is some time ago I played around with it.http://www.rtl-sdr.com/monitoring-aprs-rtl-sdr/https://sourceforge.net/projects/qtmm/https://s55ma.radioamater.si/2015/08/14/decoding-aprs-packets-with-sdr-dongle/You need to listen to the frequency the traffic is on, here in Europe it's usually 144.800, but nobody really enforces it, and since it's AX.25 data, packet freq's can be used without problems.Good luck!If you can find an old TNC-2C, it can listen 24/7 - and you can serial-into-it, and do a lastheard - and it should list the stations received. It uses a small amount of power, compared to a PC.It can also be upgraded to an APRS digipeater with specialized APRS functions:http://www.ir3ip.net/iw3fqg/uidigi-e.htmif 1200 baud 'multiplexed packet data speeds' are too slow for you.https://en.wikipedia.org/wiki/Terminal_node_controller

author: ido1990
author_rank: Newbie
timestamp: January 21, 2017, 07:10:11 pm
content: APRS is really cool.I used it to send messages to a friend over RF and to the ISS.If you need a software for linux check out Dire Wolf:https://github.com/wb2osz/direwolf

author: Lord of nothing
author_rank: Super Contributor
timestamp: January 21, 2017, 07:12:17 pm
content: DMR is better.

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 22, 2017, 03:00:50 am
content: Cool I'll check that stuff out. Still need to read up further on the exact hardware I need. Been wanting to mess with SDR too, so I might actually get into that first, since I imagine I can use SDR for this too. Probably will use a raspberry PI as the server. If I go the sound card route I'll probably just get a cheap hand held radio that I tune to right frequency then hook it up. I'd eventually run coax to an external antenna.I do need to look into getting my license as well, so I can transmit as well. Probably setup a stationary weather station or something.As for baloons, how does that work for frequencies, if someone puts an APRS transmitter on a balloon do they transmit at their local frequency or do they need to have it switch frequencies when it crosses a certain boundary? As not every continent uses the same frequency. Ex: if someone from Australia sends a balloon and it crosses my area will I pick it up if I'm listening on the North American frequency, or do I need to listen to all of them to pickup international stuff?

author: ido1990
author_rank: Newbie
timestamp: January 22, 2017, 07:18:36 am
content: For APRS you can use cheap RTL-SDR and decoding software, I use SoundModem by UZ7HO (for Windows, replacing AGW packet engine) with APRSIS32 it's working great.You can choose if you want to pass the packets to the APRS online network (and you have an iGate) or not.I'm not sure about APRS balloons because we had only 2 over our country that used the same frequency and lost their gas before the wind could take them to another continent.AFAIK, people now fill party balloon half with hydrogen and use a WSPR transmitter, in this case the transmitter changes the frequency according to the location.http://wsprnet.org/drupal/node/6252