APRS and the UV-5R

by k-twizel

60K6032

Intro: APRS and the UV-5R

So... What is APRS? APRS stands for Automatic Packet Reporting System. Amateur Radio Operators (Hams) use APRS for many different things. In a nutshell, APRS lets you transmit your GPS location out onto the radio net for others to pick up and place you on a map. This is the basic function. Other functions include messaging, relaying, I-Gating, and Weather (I'll touch on these parts later).

What is a UV-5R? It is a great entry-level, hand-held radio. Inexpensive and forgiving for those new to the hobby.

Why am I putting this together? Well, to share the knowledge and put all the research I found into one spot.

I'd like to call out to KF7BBI (Dave) and KG7IOE (Terrance) for helping me troubleshoot the issues I was having. And KC2UHB (Diana) just because.

How do I use APRS? I like to snowshoe in the winter and it is one way I can let others know where I am in case of emergency.

STEP 1: Things You Need for APRS

Three basic needs (plus one requirement)

1) A radio

2) A cable

3) An APRS solution. Mine is a smartphone with APRSDroid - https://aprsdroid.org/

(The requirement is having an Amateur Radio License)

Description:

My trusty UV-5R with extended life battery and upgraded antenna (check the Amazons or eBayz for the cool dealz)

This cable was a great find by Dave. It provides ground isolation so the that the PTT is activated on transmit. If you don't have this (or a TNC) the radio will key open and disturb others (see Ham Etiquette). The cable was put together here: https://github.com/johnboiles/BaofengUV5R-TRRS (another call out to John Boiles for this awesome project).

My phone is a previously used Samsung Android-based smartphone. The key to this is to factory reset the phone and not log it back in to Google... more on that later.

To operate (that means transmit) on Amateur Radio frequencies, one must get a license. The best way is to search around your community for a local club that can guide you the study material for the test. 'Technician' is the first level of license and is all you need to Transmit. If you want to monitor or listen, no license is needed... but what fun would that be. I've had mine for 3 years now... KG7IOA.

STEP 2: Configuration

It all comes down to the details!!! This is were Terrance really helped out.

This configuration is how I was able to put all the parts together and make it work. I did struggle as my transmissions were not hitting the relay or being rebroadcast to the I-Gate. Terrance had a known-good working setup on his phone that I was able to test with and compare configurations to my phone to get it too work.

What was happening ... well when APRSDroid would transmit, I would see the transmission from my radio but I wouldn't see it come back from the Relay or hit the I-Gate. Turns out that the default setting in APRSDroid is to send the signal out on the 'phone/voice' of the phone. This signal was so incredibly weak that I couldn't get the relay to pick it when I drove past it.

I switched to the 'Ringtone' setting in APRSDroid. This kept sufficient signal power for the transmission to be picked up by the Relay which passed it onto the I-Gate.

The Vox on my radio was an enigma wrapped in a mystery as well... the radio documentation (and much of the Interwebz) couldn't really tell me that Vox setting 1 was open-all-the-way sensitivity and 10 was just-slightly-open sensitivity. I only found this by trial and error on my own while watching my signal being push out from my radio. The radio has an LED that illuminates, to the color of your choice, on Tx and Rx (transmit and receive).

*** Update!! v2 ***

Phone volume must be 3/4 of the bar. You will hear the 'squawk' of the transmission but if the volume is too low, even with Vox at 1, nothing will transmit. I put a sound muffler on my phone speaker so it doesn't spook me while driving.

These are the settings that worked best for me to get this whole thing working properly... your mileage may vary.

*** Update v3 ***

See the updated photo of the volume settings... This will be completely silent, sending all AFSK out the headphone jack to the radio.

STEP 3: Conclusions...

Filling in the gaps...

Why did I not log my phone into the Googlez? Once you do, all the notifications from Insta-Face, Snap-Books, and the like will come through the phone when one of your compadres posts a new cat video or a new noodle truck. And if you are APRSing, those notifications will then be transmitted over the air. "Das ist verboten" per the us FCC rules for spurious transmissions. Also, I don't have a SIM card in the phone.. who wants to get a phone call out in the mountains. That's the whole reason for getting out and about.

What is a Relay and what is an I-Gate? A Relay is just that... it takes your transmission, usually of lower power, and rebroadcasts at a higher power so that it covers a larger area... Search and Rescue can't get to you if your coordinates aren't pushed out.

APRSDroid takes advantage of the GPS of the smartphone for coordinates. That is what get transmitted along with your callsign and and optional short message.

APRSDroid also allows for direct messaging to individuals... just slide over to the "Messaging" tab to send a note to another Ham using their callsign. They can then ack from their APRSDroid.

I didn't forget... an I-Gate is a relay that is connected to the Interwebz. Why? A very cool Fin put aprs.fi together to take APRS transmissions and post them onto a modified Google Maps (uses the Maps API). That way you can see the Hams in your area or those traveling through or if you want to send a message to a fellow Ham in Australia or Scotland, you can see if they are out and about with APRS capability.

(Pro Tip: If you are geographically separated from one of your compadres [not in LOS between the radios], a message can be sent through an I-Gate similar to IRLP. This is untested by me, though).

Oh and Weather!!! One of my other hobbies... APRS can be used to transmit weather data from compatible weather stations... why? For the fun of it!!! The APRS Wx packets are simple enough to program into your 'duino/bone and send over the link. I have an additional project that I am ruminating on to inject Wx data into my APRS tracking while out snowshoeing.

Finally, if you are into hard-core 'tactical reclamation operations' (e.g. hacker, et al.) this chap (http://unsigned.io/projects/microaprs/) has a home-brew version that could easily accommodate a GPS shield to his 'duino project.

Thanks for following along and sharing my excitement. 73 - KG7IOA clear

22 Comments

ve7tgt 1 year ago

I played a lot with this setup - its easy to transmit your location with message.
My issue is I am a outdoor freak - how can I beam my location without internet?
How can it be possible to collect location from phone and TX it with Baofang 144.3900

yigitsahin2005 3 years ago

Can i just use a regular aux cable directly between my phone and my radio? And thanks.

k-twizel 3 years ago

I'd say yes but you would only be able to receive transmissions. The dual cables (or TRRG) allows for PTT activation to transmit.

That said, if you don't have a license, then you are legally only allowed to rx.

f8bmb41 3 years ago

Hello, I made several interfaces and the last one with Jhon Boyle's interface, but I send the frames that I receive correctly on the fixed station, however no reception, the microphone is not connected to the Smartphone as such, the microphone of the smartphone remains the external one, so no frame is received, because it does not fit in Aprsdroid, do you have a lead?
thank you in advance
HUAWEI P9 LITE, AprsDroid.

Jean-Paul F8BMB

k-twizel 3 years ago

I would look at the phone configuration. At the beginning of this project, I had difficulty tx out because I didn't have my phone configured correctly. My output from the phone was coming out the speaker rather than the headphone. I then had to ensure the output levels were good to trigger the PTT on the phone as well.

That's where I would start.

StickyC 4 years ago

Regarding the not signing into Google bit to not end up rebroadcasting notifications - If you don't have a SIM card (and don't connect via WiFi anywhere), wouldn't that solve the problem? Otherwise, do you need to do some 'hacky' steps to get the APRSDroid app installed?
(Thanks for the awesome writeup, BTW! Plan to try it with one of my obsolete Android phones)

k-twizel 4 years ago

There's two parts to you question, it looks like. APRSDroid can be installed from Google Play but it can also be downloaded from the APRSDroid website and installed manually. APRSDroid isn't really being developed by the creator but send a donation to show your support.

The rebroadcasting notifications is related to the normal notifications the phone makes for sms, email, etc. I keep the phone in Airplane mode, to save battery, with GPS activated to eliminate any accidental transmission of phone 'noises' over the radio.

Thanks for the feedback. I'll look over my verbiage for any clarifications I can make.

eliasmajorek 4 years ago

What would be transmitted if I get notifications? Would it be just the sound, or something else?

StickyC 4 years ago

Thanks for the clarification, I understand what you're talking about with the OS-level notifications getting rebroadcast (as well as user-communication messages).

Diver433 4 years ago

Does the phone have to have a cellular plan? Could an Android tablet work as well? Interested in building one.

k-twizel 4 years ago

No cell plan needed. My phone stays in airplane mode with the GPS turned on; the phone provides GPS to the app then the app communicates with the radio which transmits the data out. The receiving station (if it is an iGate) will push the data out to the interwebz. If it is an APRS repeater, it will retransmit the data based on the WIDE settings in the app. Hope that helps

bcurnutte 4 years ago

Thanks for the write-up! KE8KNX

cloutier172 5 years ago

I don't seem to be receiving any packets. What volume level did you set the radio volume at? Did you change any other settings on the baofeng? I have driven from over 250miles and I can see my data getting on to APRS.fi but I am not seeing any packets coming in and I would have thought I would have seen something.

k-twizel 5 years ago

I don't think it is a BaoFeng volume issue. If you are seeing tracks on APRS.fi then you are getting out of the radio and an iGate is receiving. I reviewed my instructions and updated one pic but all the other settings for the radio and phone are good.

When you run APRSDroid, your callsign will be at the top of the screen. Tap your callsign to see all the TX and RX traffic. There is a .log file that is saved on the phone which can be read with a txt editor. Review this log for TX records from your phone and RX records back to you. I copied mine onto a microSD to transfer to my laptop. This will have everything your APRSDroid has TX or RX.

Let me know if this helps.

MarkS926 5 years ago

Man I'm bummed. First, this is a great tutorial. I've been eager to monitor APRS traffic on the go and thought since I can easily use my RTL-SDR on the computer and decode APRS traffic, I thought for sure I could use my Baofeng and my Android pbone. The only problem is I'm not licensed and I didn't realize until after I bought the audio cable and APRSDroid, that the app is useless without a callsign. I completely understand that fully utilizing APRS you need to transmit, but it sucks there isn't a monitor-only mode that doesn't require a callsign.

k-twizel 5 years ago

With SDR, you should be able to pull the signal and use an AFSK interpreter to decipher the audio without the need for a ham licence. Theres a few linux based tools that the SDRs work with that can help. APRS is not encrypted but the app presumes you are going to transmit thus requires a key/callsign to use.

MarkS926 5 years ago

Thanks for the reply, k-twitzel. Indeed you are correct. I've been using qtmm for Windows and it works well on my PC.. Albeit it's just raw data. APRSDroid has a cool way of laying it all out in a nice table that made it look attractive.. I was hoping to use my mobile phone and my HT to see if I could see the same data while on the road. Either way, it's more motivation to study and get that license :-) I suppose I could use some of the Linux tools on android, but it is a bit cumbersome to run command line utilies on a mobile device.

RandallM28 5 years ago

Need to get your ticket and join us on the APRS map! Its easier than ever now to get licensed! 35 question multiple choice test and the question pool with answers is online plus practice exams on websites too! Only gotta make a 70% to pass I think it is. 70 or 71% I forget.

www.qrz.com is the most popular site I think. tons of resources even for those without a call sign!

Also depending on your local I-gate you can see National Weather Warnings boxes on the map once you get a Call sign and run APRS software. All from the RF channel! Plus tons of other features too! Text like messaging, Objects ( events, traffic issues, local repeater info, club meetings and even disaster / emergency info ). Email features, call sign data base features and tons other stuff not just tracking as most people think what APRS is for! Automatic Packet Reporting System not just station tracking! =]

They even have APRS on the International Space Station! ( although its intermitten due to what is taking place on the ISS). I see it and PCSat ( another satellite running APRS ) on my APRS map all the time from the RF feed. Online anyone can but say in a grid down situation its tons of stuff APRS can offer to local Ham NETs and Emergency Management. It offers a ton of more visual information than just talking on a voice channel and is available when ever you need it vs having to listen to a voice channel waiting for a call that may not ever come!

But even with APRS aside its tons of things to do on Ham Radio! Join us! =]


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