Baofeng with iOS app

[Jacob Conell]

Anyone have trouble sending a beacon with the app?

I connected an iPhone XR and an iPad with the BTECH cable. I had to use the lightning adapter which I think might be the problem. At first when I turned on the VOX it would constantly key the radio no matter what the sound level was set on the phone. No it wont key the radio at all. I tried adjusting the VOX on the radio which did not help. 

This worked well with an old android phone I had.

Anyone have any ideas?

   Jacob

[Don Rolph]

Mine is working fine.  Set. up is per attached document.  You have to purchase a subscription to be able to transmit.

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73,

AB1PH

Don Rolph

[Don Rolph]

I have this working properly.

You can find configuration information at the attached link:

- https://atgp.groups.io/g/aprs-projects/files/Configs/SmartPhone%20APRS%20project/Explorations%20of%20smartphone%20APRS%20environments%20rev%201-1%2020211128.docx

You need to buy a subscription to aprs.fi if you wish to transmit.

On Tue, Dec 14, 2021 at 9:26 AM Jacob Conell <kc3...@gmail.com> wrote:

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[Jacob Conell]

Yeah, I got the subscription and if VOX is turned off I can hold down the transmit key on the radio while the app sends the beacon and it works. It's just while on VOX mode it constantly keys the radio no matter what setting the VOX level is. I'll try it with a different radio at some point. Hopefully i'll be getting the FT-5DR for christmas and it won't matter anyways haha. 

73 

Jacob 

To view this discussion on the web visit https://groups.google.com/d/msgid/aprsfi/CAKpxnB3%2B4%3D7m%2BBJWbWTELCXwTiGowt7jHj1gVaVvqZuEH%2BmGkg%40mail.gmail.com.

[Don Rolph]

Hmm, I typically set VOX to about 5.  If VOX is constantly tri[p[ping then this suggests you are getting additional noise on the cable besides the primary audio signal.  You can try tpo up VOX to the max which is I believe 9.

I am working fine with a Baofeng UV-5R and VOX set at about 4 or 5.

To view this discussion on the web visit https://groups.google.com/d/msgid/aprsfi/CAC_AymNhHy9rTGQGiubyLpBTsHPMJXG869iGUWcz-N6aek9Paw%40mail.gmail.com.

[Douglas Smith]

I am having the same issue. I using an uv-5r with the BTech cable to an iPhone XS. I have the subscription and am using the software TNC. The squelch is set to 1, the VOX to set to 9 on the radio, and I have setup aprs.fi by the attached doc. Within a few seconds of launch the app, the vox trips and the radio starts transmitting and does not stop. I'm monitoring the frequency with another radio and the signal is quiet, no apparent noise. 

I can connect the radio to my Linux notebook using the YAAC, Direwolf, and the BTech cable and it works fine. 

Thanks, Doug

[Alex Savage]

The DireWolf author has a section in the user manual regarding the downsides to using the HT’s built-in VOX circuit to control keying. The short version is even if you overcome the “sticky” VOX being described in this thread, the usual key-up timings appropriate for HT VOX might be long enough in packet modes to make it hard for the normal operation of APRS digipeaters.

https://github.com/wb2osz/direwolf/raw/master/doc/User-Guide.pdf

> My recommendation is to avoid using VOX, built into a transceiver, unless you can be sure the transmitter will turn off very soon (e.g. less than 50 mSec.) after the audio signal is no longer present. If you insist on using VOX, be sure the “VOX delay” setting is at the shortest setting.

I am of course completely sympathetic to trying to make things work with the tools available, but this seems like food for thought. :)

Cheers,

Alex W9SAV

[Daniel Kingshott]

Throw a ferrite choke on the aprs cable by the k connector.

I had a similar situation with a baofeng, that cured it.

To view this discussion on the web visit https://groups.google.com/d/msgid/aprsfi/0a4701b5-dbe3-4b17-ba42-e2515c8ab4f7n%40googlegroups.com.

[Heikki Hannikainen]

Jacob and Douglas,

Sorry for the slow reply. Have you found a solution from the suggestions
yet?

I don't have a Baofeng to try with. But I have the Btech cable, and I have
successfully developed and tested the aprs.fi app using the cable with the
Kenwood TH-D72 and a cheap chinese Puxing radio which should be comparable
to a Baofeng.

I have received a few complaints from users with the Baofeng, which all
sound a bit like some signal leaking to the microphone input of the
Baofeng, triggering VOX unnecessarily. I think two have resolved the issue
with ferrite chokes, a few have not reported about progress and the
discussion hasn't continued.

It sounds weird if it only starts when you launch the app - it would
suggest the app would generate audio towards the radio which would then
trigger the VOX. It should not do such a thing, but if it does, it should
be possible to measure by recording the output from the iPhone, or by
looking at it with an oscilloscope. Or just by attaching headphones to the
iPhone, wearing the headphones and starting up the app.

The app should only generate audio when it actually transmits a packet.

With an oscilloscope it should be possible to see if there is some
subaudible tone in the output, which could potentially trigger the VOX.

> Anyone have trouble sending a beacon with the app?I connected an iPhone XR and

> To view this discussion on the web visithttps://groups.google.com/d/msgid/aprsfi/CAC_AymNhHy9rTGQGiubyLpBTsHPMJXG869iGUWcz-N6aek9Paw%40mail.gmail.co
> m.
>
>
>
> --
>
> 73,AB1PH

> Don Rolph
>
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>

- Hessu

[aprs.fi]

Hi,

I did some testing and experiments with my iPhone 12, a Belkin headphone/charging adapter (allows charging iPhone while using a headphone/mic… or APRS!), a Puxing PX-777 2m radio, the BTECH APRS-K1 cable, and a Siglent digital storage oscilloscope. I wanted to confirm the levels and make sure there’s no leakage in the APRS-K1 cable.

This is the Belkin adapter: https://www.apple.com/shop/product/HLJV2ZM/B/belkin-35-mm-audio-charge-rockstar

And this is the APRS-K1 cable I have: https://baofengtech.com/product/aprs-k1/

The oscilloscope has an AWG waveform generator feature, so I could use it to feed in audio to the “headphone output” pin of the APRS-K1 cable, just like the radio would do. I adjusted the output level of the waveform generator to a level which, in the aprs.fi app’s TNC oscilloscope view, would show a nice waveform within the green range. At the same time I watched at the “microphone” pin of the APRS-K1 with the oscilloscope, just to observe that the “received” signal would not leak to the microphone input, which could trigger the VOX. No leakage/crosstalk observed at all with my APRS-K1 cable.

The APRS-K1 cable has level conversion components, and some protection components within the dongle in the middle of the cable. I just wanted to check that it has no internal coupling which could cause such leakage.

I then continued with some other tests. A little bit of background info:

The Lightning-3.5mm adapter is not just an adapter with wires and connectors - the Lightning connector is digital only, and the adapter contains tiny A/D and D/A converters to produce and record analog audio. The iPhone has a complex power saving system, and it powers up the audio adapter only when audio is played or recorded.

The digital storage oscilloscope is configured to trigger (capture data) when it sees any output exceeding 25 mV. This way I can capture outgoing transients, pops, and the very beginning of the audio waveform when the app starts transmitting a packet, and make screen shots (over ethernet, or to an USB thumb drive). It was also easy to confirm that there was no audio going out from the app at the wrong time, and that there is no subaudible hum or anything like that in the output.

Findings:

1. The app does not, in my test, leak any audio which could trigger the VOX. This is what I have tested and observed before during development, naturally.

2. The waveform of the outgoing packet seems quite alright. There is some low-level high-frequency noise, being picked up on the cable, but that’s just the computers and power supplies and digital things on my table, and that noise is present even if the lightning adapter is not connected to the iPhone. Screen shot of the beginning of a packet, HDLC flags being sent during txdelay, and a close-up shot of the beginning to look at the waveform:

3. When the DSP TNC in the app is started with the “Connect TNC” button (or the app is started with the TNC automatically starting, if it has been connected before), audio recording and playback by the modem starts. At this point iPhone powers up the external A/D and D/A converter in the lightning-3.5mm adapter. When the D/A converter is powered up, there is a small transient noise emitted (you may hear a very short and quiet “tap” in earphones). It is short and quiet enough that the Puxing PX-777 VOX will not key up the transmitter. The same noise waveform is emitted when any iPhone app starts playing or recording audio (iTunes playback starts, a phone call is started, Voice Memos app starts recording), it is not coming from the aprs.fi app. Just a side effect of the D/A converter and iPhone power saving features. It could however potentially trigger the VOX of another radio, and another lightning adapter might have a louder pop emitted when it is powered up! The Belkin “pop” is about 80 mV peak-to-peak. Here are screen shots from the oscilloscope, with two different timebases (horizontal time scale, "zoom" in time). In repeated tests the waveform is always pretty much the same.

4. The Puxing VOX does not work if the squelch is fully open. This is unfortunate, as the squelch is slow and eats the beginnings of received packets, unless other transmitting stations use a very long txdelay! It is however an understandable design choice - if a headphone/mic cable would not be attached, the received audio going out on the speaker of the radio would go in to the microphone and trigger VOX and transmission. The settings with the Puxing need to be: 

- Puxing VOX level 9

- Puxing Squelch level 5 (or something that is suitable with the noise level)

- Puxing volume level 50%, which (with squelch open) shows a waveform in the TNC view which stays in the green range

- iPhone volume, after attaching the Belkin adapter, set to quite exactly 50% - this controls the output audio level to the microphone input of the radio

- In aprs.fi settings, txdelay set to 50 (a very large value, 500 milliseconds, but the Puxing VOX is slow)

Normally one would want to have Squelch set to 0, so that the squelch would be continuously open, and the squelch delay would not prevent the very beginning of each received packet to be eaten away, but then VOX on Puxing won’t work. This is *not* a good radio for APRS. It also transmits a very long quiet tail after every packet, preventing the app from hearing when digipeaters retransmit the packet just sent by the app. VOX for APRS is awful.

So, as far as the app goes, it seems to work alright for me in this test. What could be wrong if it doesn’t work for you?

- Do you have a genuine BETCH-APRS-K1 cable? It should have a dongle in the middle, containing the level conversion and some other protective components. Mine looks like this:

- If the radio does not transmit at all, and if squelch is open on the radio, it might be that VOX is not operative on some radios, to prevent a feedback loop (received audio triggers VOX, when a speaker is used). Try adjusting squelch so that noise is not emitted when there's nobody transmitting.

- VOX level is too low, or volume setting on iPhone (after connecting the lightning-3.5mm adapter) is set to a too low value - a too high volume setting will cause distortion on transmitted audio, too. iPhone remembers different volume settings for the 3.5mm output, video/music playback on the speakers, and telephone calls on the same speakers, so remember to adjust the transmit level with the 3.5mm adapter attached. Listen to the transmissions on another radio, and make them the same level as other APRS stations in your area. A service monitor for deviation adjustment would be great but I understand not everyone has those around.

- If the radio starts continuously transmitting when the cable is connected or the app is started, perhaps the “pop” from the power-on of the D/A converter triggers VOX transmission and RFI from the transmitted signal keeps it on. Snap-on ferrites on either end of the APRS-K1 cable may help (one of the ends may help more, depending on if the RFI is going to the radio, or the lightning adapter).

I’ll now order a Baofeng UV-5R. I don’t really need or want one as such, but I guess I should test with one as it is quite popular.

- Hessu

[Heikki Hannikainen]

Hi,

I posted on Twitter about ordering an UV-5R for testing this, and Rob
Riggs of Mobilinkd (who makes the TNC3) had this to say:

"They can have horrible RFI issues. I have a Baofeng that seems to emit
more RF through the speaker-mic jack than the antenna. You may not be
able diagnose with just one radio. Some work OK."

https://twitter.com/Mobilinkd/status/1483162587269369869

Rob obviously has more riggs to test with (sorry, couldn't help myself),
but the advice to put a clamp-on ferrite choke (or a few) on the cable to
the baofeng may be spot on. The cable making a few rounds through a single
larger ferrite may be more effective than going once through a smaller
ferrite. Something like this, or just pick any ferrite that you happen to
have around, or easily available:

https://fi.rsdelivers.com/product/tdk/zcat2235-1030a/tdk-openable-ferrite-sleeve-28-dia-x-35mm-for-emc/7413056P

Please keep us posted if you find this helps!

> Anyone have trouble sending a beacon with the app?I connected an iPhone

> To view this discussion on the web visithttps://groups.google.com/d/msgid/aprsfi/CAC_AymNhHy9rTGQGiubyLpBTsHPMJXG869iGUWcz-N6aek9Paw%40mail.gmail.co

> m.
>
>
>
> --
>
> 73,AB1PH
> Don Rolph
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- Hessu

[Heikki Hannikainen]

Hi,

I have good news and bad news. Which ones would you like to hear first?

I got the UV-5R last week, and tested it very briefly last night.

The good news is that the issue reproduces easily, and it fails
spectacularly for me, too. I can then diagnose it further without help
from others (it has been a bit quiet here, the people reporting the issue
have not replied to inquiries for more information).

The bad news is that the few ferrites I had around did not help. I will
try others, and I'll try more ferrites once I find some.

I thought it might potentially depend on the power radiated from the
antenna, so I tried with a dummy load, but it didn't help. Video:

https://twitter.com/aprsfi/status/1485710975458234373

As soon as the lightning-3.5mm adapter is powered on, by the aprs.fi app,
or any other app, the transmitter goes on and does not turn off until the
time-out kicks in (too long transmission, adjustable in radio settings).

It's either RFI, or some other sort of incompatibility between the radio,
the APRS-K1 cable, and the 3.5mm adapter. It *is* a Baofengtech cable, so
it should work, and it works fine with Kenwoods (D72, D74), and the
Puxing.

The transmitter goes on when any app starts audio recording or playback,
as the 3.5mm adapter is powered on at that point. If there's no
record/playback happening, it does not get power (the A/D and D/A
converters are inside the adapter), a battery saving feature.

So, in the iPhone Camera application, when you switch from still photo to
video mode, it starts recording audio too, and the Baofeng starts
transmitting. Switch back to still photos, and after a few seconds (VOX
delay), the transmitter goes off. Yay. Any audio-emitting or
audio-recording app will trigger it.

Some people report that they have no issues, some report that ferrites
helped. It may depend on the radio unit, some are worse than others. I
guess I got lucky.

Jim here reports a Mobilinkd TNC3 works great with his baofengs, but the
direct cable connection from iPhone is a headache.
https://twitter.com/jimiDFIR/status/1483212074947907585

I also tried with an iPad, which has a 3.5mm socket and does not need the
Lightning adapter. Problem is present just the same.

I guess the next step is opening up the guts of the APRS-K1 cable, and
looking at the signals with an oscilloscope and a spectrum analyzer.

- Hessu

> https://groups.google.com/d/msgid/aprsfi/alpine.DEB.2.21.2201190956300.18986%40jazz2.he.fi.
>

- Hessu

[Nosey Nick VA3NNW]

Have you tried programming it with the CHIRP software? There's a bunch  of <cough> "less well documented" config options you can tweak via CHIRP  but can't get to through the menus. I vaguely recall that there are some  vox sensitivity options among them?

On the RX side, it is frequently possible to "fix" a broken "almost  stuck closed" squelch that way too, by the way.

BACK UP all your settings before you begin tweaking though, it is  DEFINITELY trivial to mess it up - ummm, worse than the manufacturer I mean  and you will desperately wish you could just go back to something that almost-worked before   :-/

Nick VA3NNW

On Tuesday, 25 January 2022 at 03:23:20 UTC-5 Heikki Hannikainen wrote:

I got the UV-5R last week, and tested it very briefly last night.

The good news is that the issue reproduces easily, and it fails

spectacularly for me, too. [...]

The bad news is that the few ferrites I had around did not help. I will

try others, [...]

As soon as the lightning-3.5mm adapter is powered on, by the aprs.fi app,

or any other app, the transmitter goes on and does not turn off [...]

[Don Rolph]

Ok, I have done some more testing on my end.

I am using a Baofeng UV-5R and the Btech cable BTECH-APRS-V01.

I am connecting to an iP{hone Xr. using the lightning port and an iPad air using the headphone jack.

I can duplicate the always on failure using the iPad and 3.5 mm phone jack IF the plug is not fully pushed in.  Indeed with the case on, it is impossible to fully insert the plug..

If the plug is fully inserted, then the system works as expected.

If I use the lightning jack with adapter on the iPad (adjusting vox level), it works as expected.

On the iPhone Xr, using the lightning jack and adapter it works as expected.

I am suspicious that the problem may be fully inserting the plug into the 3.5 mm phone jack.

My 20 mils worth.

Your mileage can and will vary.

To view this discussion on the web visit https://groups.google.com/d/msgid/aprsfi/alpine.DEB.2.21.2201251007290.22929%40jazz2.he.fi.

[Geoffrey Dann]

I agree, it's a lot easier to program the radio using Chirp than by using the key pad. Was there a specific setting in Chirp that will help with RFI, besides squelch level and vox level?

My experience (6 months ago) are essentially the same as Hessu's experience. The radio keys when it should not. Ferrites helped some, but did not cure the problems. (I used ferrites that I already had, and do not know if they are the right "mix" for the frequency of the radio.)

geoff, N3CFX 

[Gwen Patton]

Isn't the Apple headphone jack TRRS, not the usual TRS? Does an earbud cable have the tip, two rings, and the sleeve? That may be the problem.

-=-=-=-=-=-=-=-=-

73,

Gwen, NG3P

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[Heikki Hannikainen]

On Tue, 25 Jan 2022, Nosey Nick VA3NNW wrote:

> Have you tried programming it with the CHIRP software? There's a bunch  of <cough> "less well documented"
> config options you can tweak via CHIRP  but can't get to through the menus. I vaguely recall that there are
> some  vox sensitivity options among them?

No, I don't have a programming cable. The document here lists the
adjustable settings in CHIRP and the respective menu items:

https://wiki.radioreference.com/index.php/Baofeng_UV-5R#Squelch

It says "VOX Sensitivity" in CHIRP advanced menu adjusts the same thing as
item 4 VOX on the radio. There's just that one VOX thing there, and it's
also adjustable on the radio.

- Hessu

[Heikki Hannikainen]

On Fri, 28 Jan 2022, Gwen Patton wrote:

> Isn't the Apple headphone jack TRRS, not the usual TRS? Does an earbud
> cable have the tip, two rings, and the sleeve? That may be the problem.

It is a TRRS, but the cable which is being discussed, the APRS-K1 has a
TRRS plug and it is specifically designed to be used with Apple and
Android devices and these radios.

https://baofengtech.com/product/aprs-k1/

- Hessu

[Heikki Hannikainen]

Hi,

I have some prior experience in inserting 3.5mm plugs, and I'm relatively
confident I'm plugging it in right. :)

With the UV-5R I have, the problem reproduces consistently with the BTECH
APRS-K1 cable, with either an iPad Mini 2 (directly), or the lightning
adapter.

If I, however, replace the UV-5R in the other end of the cable with a
Kenwood TH-D72, a TH-D74, or a chinese Puxing radio, they problem goes
away.

So I'm kind of leaning towards the UV-5R having a problem.

Rob Riggs of Mobilinkd has some past experience as well:
https://twitter.com/Mobilinkd/status/1483162587269369869

- Hessu

> To view this discussion on the web visithttps://groups.google.com/d/msgid/aprsfi/CAKpxnB1_a0aVYbj5io6%2Brr_1QxvV9gqPkPyLfKnC1O%3Djj%3DBF8w%40mail.gm
> ail.com.
>
>

- Hessu

[Daniel Kingshott]

Heikki,

I’d also say I don’t think this issue is apple specific, I mess around a lot with these cheap handsets, I’ve experienced this exact problem with iPhones, Android, various tablets, USB TRRS audio interfaces, etc.

They simply aren’t shielded well internally - this is why if you set the handset for VOX and drop it in the charging cradle It will immediately key up and not stop until timeout. I’ve also messed around with various chirp settings, none of these make a difference.

I gave up trying to get VOX to work, even once I solved my keying up issue (with a choke - that I see didn’t work for you) the squelch still didn’t drop reliably enough to receive APRS packets (and yes - I adjusted the actual values behind the 1-10 squelch settings in chirp).

Given my love of cheap Chinese handhelds, I now simply use one of a lanchonlh hg-uv98, with the community firmware. I switch off beacons in the H/T and let aprsdroid do it’s thing through a bluetooth connection to it’s internal TNC.

dan.

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[Don Rolph]

The data is the data.

To view this discussion on the web visit https://groups.google.com/d/msgid/aprsfi/alpine.DEB.2.21.2201282316440.23211%40jazz2.he.fi.

[Heikki Hannikainen]

Alright folks,

I got myself a TRRS extension cable from Ebay, gutted it so I can look at
all the signals with an oscilloscope. Found out that whenever my Baofeng
UV-5R is attached to an iPhone or iPad with the APRS-K1 cable, there is a
rather loud ~500 kHz signal on all the wires.

Attach to another non-Baofeng radio, no problem. Attach to my Android
phone, no problem.

It seemed like some sort of oscillation or feedback, as the frequency was
drifting, so I experimentally added an extra 470 nF capacitor, which fixed
the problem for me.

Details:

http://blog.aprs.fi/2022/02/baofeng-btech-aprs-k1-iphone-problems.html

Since some people have this problem, and some don't, it is possible that
the fix also does not work for some people, as it may depend on some build
quality issues of this equipment. But it's worth trying as it's not too
hard to put in a capacitor, or remove it.

I also now found out that my UV-5R is deaf, but that's a separate story.
No, I won't try to fix it, I'll put the radio in the box of radios I don't
use. :)

[Allen Lord]

Am I correct in assuming that this problem came up when you used a rubber duck antenna with the Baofeng? We have seen this a lot with the CHICOM Noisy Beast ( As I affectionately call the UV5R...) The Baofeng is a little more manageable with an external antenna; a little bit of gain makes a reasonable hearing aid for it's otherwise deaf receiver, and seems to mysteriously quiet it's noisy RF front end. 

The Micro-Trak products that incorporate a  radio and a TT3/TT4 in them make generous use of 4700 pF caps to bypass all that noise to ground!

73,

Allen AF6OF 

VHS/Byonics

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[Heikki Hannikainen]

On Sun, 20 Feb 2022, Allen Lord wrote:

> Am I correct in assuming that this problem came up when you used a rubber duck antenna with the Baofeng?

No, it happens with an external antenna on the roof, or a dummy load.
Please read the blog post... I used a dummy load so that I'd have
something meaningful on the oscilloscope display.

In fact the oscillation on the audio wiring is present even with the
Baofeng powered off. :) So it seems like an interaction with the audio
circuitry on the iPhone side and the Baofeng, and the APRS-K1 cable
doesn't have the right components to tame it.

- Hessu

[Nosey Nick VA3NNW]

Heikki Hannikainen wrote:

[...] experimentally added an extra 470 nF capacitor, which fixed
the problem for me.
http://blog.aprs.fi/2022/02/baofeng-btech-aprs-k1-iphone-problems.html

On another ham-radio forum, someone recently pointed me at https://github.com/johnboiles/BaofengUV5R-TRRS which has a similar solution but also includes a voltage-divider

Nick VA3NNW

[Heikki Hannikainen]

Please read the block post, Nick. The btech APRS-K1 cable *also* has a
voltage divider on the baofeng-to-iphone-mic path, just like
https://github.com/johnboiles/BaofengUV5R-TRRS has.

The Btech cable has a series capacitor (DC block) on the
iphone-earphone-to-baofeng-mic path - the johnboiles cable doesn't have
that, it's just a straight cable with that schematic.

- Hessu