Tag Archives: Android

Ohio Section Journal – The Technical Coordinator – November 2021 edition

One of the responsibilities of the Technical Coordinator in the Ohio Section is to submit something for the Section Journal. The Section Journal covers Amateur Radio related things happening in and around the ARRL Ohio Section. It is published by the Section Manager Tom – WB8LCD and articles are submitted by cabinet members.

Once my article is published in the Journal, I will also make it available on my site with a link to the published edition.

You can receive the Journal and other Ohio Section news by joining the mailing list Tom has setup. You do not need to be a member of the ARRL, Ohio Section, or even a ham to join the mailing list. Please sign up!

If you are an ARRL member and reside in the Ohio Section, update your mailing preferences to receive Ohio Section news in your inbox. Those residing outside the section will need to use the mailing list link above.
Updating your ARRL profile will deliver news from the section where you reside (if the leadership chooses to use this method).
Go to www.arrl.org and logon.
Click Edit your Profile.
You will be taken to the Edit Your Profile page. On the first tab Edit Info, verify your Email address is correct.
Click the Edit Email Subscriptions tab.
Check the News and information from your Division Director and Section Manager box.
Click Save.

Now without further ado…

Read the full edition at:

Jeff Kopcak – TC

DSCF5081 K8JTKHey gang,

Users of the DROID-Star application ran into a problem with an update earlier this month. After upgrading, then trying to connect to a DMR, D-STAR, NXDN, or System Fusion network, users were greeted with a “no vocoder found” message.

DROID-Star is known to users of digital modes. Namely used by Android or iOS users, it connects the user to ham radio digital networks. Later AllStar support was added through IAX, not using the AllStar Link network rather through the Inter-Asterisk eXchange protocol. AllStar is built on Asterisk and IAX requires separate accounts for access. DROID-Star supports MMDVM in hotspot or standalone transceiver configurations. MMDVM is written by G4KLX and the standard for ham radio digital linking via hotspots, interface boards, and applications.

Modes that can no longer be used out-of-the-box, after the November update, are all of the AMBE modes. AMBE is the voice encoder used in DMR, D-STAR, NXDN, and YSF. The no vocoder found message is seen when connecting to any of these modes. Unaffected modes are IAX, M17, and P25. IAX uses codes available to Asterisk. M17 uses the free and open source Codec 2. P25 (phase I, as used in ham radio) uses the IMBE codec. All three of those modes can be used without additional configuration.

First thought, there was a licensing issue or dispute. I found a forum post where the Pi-Star author recommended keeping packages separate in DROID-Star making them easier to maintain and packages can be built without including unnecessary extras. I believe this to be the reason the packaged codec in DROID-Star was removed.

No vocoder found. No hardware or software vocoder found for this mode. You can still connect, but you will not RX or TX any audio. See the project website (url on the About tab) for info on loading a sw vocoder, or use a USB AMBE dongle (and an OTG adapter on Android Devices)

As the message indicates, the user can connect to a reflector or talkgroup, but no audio will be heard. That’s about as useless as a glass hammer. I guess you can connect to make your presence known, but transmissions and reception is done through ESP? First thing I did was to visit the project URL to obtain information about finding a vocoder as suggested.

I have no information regarding aquiring a software vocoder.
There are no software vocoder plugins available in this repository, and I have no information on obtaining one. DONT ASK!

Super helpful. It does say there is an option of using a DV3000 and OTG cable. If you haven’t seen a DV3000, it’s about the size of a USB thumb drive. Do DROID-Star users need to have a hardware dongle hanging off their phones to make digital connections? Maybe. I was planning to test this method but realized I switched to a phone with USB-C connector and the OTG cables I had for previous devices were Micro USB. Make sure to obtain the correct cable for your phone or tablet.

USB OTG stands for On-The-Go. By default, phones/tables act as a peripheral. For example, plugging into a PC allows access to the phone’s storage. In order to set the phone in host mode, allowing it to accept input from other devices, a special cable containing an extra pin is required. This cable with an extra pin informs the device to enter host mode. OTG cables are readily available from a favorite online store or local computer shop. Search for ‘Micro USB OTG cable’ or ‘USB-C OTG cable’ depending on the device’s connector type. Description should make reference to being an ‘adapter for smartphone.’

Not seeing any other solutions early on, I rolled back the application to an earlier version. This is not for the faint of heart nor for someone worried about installing unofficial versions of applications, called “sideloading.” Not responsible for any damage or legal issues. This is for informational purposes only. Updates to the operating system may keep this app from working properly in the future. Any app updates/enhancements/features/bug fixes to DROID-Star will not be available without using a later version and running a vocoder. Downgrading is not possible through the Play Store. I downloaded DroidStar 1.0 (58) from the APKPure website. Hashes and additional info available on this page. I had to remove the newer DROID-Star version (which removes settings) from my phone and install the downloaded version manually. There is a “How to install APK / XAPK file” on the download link. It will explain sideloading an app and required settings to change.

After doing more digging, I was able to find a more appropriate and supported solution. The instructions to load the plugin on the project page are wrong. Saving to the Download directory did not work. To install the vocoder on an Android device:

1. Install the latest version of DROID-Star (Play Store, 3rd party store, official APK).
2. In the browser of the mobile device, visit this website: http://pizzanbeer.net/plugins/

3. Press and hold the filename for your device (arm, arm64). If you’re not sure which one to use, in DROID-Star hit About and look for Architecture.

4. Tap Copy link from the popup

5. In DroidStar, go to Settings
6. Scroll to the bottom (now located just above the MMDVM and level settings in later versions) and paste the URL in the Vocoder URL field (tap the Vocoder URL box. When the cursor is displayed, press and hold the same field. Click Paste).
7. Tap Download vocoder

8. A message saying “Updating, Check log tab for details” is displayed. Tap OK.

9. The Log tab should display “Downloaded vocoder_plugin.android.arch.”

You’re ready to go! If this is not seen, there was an error or the download couldn’t complete. Though these instructions are for Android, they are nearly the same for iPhones and iOS devices, except choose the “darwin” platform file instead of arm/64.

These steps might have to be repeated often. The release I used as of this writing (Nov 24) DROID-Star did not retain the vocoder settings. Now, I could have corrupted a database or borked permissions during testing and re-installing previous versions on my phone. Apparently other users are experiencing the same issue. Doug – AD8DP, the author of DROID-Star, seemingly doesn’t want to be bothered with issues. His repositories state the applications are offered “as is.” There is no E-mail on his QRZ and the GitHub repository has the “Issues” tab disabled. Normally, the issues option is used to report bugs with GitHub projects for developers or other community members address.

Other links about AMBE and contributing to the projects:

W9OB meeting. Photo courtesy of Dave – KB9VZU

Although not in our section, I do know they read our OSJ, quick shout out to the Henry County Amateur Radio Club in New Castle, IN – W9OB. I gave a presentation on AllStar Link and linking with digital modes. Been awhile since I’ve done a meeting over the air. Presentation was done using their local repeater via my local AllStar node. If your club would like a presentation on digital and VoIP modes or how my DVMIS works, get in contact with me.

Time off of work or wanting a break from the madness is a great time to get on the air and work special event stations. Some nets will even get children, grandchildren, and neighborhood kiddos in touch with Santa! The Santa Net is held every evening between Thanksgiving and Christmas on 3.916 MHz at 8:15PM eastern time. If HF is not available, the DoDropIn Echolink conference is hosting the Santa Watch Net on Christmas Eve! It begins at 6:00PM eastern on the 24th and runs about 4 hours. Third party traffic is always on the nice list.

On the ARRL Special Event Station calendar, W9WWI is hosting Christmas in Bethlehem on Dec 4. KC5OUR is hosting Bethlehem on the Air, Dec 18-24. N0T, N0R, N0A, N0I, and N0N make up the Christmas Train crew to Celebrate Christmas Time and Holiday Cheer through Ham Radio, Dec 23-26.

Let us not forget, the attacks on Perl Harbor that happened Dec 7, 1941. A number of stations including W2W, W9CAP, NE1PL, N7C, N7D, and N7N will be on the air to commemorate 80 years and the men and women who served.

Thanks for reading. Happy holidays, Merry Christmas, and Happy New Year! 73… de Jeff – K8JTK

Dongle Bits: Settings, Programs, & Apps for Software Defined Radio

This article appeared in the The Lake Erie Amateur Radio Association newsletter The Spirit of ’76 and ’88 October 2014 edition and The Wood County Amateur Radio Club newsletter CQ Chatter November 2014 edition.

Read the rest of the series in the Dongle Bits articles category.

Last time on Dongle Bits, I talked about the $20 European TV tuner dongle that was hacked allowing direct access to the signal data. The result is a cheap wideband receiver for your computer. We’re going to take a look at key settings you should know about when using these devices. Then look at some software and projects that transform these into systems that would have cost hundreds or thousands of dollars!

PPM and Settings

An important thing to know about these dongles: they are cheaply made and not tested for accuracy. They are designed to receive DVB-T signals at a bandwidth of 6 – 8 MHz where a few KHz error doesn’t matter. This is obviously not true when you’re dealing with FM signals that are 16 KHz wide or digital at 12.5 where a few KHz will put you on a completely different frequency or channel.

PPM stands for parts per million and is the difference in received frequency vs. frequency shown. To visualize this, use SDRSharp to receive a known FM signal. The center frequency shown will be different from the signal on the scope. Typical PPM offset is anywhere from 45 – 65 and will be in the programs settings. The dongle will drift another 2 – 5 PPM over the next 20 – 45 minutes as it warms up. Gain is obviously another setting that will help you receive signals. The RTL AGC setting works but will err on the side of too much gain. Manually, using more than 32.8 dB will overload and produce duplicate signal spikes. The Correct IQ setting will get rid of phantom spikes at lower gain settings.

PPM at 0
Dongle with no frequency correction. The actual 162.550 frequency is just to the left of the displayed frequency. 162.550 is one of the NOAA Weather Radio frequencies.
RTL-SDR Settings (PPM corrected)
Shows the gain and PPM frequency correction of 55 for the dongle I’m using.
PPM Corrected
Shows 162.550 centered with frequency correction applied.

The crystals on the RTL-SDR dongle can be replaced with higher accuracy temperature controlled crystals (TCXO) that have a variance of 1 ppm! These crystals are $10 but you have to wait for them to ship from China. Pre-modified dongles are available but you will pay three times the price for the dongle.


PCs aren’t the only place these SDRs can be used. They can be plugged into an Android device too. You will need a USB OTG cable (on-the-go) and Android 3.1 or later. Search Amazon or EBay for “USB OTG.” OTG is a standard for plugging in USB keyboards, mice, and thumb drives into mobile devices. Running external USB devices off the internal battery will drain it much faster. A powered USB hub would off-load the dongle power consumption. Apps include SDR Touch (wideband receiver program), ADSB Receiver, and SDRWeather for monitoring NOAA weather alerts on your device.

This is the RTL-SDR running on my Android Nexus 7 tablet with SDR Touch receiving the 146.880 repeater in Lakewood, Ohio. It is connected with a USB OTG cable to the RTL-SDR dongle, then to an MCX to SMA, and then SMA to PL259 adapter.
This is a screenshot of the above setup with SDR Touch.

What can I do with this thing?

The definitive source on all things RTL-SDR is at the appropriately named www.rtl-sdr.com website. This site has it all. They regularly post software, updates, projects, and new developments. There is something new just about every week.

Some features of RTL-STR.com are The Big List Of RTL-SDR Supported Software. This is the list of software packages that support RTL-SDR on all platforms. Software ranges from wideband receivers to single purpose programs. This will give you some ideas of things to try with RTL-SDR. SDRSharp was written to have plugins extend the functionality of the program. These include plugins that make SDRSharp scan frequencies, add an audio FFT, scope, level meter, or CTCSS (PL) detector.

There is an extensive list of projects and write-ups including an Amateur Radio category. Some interesting ones are receiving live NOAA satellite imagery, analyze cellular phone GSM signals, radio astronomy, signal strength heat mapping (foxhunting?), and how Brazil uses our military satellites to transmit SSTV images.

With the onset of many digital standards and narrowbanding, there are more digital signals out there you may not be able to identify by hearing them or seeing them on the waterfall. This Signal Identification Guide has known types, frequencies they may be heard on, mode, bandwidth, sample audio, and waterfall image. I find myself using the Radio Reference database search utilities to help identify signals and their owners (a premium account maybe needed for some features).

My first SDR project was to use the Raspberry Pi as a SDR remote network server. The Raspberry Pi could be placed in an attic or basement connected to an antenna and controlled by another computer.

Audio can be piped from one program into another using Virtual Audio Cable (VAC). Some time ago, during one of the digital nets on the .76 repeater in Cleveland, I used SDRSharp and VAC to receive the FLDIGI messages being passed on the net. The signal path looked like this: received RF signal (146.760) -> RTL-SDR (signal data) -> SDRSharp (audio out) -> Virtual Audio Cable -> FLDIGI (audio in) -> message decoded on screen. If I had a HackRF, I probably would have been able to transmit messages without using any “ham” gear.

The next and probably final article, I will demonstrate tracking airplanes equipped with ADS-B transmitters and listening to trunked P25 public service radio systems for under $100.

DVAP Pi Hotspot

DVAPDongleOne of my interests is digital modes, so I’m a D-STAR fan.  My first project with the Raspberry Pi would be the DVAP Pi Hotspot.  The DVAP normally connects to a computer and has a low power, 10 mW 2m or 440 transceiver that works with a D-STAR radio.  It passes the bits from the Internet & D-STAR network over the air to your D-STAR radio and vice versa.  The radio does the encoding and decoding.

Thanks goes out to the guys over at AmateurLogic.TV.  Tommy, N5ZNO, did a DVAP Pi segment in episode 57 that I used to build mine.


Much like Tommy, my DVAP Pi had to be portable (battery operated), headless (no monitor, autostart), use a cellphone WiFi hotspot, and administered through SSH and VNC if needed.  On Windows, I use PuTTY and TightVNC.  On Android, I use JuiceSSH and PocketCloud.


With this tutorial, I’m assuming anyone setting this up is already familiar with D-STAR, registered on the D-STAR network, and familiar with using the DVAP on a PC.

This guide is step-by-step in nature, meant for beginners, with brief explanations of the steps.  It will help to have an understanding of Linux commands and scripting.  Capitalization is important in Linux!

DPRS problem

I was hoping to use the DVAP Pi as a portable DPRS (D-STAR APRS) iGate to report location data to the APRS network.  It currently does not.  It only reports D-PRS data to the gateway system you’re connected to.  No further.  It will show up on the gateway’s DPlus Dashboard but the DVAP Tool nor the gateway/reflector/repeater will not pass location data to the APRS network.

If you come over the RF side of a repeater with a GPS enabled radio, it will pass the location data to the APRS network.  The repeater will not pass location data to the APRS network when transmitting through a DVAP linked to the system.

This is true when the DVAP is connected to a PC or the Pi.

Program versions

I used a Windows 7 64 bit PC. Applications and versions used in this writeup:

  • Wheezy Raspbian 2014-01-07
  • Win32 Disk Imager 0.9
  • PuTTY  0.63
  • TightVNC 2.7.10 64 bit
  • DVAPTool 1.04
  • Mobile Hotspot ? (added after publishing)
  • JuiceSSH ? (added after publishing)
  • PocketCloud ? (added after publishing)

Parts list

Listed below are all the parts needed to get this project working.  It is noted when items can be left out or substituted.

That’s all the parts needed for this project.  Check out the AdaFruit Raspberry Pi page for other hardware that might be useful, like the USB to PS/2 adapter for example.  Many of these parts are included in the Raspberry Pi Starter Pack.



Go to http://www.raspberrypi.org/downloads and find the “Raw Images” section.

Download the Win32DiskImager and Raspbian image (800 MB).  Save them in your Downloads folder.