Category Archives: Amateur Radio

Ham Radio topics.

Getting Started with MMSSTV

Table of Contents

Introduction – page 1

Download and installation – page 2

Configuration – page 3

RX – page 4
-Logging

History – page 5
-Saving images

TX – page 6
-Modes
-Loading images
-Picture clipper
-Transmitting an image from s.pix
-Transmit loaded image

Template editing- page 7

Introduction

This document will demonstrate installation, setup, and basic use of MMSSTV. MMSSTV stands for Makoto Mori (JE3HHT, creator) Slow Scan TV. It has been the defacto standard SSTV application for many years.

This is written with the beginner in mind and many concepts outlined step-by-step. It will provide direction for further experimentation on your own or on the net and direction for troubleshooting.  For SignaLink and audio setup, visit the Radio Interface Setup post.

Prepared for The Lake Erie Amateur Radio Association’s Digital Net (http://www.leara.org/).

Program versions

Program versions used in this document.

Windows 7 – 64 bit
MMSSTV 1.13A – only available on the Windows platform.

Resources

http://en.wikipedia.org/wiki/Slow-scan_television – Wikipedia, history and current systems.

http://hamsoft.ca/pages/mmsstv.php – MMSSTV homepage, sample audio files (to route through the Windows audio system), and help files.

http://www.wb9kmw.com/WB9KMW/sstv_files/tutorial/SSTV_tutorial.pdf – SSTV for beginners. WB9KMW answered some questions with MMSSTV. I’ll plug his introduction. His website has a collection of HF SSTV receivers that can be used to check reception and propagation.

Calibration

Sound card calibration is important in SSTV.  See the “Sound card clock calibration” section in the “Radio Interface Setup – For getting started with Ham Radio Sound Card digital modes” document.  MMSSTV methods: http://www.wb9kmw.com/WB9KMW/sstv_files/tutorial/That_Pesky_Slant.pdf. I prefer this method: http://www.wb9kmw.com/WB9KMW/sstv_files/tutorial/That_Pesky_Slant_WWV_Alternative.pdf.

Getting Started with Fldigi – Including Flmsg and Flwrap

Updated: 03/26/2017

Table of Contents

Introduction – page 1

Download and installation – page 2
-All 3 programs

Configuration – page 3
-Fldigi
-Flmsg

Receiving
-Fldigi – page 4
-Flmsg – page 5
-Flwrap – page 6

Transmitting
-Fldigi – page 7
-Flmsg – page 8
-Flwrap – page 9

Introduction

This document will show installation, setup, and basic use of Fldigi, Flmsg, and Flwrap. Fldigi stands for Fast Light Digital modem application created by W1HKJ (David Freese, Jr.) and associates. Flmsg is a forms manager with standardized forms like MARS, plaintext messages, Radiograms, Red Cross, and Weather report forms. Flwrap is a file encapsulation and compression tool allowing for reception of a file exactly like the original.

The Fldigi suite has many applications and can operate many, many different modes. For the list of modes, click the “Op Mode” menu in Fldigi. A quick description of the Fldigi suite from W1HKJ:

Fldigi – Digital modem program.
Flarq – AutomaticReQuest file transfer program (works with Fldigi).
Flamp – Amateur Multicast Protocol file transfer program.
Flwrap – File encapsulation for error free transfers over amateur radio.
Flmsg – Formatted message manager – 25 forms including Radiogram.
Flrig – Transceiver control program.
Flwkey – Winkeyer control program.
Fllog – Logbook program – works with Fldigi, Flwkey etal.
Flnet – Net management and database program.

The Digital Net typically operates Fldigi using NBEMS standard methods for VHF and UHF communication. NBEMS stands for Narrow Band Emergency Messaging System (or Software) (http://www.arrl.org/nbems). NBEMS VHF/UHF operating mode is MT63-2KL and Olivia 8/500 or 16/500 for HF operation. HF digital operation is considerably different than VHF/UHF FM digital. HF station operating tips are not covered however application usage is similar.

Flwrap is no longer considered part of NBEMS but is a useful program to send small files.  If only operating NBEMS, Flwrap can be omitted and ignored.

This is written with the beginner in mind and many concepts outlined step-by-step. It will provide direction for further experimentation on your own or on the net and direction for troubleshooting.  For SignaLink and audio setup, visit the Radio Interface Setup post.

Prepared for The Lake Erie Amateur Radio Association’s Digital Net (http://www.leara.org/).

Program versions

Program versions used in this document.

Windows 7 – 64 bit

Fldigi 3.23.21

Flmsg 4.0.1

Flwrap 1.3.4

Resources

http://www.w1hkj.com/beginners.html – Beginners guide to Fldigi.

http://www.w1hkj.com/FldigiHelp/index.html – Fldigi help.

http://www.w1hkj.com/flmsg-help/index.html – Flmsg help.

http://www.w1hkj.com/Flwrap/index.html – Flwrap help.

Calibration

Sound card calibration for some modes Fldigi supports is important; it is recommended regardless of mode. See the “Sound card clock calibration” section in the “Radio Interface Setup – For getting started with Ham Radio Sound Card digital modes” document. Fldigi method: http://www.k8jtk.org/2015/10/19/nbemsfldigi-sound-card-calibration/.

Radio Interface Setup – For getting started with Ham Radio Sound Card digital modes

Table of Contents

Introduction – page 1

Configuration
-Playback settings – page 2
-Recording settings – page 3

Testing and troubleshooting – page 4
-Transmit
-Receive

Recording with Audacity – page 5
-Recording settings
-Record all received and transmitted audio
-Timer recording
-Saving
-Playback

Sound card clock calibration – page 6

Introduction

This document will demonstrate basic setup of a radio interface device in the Windows Sound Control Panel to use with Ham Radio Sound Card digital modes. Programs include: Ham Radio Deluxe DM780, MMSSTV, Fldigi, wsjtx, FreeDV, Easypal. In addition, it will demonstrate how to record digital transmissions and play them back.

This is written with the beginner in mind and many concepts outlined step-by-step. It will provide direction for further experimentation on your own or on the net and direction for troubleshooting.

The SignaLink USB was used but these instructions can be adopted for similar devices. Those using other methods may find the settings and techniques useful.

SignaLink and many other external interfaces have external volume controls. Set these controls at half to start. Adjust these controls first as they are the easiest to adjust and fine tune while operating. If a situation occurs where you have too much/little audio with the volume controls set low/high, then adjust the Windows audio levels second.

It is important to point out:

  • Plugging the same device into a different USB port will be recognized as a new device by the system. This means the audio settings will need to be re-configured. In addition, the audio device settings in the digital mode program may need to be re-configured as well.
  • The process of setting audio levels is not exact.  Each system is different, drivers are programmed differently, hardware interacts differently with the operating system. It will take some time to fine tune audio levels.

Prepared for The Lake Erie Amateur Radio Association’s Digital Net (http://www.leara.org/).

Program versions

Windows 7 – 64 bit
Audacity 2.0.6

Resources

Still having trouble after using this tutorial? Read through the product manual and support documentation. Below are links for popular devices.

Specific instructions can be found online typically by searching: [name of application] [radio interface device]. Example: Fldigi SignaLink USB.

SignaLink

Homepage: http://www.tigertronics.com/

General support, operating tips, manuals, and modifications (all models): http://www.tigertronics.com/sl_suprt.htm

SL USB troubleshooting: http://www.tigertronics.com/slusbts.htm

Rigblaster

Homepage: http://www.westmountainradio.com/

Knowledge base: http://www.westmountainradio.com/knowledge_base.php

Drivers and manuals: http://www.westmountainradio.com/content.php?page=wmr-downloads

SSTV Transmissions from the International Space Station – April 2015 edition

The ARISS team planed to activate SSTV from the ISS again on April 11.  Check the ISS tag for my other ISS SSTV posts.

Station setup: MP Antennas Classic Mobile NMO Antenna – This is a local company in Cleveland and were reviewed in QST. Been using their antennas for a long time with great success. Since the antenna is multi-polarized (the MP in the company name), it is supposed to be a good substitution for receiving satellite transmissions without a directional antenna and not worrying about Doppler Shift (which needs to be accounted for in some cases). The height is about 15 feet.

The antenna was connected to my ICOM IC-7000 with DSP settings turned off on 145.800 MHz FM. Used this radio only because my SignaLink USB is connected to it and the one I use for digital operation on all bands. MMSSTV is the Slow-Scan TV program I use.

I have tutorials available to help get your station setup and getting started with MMSSTV to receive images from the ISS.

Many of the passes weren’t great or even over the U.S.  I received 7 images total from my location near Cleveland (EN91bl).

SSTV-Transmissions-from-the-International-Space-Station-2015-04-11-2334
2015-04-11 2334 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-04-12-0114
2015-04-12 0114 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-04-12-0247
2015-04-12 0247 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-04-12-0253
2015-04-12 0253 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-04-12-0428
2015-04-12 0428 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-04-12-0601
2015-04-12 0601 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-04-12-2105
2015-04-12 2105 UTC

 

SSTV Transmissions from the International Space Station – February 2015 edition 2

The ARISS team planed to activate SSTV from the ISS again, February 21 through February 23.  However, spacewalks delayed transmissions until February 22 and February 23, 2015.  Check the ISS tag for my other ISS SSTV posts.

Station setup: MP Antennas Classic Mobile NMO Antenna – This is a local company in Cleveland and were reviewed in QST. Been using their antennas for a long time with great success. Since the antenna is multi-polarized (the MP in the company name), it is supposed to be a good substitution for receiving satellite transmissions without a directional antenna and not worrying about Doppler Shift (which needs to be accounted for in some cases). The height is about 15 feet.

The antenna was connected to my ICOM IC-7000 with DSP settings turned off on 145.800 MHz FM. Used this radio only because my SignaLink USB is connected to it and the one I use for digital operation on all bands. MMSSTV is the Slow-Scan TV program I use.

I have tutorials available to help get your station setup and getting started with MMSSTV to receive images from the ISS.

I received 15 images total from my location near Cleveland (EN91bl).

SSTV-Transmissions-from-the-International-Space-Station-2015-02-22-1719
2015-02-22 1719 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-22-1853
2015-02-22 1853 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-22-1858
2015-02-22 1858 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-22-2032
2015-02-22 2032 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-22-2210
2015-02-22 2210 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-23-1626
2015-02-23 1626 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-23-1805
2015-02-23 1805 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-23-1941
2015-02-23 1941 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-23-2116
2015-02-23 2116 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-23-2257
2015-02-23 2257 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-24-0031
2015-02-24 0031 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-24-1534
2015-02-24 1534 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-24-1707
2015-02-24 1707 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-24-1848
2015-02-24 1848 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-24-2025
2015-02-24 2025 UTC

SSTV Transmissions from the International Space Station – February 2015 edition 1

Had great success last time the ISS sent SSTV images in December and saw the ARISS team planed to activate SSTV from the ISS again, January 31 and February 1, 2015.  Check the link of my previous post for details on my setup and ISS tag for my other ISS SSTV posts.

Station setup: MP Antennas Classic Mobile NMO Antenna – This is a local company in Cleveland and were reviewed in QST. Been using their antennas for a long time with great success. Since the antenna is multi-polarized (the MP in the company name), it is supposed to be a good substitution for receiving satellite transmissions without a directional antenna and not worrying about Doppler Shift (which needs to be accounted for in some cases). The height is about 15 feet.

The antenna was connected to my ICOM IC-7000 with DSP settings turned off on 145.800 MHz FM. Used this radio only because my SignaLink USB is connected to it and the one I use for digital operation on all bands. MMSSTV is the Slow-Scan TV program I use.

I have tutorials available to help get your station setup and getting started with MMSSTV to receive images from the ISS.

I received 13 images total from my location near Cleveland (EN91bl).  Not sure why there was a sync issue on the second day (noted by the green line on the left in some of the images).

SSTV-Transmissions-from-the-International-Space-Station-2015-02-01-0124
2015-02-01 0124 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-01-0258
2015-02-01 0258 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-01-0436
2015-02-01 0436 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-01-0615
2015-02-01 0615 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-01-0754
2015-02-01 0754 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-01-0927
2015-02-01 0927 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-02-0032
2015-02-02 0032 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-02-0205
2015-02-02 0205 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-02-0211
2015-02-02 0211 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-02-0344
2015-02-02 0344 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-02-0525
2015-02-02 0525 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-02-0658
2015-02-02 0658 UTC
SSTV-Transmissions-from-the-International-Space-Station-2015-02-02-0838
2015-02-02 0838 UTC

 

Dongle Bits: ADSB Radar and $60 Police Scanner

This article appeared in the The Lake Erie Amateur Radio Association newsletter The Spirit of ’76 and ’88 February 2015 edition and The Wood County Amateur Radio Club newsletter CQ Chatter March 2015 edition.

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


The holidays were a busy time at the K8JTK laboratories with a couple RTL-SDR projects. The RTL-SDR is the European TV tuner dongle that was turned into a software defined radio receiver.

Thanksgiving is one of the busiest travel seasons and I wanted to decode ADS-B data to see how many aircraft were flying around. ADS-B stands for Automatic Dependent Surveillance – Broadcast allowing aircraft to be tracked by ground stations and provide situational awareness to nearby aircraft. This is part of the FAA’s NextGen project and mandated by agencies across the globe.

I saw this project in the January 2014 edition of QST written by Robert – W9RAN. He covered building a Collinear Array for the ADS-B frequency of 1090 MHz. I used one of my ham antennas. The RF signal received by the dongle is turned into data packets by a program called ADSB# (included in the SDR# download). VirtualRadar receives those packets, decodes the data, and plots aircraft on Google Maps. This setup can work with a Raspberry Pi and I hope to try this in the future.

adsb-07_browser-06_thanksgiving_travel_and_take_off
Thanksgiving travel in Cleveland, Ohio.

Over the Thanksgiving holiday, I saw 25 aircraft flying around Cleveland on average. I think the most I saw was 48 at once. Not all aircraft have full ADS-B implementations. For example: I would see a call sign but no position data. My receive range (depending on aircraft altitude) was east of Toledo to the PA border and south to Canton. Visit my write-up on this project: ADS-B Decoding with ADSBSharp and VirtualRadar Server.

The second project is a little more complicated but it helped me understand how trunked radio systems work. With the FCC narrowbanding mandate in certain RF spectrum, many public service agencies have decided to “go digital.” In my area the MARCS-IP system and the Greater Cleveland Radio Communications Network are most popular. Both are P25 trunked digital systems. P25 is a specification for voice and data transmission. Trunked radio systems operate by having a radio send data to the control channel requesting communication on a talkgroup. The control channel directs all users of that talkgroup to a specified channel. When the user is done transmitting, all radios switch back to monitoring the control channel for further instructions. This is done seamlessly and allows many users (agencies) to use a small set of radio frequencies. Users only hear the conversations on their assigned talkgroup and not other users on the same system.

dongle-bits-06-p25_trunked_decoding-single_voice_decoder
P25 trunked decoding with a single voice decoder.

Scanners that receive these systems run $500 and go up from there. Using two RTL-SDR dongles and software (mostly free), I’ve been able to receive P25 trunked systems for about $65. One dongle monitors only the control channel and other dongle(s) jump frequencies to receive the digital voice modulation with a program decoding the audio. I can have as many voice receivers as I want whereas a scanner cannot be expanded. Most I’ve heard of is eight. There are some drawbacks like portability. Find out my experiences in my P25 Trunked Tracking post.

Fresh Baked Pi

Raspberry Pi foundation released new models over the last couple months. The biggest news coming at the beginning of February: the Raspberry Pi 2. This model comes with a quad-core CPU and 1GB RAM offering a six times speed improvement, still at $35. Initial reports are it is a lot faster!

Raspberry Pi 2

Along with the new Pi2 came a new version of the Raspbian operating system with optimizations and a new look. In the near future, Microsoft will be releasing a version of Windows 10 Embedded for the Raspberry Pi 2 FREE OF CHARGE! (see the Raspberry Pi 2 link above.)

That’s A Wrap

A goal behind this series has been to expose many hams to newer technologies and younger people to ham radio. These technologies are getting young people interested in experimenting, programming, and even Ham Radio. On podcasts I watch, I’ve heard “I want to get my Ham Radio license” by 20 and 30 year olds like I’ve never heard before. These are young people interested in experimenting, making things, building things, and hacking things — all of which are the foundation of Amateur Radio. Making has evolved into writing software, sending a chip a set of commands and analyzing what is returned, or analyzing packets. Then figuring out “what can I do with this?”

I saw a great technology round-table over the holidays and they talked about getting kids into technology. Many of the methods apply to Ham Radio. As a builder, you build something and presume what will happen. Then something different happens and now you have a mystery to solve. “Why did X happen and not Y?” A new theory develops and sucks you in. This is exactly how the Raspberry Pi, RTL-SDR, and every project surrounding them came to be. It is my opinion that we, as the Amateur Radio community, need to encourage, capitalize, and focus efforts on younger makers and hackers to get them licensed.

As this is my last planned article, I would like to take time and thank the newsletter editors for thinking this series was worth publishing and recreating all the links I included. Thank you to those who told others about this series. I got a ton of feedback and couldn’t be happier that others have found this interesting and sparked them to start experimenting. Most of all, thank you for reading.

My Experiences as a New HF Ham Radio Operator

Updated: 5/29/2018

I’ve been licensed since 1999 and upgraded to General and Extra in 2008 but I hadn’t been on the amateur HF bands very much.  When I graduated from Grad School, I bought myself and setup a new HF station.

This post is going to be about my experiences, things I’ve learned along the way, and maybe some things that may not be obvious to someone starting out.  I will add to this post.

This is not meant to be “all-inclusive” by any means and not meant to be a substitute for elmering and experience.  It’s meant to be for someone who has operated VHF/UHF for a long while but just venturing out into HF.

I’m bitter in alot of this post because many points draw on real interactions I’ve encountered.  It’s not to discourage you to operate HF but to be better than the other guy acting like a jerk.  Common sense helps tremendously.  Folks out there who are all about the points, number of exchanges, getting that last contact, and awards common sense almost always goes out the window.  Just remember you have a choice to not work those stations.

A quick note… ac6v.com has a TON of good information on everything from “antennas to zones.”  I think it could be organized a little better and layout is a little 1996ish, regardless 700 amateur radio topics are covered. The Google search at the top really helps finding things.

Let’s get started.

SSTV Transmissions from the International Space Station – December 2014 edition

I saw a news story on the ARRL website that talked about the Russian International Space Station cosmonauts plan to send Slow Scan TV images around the holidays.  December 18 and December 20, 2014.  Those are two of my interests, SSTV (or digital modes in general) and spaceflight.  From the news story:

The Russian Amateur Radio on the International Space Station (ARISS) team members plan to activate slow-scan television (SSTV) from the ISS on December 18 and December 20. The expected SSTV mode will be PD180 on a frequency of 145.800 MHz with 3-minute off periods between transmissions.

I setup my station to monitor 145.800 MHz on both days to see if I could receive any images, I did!

Station setup: MP Antennas Classic Mobile NMO Antenna – This is a local company in Cleveland and were reviewed in QST.  Been using their antennas for a long time with great success.  Since the antenna is multi-polarized (the MP in the company name), it is supposed to be a good substitution for receiving satellite transmissions without a directional antenna and not worrying about Doppler Shift (which needs to be accounted for in some cases).  The height is about 15 feet.

The antenna was connected to my ICOM IC-7000 with DSP settings turned off on 145.800 MHz FM.  Used this radio only because my SignaLink USB is connected to it and the one I use for digital operation on all bands.  MMSSTV is the Slow-Scan TV program I use.

I have tutorials available to help get your station setup and getting started with MMSSTV to receive images from the ISS.

I received 6 images total including 2 partial images from my location near Cleveland (EN91bl) as the ISS was flying overhead.

SSTV Transmissions from the International Space Station 2014-12-18 1901
2014-12-18 1901 UTC
SSTV Transmissions from the International Space Station 2014-12-18 2037
2014-12-18 2037 UTC
SSTV Transmissions from the International Space Station 2014-12-18 2214
2014-12-18 2214 UTC
SSTV Transmissions from the International Space Station 2014-12-20 1719
2014-12-20 1719 UTC
SSTV Transmissions from the International Space Station 2014-12-20 1854
2014-12-20 1854 UTC
SSTV Transmissions from the International Space Station 2014-12-20 2029
2014-12-20 2029 UTC

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.

Android

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.

IMG_0003
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.
Screenshot_2014-09-25-21-24-12
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.