DroidSSTV lets you transmit and receive Ham Radio SSTV (Slow Scan TV) on you Android Smartphone or Android tablet. A great tool for portable or home based Amateur Radio SSTV operation. Just connect your phone or tablet though a small interface to an HF radio (or even set it next to the radio’s speaker), tune in an SSTV frequency, and watch the pictures.
DroidSSTV supports the modes Scottie 1, Scottie 2, Scottie DX, Martin 1 and Martin 2 at this time. The screenshots of DroidSSTV in the following manual are taken from a Samsung Galaxy phone. The layout on other phones and tablets might be different.
- Receiving screen
- Transmitting screen
- Selecting an image
- Template editor
- History screen
- Interfacing a phone to a radio
- SSTV Frequencies
- Spectrum analyzer graph for easy tuning
- Auto synchronization (auto slant correction)
- Auto mode detect
- VIS encoding (detects SSTV header and sets mode automatically)
- Level bar for adjusting the audio signal
- Auto save received pictures to SD Card.
- Share received pictures (Email, Dropbox etc.)
To decode a SSTV image just hold your phone/tablet’s microphone close to a speaker of your ham radio receiver or transceiver. SSTV uses a 1200Hz synchronization signal as well as the luminance frequencies between 1500Hz and 2300Hz. The frequency spectrum is shown in the FFT graph. DroidSSTV will try to detect the header signal (VIS signal). If DroidSSTV can’t find the VIS code it will try to set the mode by measuring the time between the synchronization signals.
The level bar next to the FFT graph shows the signal strength of the received signal. The audio level of the radio should be adjusted so that the only the green boxes and not the red boxes light up. Overdriving might cause distorted images.
After DroidSSTV receives a full image the image will be saved to the SD Card and can be viewed in the History screen. The auto save function can be turned on/off in the DroidSSTV settings.
A macro button can be used to enter QSO data like “his call sign” or “my RST”. This data can be used in the templates for transmitting.
- Pre-loads up to 9 pictures from the SD Card into DroidSSTV’s gallery
- Adjusts contrast, brightness and saturation
- Template editor for easily overlaying templates over images
- Macro’s for use with templates
To transmit you must first select the appropriate mode. Press the blue mode button on the top and choose between Scottie 1, Scottie 2, Scottie DX, Martin 1, or Martin 2
In DroidSSTV you can choose images for transmission and you can overlay them with a template. On the botton of the screen you find an "icon bar" with "red frame" icons for images. If you scroll the "icon bar" to the left you will see icons with a "green frame" which are used for templates.
Now an image needs to be selected. Right click a “red framed” icon on the bottom and the image selector / editor will show up If you have previously selected an image, just click on that image and it will be copied into the transmit image window.
Templates can be created by long-clicking a “green framed” icon (scroll the bottom icon gallery to the right).If you have previously created a template, just click on the icon and the template will overlay the image.
To start transmit press the “start tx” button.
The header in the image prints your callsign on the left and the DroidSSTV version on the right. The header can be turned on/off with the “Header” button.
This menu lets you select the app that will used to choose the image. The menu might look different on your device but the “gallery” item should be always present. By clicking on gallery the gallery opens and an image from the phones memory or SD Card can be selected.
After the picture has been selected you may adjust the picture’s brightness, contrast, and color saturation. You can also move and crop the picture–tap and drag the red rectangle in the center to move it across the image; tap it on the bottom right area to crop it. Press the “select” button to save the image and return to the transmit screen
With the template editor templates can be created to lay them over a picture. To create a new template long click an icon with a green frame from the transmit screen.
A new text can be created by pressing the button with the green +. The text “notext” shows up in the middle of the window. The text can be dragged across the screen. To edit the text click the white edit field. A keyboard shows up and the text can be edited. Macros can be added to the text. The following macros are available:
- %m my callsign
- %c his callsign
- %n his name
- %q his QTH
- %r his RST
- %s my RST
A macro can be selected from the list which appears when the “Macro” button is pressed. The macro can be also typed into the text edit field. Macros and regular text can be combined; for example “de %c”
The font size can be adjusted with the “font size” slider. The font color can be changed by pressing the “font color” button. A “color selection window” will appear. A stroke can be placed around the text. The stroke size and color can be selected/adjusted the same way as the text.
A text can be deleted by pressing the red X button.
The “save template” button saves the template and returns to the transmit window.
Complete received images will be saved to your device’s memory or SD Card. The images can be accessed through the “History” button. A long-click on an image will open a “share” menu and the images can be shared by email or another installed app which supports image sharing. The auto save function can be turned on/off in the DroidSSTV settings.
Several user adjustments can be made in the settings. The “screen lock” prevents the phone from going into sleep mode. This consumes more battery power since the screen is always on. The best way to save battery power is to set the “screen timeout” (in Android settings) to a higher value (like 5 minutes) and uncheck “Screen lock” in Android settings. This way the phone will not go into sleep mode while transmitting an image.
The “hide notification” should be enabled on phones with a smaller screen.
In the “Graph settings” item the delay and speed of the FFT graph can be adjusted.
In the “TX settings” your call sign can be set. This call sign can be later used in templates.
The “save images to SD Card” setting switches on/off the auto-save function for received images.
This is a small interface which makes it possible to connect an Android cell phone or tablet to a FT- 817. This circuit might work on other radios as well but I was only able to test it on a FT817 and an IC756PROII. The goal was to build an interface which doesn’t need an external power supply. Since the Android device doesn’t have a serial port to switch the PTT another solution had to be found. After some research on the internet I found a nice schematic from KH6TY (https://sites.google.com/site/kh6tyinterface/ ). I built the board but all the available Android cell phones and tablets (Droid Incredible, Dell Streak 7 and Motorola Xoom) only provided about 200mVss audio output which is not enough to switch a transistor. The solution is use the 1.5V – 2.5V voltage supplied in the audio in pin of the phone. This voltage can be used to drive a transistor and amplify the audio out signal. The amplified signal is then rectified and drives a transistor which switches the PTT.
The following schematic has been tested on the following devices and always performed fine: Motorola Xoom, HTC Flyer, Samsung Galaxy Nexus, HTC Droid Incredible, and Dell Streak 7.
70 cm: (FM)
430.950 MHz SSB SSTV Call Freq.
1.25 m: (FM)
223.850 MHz 1.25m Band SSTV Call Freq.
2 m: (FM)
145.500 MHz 2m Band SSTV Call Freq.
145.600 MHz 2m Band SSTV Call Freq.
144.550 MHz SSB SSTV Call Freq.
6 m: (FM)
50.680 MHz 6m Band SSTV Call Freq.
50.950 MHz SSB SSTV Call Freq.
10 m: (USB)
28.680 MHz 10m Band SSTV Call Freq.
11 m: (USB)
27.700 MHz France, Australia
27.420 MHz Australia
27.235 MHz Northern Ireland
12 m: (USB)
Every day 24.975 MHz
15 m: (USB)
21.340 MHz 15m Band SSTV Call Freq.
20 m: (USB)
14.230 MHz 20m Band SSTV Call Freq.
14.233 MHz 20m Band SSTV Call Freq.
14.240 KHz Europe SSTV Call Freq.
40 m: (LSB)
7.033 MHz 40m Band SSTV Call freq.
7.171 MHz 40m Band SSTV Call Freq.
7171 KHz Europe DIGITAL SSTV Call Freq.
7040 KHz Europe SSTV Call Freq. (7043)
80 m: (LSB)
3845 KHz 80m Band SSTV Call Freq.
3730 KHz Europe Call Freq.
3733 KHz Europe DIGITAL SSTV Call Freq.
160 m: (LSB)
1890 KHz 160m Band SSTV Call Freq.