The hardware required to add video to digital voice
Hardware Setup for FreeDV plus Video in Two Easy StepsClick the link below to open the legacy hardware setup page (recommended for older PC's with limited processor capability -- requires an additional USB sound card).
Legacy hardware setup page
When a higher-performance PC is available, the Video TX, FreeDV, and Video RX software are installed on the same PC (as shown in the diagram below). Otherwise, two PC's are used: one for Video TX/FreeDV, and the other for Video RX.
You might want to set up and operate with digital voice first before adding video. Connect the hardware as shown in the diagram below. See the "Software" page for the software required to run FreeDV plus Video.
Step 1: Setup for FreeDV Digital Voice (without Video)
HF Transceiver:The bandwidth for FreeDV+ is 3.5 kHz, so make sure that your transceiver's TX and RX bandwidths can be adjusted accordingly. Another requirement is that the IMD3 must be better than -40 dB for the transmitted signal, requiring either Class-A outputs (some Yaesu transceivers) or adaptive predistortion (soon to be available with Flex Radio transceivers; or use an Apache Labs transceiver with PureSignal). WA6NUT uses PureSignal with an Apache Labs ANAN-10E SDR and an Ameritron AL-811 amplifier. See the link below for information on the ANAN-10E. For more information on adaptive predistortion, see the "PureSignal" and "Technical" pages (links at the top of this page).
Sound Card Interface: The author uses a sound card interface similar to the W1ZE design described in the May 2007 issue of the Yavapai Signal newsletter, pp. 10-11. Substitute Triad TY-145P transformers (Jameco P/N 630459) for the Radio Shack units specified in the article.
The TXfftCO5L application provides an output from the sound card regardless of PTT status. Consequently, if a VOX-operated sound card interface is used, the VOX feature (Auto-PTT™ on SignaLink™ sound card interfaces) must be bypassed, using a USB-to-serial adapter cable and a simple switch circuit (the JP-1 jumper between the SignaLink™ PTT output and the transceiver PTT input must be removed). The adapter cable is connected between one of the PC's USB ports and the DB-9 input of the 1-transistor switch circuit described in the W1ZE article (see the link below). The adapter cable serial output, generated from the PTT button on the FreeDV app GUI, is applied to the switch circuit. The circuit's PTT output is applied to the transceiver PTT input. Thus the FreeDV app PTT button is used to control PTT rather than the sound card interface VOX circuit.
Click on the link below for the W1ZE article, and go to pp. 10-11.
W1ZE Article Link
USB-to-Serial Cable: Required if the sound card interface uses a serial port for TX/RX (PTT) control, and if the Video TX/FreeDV PC has no serial port (connects between the sound card interface and the PC or hub USB port for TX/RX control). The author has used a Gigaware cable (Radio Shack P/N 26-949) with good results. Many amateurs report better performance with USB-to-Serial cables using the FTDI chipset (instead of the Prolific chipset).
USB Sound Card: The author uses a Manhattan Model 151429 USB sound card. A USB sound card with an "input monitoring" feature (such as the Turtle Beach Amigo II) can be used, but will allow undecoded receiver audio to appear at the speakers along with the decoded FreeDV audio (adding noise to the decoded FreeDV audio).
USB Hub: A USB hub is not required if the Video TX/FreeDV PC has 2 or more USB ports. The author has used an older Belkin FSU237 USB hub with good results.
Amplified Speakers: The author uses amplified speakers similar to Cyber Acoustics CA-2014RB speakers
Computer Mic: Almost any electret computer mic will be suitable. The author uses a mic similar to the Cyber Acoustics CVL-1064RB.
Laptop PC: When a higher-performance PC is available, the Video TX, FreeDV, and Video RX software are installed on the same PC. Otherwise, two PC's are used: one for Video TX/FreeDV, and the other for Video RX. A clock speed of 2 GHz or greater is recommended. The author uses an HP 8540w laptop running Windows 7.
Step 2: Setup for FreeDV plus Video (video added to FreeDV)USB Webcam: The author uses the built-in camera on his HP8540w laptop PC (an older Logitech E3560 webcam has also been used with good results).
Laptop PC: If separate PC's are required, the second PC will be used for Video RX. A clock speed of 1.5 GHz or greater is recommended. The author used an Acer Aspire 5516, running Windows Vista, before acquiring his HP8540w laptop.
- 5 July 2013 -
Back to WA6NUT home page