1.) The headset and mic must be the Windows default sound playback (headphones/speakers) and recording (microphone) device. The HelpDesk article, How To Set The Windows Default Playback & Recording Audio Device describes how to set the headphones and mic connected to the PC as the default Windows sound devices. If you are using a USB headset, you will want to connect it to your PC and configure it as the default sound device. Also, if you are using VAC or DAX to operate digital modes with your FLEX Software defined radio, you may need to change the default sound device that Windows automatically assigns when new sound devices are added to your computer. Right-click the listing for your sound card or audio device, then select Update driver Browse my computer for driver software Let me pick from a list of device drivers on my computer. Select the audio device whose driver you want to update, select Next, and then follow the instructions to install it. Flexradio systems FLEX-6500 Pdf User Manuals. View online or download Flexradio systems FLEX-6500 Installation Manual. (Sound Card Interface) 40. Download and unzipp '986LCD-M Audio Vista-Win7 R241.zip' from Kontron web site for system sound card driver. Update system sound card driver ( Realtek High Definition Audio ). Other system devices use drivers included in Windows 7. PowerSDR performance will benefit from disabling Windows search indexing ( 'Windows Search' service ).
Recently, Guy Atkins mentioned his first software defined radio receiver, the FlexRadio SDR-1000. In particular, he mused about trying to get this gear to work with different PC sound cards.
Remember sound card radio receivers? For many of us, our first experience with analog to digital conversion (ADC) was with sound cards in our computers. Here is how those early SDR worked, around twenty years ago.
Motorola engineer Dan Tayloe invented a quadrature sampling detector. You could use this very simple circuit to convert radio signals down to quadrature (I/Q) signals at baseband. What was neat about this approach was your ability to just feed these baseband signals into the stereo sound card on your computer, and do the rest of the demodulation in software. Effectively, you created a direct conversion or low IF receiver using the Tayloe product detector.
Flexradio Sound Cards & Media Devices Drivers
How good were these early SDR sound card radios? That depended on the sampling rate and bit depth of your PC sound card. Early sound cards ran around 44 kHz sampling rate at 8 bits. With a stereo sound card, the sampling bandwidth was the same as the sampling rate. Dynamic range depended on number of bits. Early sound card radio provided similar performance as an RTL-SDR over a narrow slice of frequencies.
More expensive sound card provided 96 or 192 kHz sampling rates with data sized at 16 or 24 bits. These provided a wider spectrum display and great dynamic range, around 100 dB. You can see a list of these early QSD-Sound Card radio systems on the F4DAN web site.
The FlexRadio SDR-1000 came to market in 2003 and was the first heavy duty transceiver using sound cards for analog to digital conversion on receive and transmit. Steve Ford’s original QST Product Review described this as “new chapter in the history of Amateur Radio.” And, it was indeed.
Flexradio Sound Cards & Media Devices Driver
Sound Card Radio – Thank Gerry Youngblood
I remember reading Software Defined Radio for the Masses, a series of four articles in QEX magazine that began in Summer 2002. Read these for yourself. In easy to understand terms, Gerry took us through the use of QSD to create I/Q data. Next he wrote Visual Basic code to create an entire software defined radio. Finally, FlexRadio was born and brought the SDR-1000 to market.
If you want a deep dive, watch Gerry Youngblood tell the story of FlexRadio, the accidental company. His presentation starts at around 9 minutes into this video.
Now, of course, we have moved on to direct sampling. No more sound card radio. And, of course, FlexRadio continues to lead the way.