by Alberto I2PHD
What is a Software Defined Radio?
| Joe Mitola says, "A software radio is a radio whose channel modulation waveforms are defined in software. That is, waveforms are generated as sampled digital signals, converted from digital to analog via a wideband DAC and then possibly upconverted from IF to RF. The receiver, similarly, employs a wideband Analog to Digital Converter (ADC) that captures all of the channels of the software radio node. The receiver then extracts, downconverts and demodulates the channel waveform using software on a general purpose processor." [1] | |
SDRadio is only a subset of the above definition, dealing only with the receiver part, and the ADC is not exactly wideband, but it is what is offered by the majority of today's sound cards, i.e. either 48 or 96 kHz. Nevertheless it can be considered as a first step in that direction. |
V0.93
The FM demodulator is now implemented (thanks Barry Dieser)
A new feature
has been added, to compensate for the time skew between left and right
channels
exhibited by some sound cards
Possibility to select which sound card to use, if the PC has more than one
Minor tune up and bug fixes
V0.94
The I and Q channels are swappable, for compatibility with the SDR-1000 hardware.
When
dragging with the mouse the left or the right border of the bandpass, the
low pass and
the high pass frequencies are dynamically displayed.
V0.95
Sampling rate selectable (48 or 96 kHz).
AGC gain adjustable
Improved sound card detection
Audio filtering now works as it should...
Some streamlining of the code in the USB/LSB/ECSS decoders
V0.99
External LO frequency settable for a correct frequency display
Fine tuning with the mouse wheel
Improved audio quality (meaning that a bug has been corrected...)
Improved denoiser
Polyphase FFT for spectrum display
| click here to download a self-extracting package | |
| click here if you need the previous Version 0.95 | |
| click here to download the untested Version 1.00 |
(just a word of caution : in its present form SDRadio needs at least a 400 MHz Pentium II. Don't try with less)
A nice hardware that can be used with SDRadio is the recent project by the AMQRP club, the SoftRock40 (now V5)
| SDRadio can also be used with
simple mixers that do not produce I/Q outputs, albeit with the tunable bandwidth reduced to 24 kHz from the original 48. An example of a commercial HW useable with SDRadio to implement an HF receiver can be found here |
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