PERSEUS can be operated also in a wide band mode as a 10 KHz - 40 MHz spectrum analyzer with more than 100 dB dynamic range in a 10 KHz resolution bandwidth.

PERSEUS is a Software Defined Radio and relies on PC software applications to carry out the demodulation process. Compatibility and support of most used software will be provided by an interface DLL for Microsoft Windows operating systems and drivers for Linux.

SOMETHING MORE ABOUT PERSEUS

Advanced technical specifications.

The first PERSEUS printed circuit board, ready to be assembled but still unpopulated by passive components. The ADC driver is barely visible in the lower left corner of the photo. From left to right are also visible the receiver ADC (a Linear Technology LTC2206-14), the configurable digital down-converter (a Xilinx XC3S250E Spartan3E device) and the USB 2.0 interface controller (the ubiquitous Cypress 68013A).

MEASURING THE PERFORMANCE OF PERSEUS

Below are some pictures of the FFTs of samples buffers acquired with the PERSEUS  receiver imported and processed with Matlab. PERSEUS can store in its DDC memory up to 8192 contiguous samples at 80 Ms/s and transmit them to the PC at about 40 MBytes/s allowing a 0-40 MHz spectral analysis with a 10 KHz resolution bandwidth.

PERSEUS Noise Floor (Averaged 8K FFT, Rectangular Window, Dither OFF, ATT=0dB)

Notes: The resolution bandwidth of an 8K FFT of an 80 MS/s input is about 9.8 KHz or about 40 dBHz. The measured average noise level in this bandwidth is -118 dBm.
The receiver input noise spectral density is therefore -158dBm/Hz and the noise figure is 16 dB. 
The resulting MDS is -131 dBm in 500 Hz BW (CW) and -124 dBm in 2.4 KHz BW (SSB).
Note the 1/f excess noise which is barely visible on the low-left corner of the picture at very low frequencies.

PERSEUS Noise Floor (Averaged 8K FFT, Rectangular Window, Dither ON, ATT=0dB)

Notes: The measured average noise level with dither generator enabled is now -117/-116 dBm (again in 10 KHz BW).
The receiver input noise spectral density is therefore -157dBm/Hz and the receiver noise figure is now 17/18 dB.
Dithering affects receiver noise more than declared in the LT2206-14 ADC datasheet. This is due to the fact that the
Linear Technologies ADC requires a precise driver impedance to cancel exactely the dither signal at its output.
Unfortunately this requirement is in contrast with the requirement of band-limiting the driver noise to get out from the ADC
the best blocking dynamic range.

PERSEUS Harmonic Distortion at -1 dBFs (Averaged 8K FFT, Blackman Window, Dither OFF, RF Filter ON)

Notes: A - 7dBm (-1dbFs) signal at 6.6 MHz is injected at the receiver input with the 20 m band preselector, a six poles
12 MHz-17MHz band-pass filter, inserted. No HD2 harmonic distortion is visible at 13.2 MHz (which is within the selected band).
HD3 falls at 19.8 MHz and is not visible as well (HD2, HD3 > 110 dBFs). Birdies at 25.1, 31 and 33 MHz are at -107 dBFs (dither is off).
Among others, the scope of the Perseus band-pass filters bank is that of reducing the amplitude of  input signals with frequencies such
that their harmonics fall in the selected band. In this example the preselector introduces at least 15 dB of attenuation at 8.5 MHz,
which is one half the selected upper band limit (17 MHz). Without preselection filters, harmonic distortion in direct sampling
receivers is the source of high spurious signals since even the best wideband amplifiers can't provide the required 110/115 dB HD
suppression.

PERSEUS IMD3 Distortion with two input tones -15 dBm (Averaged 8K FFT, Blackman Window, Dither OFF)

Notes: In a direct sampling architecture the two-tone IMD3 performance is not influenced by carrier spacing (at least it should not).
Here, to simplify the instrumentation setup, the carrier spacing is about 1.8 MHz. The noise floor at mid band is due to the poor noise performance
of the signal generators which have been used for the test. Averaged third-order IMD products are at about -110 dBm. Resulting IIP3 is approx. 32.5 dBm.