capture a whole ham band

[wb4jfi at knology.net]

Yes, it is possible.  The entire 20M band is only 350kHz wide.  In general, if you want to capture that wide a spectrum swath, you are looking at direct down conversion (DDC) based SDR hardware, NOT QSD-based ones.  That implies more sophistication and higher cost.  Some of the better DDC-based SDR hardware packages can actually monitor more than one complete amateur band at once.

There are several SDR hardware/software packages that can suck in 384kHz or better, and store the I/Q on hard disc.  Then, it can be played back at a later time.  Noise versus signal is determined by dynamic range, etc.

I believe the SDR-IP or Net-SDR (bigger cousins of SDR-IQ) by RF Space can do that.  So can Perseus and the Quicksilver SDRs.  The openHPSDR Hermes project is being adjusted to do that, as is the multi-board openHPSDR boardset.  The HiQSDR can also do that.

The DDC-based SDR-IQ CANNOT, neither can any Flex deliverables at the moment, they are all QSD-based.  The new Flex 6000-series will be able to do much more than that.  Softrocks cannot do that, as they rely on soundcards for A/D conversion, and I’m not aware of any soundcards that sample higher than 192k.  Even if they did, the input filters would probably drop out well before 350kHz.

Our own Charleston SDR can also do that, as far as the hardware goes.  I have had my Charleston SDR RX and Quisk under Linux showing up to 960kHz of spectrum at a time, with excellent refresh rates.  That’s about its limit for now.  I know there has been some improvements to Quisk, and saving raw I/Q data is now included I believe.  So, it may be doable on a Charleston SDR setup.  But, the Charleston SDR Receiver uses a 12-bit A/D, so the dynamic range may be limited when compared to other options.  But it IS cheaper!!
73,
Terry, WB4JFI



From: Alex Fraser 
Sent: Saturday, April 13, 2013 1:49 AM
To: tacos at amrad.org 
Subject: capture a whole ham band

Is it possible to capture the entire 20 meter band and record it to disk?  I mean everything including the noise so if you played it back at a later time
you wouldn't be able to tell it from the real live band.

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