Three new SDRs in the shack

[Terry N4TLF]

Hey Alex,
If you mean that you are saving to disk the raw ADC samples, then the files will be the same size, regardless of how many or how few signals are there.  No signals just means a lower value will be recorded to the disk.  But probably very few 0x0000 values.  More stations just means more recorded samples with higher values.  The file size will depend only on number of bits per sample, the sample rate, and the length that samples are recorded.

Same with noise versus no noise.  This all assumes NO fancy compression techniques are used on the file.  No noise means sample values will be closer to zero, noise means more randomness of, and higher values in the samples.
73, Terry, N4TLF


From: Alex Fraser 
Sent: Tuesday, May 30, 2017 12:54 PM
To: AMRAD Tacos 
Subject: Re: Three new SDRs in the shack

I was thinking this morn, probably the coffee.  
So if you record to disk I would think that if you captured a portion of the spectrum with many stations that the file size would be greater than a less busy part of the spectrum.   Is that true? Then I thought if you recorded a part of the spectrum with noise at a certain level and then recorded another part of the spectrum with a higher noise level, then would the 2 files sizes be the same or different? I'm ignoring OS overhead.
I'm sure there is a mathematical explanation for this and if need be I WILL drink more coffee...

Terry Fox wrote on 5/29/2017 8:46 PM: 
  I have recently purchased three new SDRs for testing and playing with.  Up front:  I have NO RELATIONSHIP with any of these companies, other than being a customer, who paid full-price for everything. 

  1/2:  BooyaSDR 
  The first two are BooyaSDR units.  These are different than almost all other SDRs available to RF enthusiasts at the moment, in that they sample the RF input directly, then send ALL those samples to the host computer.  No FPGA or other device to reduce the amount of samples.  The host computer then does all the computations to show the FULL bandwidth of their respective input.  The software shows this spectrum display in a series of waterfalls stacked on top of each other.  I purchased one of the 100MHz full SDR & antenna, and then a 16MHz digitizer set, less antenna.  I also have a 64MHz oscillator that I can put in place of the socketed 100MHz oscillator, so I can test the boards at that lower rate. 


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