[TangerineSDR] Functional Specification v 0.3

[Engelke, Bill]

Tom – a question for you – are you sure it is necessary to convert the 24-bit I and Q to single precision floating point? When I read the Digital RF 2.0 documentation, I find the following:

Another design decision underlying Digital RF is the requirement to support storing RF data in
rf_data in a variety of data types. Data can be written as either complex or real (i.e.,
single-valued) numbers. Data formats can be any data format supported by the HDF5 standard,
from bytes to 128 byte floating point numbers.

Are you referring to a different version of Digital RF?    -73- Bill, AB4EJ



From: Tom McDermott <tom.n5eg at gmail.com>
Sent: Sunday, May 26, 2019 9:08 PM
To: TAPR TangerineSDR Modular Software Defined Radio <tangerinesdr at lists.tapr.org>
Cc: Scotty Cowling <scotty at tonks.com>; Engelke, Bill <bill.engelke at ua.edu>
Subject: Re: [TangerineSDR] Functional Specification v 0.3

Hi Bill - thanks for iterating the specification.  Here are a few comments on 0.3:

There are no paragraph numbers to  reference, and the page numbers may change
depending on how mark-up is selected by the reader, so I'll reference the Title of the paragraph.

General Requirements - Assumptions and Dependencies:

1. The HD may be able to be reduced to 2TB if the 20GE snapshot
can be made while recording to the ring buffer.  2T SSD drives
are coming down in price faster than 4T.

Technical Notes

I am skeptical that a SBC-based host can run HDF5 and keep up
with the received data. My quad Core I7-3740 3.4 GHz can not
keep up with 4 x 192k from one antenna (one fourth the DE
requested throughput). It may be better to run HDF5 only on the
snapshot that is uploaded to the Central Server. That way it
doesn't have to run at real-time speed, it only needs to code a small
subset of the data and can run at a much slower rate paced by how
fast the upload link is.

Data format.  The DE will downconvert and decimate the received
samples. This will produce 24 bit I and 24 bit Q samples, probably 2's
complement binary.  These will need to be converted to single
precision floating point I and floating point Q prior to HDF5 encoding.

 -- Tom, N5EG



On Fri, May 24, 2019 at 12:40 PM Engelke, Bill via TangerineSDR <tangerinesdr at lists.tapr.org<mailto:tangerinesdr at lists.tapr.org>> wrote:
Scotty - Please see attached, updated to include some of the things discussed at Dayton.  Next I will work on the Functional Specifications for the Central Control & Database system.

If anyone would like me to start posting to the TAPR github or somewhere, please just text credentials to my mobile number, below.  I can assure everyone that I will not make a mess of it, having done this before.

W. D. Engelke (Bill), Asst. Research Engr.
Center for Advanced Public Safety
Cyber Hall
The University of Alabama
Tuscaloosa, AL 35487
Desk: (205) 348-7244
Mobile: (205) 764-3099

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