[TangerineSDR] VLF-RX tools

Jonathan emuman100 at gmail.com
Thu Mar 11 19:02:30 EST 2021

Hi Phil,

The stream format is not documented, however, it can be derived from the 
source code of many of the utility programs, like vtcard, vtcat, vtraw, 
and vtwavex to name a few. It's single-channel or multi-channel pcm with 
timestamping information. vtcat can combine single channel streams, say 
from an E-Field receiver and two B-Field receivers into a multi-channel 
stream and align timestamps of all channels.

I'm not an expert at C by any means, and I haven't really looked at 
understanding the stream format in the source code yet. For a conversion 
utility, would the stream have to be copied and phase-shifted to generate 
IQ data?

vlfrx-tools captures and works with data in its original form. From the 
soundcard, it's a pcm audio stream. There are utilities vtrtlsdr and 
vtsdriq that read data from a RTL dongle or SDR-IQ receiver respectively. 
vtsdriq can output either I and Q data in two channels or a single channel 


On Thu, 11 Mar 2021, Phil Erickson wrote:

> Date: Thu, 11 Mar 2021 04:33:08 -0500
> From: Phil Erickson <phil.erickson at gmail.com>
> To: TAPR TangerineSDR Modular Software Defined Radio
>     <tangerinesdr at lists.tapr.org>
> Cc: Jonathan <emuman100 at gmail.com>
> Subject: Re: [TangerineSDR] VLF-RX tools
> Hi Jonathan,
>  I looked at the documentation (HTML page) but I cannot find a precise
> definition of the stream format.  Where is that located or could you
> summarize that?  It would then be possible for those of us familiar with
> DigitalRF, and in particular the Haystack team who maintains it, to examine
> the ways in which a .vt file could be translated to DigitalRF or the other
> way around.
> 73
> Phil W1PJE
> On Wed, Mar 10, 2021 at 10:46 PM Jonathan via TangerineSDR <
> tangerinesdr at lists.tapr.org> wrote:
>> Hi Tom,
>> Thank you for looking at the documentation for vlfrx-tools! I'll list some
>> useful utilities included in vlfrx-tools to try to illustrate how useful
>> they can be. A utility can be written to convert to DigitalRF/HDF5,
>> however, vlfrx-tools does not normally generate IQ data.
>> For others on the list, the vlfrx-tools documentation is
>> available at http://abelian.org/vlfrx-tools/ and this also includes the
>> source code. Also, for the others on the list, I'd like to make the
>> argument that vlfrx-tools is advantageous because of its useful toolset in
>> analysis and post-processing of both natural radio, amateur radio in the
>> VLF band, and VLF transmitters. Such tools don't exist (to my knowledge)
>> for formats like DigitalRF. Since vlfrx-tools is such a diverse and
>> usefull toolset that already exists, it's advantageous to utilize it in
>> post-processing on the PSWS database to make available SID events,
>> whistler and chorus events, and lightning location data, just to name a
>> few.
>> vtblank - an impulsive noise blanker that removes sferics and other
>> impulsive noise from the VLF spectrum. It's useful in studying VLF
>> transmitters and especially useful for VLF QSOs.
>> vtam - used to extract the magnitude of a non-stationary signal like a
>> sferic. You can examine the timing of sferics, whistlers, and the edges of
>> timing signals like WWVB.
>> vtpolar - generate a polar plot movie of a triple axis VLF stream. This
>> allows you to see the bearing of incoming VLF signals like whistlers.
>> Please watch the movie in the documentation!
>> vtsid - automatically  detects sudden ionospheric disturbances with VLF
>> transmitters like NAA. It generates a plot and a data file. The extraction
>> utility can extract records from that data file.
>> vtevent - automatically detects whistlers and chorus and generates a
>> spectrogram plot, data file, and audio file of the event.
>> vttoga - creates time of group arrival data from sferics the incoming VLF
>> stream or a file.
>> vtspot - used to generate lightning location data from vttoga data from
>> VLF receivers around the world. The PSWS database can provide lightning
>> location data using a network of receivers.
>> vtping - used to detect meteor ping.
>> vtwrite - writes a VLF stream, either from a ring buffer or network
>> socket, to file for storage.
>> vtread - reads a .vt file into a ring buffer or network socket.
>> vtraw - extract raw audio froma VLF stream. This also removes the
>> timestamping.
>> vtwavex - extract a wav file from a VLF stream. This also removes the
>> timestamping.
>> These are just some examples of useful utilities of vlfrx-tools. A utility
>> to convert a .vt file to DigitalRF/HDF5 can be written (however, I cannot
>> support that). Also, vlfrx-tools does not generate IQ data normally. But,
>> with such a toolset, so much can done. I would hope this convinces some of
>> those who may be skeptical. In any case, I urge you to look at the
>> documentation.
>> Jonathan
>> On Wed, 10 Mar 2021, Tom McDermott via TangerineSDR wrote:
>>> Date: Wed, 10 Mar 2021 12:07:26 -0800
>>> From: Tom McDermott via TangerineSDR <tangerinesdr at lists.tapr.org>
>>> To: TAPR TangerineSDR Modular Software Defined Radio
>>>     <tangerinesdr at lists.tapr.org>
>>> Cc: Tom McDermott <tom.n5eg at gmail.com>
>>> Subject: [TangerineSDR] VLF-RX tools
>>> Hi,  I don't have Jonathan Rizzo's direct email, so sending this to the
>>> list.
>>> We talked a bit about the VLF receiver on the last conference call, and
>> the
>>> VLFRX tools.
>>> I'd like to email with Jonathan directly.   It appears those tools have
>> the
>>> ability to
>>> read from a file (and thus in Linux from a named pipe).  Gnuradio can
>> write
>>> to a named pipe
>>> as well to DigitalRF (HDF5).   Perhaps this may provide a mechanism to
>>> hook the receiver both to the Tangerine archiving method as well as to
>>> VLFRX.?
>>> -- Tom, N5EG
>>> n5eg at tapr.org
>> --
>> TangerineSDR mailing list
>> TangerineSDR at lists.tapr.org
>> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org
> -- 
> ----
> Phil Erickson
> phil.erickson at gmail.com

More information about the TangerineSDR mailing list