capture a whole ham band

Sat Apr 13 16:07:20 CDT 2013

No test.  It is an open-book, self examination.  Extra points should be given to yourself for discovering inaccuracies.  Chalk this up to another lame attempt at humor before I wake up in the morning.  I guess the group is not interested in how resistance is futile when one meditates, saying ohhhhmmm, ohhhmmm, milliohhhhmmmm.  Say it ain’t so, Seven-Of-Nine.

I’ll go back to soldering my fingers together now.
Terry

From: Phil 
Sent: Saturday, April 13, 2013 11:38 AM
To: Tacos AMRAD 
Subject: Re: capture a whole ham band

Sir, is there going to be a test after the lecture? How many marks? Will it be multiple-choice? Can we use our notes? Will there be a re-test if we fail? 

Phil M1GWZ

On 13 Apr 2013, at 13:52, <wb4jfi at knology.net> wrote:

  Sorry Phil.  I forgot that this is no longer a technical group.  Once, we helped create packet radio, now we look for packets to hold the hot (mild really) sauce for our tacos.

  I use “SDR” to mean Still Da Radio, as in some of us are still interested in messing around with radios.  Yes, radios can be purchased (I like Philmores myself), but there’s nothing like burning your hand with the wrong end of a soldering iron to wake yourself up in the morning.  I sometimes also use SDR to mean “Solder Da Radio”, astute readers can usually determine which I meant by applying rules of context.

  I have a few hundred VHS tapes, but nary a working VHS machine anymore.  Can I do the same thing with a DVD burner?  I have several of those.  VHS stands for Video Home System, and was developed so that homes no longer needed $100,000 Quad video (and audio) recorders to watch soap operas.  Soap operas are episodic works of fiction, formerly on TV during daytime hours (now more often broadcast during evening hours) and was originally targeted at kids watching TV at home, skipping school to avoid getting soap in their mouths from the teachers for saying bad things.  

  TV typically stands for tele-vision, which is a method of sending and reproducing both audio and video from one location to another in more or less real time, either live or pre-recorded on Quad video recorders.  Broadcast is the process of sending information to two or more destinations without a worry as to who else might also capture it.  A Quad video recorder was called that because it used a set of four record/playback heads mounted on a fast spinning wheel that often cut across a two-inch wide, longitudinally-moving magnetic material.  Kind of like an open-reel audio recorder with a lot of complex junk thrown on top.  I use the terms audio and video to mean sounds and moving pictures.  Moving pictures is not meant to be transferring a static picture from one wall to another in your house, but rather a sequence of pictures used to capture movement.  Like a film movie but without sprocket holes.  Film is a no-longer existent method of capturing images (moving or still) using ancient birds and stone tablets.  See “The Flintstones” for an accurate representation.

  DVD stands for Digital Versatile Disc, or Digital Video Disc.  It is an interim audio/video recording & playback system that replaced VHS video recorders.  The recording medium looks a lot like a CD, only shinier.  A CD is a Compact Disc, which replaced open reel audio tape recorders, or eight-track, or four-track, or audio cassette recorders.  All of these “new” digital standards replaced analog recording methods several years ago here in the modern world.  The modern world is thought to be these later times, after when fire could be reproduced at will.

  I understand that those older, analog technologies, were all implemented using some glowing devices for analog signal processing, often called valves.  What a glowing device (valve) that required high voltages (above 12VDC) had to do with controlling liquids, I just don’t understand.  Maybe these valves have something to do with moving us into modern times, as they helped us create fire at will.

  BTW, VDC typically stands for Volts of Direct Current.  Which is not really accurate, as Volts are not a measurement of Current, that is reserved for Amperes, or more commonly Amps.  Volts is the measurement of electrical potential, and is named after the famous author and  scientific genius, Voltaire.

  BTW, BTW is not a technical term, it means By The Way.

  I have seen the “wave'” implemented with small to mid-sized crowds, usually at a rock concert.  Is that what you mean by a medium wave?  I assume that a large wave is what a crowd does at a football or soccer tournament.  Is AM another outdated abbreviation, for Analog Methods?  I  MUCH prefer DM myself (Digital Methods).  With DM, I can keep track of what is happening using my fingers.

  Rock concerts are where a bunch of semi-elderly gentlemen (and the occasional woman) get together and create weird noises and thrash around the stage, apparently trying to elicit wave action in the gathered crowd.  Sometimes this is accomplished with old analog equipment that still uses valves for lower-frequency (audio) signal creation and amplification.

  Audio is thought to be waves in the frequency range of between....  I’m tired.  Tomorrow I will attempt to explain why we no longer use horses to pull our carts, and why it is bad to look down the barrel of a cannon to see if it has been fired yet.

  Terry, WB4JFI

  From: Phil 
  Sent: Saturday, April 13, 2013 7:19 AM
  To: Tacos AMRAD 
  Subject: Re: capture a whole ham band

  Gosh, what a lot of abbreviations and jargon. I've seen the whole medium wave (AM to you guys) broadcast band recorded for three hours on a domestic VHS video recorder, about twenty years ago. Who needs digital? 

  Phil M1GWZ

  On 13 Apr 2013, at 07:33, <wb4jfi at knology.net> wrote:

    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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