Regular reports of my grabber activity and that of others, plus information on QRSS software, hardware and technique that comes my way

Wednesday, August 29, 2012

Using DropBox to Build an On-Line Grabber

Building an on-line grabber is a two step process.  First, download and learn to use a waterfall display grabber such as ARGO or SpectrumLab.  Of the two, ARGO is much simpler to use while SpectrumLab is more versatile....I have a SpectrumLab turorial on this blog to help overcome the learning curve.

Second, upload your grabs either to a web page or to the DropBox photo sharing service.  The web page approach is more versatile and sophisticated but has a steep learning curve if you don't already know how to design a web page and get in online.

That's where DropBox comes in.  All you need to do is open a FREE account which links a folder on your computer directly to one at DB.  Then as ARGO or SL makes the grabs and stores them in the computer's DB folder they magically appear in the one at DB.  Furthermore, DB is designed for image sharing and all you need do is obtain the link to the image in question and show it to the Knights so they can view it.

I've been running an auxiliary online grabber using this method and it works FB...with one will not automatically update and the user needs to click his refresh button to see the latest grab.  This is not considered objectionable according to several comments I've received.

Here are the details of the DB folders.

After setting up the *Free* DB account this is the opening screen you will see.  You are provided with two basic folders, one called Photos, which we will be using, and another called Public which is useful for other files such a programs and sound files.  Note also the Getting Started file which will explain everything.

Next open the Photos folder which will look something like this:

The only one of interest to us is 10 Minute Grabber which is where the grab ends up.  Open this one and we see,

a single file which is the actual .jpg  uploaded from the grabber and which is to be viewed by the user.  Click on the "link" icon to the right to copy the link and pass it along to your potential user.

This is the actual folder set-up at DropBox and there is a similar one on your computer at a location you specify when setting it up.  This is where you direct the grabs made by ARGO or SL.

Note that I gave the file a rather strange name..."W4HBK Grabber  (REFRESH for latest grab)".  That's so a message will show up at the top of the screen to ID my grabber and remind the user to hit the REFRESH button once in a while.

Here is the link to my DB grabber.  I can't guarantee it will be active but there will be the last grab I made.

I shortened this using the Google URL shortener to:

de w4hbk

Sunday, August 19, 2012

Dopplergram Catches a Solar Flare

Yesterday I took a day off from grabbing to try my new Dopplergram on the WWV 10 MHz signal.  As luck would have it an M-class Solar Flare occurred during the recording:

Figure 1.  Solar Flare of 18AUG12 as seen on Dopplergram

Figure 2.  Solar Flare of 18AUG12 as seen on 10 minute grabber

Figure 3.  GOES X-ray flux

An M-class flare commenced just before 1610z.  The increasing frequency means the path length was decreasing as the reflecting layer moved downward

This is the cleanest data I've recorded of a flare and justifies a calculation of Ionospheric motion from the observed Doppler shift.  I assumed a simple triangle relationship of the radio path (Earth's curvature ignored) and obtained distance parameters via the Internet and the take-off angle of the signal from W6EL's propagation program.  The calculations are as follows:

Figure 4.  Calculations of vertical velocity of Ionosphere in response to Solar Flare of 18AUG12

The estimated vertical velocity of the reflecting layer was ~ 250 km/hr for a 1 Hz shift or 750 km/hr (466 mph) for the maximum 3 Hz shift as seen in Figure 2.

If we assume the average speed was 104 m/s (corresponding to an average Doppler shift of 1.5 Hz) then the distance moved by the Ionosphere over a period of 45 seconds was  4.7 km which is small compared to the starting distance, h, of 217 km.  Thus h can be assumed constant.

Bottom line:  the Ionosphere moved vertically downward in response to the stimulus of the Solar Flare at an average speed of 500 km/hr (310 mph).

There is a nice discussion of the Doppler effect at Wikipedia and you can check my math since I've been retired for almost 20 years now and seldom use calculus any more.

Wednesday, August 15, 2012

cURL .. A New Command for FTP Upload

While playing with Puppy Linux I discovered a versatile command for uploading data with URL syntax.  Not only FTP uploading but a host of other things:

"curl is a command line tool for transferring data with URL syntax, supporting DICT, FILE, FTP, FTPS, Gopher, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMTP, SMTPS, Telnet and TFTP. curl supports SSL certificates, HTTP POST, HTTP PUT, FTP uploading, HTTP form based upload, proxies, cookies, user+password authentication (Basic, Digest, NTLM, Negotiate, kerberos...), file transfer resume, proxy tunneling and a busload of other"

It was so easy and direct to use in Linux that I adopted it as my official FTP uploader.  It has been ported to Windows so I use it there also for all my grabber operations. It has so many features that there is even a web site just for this one command:  You can download cURL and it's associated files here and read the many help files on it's syntax and use.

If you are concerned just with FTP uploading there is probably no reason to use cURL instead of DOS commands but I wanted to learn it for future applications involving all those buzz words in the quoted text above.  Also, I flip back and forth between Windows and Linux and the syntax is the same in either OS.

Here's what the command line looks like in Spectrum Lab:

exec ("\SLuploader\curl -u username:password -T  \SLuploader\SL1.jpg ")

The root folder SLuploader contains the curl command and it's associated files.  I send grabs from both of my grabbers to that folder and it sends them to the corresponding online grabber pages.

For comparison to FTP via DOS commands see my previous post Uploading Files Using DOS Commands .  As I said above, if you are happy with the DOS method there is no compelling reason to switch to cURL just for FTP uploads but I wanted to point it out because of it's many advanced features which may be useful in other applications.

de w4hbk