opening

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

Wednesday, November 14, 2018

Meteor Scatter via 17m and 20m QRSS

This is a summary of  Meteor Scatter test being conducted on 20m by WD4AH, WD4ELG and myself.   G0FTD and company in England have pioneered the use of QRSS on 10m to observe meteor pings and do so on a regular basis.  We have been pushing to explore the bands below 10m to see if meteor scatter can be detected there.  I have observed many pings from a sw brodcast station 220 miles/357 km to the north of me on 12050 kHz so know it's feasible at high power levels but how about at the low powers used by the QRSS community?  As a starting point we have concentrated on 20 and 17m.  WD4AH is 276 miles/444 km ESE of me while WD4ELG is 584 miles/ 935 km NE of me.  The strength of meteor pings decreases as the 4th power of the distance so for identical equipment ELG's signal should be about 20 times weaker than that of AH.

Our first test was on August 13 during the Perseid shower, a second on September 29 during the Sextantid Daytime shower and a third on October 23 during the Orionids shower.

Perseids  -  This was indeed a learning experience for us all.  We attempted to use 2 bands with AH and ELG transmitting on 20m to my  grabber and with me transmitting on 17m to their grabbers.  Here's a spreadsheet of the plan:

Station                 MEPT                                  Grabber                      QRSS Mode

W4HBK         TS-480 @ 5W on 17m         TS-440 on 20m                  CW

WD4AH         U3S @ 1/2W on 20m           SDR on 17m                    DFCW

WD4ELG      U3S @ 1/2W on 20m            SDR on 17m                    FSKCW


AH and ELG immediately ran into a problem of overload of their SDR receivers from their simeltaneious transmission on 20m.  The attempt on 17m was abandoned.

On 20m I  could see two components to their signals one which appeared to be meteor pings and another which appeared to be a contribution from the ionosphere or troposphere.  The skip was unexpected as it occurred between midnight and Sunrise when the band was normally dead as a doornail.  However it was during the Es season so that is a possibility.  We interpreted the results as a weak background of skip punctuated by meteor pings.

As to meteor pings only one possibility was seen on ELG, Figure 1,   while many were seen on AH, Figure 2.

Figure 1.  WD4ELG Meteor Pings
Figure 2a.  WD4AH pings
Figure 2b.  WD4AH pings

Figure 2c.  WD4AH pings


A problem I found in looking for pings was the nature of the message used.   We chose "regular" QRSS messages.   ELG used fsk cw and AH, dfcw, both with a shift of 5 Hz.  The short time span of a ping along with it's Doppler shift made a confusion of the observed data.  Lesson learned: the best signal for ms work is a continuous, unshifted signal but that wouldn't be QRSS, would it.  Likewise  propagation condx which interfere with pings should be avoided if possible.

Sextantids  -   This is a daytime shower about which little is know since most ms observations are oriented towards visual sightings.  We chose a message with only a 1 Hz shift since this is almost a straight line but still a legal  and readable QRSS signal.  The plan was to have WD4ELG and WD4AH transmit on 20m with W4HBK doing the grabbing.  Equipment failure forced ELG off the air but we pressed on with AH's signal.  As if that weren't enough a major RTTY contest started up which forced AH to QSY to the low end of the band at around 14001.84 kHz.  Following this adjustment we recorded numerous pings plus what appeared to be weak skip or tropo as we had seen during the Perseids.

Figures 3a and 3b show some of the pings on individual 10 minute grabs.  Figure 4 is from my slow grabber and shows the overall signal from AH during the test.  The jump in frequency identified as "SL Hiccup" was a spontaneous change in center frequency, a quirk of Spectrum Lab.  Also at 1600z there was a very strong increase in AH for about 3 minutes.  Actually,  I recalled having seen this before on his signal on my 20 and 30m grabbers during regular QRSS activity near Sunrise.  The distance is well within my skip zone and I  rarely see  QRSS stations that are "too close" and which I know are QRV  More about this below.

Figure 3a.  WD4AH pings

Figure 3b.  WD4AH pings



Figure 4.  WD4AH on 8 hr Grabber


I also did a stack of most of the 10 minute frames between 1330z and 1530z that combines all the pings which I will call tropo effect, Figure 5.

Figure 5.  Stack of  WD4AH 10 Minute Grabs




A Google search for what might be the cause of the weak background found that coastal tropo is common in Florida  The path between Alachua and Pensacola indeed skirts the northern Gulf coast and is likely the cause of the background. Generally a vhf/uhf phenomena it decreases with frequency but is probably ignored on HF because of all the other modes of propagation available.

In summary, we believe we have definitely seen many meteor pings on 20m during the Daytime Sextantids Metero shower and possibly have stumbled on a 20m tropo effect which has been ignored or forgotten.

Lessons learned so far: (1) use as continuous a signal as possible with as little frequency shift as possible, (2) check for contests and (3) check equipment including grabbers before the test.

Orionids   For this test W4HBK transmitted a 5 Watt QRSS-CW signal on 17m while WD4AH and WD4ELG did the grabbing honors.

The results for AH were straightforward in that we saw a number of pings with no background as discussed above.  Figure 6 is a stitch of all images and shows the total pings from roughly midnight to sunrise.

Figure 6.  Stitch of WD4AH 10 Minute Grabs


WD4ELG's signal produced what I'm fairly certain are a number of pings but signal fell right between two extraneous lines that often appear on our waterfall displays, Figures 7a,b,c,d.
Figure 7a.  WD4ELG Meteor Pings
Figure 7b.  WD4ELG Meteor Pings
Figure 7c.  WD4ELG Meteor Pings

Figure 7d.  WD4ELG Meteor Pings

In addition there was also a background signal which was probably due to either tropo or ionospheric propagation though the latter would be TOTALLY unexpected for the hours between midnight and sunrise local time.  Figure 8 is a stitch of some of the 10 minute grabs  showing what we think are the meteor pings superimposed on a non-meteor effect during the first half of the image and transitioning to ionospheric skip at Sunrise.  The signal at the lower right is KJ6ANV in New Mexico.  The wavy nature of the signal is probably due to drift in my TS-480 transceiver as it heats and cools during the 10 minute frame.

Figure 8.  Stitch if WD4ELG 10 Minute Grabs
Once more we seem to see a combination of meteor pings overlaying an unexpected effect by either the tropohphere or ionosphere.  The latter could be weak Sporatic E trying to happen and then being augmented by meteors.  Tropospheric ducting can't be ruled out either since the weather pattern over the Southeastern USA has been unusual this year, warmer and wetter with a delay in the cool, clear days normally seen.  This may be conducive to temperature inversions though we did not record wx data during our test period.

We have tried to use lessons learned to improve as we went along but equipment and planning failures still were a problem.  The latter as caused by not being aware of a major RTTY contest which made intolerable QRM.

Our conclusions are that we have definitely seen meteor pings on the shorter path between W4HBK and WD4AH on both 20 and 17m  What seems to be pings on the longer path between W4HBK and WD4ELG is tantalizingly close to certain but needs further study.  As I said in the opening paragraph "The strength of meteor pings decreases as the 4th power of the distance so for identical equipment ELG's signal should be about 20 times weaker than that of AH."












Friday, October 5, 2018

Antenna comparison on 160m using QRSS

My main antenna utilizes a 50 foot (15m) aluminum mast with a multiband inverted V at the top for 20 thru 10 meters.  On all bands below 20m the coax is connected to the mast, which is insulated from ground, and fed as a top loaded vertical.  The ground consists of sixteen 30 foot radials plus six more varying between 60 and 100 feet.  It works all the dx I want on all bands.

There are two problems.  Firstly, it's in a swamp which  is full of spiders, snakes, mosquitoes, etc plus saw palmettos and thorn vines which will lacerate arms and legs not protected by heavy clothing.  Except in our brief dry season there is standing water and boat boots are a necessity. Secondly, it is a heavy rig and takes all the strength I have to haul it up and I'm not getting any younger.

I designed a new antenna based on the one above which is smaller and much easier to manipulate and is located in the "civilized" part of my property which we call our yard and garden.  This antenna is based on a thirty foot mast and sports an inverted V for 40 thru 10 meters and tunes on 160/80m as a top-loaded vertical with just four 30 foot radials.  Figure 1 is a scale drawing of the two antennas.

Figure 1.  Comparison Antennas


I suspected the ground losses on 160m must be much higher than on the bigger antenna in the swamp and arranged a test to compare the two using QRSS.  Both WD4ELG in North Carolina and VE1VDM in Nova Scotia have been running grabbers on 160m which I took advantage of by sending my call on alternating 10 minute frames for each antenna.

Here's how the tests were performed.  I keyed my TS-480 using the program QRS written by ON7YD at a speed of 8 dot seconds resulting in a total message length of about 8 minutes.  The antennas were connected to the A and B ports of the 480 and switched by hand at the beginning of each ten minute frame.  Over a one hour period I recorded three frames for each antenna, cropped and placed them together as a photo collage, Figure 2a.  The Spectrum Lab grabber at WD4ELG has a color scale for estimating signal strength which goes from RED (max) Orance Yellow Green to Blue (min).  The color variations are difficult to see but it does appear that the old antenna has a bit more red than the new one, i.e., the older antenna is slightly better.  I also tried averaging by stacking the images using StarStax with the "averaging" option selected, Figure 2b.

Be careful when making such comparisons not to over saturate by adjusting the exposure and contrast lest the true photographic density is ruined.  Note that these images appear underexposed and a little difficult to read but that's necessary to access the true image densities.






A similar comparisons was made using the grabs at VE1VDM which indicated the same thing, that it's difficult to distinguish between the two antenna.

I was both amazed and pleased to see the new antenna works almost as well as the old one but perplexed as to how a much shorter mast with a far simpler ground can do so. You should be able to see for yourself that how difficult it is to distinguish between the two but beyond any doubt the new, smaller antenna is doing a great job.

My QTH is about 1000 feet from Pensacola Bay and located on the slope of an ancient marine terrace.  What I call my swamp was once an nearshore trough which has filled in with organic muck  resulting in poorly drained soil.  My yard just up slope from the swamp has a six inch veneer of rich soil over white sand from the once sandy beach.   I'm just guessing but it seems that the ground conductivity in my yard is much better than expected  Occasionally hurricanes push salt water up to the yard so there is a possibility that salt may still be in the sand and soil.  In addition my QTH is on a long, skinny peninsula and the presence of a salt water ground plane, though at a distance, may also help prevent the low angle "suck out" phenomena which plagues vertical polarization.

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Monday, April 2, 2018

Keying a Tranceiver for QRSS Work

A conventional transceiver can be keyed for QRSS work using ON7YD's QRS software.  I often do this using my TS-480 to run 5 Watts on the 80m and 160m.

The software is versatile, easy to use and provides a keying output on both serial and parallel ports.  Here is the circuit diagram between the port and the transceiver keying jack:


Note that it requires no source of power.  I use an old serial port cable with a small Manhatten style pcb  at the transmitter end for the components with the output leads clipped across my hand key.

The  help file included with the software explains everything and ZL2IK has more info at his blog

ON7YD developed his program back in the dark ages of QRSS when it was virtually impossible to find a keyer that would send at our low speeds.  It was actually the keyer used when I built my first QRSS rig 10 years ago.  I've used it off and on for homebrew rigs as well as recently to key my TS-440 and TS-480.  It's definitely a handy accessory to have around the QRSS shack.




Saturday, August 22, 2015

Precision Markers at Any Frequency Using an OCXO with Spectrum Lab

I recently purchased an Oven Controlled Crystal Oscillator (OCXO) on eBay to use as a "house frequency standard."  It features an SC cut crystal with a double oven and a sine wave output at 10 MHz.  The question is, how to use it on all frequencies covered by my TS-440?

I calibrated the OCXO by comparison to WWV to an accuracy of just better than 1 Hz and verified by repeated observations that it is virtually drift-free, at least for QRSS work.  I'll describe how to do this in my next post.

In the old days of tube receivers a standard method for finding the band edge was to use a 100 kHz crystal oscillator with a harmonic generator to provide markers every 100 kHz.  This posts describes a similar approach to allow the 10 MHz oscillator to provide markers every 2.44 kHz with an accuracy of 1 Hz up through the Ten Meter Band.  It couples the OCXO with a binary divider to divide down to 2.44 kHz, or 2.4414060 to be exact, then produces harmonics which occur at this interval up through 10m.

Several years ago I purchased a frequency calibrator kit from W8DIZ which used this scheme with a TCXO and a 74HC4040 12 bit Binary Counter which can be configured to divide by up to 4096.  The DIZ kit used only the divide-by 2, 4 and 8 to produce strong markers at 10, 5 and 2.5 MHz but I reconfigured it for the 4096 maximum and was pleasantly surprised to see a plethora of harmonics throughout the HF spectrum.
Figure 1.  W8DIZ Frequency Standard
The next step was to see if the sine wave output of the OCXO would do the same since Binary Counters are designed to work with square waves....and it does.  I suspect the strong output of the OCXO overdrives the 4040 counter and acts like a square wave due to clipping.  The output of the OCXO was injected directly into the DIZ circuit at the base of Q2.   To select the 4096 divide-by I scratched through the trace from pin 7 of the divider and jumpered over from pin 1.  As a sidenote, this method surpressed the output of the TCXO but by adding a gimmick capacitor between the OCXO and Q2 to reduce it's amplitude I can also see harmonics from both sources.

The output from J2 was injected into the receiver's input through a BNC "T" adapter with a gimmick capacitor to adjust the amplitude.

The difficulty of having 2.44 kHz harmonics is that they are not likely to be close enough to the frequency span of a waterfall grabber to be seen.  Consider a typical grabber screen on 30m which extends from 10130.9 to 10140.1 kHz.  The nearest marker from the OCXO is at 10139.159 kHz or about 740 Hz below the grabber window.  What to do?

Spectrum Lab is a bottomless pit of useful features along with a tiny programming language to make them work.  One of these features is an internal audio oscillator by which the frequency can be set either manually or under computer control.  The programming command to set the frequency is,

      generator[0].freq = "desired frequency",

[0] refers to the first of three oscillators and note that "desired frequency" can be an algebraic expression.

There is also a special command to measure the peak frequency of a signal in a specified interval,

     peak_f(f1,f2).

Putting it all together,

      generator[0].freq = 879 + peak_f(450,470).

I use the "Conditional Actions" section to execute the command every 1000 milliseconds.  Use "always" as the "if" statement and the generator command as the "then" statement.

The OCXO harmonic appears at an audio frequency of about 461 Hz and the second part of the above equation measures it's exact value, after which 878 is added to move the audio oscillator output frequency to a nominal value of  1340 Hz which is well within the grabber window.  I used 879 just to illustrate how to move the OCXO signal but other values could be used to move it, for example, to be close to a signal being studied.

You can familiarize yourself with the Spectrum Lab commands by clicking on the help screen and scrolling down to  Interpreter : -commands, -functions, -expressions.

Make sure your receiver's bandpass is wide enough to allow the marker frequency as well as the grabber window.

Here's an example:


This is a high resolution study of WA5DJJ's GPS stabilized fsk QRSS signal.  The individual dots and dashes are not evident because the scan speed is very slow.  Note that the frequency range is only 20 Hz.  The slow drift of the OCXO is due to temperature changes in the receiver and can be used to correct the frequency of the signal being measured by subtraction, ie, the OCXO is the baseline.

Near the right side you can see a gap in the OCXO signal.  This was caused by QRM down at the frequency of the OCXO marker, probably from JT65.

Though this post describes precision frequency measurement for QRSS work it can be used for other applications by choosing the appropriate Spectrum Lab parameters.

Sunday, June 7, 2015

Time-sharing a Grabber for Multiband Coverage

The most popular band for QRSS work is by far 30m.  Although at least one grabber op, G0XXX, has several receivers to allow other bands to be covered most of us cover other bands by moving on special occasions, such as a "weekend on 40m" or such.  Here I describe a technique I am now using which allows me to grab on several bands by time-sharing, i.e.,  moving the grabber periodically in ten minute frames.

The best and easiest way to control a receiver's frequency is via commands sent from the computer's serial port. Unfortunately the RS232 function in my TS440 no longer works so I've devised a technique which utilizes the UP/DOWN pins on the mic jack.  On the 440, shorting pin 3 will cause the frequency or memory to increment up while shorting pin 4 moves it down.  Computer commands can be obtained from the RS234 port by sending a binary number to the COM1 address from a simple program, which in my case is FreeBasic.  Here's an example of the FreeBasic code to make that happen:

     open "COM1:9600,N,8,1,CS,DS,RS" FOR Binary AS #1
     Out &h3fc,01      Rem set DTR low
     Sleep 250,0         Rem delay 250 ms
     Out &h3fc,00      Rem Set DTR hi

&h3fc is the address of the serial port,  01 causes the DTR pin to go from -10 to +10 vdc and 00 moves it back to -10v.  The  200ms delay gives enough time for the hardware to respond but not so much that memory moves more than one channel.  02 sets the RTS hi (mic/dwn)

The RS232 voltages need to be converted to an open/short condition with a level converter.  This is the circuit I use (two needed) :

Circuit from QRS by ON7YD

At present I use just three bands, 40m, 30m and 20m, with 40m being replaced by 10m or 15m during the daylight hours.  Here is the program written in the QuickBasic dialect of FreeBasic:

----------------------------------------------------------------------------------------
#Lang "qb"

Dim m As Integer
OPEN  "COM1:9600,N,8,1,CS,DS,RS" FOR Binary AS #1
Out &h3fc,00
m=Val(Mid$(Time$,4,1))


Print "start"
zero: Rem inc To Next frequency when m changes (10 minutes)

If m=Val(Mid$(Time$,4,1)) Then GoTo zero
GoSub inc

Rem Print "at one"
one:  Rem inc To Next frequency when m changes (10 minutes)

If m=Val(Mid$(Time$,4,1)) Then GoTo one
GoSub inc

Rem Print "at two"
two:  Rem dec back To first frequency

If m=Val(Mid$(Time$,4,1)) Then GoTo two
GoSub dec

inc:
Print "inc"
Out &h3fc,01 Rem set DTR low
Sleep 200,0  Rem delay 250 ms
Out &h3fc,00 Rem Set DTR hi
m=Val(Mid$(Time$,4,1)) Rem set New m
Rem Print "leaving inc"

Return


dec:
Print "dec"
Out &h3fc,02 rem dec twice To Return To start frequency
Sleep 200,0
Out &h3fc,00
Sleep 1
Out &h3fc,02
Sleep 200,0
Out &h3fc,00
m=Val(Mid$(Time$,4,1))
rem Print "leaving dec"

GoTo zero

-----------------------------------------------------------------------------------------------
The program starts on the first frequency and checks the tens digit of minutes until it changes and increments to the second frequency. Repeats this a second time to reach the third frequency and finally decrements twice to return to the first frequency.  The "print" commands are for debugging.

In order to make the Spectrum Lab frequency scale show the correct values it's necessary to use the "Conditional Actions" feature to load in the "frequency offset" based on each ten minute period.  Here's what that looks like:



Be sure that the "sync" box is checked to activate "conditional actions"..

The start times of the first frequency are xx00 and xx30. The program can be started anytime during these time intervals in order to be synchronized.

Here's the steps to starting the program to ensure synchronization:

1.   Load the frequencies into the receiver's memory bank in sequential order and set to the first frequency.         The frequencies are the same as those specified in WSPR.

2.   Set up the "conditional actions" per figure xx and check the box in the files menu.

3.   Start the program between the first ten minutes (xx00 to xx10z) or the fourth ten minutes (xx30 to xx40z)       ensure synchronization.

I have chosen to use just 3 frequencies to allow each to be covered twice in one hour because it's a good compromise between bands and time between grabs for each band. At present 40/30/20m are covered at night and 15/30/20 during the day.  Changing from 40 to 15m for the first slot only requires entering the new frequency into memory slot one for the receiver and changing the corresponding frequency in the "conditional actions" table.

After debugging the software the only problem I've had is getting the delay correct in the inc: and dec: subroutines.  Remember, if the mic up/dwn button is held down the memory will scan until released and we want just one jog so it needs to be short enough to prevent this.  At the same time, if it is too brief the hardware does not have enough time to react.  For your system you may have to play with the delay.

Reference:   http://www.freebasic.net/

















Thursday, July 3, 2014

Using Google Analytics to Track Usage of Your Grabber

I used to have one of those cute little Maps on my grabber page that shows who's using it.  These apps are provided free and I read that they are a means of collecting user data, including IP addresses.  The provider can then sell this data to advertising companies, etc.  When I learned this I immediately removed the apps from my web page at QSL.net.

I really wanted a way to see if my grabber was being utilized since I rarely get feedback indicating it is.  I ran across a reference to Google Analytics which allows a web site operator to collect the data without obtaining personal data and IP address.  I've found it to be a useful and safe tool to monitor site activity and the most detailed info I get is rough geographic location and how many times my web page is accessed.   Here is what the info looks like:



I chose to watch on a daily basis but you can also select hourly, weekly or monthly.  In the graph above I can see that the peaks occur on weekends and the minima at mid-week.  Country information is also available.  There is also an option to monitor in real time so I can see who is accessing the web page now.

To install the app just to to Google Analytics and set up an account then follow the instructions.  You can also get reports for other web sites you may operate.

de w4hbk

Friday, May 30, 2014

One Billion Miles per Watt on 20m

Back in 2011 Dave, WA5DJJ, and I became interested in just how low we could go in power and still be able to copy his call letters, which is our definition of QSL for QRSS work.  On 30m we were able to make it down to 8.51 uW using image stacking technique.

Since that time we have kicked around the possibility of going down to 1 uW and last November started a new campaign to do so.

By early May of 2014 we had reached 15 uW on 30m after months of trying but could go no lower.  We need long periods of time free from interference in order to obtain a sufficient number of 10 minute grabs to use image stacking to extract the signal from the noise. Activity has increased since 2011 both from QRSS and other digital modes.  The notorious OTHR from Akritori, Cyprus is a regular visitor also.     In addition, this was a most unusual Winter here in North Florida with frequent thunder storms related to the infamous Polar Vortex which plagued the East Coast this year.

At this point we decided to try 20m to escape the QRM and hopefully see less QRN.  The difference was amazing.  Not only did we have the spectrum all to ourselves but the QRN dropped almost to nothing.  We started at 100 uW and came down rapidly in 3 dB steps to 5.8 uW.  After that the difficulty with each 3 dB step increased exponentially with the final step from 2.5 uW to 1 uW requiring 12 days until all the variables lined up in our favor.  Here's a 3-day stitched image showing our approach to the 5.8 uW level:



Note that the WA5DJJ signal was still drifting a bit until Dave installed the MEPT in a thick-walled styrofoam box.

On the night of May 17 the 1 uW signal was visible in and out on the 8 hour grabber from 0430z to 1040z.  Thirty-eight 10 minute grabs over this time period were processed with the stacking software Rot'n'Stack to produce a barely discernible image in which I could read all the letters of Dave's call.  That's 1 uW over a distance of 1164 miles/1873 km.  If you do the math that's over one billion miles per Watt for a signal propagated via the ionosphere.

Here is the results of the image stacking:



Note the use of a second signal from WA5DJJ from an older MEPT feeding a vertical.  It was not stable in time thus preventing stacking.  We used this to give some idea of propagation.  KB5R also joined in for the same purpose.  The cw signal from IK6ZEW was strong but not stackable.  The 1 uW signal eminated from a QRP Labs U2 mept feeding a Cushcraft A3 triband Yagi.  The receiving antenna at W4HBK was a 30/40m inverted V with the apex at 18 meters.

For comparison here is one of the better 10 minute grabs:


It's fun to compare our miles/Watt to that of the NASA's deep space probe Voyager 1 which at a distance of 11.8 billion miles from Earth running a 20 Watt transmitter which gives 590 million miles per Watt.  Of course they are sending HiDef images and telemetry compared to our 6 scratchy letters but on the other hand they are using a 70m dish at the receiving site.

Here is the story from Dave's point of view:

http://www.zianet.com/dhassall/BILLIONMPW.html

de w4hbk