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

Wednesday, January 16, 2019

QRSS Signals as Indicators of Sporatic E

This is a quick compilation of observations taken during a Sporatic E opening recently on 10m.  I initially noted a fuzzy broadening on the signal of KD5SSF who is located 10 miles north of me and having seen it before thought that the only thing to cause it was reflections from a turbulent layer "up there".  On this occasion I had the presence of mind to check with the Sporatic E map provided online by G7IZU, which is compiled from reported QSOs on 10m and above.  Figure 1 is one of the maps showing the QSOs:

Figure 1.  G7IZU Sporatic E Map



The signal of KD5SSG observed at the same time is shown in Figure 2:





Figure 2.  KD5SSF Signal with Suspected Es Broadening
There is also a ionogram from the GIRO sounder 40 miles to the east of me which may also be showing ing reflections from an Es layer, Figure 3:

Figure 3.  Ionospheric Sounder from Eglin AFB 40 Miles to the East

Note in particular the reflections recorded along the bottom most trace...the others above it are roundtrip reflections which usually indicates a strong reflection.

My QRSS grabber was active on 10m at this time and the map shown at wsprnet.org looked like this"

Figure 4.  WSPR Spots Taken During the Es Opening

Putting it all together I think the broadening of KD5SSF's signal is caused by backscatter from an overhead Sporatic E cloud at a height of 100 km which is the average height of the E layer.  Also, the ionogram trace is showing the Es activity.  At least this is my guess at this time.

If you are close to a QRSS station and see a similar broadening it may be an indication that a Sporatic E layer is overhead.  

Tuesday, December 25, 2018

Meteor Pings on 30m Using a QRSS Signal from a Local Station

I am fortunate in having a local QRSS station about 10 miles north of my QTH.  The signal arrives via ground wave and is of moderate strength so as not to overload the waterfall display of my 30m grabber.  Patches of fuzz have were noted during the 2018 Leonids above and below the groundwave trace which I concluded are caused by backscatter from meteors.  The following observations were conducted during the December Geminids.

Meteors occur when the meteoroid (space rock) reaches the E layer where the atmospheric density is high enough to heat the rock to incandescence and produce a trail of ions and free electrons.  The recombination rate of electrons is relatively slow and allows reflection of radio waves up to a number of minutes.  The trail lasts longer as frequency goes lower.  Meanwhile the ion trail drifts with the resident winds resulting in a Doppler shift in the incident radio wave which is large enough to be seen relative to the trace of the incident signal on a waterfall display.  Figure 1 is from my 30m grabber showing the fskcw signal from KD5SSF along with a typical meteor ping and airplane reflection.

Figure 1.  Meteor Ping on KD5SSF's FSKCW QRSS Signal


During the recent Geminids I was doing an experiment with WD4AH to look for meteor pings from his signal with no thought of using the signal of KD5SSF. While looking for pings from WD4AH I could not help but notice the frequent pings on SSF whose frequency was about 10 Hz away.  I archive my 10 minute grabs and had available six days of data before, during and after the Geninids and decided to count all the pings and see if data could be presented in some way to yield information about the shower.  And lo and behold it did, as I shall now describe.

Pings vary from just a brief smudge to a lengthy, bright feature.  I considered only whether or not a ping was noted on a given 10 minute grab and made no effort to distinguish multiple pings on that frame.  I also tried to account for the stronger pings by assigning values of 1 for the regular ones and 2 and 3 for the progressively stronger ones.

Interference can produce "false pings" due to airplane reflections, other QRSS signals and pulses that come from Lord knows where,  The false pings can be identified relatively easily by their characteristic shapes.  For example, airplane reflections have a constantly curving shape which is sharp and distinct. Likewise the keying characteristics of other QRSS stations will be different from that of KD5SSF.  Most noise pulses will usually be spread across the frequency axis.  A possible ping was rejected when I could not be certain.  If anything I think I under estimated the number of pings.  The fsk keying of SSF's signal was a help also since the ping would follow the up and down shifts  which the other QRM would not.

A total of 122 ping events was counted and entered into a Google spreadsheet and grouped in several ways.  Figure 2 is a count of pings for each day.  Figure 3 is a histogram plot of pings versus time of day by dividing the 24 hours of time into 11 bins and totaling the number of pings in each bin for the six day period.  The scale is a little strange since it is divided 24 by 11 but you can see clearly that the maximum number of pings over the six day period was greatest between roughly 0900z to 1130z which is about 2 or 3 hours before Sunrise local time.

Figure 2.  Pings for Each Day



Figure 3.  Pings vs Time of Day


Figure 4.  Pings per Four Hour Period


I then counted the pings in successive four hour periods from the beginning to the end of the recording period, Figure 4.  I think the large spike on the 15th was augmented by the way I assigned higher numbers to stronger events.  That suggests there was a number of big rocks during that time.

Summary

It was a bit tedious examining all the 10 minute grabs in detail.  It took about 2 hours and 2 Salty Dogs.  I put on my reading glasses and got close to the screen to better judge each frame for pings and distinguish them from QRM.  I counted the pings using Notepad with four columns for UTC time and a "1" for a ping, a note on small, medium or large and in the fourth column the final adjusted ping number.  The final table was saved then entered into Google Sheets for analysis.  The analysis was easy and fun with Google Sheets doing all the work. 

The main thing you need for a similar project is a nearby QRSS station at just the right distance or antenna orientation to give a clean, stable, not too strong signal so you can see the fuzzy pings

Saturday, December 1, 2018

QRSS Meteor Scatter on 30 and 17m During the November Leonids Meteor Shower


Introduction

During previous meteor showers W4HBK, WD4AH and WD4ELG have observed meteor pings on 17 and 20m using QRSS techniques at sub-Watt power levels.  As discussed in a previous blogs we needed to adjust our approach for our next shower and see if we could do better on 17m and  go one band lower to 30m.

During the November 2018 Leonids Meteor Shower we used the 17 and 30m QRSS bands to look for meteor pings .  We have previously had moderately good success on 17 and 20m and our goal this test was to improve our success rate using "lessons learned" and to go one band lower and see if pings were observable on 30m.

Experimental setup

W4HBK:  tx on 30m using a U3S running 700 mW to an inverted V antenna and rx on 17m
WD4AH:  tx on 17m using a U3S running 500 mW to a random wire antenna and rx on 30m
WD4ELG rx on 17 and 30m

HBK is 276 miles/444 km from AH and 580 miles/935 km from ELG
ELG is 466 miles/750 km from AH

Based on previous tests we found that a near continuous signal with minimum frequency shift made it easiest to identify pings and can be adjusted for as little dead air time as possible.  Hence we used fskcw with a 1 Hz shift with the dot-second time adjusted to transmit for 9 minutes and allow 1 minute to cool the finals at the end of a 10 minute frame.  The duration of the test was from just after midnight (0700z) to just past Sunrise (1300z).

I also used a program called SeqDownload to record the grabber screens at AH and ELG directly to my computer in real time so that it would not be necessary to download from their archives after the test, via the Internet.  This greatly simplifies and reduces the time to process the data and avoids confusion.

Results

     17m

We were able to record many pings on 17m between W4HBK and WD4AH.  Figure 1a is a typical ping and Figure 1b is a stitch of all grabs to give an idea of the total number of observed pings.

Figure 1a  Typical  ping on 17m from WD4AH at W4HBK
Figure 1b  Stitch of all 17m grabbs of WD4AH by W4HBK


WD4AH also had 5 pings on the WD4ELG grabber, Figures 2a and 2b show two examples.

Figure 2a  Meteor Ping of WD4AH received by WD4ELG

Figure 2b  Second example WD4AH at WD4ELG

30m

Only a few weak pings were recorded of W4HBK at WD4ELG, Figures 3a and 3b.
Figure 3a  W4HBK received by WD4ELG on 30m

Figure 3b   W4HBK received by WD4ELG ON 30m







WD4AH recorded a number of pings from W4HBK.  Figures 4a and 4b are representative.  Figure 5 is a stitch of all grabs to give an idea of the total number of pings.  Note at right the band begins to open and HBK's signal becomes a combination of meteor scatter and weak propagation.

Figure 4a  W4HBK received by WD4AH on 30m

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Figure 4b  W4HBK received by WD4AH on 30m

   
Figure 5  Stitch of grabs by WD4AH of W4HBK on 30m

     Special Event

At 0916z all four grabbers recorded pings.  In addition, judging by the long duration of W4HBK at WD4ELG (Figure 3b) this may have been a fireball event.

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Conclusions

Meteor scatter is very easy on 17m QRSS over a distance of 276 miles while difficult over  a distances of 466 and 580 miles.

On 30m it is fairly easy on the shorter path and difficult on the longer one.  Additional problems on the lower bands are QRM from other signals and modes of propagation.  Examples of the latter are tropo ducting and unexpected Sporatic E.

Great care must be taken to rule out false pings from these problems.  I do this by looking for letters of the call or elements of the letters as well as the characteristic signature of meteor pings. A single dit or dah at the right time can verify the sending station.










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.