CME Effect on 40m QRSS Signal

This post is to document the effect of a Coronal Mass Ejection (CME) on a QRSS signal propagating between New Mexico (WA5DJJ) and Florida (W4HBK).  The CME occurred on July 12 and was described in my last post.

Figure 1 shows the observed effect.  DJJ transmits a fsk cw signal referenced to a Rubidium frequency standard which at this time scale produces two parallel lines corresponding to the fsk mark and space.  The Master Oscillator of my TS-440 is temperature controlled, thus the observed frequency changes are due to Doppler shifts caused by motion of the ionosphere.   As luck would have it, Dave's signal came on just before the start of the disturbance while the QRM ceased at the same time.

Figure 1.  Frequency shift of WA5DJJ signal during geomagnetic disturbance

Note these features:

1.  Start time is about 0345z
2.  As the event progressed four separate layers developed as the frequency shifted downward followed by a reversal with a decaying sine wave pattern.
3.  The apparent speed of the wave was very slow with a period or 1 to 2 hours.

Figure 2 is a corresponding magnetometer recording from Anchorage, AK which indicates time history of the geomagnetic disturbance.

Figure 2.  Geomagnetic disturbance recorded at Reeve Engineering Labs in Anchorage, AK

This leaves little doubt that the observed effect on the QRSS signal was caused by the disturbance.  However, this was not the initial arrival of the CME.  As shown in Figure 3 that actually occurred the day before at 1700z.

Figure 3.  CME history recorded by ACE spacecraft (~ 1 hr before before seen at Earth)

Our observation was related to the minor hump occurring at about 0300z.  I had made an effort to be watching for the arrival as predicted at solarham.com but, again as luck would have it, the presence of lightning forced me to secure my station at that time.

Here's how I visualize the storm as depicted in Figure 1.  After the particles slammed into Earth around the Auroral Zone an ionospheric wave spread out at a surprisingly slow speed.  This wave is indicated by the exponentially decaying sine nature of the frequency variations.  The splitting of the frequency into 4 components is also surprising and could imply either a stacked vertical layering or possibly skip points spread out horizontally...but why 4?  In conclusion, I find both the layering and the slow speed with which the disturbance spread to be remarkable.

de w4hbk

Comparison of Two Solar Flares as Observed on QRSS Signals

The past two days there were M-Class Solar Flares the effects of which were observed on the Pensacola  QRSS grabber.  I present the data here just to document the effect as a starting point for further obversations.

The first two pictures are the grabber images and the last two the measured x-ray flux.

Figure 1.  08JUL12 Solar Flare on 30m

Figure 2.  09JUL12 Solar Flare on 20m

Figure 3.  08JUL12 X-Ray Flux Observed by GOES Satellites

Figure 4.  09JUL12 X-Ray Flux Observed by GOES Satellites

In the first event there was a rapid dropout of signal called a Sudden Ionospheric Disturbance (SID) but no noticable frequency shift.  The SID lasted about 20 minutes.  The X-Ray flux was 7x10^-5 W/m^2 and the Sun was almost directly over the skip point.  The transmitting stations were to the east of me at distances of about 300 miles/482 km.

In the second event there was only a modest drop in signal strength but a noticible upward shift in frequency indicating an upward movement of the reflecting layer.  As the signal began to recover there was a noticable broadening of the frequency with a return to normalcy after about 30 minutes.  The X-ray flux was 1x10^-5 W/m^2 or about 7 times weaker than the first event.  The Sun was low in the sky to the west relative to the skip point.  The transmitting station was 1164 miles/1872 km to the west of me.

It makes sense that the difference in the x-ray flux caused the difference in observed effect but at this point I just want to save the observations and numbers in a safe place for comparison to, hopefully, future observations.  We've seen these effects in the past but I haven't written down any numbers.

de w4hbk

NU7Z DDS MEPT

Here is another DDS-based MEPT for QRSS work which produces ~ 1W output on 160 thru 20m and with a different amp will go on up to 10m.  Hopefully it will provide some ideas.

Rick, NU7Z, built a MEPT similar to mine which is also based on the N3ZI DDS2 vfo.  He even used the all-band LPF from a defunct Kenwood xcvr which saves a lot of work, as well as the 5W amp kit from W8DIZ.  Even so there is much to be done to get a finished rig.

The output of the DDS2 is quite low, ~0.25V p-p into 1000 Ohm load, so needs a buffer amp to bring it up to 2.5 p-p V into a 50 Ohm load to drive an amplifier such as this one from W8DIZ.

Here is a picture of the guts of Rick's mept:

Here is the front panel:

You can look at my version from an earlier post here.  The main differece between mine and his is that I use the program QRS to key the fsk pin of the DDS2 via the computer's RS232 port and Rick uses an onboard keyer....I'm sure the one in the QRP Labs Mept's will work FB.

I should point out another source of MEPT circuits and rigs which have been developed by Dave, WA5DJJ, out in New Mexico.  His designs go from the Model 1 crystal tx, which I copied for my first mept, up thru his all-band DDS based rig which he uses today on all bands.

One thing for sure...once you have a DDS rig working you never have to search for crystals again.