SM6FHZ 432 MHz Meteor Scatter

Patience and persistence is the mother of 70cm meteor scatter!

I have just recently started working 432 MHz meteor scatter from JO67AQ.  My first QSO was made during Quadrantides 2018. From Perseids 2019 I work 432 MHz meteor scatter from my EME QTH in JO57XJ as well.

Rig

Today (from summer of 2016) I am using a 4x9 el yagi array fully steerable in azimuth and elevation. The rig is an IC-706Mk2G driving a SSPA with an BLF184XR. The yagi array is depicted below as well as an description of the yagi and array design in an pdf-document. The IC-706Mk2G is injection locked to a 10 MHz oven reference for good frequency accuracy and stability. I can use either FSK441 or JTMS from a ASUS GL552VW computer via a home made interface circuit. For the moment I prefer FSK441 as I have not had too much luck using JTMS.

SM6FHZ 4x9el 432 MHz yagi array


432 MHz 4x9el yagi array description

The rig in JO57XJ is my EME rig consisting of my 5.5m dish and a GS23B PA.

QTH

My present QTH in JO67AQ is unfortunately on the south side of a hill and only 100 m from the steep southern slope of that hill. This means that I am shielded from signals from about 270 degrees azimuth over north and to about 80 degrees azimuth. I need to elevate the array at least 20 degrees to clear the peak of the hill. I will be limited in working meteor scatter in those directions as I need to use the elevation to beam above the obstructions. 

SM6FHZ 70 cm yagi array pointin over the hill     In this picture the array is elevated 20 degrees in an azimuth of 40 degrees.

Take off in direction south    My present take off in direction south. Antennas are slightly elevated. 

The RF-environment is quite harsh with a lot of noise and spurious signal sources all around me. This is very annoying.
A well loaded tower of a cellular site just 150 m from my antenna in SSW direction. Good filtering is needed in front of the LNA. Fortunately, I do not think there is any 450 MHz system in this tower.

Cellular mast and 70cm array

It is however fun to see what can be done in 70cm meteor scatter with these limitations and a moderate station in an suburban location.

Meteor scatter features I have experienced on 432 MHz

The meteor scatter signals on 432 MHz show some features compared to lower bands. There are still a lot of exciting things to learn about meteor scatter on 432 MHz. I would appreciate to get your feedback and you to share your experience on the 432 MHz meteor scatter features.

Direction

You can chose between direct path, Hot A or Hot B. I have not yet seen any favorites here. I do not use Hot A or Hot B on greater distances (>1100-1200 km). Choosing a time when the radiant is in a good position seems to help a lot. Perpendicular to the path and not too high or too low in the sky. Too high radiant seems to be worse than a very low radiant, as long as the radiant is above the horizon.

Doppler

I have not yet seen too much of Doppler shift on meteor scatter signals on 432 MHz, as I am aware of. Maybe some of the frequency off-sets I have seen on sked partners could be attributed to Doppler shift. It does not seem to be happening on every burst nor ping. During Perseids 2019 I got some bursts with a clear Doppler distortion. These bursts did not decode.

Doppler burst Perseids 2019 F6DRO   Burst from F6DRO received during a sked i Perseids 2019. You can see the clear Doppler distortion on the burst. The sound when receiving this burst had a clear Doppler sound to it.


Meteor showers

So far I have only experience from Quadrantides, Lyrids, eta-Aquariids, Perseides, Leonids, Ursids and Geminids of 2018 in meteor scatter signals on 432 MHz. What I have noticed, is that you need to be close to the peak of the shower to have a decent chance to complete a QSO. Persistence and perseverance is what is needed. Dedication does help as well. Do not settle for less than a 2 hour sked, you may need more than that. Only Quadrantids, Persides and Geminids have produced any completed QSO's. Lyrids, eta-Aquariids, Ursids and Leonids produced some reflections but no QSO's. It looks like a good rule to use the major showers with good meteor count and avoid the smaller showers to have as good as possible success rate. However, some of the minor showers are known to have outbursts (meteor storms) now and then, e.g. Orionids, Leonids and Ursids. Keep track of any predictions for such at the IMO web site.

Planning

There are a few parameters that are good to grasp when planning for meteor scatter skeds on 432 MHz. 

  1. Predict the time for the peak of the shower for the year in question by using RadiantCalc. Solar Longitude information can be found at the IMO web page (see link below) as well.
  2. Radiant position versus local time can be calculated with RadiantCalc. Detailed information on how to use RadiantCalc and how to download and install it is to be found here.
  3. Make sure you know that your rig is correct in frequency within <100Hz and that it does not drift in frequency with time or temperature. Locking the master oscillator to a known good source may be a good idea.
  4. You need plenty of meteors to succeed, make sure you are close to the predicted peak of the shower and that the radiant is above the horizon at the time for your sked.
  5. Try to be within +/-30 deg of the Best directions line with the direction to your sked partner.
  6. Avoid, if possible, extensively high radiant positions (i.e. >60-70 deg) for best success rate.

You can follow this procedure and use these tools for planning your 432 MHz Meteor Scatter skeds and work. There may be different opinions on some of my statements above. Please tell me if you have other experience and recommendations!

Examples of radiant graphs produced by RadiantCalc below.

Radiant position plot for Geminids for 57 deg N  Radiant position plot for Geminids at 57 deg N with Best directions line for 19 UTC


I am using RadiantCalc for prediction of the radiant position for the meteor shower in question for the year in question. RadiantCalc is written in Matlab, but is compiled to an standalone application where you need have the Matlab Run-time Environment installed on your computer. The Matlab Run-time Environment is free and is included in the installation file of RadiantCalc. RadiantCalc is still being evolved and I have a few more ideas to be implemented into it.

Handy assets

I use the following web sites to get information about radiant calculations and the probability for meteor scatter propagation on 432 MHz. 

International Meteor Organization (IMO) web site with shower lists and data: https://www.imo.net/

Sidereal time calculation on line: http://www.jgiesen.de/astro/astroJS/siderealClock/

Calculations of radiant position from IMO data: http://www.stargazing.net/kepler/altaz.html

Calculation of the time for maximum from Solar longitude (found in the meteor shower table from IMO): http://wise-obs.tau.ac.il/~eran/Wise/Util/SolLon.html

OK1TEH has a lot of information about 432 MHz meteor scatter at his web page: http://ok1teh.nagano.cz/ms_70cmlog_text.htm

All five contain relevant information.
  

Results

G4RGK 3 sec burst on 432 MHz MS 2018-08-12   I received from G4RGK a 3 seconds burst via meteor scatter on 432 MHz i Perseids 2018. 

SM6FHZ_6_sec_432MHz_MS_burst_at_OK1TEH   My final rogers as received by OK1TEH on 2018-08-12 via 432 MHz MS in a 6 seconds burst i Perseids 2018.

Burst from GM8IEM as received by SM6FHZ   A typical 432 MHz MS burst, 120 ms. This one received from GM8IEM.

QSOs

Below is a summary of all 432 MHz meteor scatter stations worked by me over time.

  Call Square My Loc Date Time [UTC] Mode Sent RST Rec. RST Prop. Mode Field DXCC Distance QTF Elevation Time relative to predicted shower peak Radiant height [Deg] QTF-Best dir. off-set [Deg] Shower Antenna
1 YU1EV KN04CN JO67AQ 2018-01-04 05:30-08:00 JTMS 26 R26 MS 1 KN 1 1565 155 10 +11h 73-82 50 CCW Quad 4x9el
2 OK1TEH JO70FD JO67AQ 2018-08-12 07:30-10:00 FSK441 26 R26 MS 2 JO 2 854 158 10 -16h 65-50 45 CCW Pers 4x9el
3 G4RGK IO91ON JO67AQ 2018-08-12 11:00-13:00 FSK441 R37 27 MS 3 IO 3 1070 236 3 -13h 45-35 10 CW Pers 4x9el
4 GM8IEM IO78HF JO67AQ 2018-08-12 16:30-19:00 FSK441 26 R26 MS 4 1026 268 8 -7h 25-28 5 CCW Pers 4x9el
5 UT5DL KN18EP JO67AQ 2018-12-13 18:00-18:50 FSK441 26 R26 MS 5 1216 141 8 -18h 20-30 10 CCW Gemi 4x9el
6 IK0BZY JN61GW JO67AQ 2018-12-14 05:00-06:50 JTMS 26 R29 MS 4 JN 6 1752 179 6 -6h 42-28 10 CCW Gemi 4x9el
7 RK2P KO93AD JO67AQ 2018-12-14 14:40-16:20 FSK441 R26 26 MS 5 KO 7 1710 96 6 +3h 5-10 20 CCW Gemi 4x9el
8 OM5CM JN87WV JO67AQ 2018-12-14 16:50-18:55 FSK441 26 R26 MS 8 1157 158 10 +5h 12-28 20 CW Gemi 4x9el
9 LX1DB JN39CO JO67AQ 2018-12-14 19:00-20:20 FSK441 R26 26 MS 9 946 192 12 +8h 28-40 30 CW Gemi 4x9el
10 F6KBF JN18BW JO67AQ 2018-12-14 20:30-22:55 FSK441 26 R27 MS 10 1172 207 12 +9h 40-58 20 CW Gemi 4x9el
11 RK2P KO93AD JO57XJ 2019-08-12 16:55-19:35 FSK441 26 R26 MS 1712 95 3 -13h 25 5 CW Pers 5.5m dish
12 DL8DAU JO40ME JO57XJ 2019-08-12 20:30-21:00 FSK441 26 R26 MS 11 857 194 10 -10h 35 70 CW Pers 5.5m dish
13 9A5M JN95GO JO57XJ 2019-08-13 02:50-04:35 FSK441 26 R26 MS 12 1387 158 8 -4 - -2.5h 70-75 10 CCW Pers 5.5m dish
14 YU1EV KN04CN JO57XJ 2019-08-13 05:35-06:25 FSK441 26 R26 MS 1538 155 4 -1.5 - -0.5h 75-85 30 CCW Pers 5.5m dish
15 F6DRO JN03TJ JO57XJ 2019-08-13 07:00-08:45 FSK441 R26 36 MS 1710 209 5 0 - +1h 60-70 10 CW Pers 5.5m dish



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Updated August 17, 2019.              http://www.2ingandlin.se/SM6FHZ.htm