Update: 9. Jan. 2021. Hits:  since 20050614.

My Automated VHF Radio set-up for Meteor Scatter, Aurora, Es & Tropospheric propagation monitoring

NOTE: You find a page on radio Meteor Scatter observing from here.

The MS-Soft's prediction features require reliable and up to date meteor shower data, but such information did not seem to be readily available. Daytime shower information seemed sparse and obsolete. As a result, I designed and set up an automated long baseline meteor monitoring VHF radio/computer system in 1993, to acquire fresh and reliable information on meteor showers. The system operates 24 h / day and with the now gone Eurosignal ,that setup counted some 1.8 million meteors every year (or over 200 meteors / hour), now somewhat less,  down to limiting magnitude of +7.5 typically, but does not store detailed information on single meteor. High counts reduce statistical noise.

For meteor data gathering, other propagation modes (Aurora, Es) are nuisances, but ways have been created to identify them. Additional confidence for this process comes from data produced by the magnetometer and VHF receiver specially set up to detect Radio Aurora. It may sound odd, but there is a lot of hardware just to detect non-meteoric propagation, but these other sensors do provide interesting information about VHF propagation conditions. Each year about 2% (+-1.5%) of the data was rejected (only 200 h). This figure follows roughly the solar cycle, as the occurrences of Radio Auroras vary: 1994: 338 h, 1995 158 h, 1996 89 h, 1997 165 h. Comparable statistics can not be made as the setup has been changed many times over the next decades.

Radio Aurora 21. Mar. 1998

An example of signal strength vs. time of Radio Auroras caused by SSC and sub storms.
Doppler smear also causes the signal's spectrum to disperse and some modulation modes to be come
unreadable - this feature helps to recognize backscatter Aurora signals.

Two examples of signal strength vs. time of Sporadic-E (Es) signals on VHF.
The signal's spectrum is unaffected and recognizing the propagation mode is easiest
by the smooth semi-regular (multipath) fading pattern, as seen above with periods of about few seconds or longer.
This fading may on some cases be almost non-existent though!

6-h long band-scan during a good sporadic-E day: all normal TV-carriers and their offsets observed. OIRT-FM band crowded
 with signals 45 dB over receiver noise floor.

Other frequencies on the CCIR FM- band had to be used starting from April 1998 since Eurosignal was shut down. Statistical comparison of Auroral propagation can not be done with the old data, since the antenna's directional pattern differs and so will the transmitter locations. From November 1998, there are two receivers on two different FM- band frequencies monitoring meteor reflections. This redundancy provides means to detect some of the non-meteoric propagation event and was at some stage used (by the file format conversion software) to reject data from the bad channel for meteoric data due to diversity effects.

The regulating authority and broadcasters have made a firm decision on filling up every frequency slot available on the FM- band and possibilities to continue meteoric data gathering on FM band  became impossible here too,  like has already happened in many other countries. The few reasonably clear gaps left, are not having high power stations at suitable distances and produce only a fraction of meteor counts compared to what was available 1998, even with the 8 dB enhanced detection level. This is a big shame and very frustrating! Around 2020 also majority of  Russian OIRT FM stations were taken off-air with just a few remaining. Band I analog TV stations were taken off the air for digital transistion to UHF few years earlier, with only a few left in eastern Ukraine.


System consists of multiple receivers and a flux gate magnetometer:


System timeline


           87.360 MHz  Eurosignal, shutdown @ 01-04-1998
          144.960 MHz, 1998-> 144.412 MHz for Aurora
           62.213 Lopik TV from 02-04-1998 to 30-09-1998, with cable TV leak problems

87.360 MHz in use initially, lost by paging network shut down 01-04-1998, moved to:
88.8 MHz Lost to Estonian Pereradio 19-09-1998 moved to:
88.7 MHz In use since 15-11-1998, lost to unk. radio station in St. P-burg  area
88.8 MHz in use since 16-11-2004
88.7 MHz in use since ??????????. lost to Party FM, Lahti.
88.8 MHz in use since 15-07-2012
50.067 MHz in use since 01-10-2014 (DC8RI design Funkamateur converter 50/28 & CRT SS 6900 transceiver)

88.3 MHz in use initially
88.3 MHz Lost to YLE, Tampere 29-01-1999, moved to:
89.3 MHz Lost to Star-FM 29-12-1999, moved to:
87.8 MHz Abandoned in favor of now clear 88.8 MHz 02-04-2000  moved to:
88.8 MHz Lost to Estonian local radio 15-10-2000, back to 87.8 MHz with -131 dBm.
87.8 MHz Abandoned because of too much Tropo interference from YLE, Vaasa, moved to:
107.9 MHz from 02-01-2001 with a separate 3-el. Yagi beaming SW, occ. interference from Narva, Est., Lost to local radio in Pernaja
104.2 MHz from 16-03-2012, too much tropo.
59.25 MHz from 18-08-2013 (2SK121, SBL-1 converter w. 40 MHz XO LO). too much tropo from 0 and +7.5 kHz offsets.
67.1 MHz from 1-09-2013 (2SK121, SBL-1 converter w. 40 MHz XO LO).
69.56 MHz from 16-06-2017 (MGF1902 preamp to UBC355CLT).
4 frequencies between 66 and 71 MHz East, from 01-07-2017 (MGF1902 preamp to UBC355CLT).
5 frequencies between 66 and 71 MHz East, from 29-10-2017 (MGF1902 preamp to UBC355CLT).
6 frequencies between 66 and 70 MHz South, from 09-01-2021 (MGF1902 preamp to UBC355CLT).


 87...90 MHz 2-element Yagi 1993...30-03-1999, SSW or SW
 87...90 MHz 3-element narrow band Yagi 01-04-1999 to 15-07-2010, SSW or SW
 87...90 MHz 3-element commercial Yagi 15-07-2010 onwards, SW
108 MHz 3-element commercial Yagi 02-01-2001 to 18-08-2013, SW
59.25 MHz 3-element HB Yagi 18-08-2013 to 31-8-2013, SSE.
OIRT FM 3-element HB Yagi 1-09-2013 onwards, ESE (100 deg), then 10-2013 onwards S (180 deg 3-el. 4.2 dBd Yagi)  (Pinsk, Belorussia, BR-1), peak MS signal power with LPDA -93 dBm. 15th July 2017 onwards 4-element modified Sirio SY68-3 to 63 deg (2* 17 kW, Bazhsky,Usogorsk,Russia)
50 MHz 4-element HB, 10-2014 onwards, N (0 deg).   9. July 2017 onwards 5-element Sirio SY 50-5 to Az 5 deg el. 5 deg. 6.5 m AGL.    August 2017 onwards 3-element mod. Sirio to Az 5 deg. 5m AGL 

    62 MHz 2-element Yagi 02-04-1998 to 30-09-1998, WSW
    144 MHz 12-element (8-el. since July 2010) Yagi, N
Detection levels:

   87...90 MHz, -123 dBm 1993 to 01-04-1998, -125 dBm 01-04-1998...31-12-1999,
                -131 dBm from 14-01-2000, -131 dBm @ 88.7 and -125dBm @88.8 from 03-04-2000 to 15-10-2000..
                -131 dBm from 15-10-2000 onwards @ 88.7 and 87.8 MHz, 88.8 and 107.9 MHz.
                -130 dBm from 22-06-2004 onwards @88.7 and -125 dBm @ 107.9 MHz
                -126 dBm on 88.8 MHz and -129 dBm on 104.6 MHz from March 2011 onwards
                -125.4 dBm on 59.25 MHz 22-08-2013 to 31-08-2013.
                -127.2 dBm on 67.1 MHz 1-08-2013 onwards.
                -  N.A. dBm on 50 MHz 10-2014 onwards.

   62 MHz N.A.

   144 MHz   FM:  -125 dBm, except -118 dBm; 2.4 kHz BW from 12-12-2004 to 04-08-2013


         Fluxgate: X and Y components,  resolution: one bit ~ 2nT, sampling interval 10 minutes.

All equipment except the magnetometer, are battery powered. The expressed RF signal levels are @Tambient = 290 K. Antennas have elevation angle of 0 degrees and feed line losses are 1.5 to 2 dB. Receivers' bandwidths are 15 kHz (-3dB) and utilize squelch detection, sampled at some 30 ms rate by a laptop computer running my own DOS software comparable to MCT5X.EXE available on the download area on my website. The same computer drives A/D-converter that reads analog data, from the home-made two-axis Fluxgate Magnetometer with Magnetic Research FG-400 sensors. The Fluxgate components costs a few hundred US $. Magnetometer's components were eventually funded by a grant from the Finnish astronomical society Ursa. Ursa also awarded my efforts of combining amateur radio and amateur astronomy with the distinguished Stella Arcti prize in 1998.

Annual operating costs vary from  100€ to 1600€ depending on needs to replace broken equiment. The monthly routine data processing, reporting, filing, hardware and software upgrades and troubleshooting/fixing equipment and solving problems has taken a lot of time overall, typically never less than 1.5 h/month.

Meteor reflections.

Audiogram of meteor reflections from TV carriers (R4 8P). Click the image an listen!

Can't see a

3 main types of radio signals bounced from meteor trails.

Distant doppler radar received simultaneously via the moon and meteor trail

In spite of common difficulties in interpreting radio data, the system has produced useful results also from the viewpoint of meteor astronomy by detecting and verifying several significant meteor outburst events from different showers, like Perseids, Leonids, Ursids, a-Aurigids, a-Monocerotids, July Bootids, Draconids. This receiving site is co-operating with Dr. P. Jenniskens at SETI Institute and is dedicated to detect meteor outbursts.

certi and minor planet 15703 (1987 SU1) by IAU div. F in 12. July 2014.

87.360 MHz MSDATA from 1994 & 1995

These one year / 24h images revealing annual meteor activity are based on summing of two years of meteor scatter data. The upper panel is produced from hourly raw counts and lower on hourly duration of the longest reflection. Article based on this data is published on: I. Yrjölä, P. Jenniskens,"Meteor stream activity IV. A survey of annual meteor activity by means of Radio Forward Scattering.", Astronomy & Astrophysics, 1998".

You may find my radio MS or video data being used on at least in these scientific publications:

Astronomy & Astrophysics (and other) articles can be searched and viewed via the NASA ADS service. Some of the A&A articles can be accessed with user name 'astro' and password 'free'.

Copyright 1997...2021  Ilkka Yrjölä.  1987 SU1