Context. Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile – hence precious – meteorites must be recovered rapidly to avoid their alteration. Aims. The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receivers and covers an area of about 1.5 × 106 km2. Methods. The FRIPON network, fully operational since 2018, has been monitoring meteoroid entries since 2016, thereby allowing the characterization of their dynamical and physical properties. In addition, the level of automation of the network makes it possible to trigger a meteorite recovery campaign only a few hours after it reaches the surface of the Earth. Recovery campaigns are only organized for meteorites with final masses estimated of at least 500 g, which is about one event per year in France. No recovery campaign is organized in the case of smaller final masses on the order of 50 to 100 g, which happens about three times a year; instead, the information is delivered to the local media so that it can reach the inhabitants living in the vicinity of the fall. Results. Nearly 4000 meteoroids have been detected so far and characterized by FRIPON. The distribution of their orbits appears to be bimodal, with a cometary population and a main belt population. Sporadic meteors amount to about 55% of all meteors. A first estimate of the absolute meteoroid flux (mag < –5; meteoroid size ≥~1 cm) amounts to 1250/yr/106 km2. This value is compatible with previous estimates. Finally, the first meteorite was recovered in Italy (Cavezzo, January 2020) thanks to the PRISMA network, a component of the FRIPON science project.

&lt;p&gt;BRAMS (Belgian RAdio Meteor Stations) is a network using forward scatter of radio waves on ionized meteor trails to study meteoroids. It is made of a dedicated transmitter and of 42 receiving stations located in or near Belgium. The network started in 2010 but has recently been extended and upgraded.&lt;/p&gt; &lt;p&gt;The transmitter emits a circularly polarized CW radio wave with no modulation at a frequency of 49.97 MHz and with a power of 130 W. Each receiving station uses a 3-element zenith pointing Yagi antenna. The first stations used analog ICOM-R75 receivers and a PC. Since 2018, new improved stations have been installed using digital RSP2 receivers, a GPSDO and a Raspberry Pi, providing better dynamic, sensitivity and stability.&lt;/p&gt; &lt;p&gt;A vast majority of the meteor echoes detected by BRAMS are specular, which means that most of the power of the meteor echoes comes from a small region along the meteoroid path centered on the specular reflection point, a point which is tangential to a prolate ellipsoid having the transmitter and the receiver as the two foci. This puts important geometrical constraints on whether a specific meteoroid trajectory can be detected or not by a given receiving station since the position of the reflection point must fall within the so-called meteor zone.&lt;/p&gt; &lt;p&gt;As a consequence, for meteor showers, the observed activity based on the raw counts of meteor echoes recorded by a BRAMS station is modulated by the position of the radiant throughout the day and does not truly reflect the real activity of the shower.&amp;#160; A possibility to correct these raw counts is to compute the so-called Observability Function (OF) introduced by Hines (1958) and further developed by Verbeeck (1997). This OF contains a geometrical part which provides the location of potentially observable meteor trails at a given moment and for a given station, and another part which takes into account which fraction of these trails will actually be detected by the receiving station.&amp;#160; Indeed, whether a meteor echo will be detected at the station also depends on the sensitivity of the receiving chain, on the power transmitted and on the ionization at the reflection point, the latter depending on the initial mass of the meteoroid.&lt;/p&gt; &lt;p&gt;We will describe how the geometrical part of the OF is calculated and will provide results for several receiving stations of the BRAMS network to emphasize the importance of the geometry. We will also describe how we take into account important characteristics of the system to determine the sensitivity of the receiving chain such as the gains of the antenna in the direction of the meteor echoes.&amp;#160; Finally, we will apply the OF to the raw counts of a few main meteor showers (e.g. Perseids, Geminids, Quadrantids) obtained from the Citizen Science project, the Radio Meteor Zoo, that we have developed since 2016 in cooperation with Zooniverse (https://www.radiometeorzoo.be).&lt;/p&gt; &lt;p&gt;&amp;#160;&lt;/p&gt; &lt;p&gt;Hines, C., Can. J. Phys., 36, 117-126, 1958&lt;/p&gt; &lt;p&gt;Verbeeck, C., Proceedings of the International Meteor Conference, Apeldoorn, the Netherlands, 122-132, 1996&lt;/p&gt;

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&lt;p&gt;In this study, optical video observations of meteors with the CAMS (Camera for All-sky Meteor Surveillance)-BeNeLux network and radio forward scatter observations with the BRAMS (Belgian RAdio Meteor Stations) network obtained on 4-5 October 2018 &amp;#160;are combined in order to obtain an ionization profile along a meteor path.&lt;/p&gt;&lt;p&gt;The trajectory, initial speed and deceleration parameters of a given meteor are provided by the CAMS-BeNeLux data. For a given trajectory, the positions of the specular reflection points for radio waves are computed for each combination of a given BRAMS receiving station and the BRAMS transmitter. For each receiving station which recorded a meteor echo (depending on the geometry and the SNR ratio), the power profile is computed and the peak power values of the underdense meteor profiles are used to determine the ionization (electron line density) at the various specular reflection points along the meteor path. This is done using the McKinley (1961) formula which is strictly valid for underdense meteor echoes.&amp;#160; We discuss how we compute the gains of the antennas, the polarization factor, and how the peak power values are transformed from arbitrary units into watts using the signal recorded from a device called the BRAMS calibrator. We also discuss how to extend this study to overdense meteor echoes or those with intermediate electron line densities.&lt;/p&gt;&lt;p&gt;Finally, these results are combined with a simple ablation meteor model in order to obtain an estimate of the initial mass of the meteoroid.&lt;/p&gt;&lt;p&gt;Mc Kinley D.W.R., Meteor science and engineering, Mc Graw-Hill eds, 1961&lt;/p&gt;