Revised: Aug. 18. 2000. Hits:  since 20050614.

Common definition for Amateur Radio MS terminology on "pings" and "bursts" accepted in IARU Region 1 meeting, Lillehammer, Sept. 1999

(Based on the preliminary report from SRAL's delegate, OH6DD)

After the original and perhaps too scientific sounding proposal concerning the subject was rejected in previous (like almost everything on the first try) Region 1 meeting, it now became unanimously accepted on the second try.

This will not solve the problems of our world, but is just one tiny insignificant bit in a tiny corner far outside main stream Ham Radio hobby. So far, that I was amazed on the furious feedback during the "RFC" period at first, but I think common sense won this time - so how about implementing it?

If you did not know, the European MS ham community uses non mandatory ping/burst counts, when reporting on MS contacts to express something on the quality of the reflections received during the whole contact. The usual two digit report exchanged in the contact, is not very useful as it not updated during the contact because of the QSO procedure. There has been an older general understanding of the "ping" as to be a reflection from an underdense trail (see the document below) which was also accepted in US. In Europe the "ping" was usually considered as something that did not carry any information (originally because of the short duration and the technical limitations in the 1970's). This definition has not been formally documented anywhere and to my opinion it is not needed or even useful nowadays.

The method outlined below is very simple, if one wishes to keep records of pings and bursts on MS QSO's: Just compare the duration of the reflection and if it is shorter than what the table says, consider that one a "ping" and the longer ones exceeding the duration limit on the table as "bursts". Please note that this sorting and counting is voluntary. IARU, me, or anyone else is NOT demanding you to register the total number of pings and bursts, but as the document below explains it's usefulness, please use this method. MS-Soft already does the classification and reporting automatically by counting the number of received characters on each reflection related to transmission speed and frequency band.

Radio Amateurs have in the past contributed to radio science also in the field of propagation research, which has it's own chapter in the VHF Manager's Handbook. When logging data on Meteor Scatter contacts, we may also be able to contribute to Meteor Astronomy. For instance the a-Aurigids meteor outburst few years back was witnessed only by two less favorably located US visual meteor observers along with one French ham radio operator (reporting the event on Dubus) giving significant confirmation on the timing of the event.

I would like to thank Jukka, OH6DD for his great help with this proposal.

Copyright 1999...2014, Ilkka Yrjölä.


The following text will be added to IARU Region 1 "VHF Managers Handbook".

Doc/99/LH/C5.3 rev.1


SRAL Finland

At the moment there is no common and exact definition for a ping. For the analysis of scientific data the old way of defining a ping and a burst, which depended on information / no information, is not relevant.

Therefore for the correct analysis the following definitions should be used:

Ping: Reflection from an underdense meteor trail

Burst: Reflection from an overdense meteor trail.


Radio Amateurs have used the term "ping" to describe a "short" reflection. Most of the European operators define "ping" as a reflection too short to pass information. This definition was most likely evolved in the 1970's, when high speed CW (then < 600 LPM) gained popularity in Europe. With the less efficient equipment used those days, the shorter reflections were either too short to pass full characters due to slow speed and/or too weak to decode with the equipment available at that time.

Some operators define "ping" as a reflection from an underdense meteor trail and "burst" as a reflection from an overdense trail. This is also how "ping" and "burst" are described in The VHF/UHF DX Book (published by RSGB). Generally it can be said that most good reflections come from overdense trails and short/less usable reflections (pings) from underdense trails. Overdense and underdense reflections can be roughly separated by duration of the reflection (reference 1).

The principal difference of underdense and overdense trail is the mechanism that re-emits RF-energy. On underdense trails the RF-energy penetrates the trail and makes electrons oscillate and re-radiate energy, while on overdense trails, no penetration occurs and the trail is modelled as a metallic cylinder reflecting RF-energy. When receiving meteor reflections the audible differences are found in signal strength, duration and decaying shape.

CW speeds used in MS have increased since 1970's by about four times and new digital equipment (i.e. DTR) make copying useful information from a weak reflection now much more easier. The old way of defining a ping has thus become invalid and does have serious lack of logic by definition, while the underdense/overdense division is based on well known and studied physical facts, as described in scientific literature.

It would also be extremely useful, if MS working results published i.e. in DUBUS were of scientific use. Such working results could be used by people like OH5IY, who are doing scientific research on meteor scatter. QSO information in DUBUS contain the number of pings and bursts of every contact. This information is of little use, however, if ping is understood as a reflection with no information, thus depending on speed used. Instead, if ping is defined as an underdense reflection this kind of information would be of great value. The relative number of underdense and overdense reflections could be compared between different showers and between consecutive hours in the same shower. This would provide us new knowledge of meteor showers and sporadic meteors.

Aid for defining underdense and overdense trails:

Underdense and overdense reflections can be roughly separated by duration of the reflection (which varies by frequency). The threshold is not sharp, but a simple approximation can be made. On 50 MHz overdense trail durations are typically greater than 0.5 s (reference 1) and maximum underdense trail durations approximately 0.5-1 s (reference 2).

In the following table a 1 s reflection on 50 MHz has been taken as upper limit for the underdense trails. Durations for other frequencies have been derived from it according
to following formula (reference 3):

where t = duration in seconds,

f = frequency in MHz

Maximum duration of an underdense reflection (ping):
CW speed
Number of letters received
50 MHz
1 s
100 LPM
1000 LPM
2000 LPM
70 MHz
0.5 s
100 LPM
1000 LPM
2000 LPM
144 MHz
0.1 s
100 LPM
1000 LPM
2000 LPM
432 MHz
0.013 s
100 LPM
1000 LPM
2000 LPM

This table corresponds well with the situation as presently encountered on the popular 144 MHz band. For example, a reflection on 144 MHz with the speed of 1000 LPM containing up to two letters when decoded would be a ping. On the 432 MHz band pings are so short in duration (less than 0.013s) as to be almost impossible to detect.


1. The evolution of meteor burst communications system, P.S. Cannon & A.P.C Reed,

Journal of the Institution of Electronic and Radio Engineers, Vol. 57. No.

3, pp 101-112, May/June 1987.

2. J.A.Weitzen & al., An Estimate of the Capacity of the Meteor Burst Channel,

IEEE Transactions on Communications, Vol.Com-32, No.8. August 1984.

3. W.T. Ralston & al. Distribution of underdense meteor trail durations and

duty cycle and applications to meteor scatter communication system design.

Radio Science, Volume 28, Number 5, pp 747-757, September-October 1993.