DX cluster

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DX-Cluster ( . English DX about receiving distant radio "radio reception over long distance" and cluster "pile, group, Grape", "group pictures to receive radio transmissions over long distance") are networked world of radio amateurs powered server , the messages (so-called DX spots) and forward them to all connected participants. These messages include:

  • which radio amateur
  • at what time
  • what call sign
  • on what frequency

heard. In addition, a comment z. B. possible via the reception quality.

purpose

The connected participants are usually active radio amateurs or shortwave listeners who want to find out about activities on the amateur radio bands in a timely manner, and who also occasionally send messages themselves. If a DX cluster receives a new message, this is immediately sent to all connected participants and to all DX clusters, which in turn forward to their connected participants.

DX clusters are connected via the Internet and / or via the packet radio network set up and operated by radio amateurs or HAMNET . The individual participants are connected to a DX cluster of their choice with their computer using Telnet and, if necessary, a graphic user interface (DX cluster software).

In DX clusters, radio amateurs report when they hear a rare or particularly interesting station on one of the different bands or if they have a radio connection with it. The analysis of several DX-Cluster messages can also be used as an indicator for propagation conditions and their change, e.g. B. tape openings are used.

The DX clusters also allow access to continuously updated information and external databases, e.g. B. Address directories. It is also possible to exchange messages with other participants or to send text messages to all participants in your own cluster or worldwide.

DX cluster data

This is what DX cluster data looks like, for example, when a radio amateur receives it in real time from a DX cluster: 

N4BAA      3503.0 VP5/K4SV                                  0028 07 Aug
ND3F       3503.1 VP5/K4SV                                  0026 07 Aug
N4BAA      3505.0 C91CW       Tnx! Up 2.2                   0026 07 Aug
W2QN-@     3793.0 OK2BJJ      cq                            0025 07 Aug
UY5ZZ-@    3505.0 C91CW       up 2 tnx QSO                  0024 07 Aug
DL3KVC-@   3649.0 5B4AGL      CQ CQ CQ                      0024 07 Aug
UA9CGL     3505.0 C91CW       QSX 3507.01 up2               0017 07 Aug
MM0NDX     3799.0 LU6QI       clg you                       0016 07 Aug
W1IBQ      3505.0 C91CW       weak but workable in GA       0015 07 Aug
W5VU       3505.0 C91CW       QSX 3507.00 good sig MA       0001 07 Aug
NO2R       3505.0 C91CW       up 2                          2357 06 Aug
N2MF-@     3505.0 C91CW       Cpy in NE USA, Lsn up 2       2356 06 Aug
PA3EWP     3796.0 9G5OO                                     2343 06 Aug
DL7ON      3505.0 C91CW                                     2340 06 Aug
SP4AWE-@   3505.0 C91CW       up2                           2335 06 Aug
UR4LRG-@   3505.0 C91CW       yess! weak sig                2334 06 Aug
VK6HD      3502.1 DL1EL       tnx qso ralf                  2326 06 Aug
DL1EL      3502.1 VK6HD                                     2325 06 Aug
9G5CR      3796.0 9G5OO                                     2318 06 Aug
IZ7EDQ     3725.0 IZ7AUH      test                          2310 06 Aug

In the first column is the radio call sign of the reporting radio amateur. The second column contains the frequency on which the rare station was heard. This is followed by the call sign of the rare station in the third column and then further comments on the DX station or the radio connection. At the end of a line, the time and date on which the radio amateur reported the connection is noted. The time is given in UTC .

criticism

The first DX clusters were only connected to each other at the local level via packet radio , so a DX spot was only broadcast on a few neighboring DX clusters, and user access was also only possible via packet radio. By linking all DX clusters worldwide via the Internet and providing countless anonymous accesses via Telnet , the ratio of usable to unusable spots in the DX cluster has, according to some radio amateurs, decreased significantly in recent years. Most DX cluster programs today have filter functions that enable the user to only display messages that are of interest to him.

For the shortwave amateur radio bands, a myriad of fake spots are sent via the anonymous Telnet access, especially in amateur radio competitions, mostly with a fake sender call sign for the own call sign (so-called selfspotting ). Another point of criticism is that due to the increasing spread of the DX cluster, many radio amateurs no longer bother to look for radio signals themselves, but only rely on the DX cluster and wait until a coveted station is reported there .

Another point of criticism is that the reporting of particularly rare radio stations in the DX cluster often leads to a huge rush of callers on the reported frequency, which often ends in total chaos. Only the best equipped radio amateurs then have a realistic chance of establishing a radio link with the rare station.

Use of the DX cluster for the VHF range

DX spots in the VHF, UHF and microwave ranges are almost always valuable information that allows the propagation conditions to be studied. There are a number of post processors, e.g. B. DX Robot on the Internet and LiveMUF as a local client at the user's, which based on the cluster information , allow displays of the usable connection paths in the event of overreach , in particular the rarely occurring sporadic e-overreaches, or users registered automatically via e-mail and SMS to inform.

In addition to the DX clusters, the chat room operated by the Belgian radio amateur Alain Stievenart, ON4KST, is of great importance for propagation attempts, especially in the microwave areas, where many radio connections are agreed in advance due to the very narrow opening angles of the high-gain antennas.

German DX cluster map

German DX cluster map, overview of the connections between DX clusters in Germany

Web links

Individual evidence

  1. ↑ Report by K1TTT about suspicious DX spots in the ARRL SSB Contest 2006. Accessed on October 8, 2009 (English).