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My callsign on APRS Map

VHF Propagation Map 

Emergency messages via APRS network

Commands for APRS services

Make QSOs via CQ APRS group (CQSRVR)

Using this feature, you can make contacts with other APRS users, which are part of CQ group. This feature uses a special APRS server, named CQSRVR (this service was developed by AE5PL). In order to use this service, you should do the followings:

  • prepare a new message to CQSRVR;
  • in the body message type a string with the following format:  CQ [group_name] [main_message];
  • in this string, [group_name] is CQ and all registered users to this group will receive your message, specified in the [main_message] field. After this message, maybe somebody will respond.

Other groups could be: AMSAT, JOTA, ECHOLINK (Send CQ and the give local node), ISS etc.

When you send a CQ message to a group, you will be automatically registered in that group. In order to indicate your continous presence on specific group, you must send a CQ message to this group at every 30 minutes. If you are innactive for more than 12 hours, you will be unregistered automatically. Same rule is applied also for the group.

To unregister from a group, send an APRS message to CQSRVR with the following format: U [group_name].

The CQSRVR service provides also another useful commands:

  • ? - list of all active groups
  • ? [group_name] - how many users are in the group
  • L - list all groups where you are member

Another special APRS server is ANSRVR. It is similar with CQSRVR but allows to join quietly to a group and also to send announcements to other users.

An announcement can be send via an APRS message to ANSRVR, with the following body text: CQ <Group> "Announcement Text".

Other commands supported by the ANSRVR server are the following:

  • ? - Show all groups (# in parenthesis is number of members)
  • ? group - Show member count in group
  • D show groups with descriptions, also sending D <group> description text, will supply a description of the group to the server
  • L - List groups you are a member of (with member count including self)
  • J group - Join group quietly
  • K group1 group2 group3 … - Quietly Keepalive multiple groups (be careful of APRS message length limits)
  • CQ group text - Join group and send text to all current members, if the group does not exist it will be created and you will be the owner
  • U group - Leave (Unjoin) the group

Satellites prediction using APRS

Any APRS platform capable to handle message, can be used to predict the next passes of some amateur satellites. For this purpose, you have to send an APRS message to a satellite name available between brackets at the following link:

http://www.celestrak.com/NORAD/elements/amateur.txt 

This file contains the TLE coordinates used by a lot of prediction applications for ama.

If you decide who is the recipient (which means what satellite pass you want to predict), then, in the message body you have to enter your call-SSID. Prior to this, we assume that recently, your position for this call-SSID was sent via APRS.

 As a result, you will receive a message about the next or current satellite pass, as follows:

  •  If there is more then one hour to the next pass, you will be informed about the AoS (Acquisition of Signal) start time and direction plus maximum elevation of this pass;
  • If there is less than one hour to the next pass, the information will contain the start AoS and direction, followed by maximum direction and elevation and finally the LOS (Loss of Signal) direction and total time between AoS and LoS;
  • If the satellite is already in your sight, in ascension phase, you will get the current direction and elevation of the satellite, followed by the direction and maximum of the predicted elevation and at the end, the direction and time remaining till LoS.
  • If the satellite is in your sight, but in descending phase, you will receive the current direction and elevation of the satellite, followed by the direction and time remaining till LoS.

You can test this APRS feature starting with the International Space Station, during evening and nights with clear sky, because you can really see the object. First, beacon your position, then send an APRS message to ISS with text body yourcall-SSID. Be sure that yourcall-SSID is the same used when you prior beacon the position.

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