CHASE

Use the CHASE command to call a host who is on the air and start a QSO. Follow it with a position report within 5 minutes, and the OTA bot relays your callsign and grid square to the host.

Your position report must come from the same callsign and SSID that sent the chase. W1XYZ-5 chases, so W1XYZ-5 beacons, not W1XYZ or W1XYZ-9. A beacon from any other station does not satisfy the window.

See Make a contact for the whole QSO, step by step, and QSL for how the host confirms it.

You can leave the SSID off

CHASE K7ABC is the same command as CHASE K7ABC-6. A callsign runs one op at a time, so the callsign on its own is all the bot needs to find the op. That saves you two or three characters on every chase you thumb into a radio.

Every SSID form works too, so a callsign you copied straight off a CQ reply needs no editing.

Only the host’s SSID is optional. Your own still has to match, because your position report has to come from the exact station that sent the chase.

The short form

A message that opens with the callsign itself is the same command. It is the shortest chase there is, which is worth knowing when you are thumbing letters into a radio:

Both spellings are permanent. CHASE @K7ABC-6 is accepted as well, so nothing you learn here has to be unlearned later.

How fast you can chase

OTA limits your chases to 4 per minute and 8 per 10 minutes. This limit applies to all SSIDs for your callsign. These limits are carefully calibrated to be high enough to work down a long CQ list, but still keep the frequency in your area usable for everybody else.

Why there is a limit

Every APRS message you send over RF puts traffic on the air in your local area. The CHASE command puts a lot of traffic on the air. OTA answers an accepted chase with a prompt for your position report, a receipt once it arrives, the host’s message if they wrote one. Your radio transmits an acknowledgment for every one of them.

All of that shares one channel. APRS runs at 1200 baud, every station in your area is on the same frequency, and only one of them can transmit at a time. A single message takes most of a second. If you could chase a fifteen op CQ list in a minute, that one burst would put around fifty messages from OTA onto your local channel, plus your acknowledgments and the retries for whatever collided. Position reports and messages from everyone else nearby, including other players, would be stepped on while it cleared.

The limit has two parts, and each does a different job.

• 4 per minute should let you chase about as fast as a normally caffeinated human can do it. It stops scripts and bots from firing chases faster than anyone types.
• 8 per 10 minutes paces how much traffic a single chaser can put on their local airwaves. On a busy night, you still get to chase all the ops, but you may need to do it in two batches.

Only chases OTA accepts are counted. A chase it turns away for another reason, like a host who has gone off the air, doesn’t use any of your limit. Neither does sending the same chase again while OTA is still waiting for your position report, because that is a retry of a chase already counted.

When you hit the limit

If you reach either limit, OTA tells you once, and says how long to wait.

That chase was not saved, so send it again once the time is up. Sending it sooner gets no reply, because OTA has already told you. Your radio will still show those messages as delivered. OTA acknowledges every message it receives before it decides what to do with it.

The per-minute limit clears within a minute, so it usually means a short wait. The longer limit can mean waiting several minutes. Either way, the message tells you how long.

Reference