Glossary

Terms used throughout this handbook, gathered in one place. See also Q-codes for the on-air abbreviations used inside messages.

Beacon

A position report you send that tells the OTA bot (and anyone else listening) where you are. Also just called a position report.

Callsign

The identifier your licensing authority assigned you, like K7ABC. To OTA it is who you are: one operator page, one scoreboard and one op at a time, whichever station you are using. Where a bot command takes a callsign, a station works too. OTA reads the callsign off it, so INFO K7ABC and INFO K7ABC-6 ask about the same op.

Chaser

An operator who calls in to make contact with a host’s op. POTA calls this role “hunter”; this handbook always says chaser.

Combo

A name for a pattern of stamps on one QSO, like Brackish when one party was on a lake and the other at sea. A combo has no points of its own: it is worth exactly what the stamps it names are worth, and it exists to give a better name to a combination worth noticing. Because it adds nothing, a combo can be invented later and still apply to old contacts without changing what any of them scored. The catalog is on the stamps and combos page.

Command

The instruction inside a message’s text when the message is addressed to the OTA bot. It is the first word, like HOST, CQ, or QSL. Some commands have a traditional Q-code you can use instead (QRV for HOST, QRT for DONE). All commands are listed in OTA bot commands.

Exchange

A linked run of packets (messages and any position reports) that together make up one interaction with the OTA bot: a command and whatever comes back in response. Most exchanges are short (a command and a single reply); going on the air is a four-packet exchange: your HOST, the bot’s request for a position, your position report, and the bot’s confirmation.

An exchange is the plumbing that links packets together. A QSO, below, is the bigger thing that emerges once one or more exchanges result in a confirmed contact.

Frame

The raw data demodulated off the air (or relayed via APRS-IS), also called a packet. A frame has a type, such as message or position report.

Host

The operator running an op, the one who goes on the air and waits to be chased. POTA and SOTA call this role “activator”. Since there are no geographic constraints to APRS OTA, you aren’t activating a location, so we use host instead.

Maidenhead locator or grid square

A Maidenhead locator, commonly referred to as a grid square, compresses latitude and longitude into a short string of characters. Some resolution is lost, but for most ham radio uses, the precision of multi-digit latitude and longitude is not required. Maidenhead locators also remove the negative/positive and east/west confusion of latitude and longitude. Maidenhead locators are widely used in ham radio for contest logs and grid square awards

A locator is a four tier hierarchical grid:

• a field is the coarsest division, a 20°-longitude × 10°-latitude cell identified by two letters (A–R for each axis, covering the whole globe in an 18×18 grid)
• within each field, a square subdivides it into a 10×10 grid of 2° × 1° cells identified by two digits (0–9)
• within each square, a subsquare further subdivides it into a 24×24 grid of 5’ × 2.5’ cells identified by two more letters (a–x)
• within each subsquare, an extended square divides a subsquare into a 10x10 grid identified by two digits (0-9)

Extended squares are not used very often, the most common Maidenhead locates are six characters. Even though a six character locator includes a subsquare, it is still commonly referred to as a grid square.

A six-character locator like DN40bi identifies a location within a few kilometers.

APRS position reports natively use the DDMM.mmm format for latitude and longitude, and the transmitter can choose to omit certain digits for less precision. APRS OTA shows the exact position transmitted on the map. When the OTA bot relays messages between hosts and chasers, it uses the shorter, but less precise, Maidenhead grid subsquare.

Message

An APRS packet addressed from one callsign to another, as opposed to a position report or other packet type. If a message is addressed to the OTA bot, its text is a command.

Op

One on-air session created by a host. Chasers make QSOs with the host while the op is on the air. POTA and SOTA call this an activation, but since there are no geographic constraints to APRS OTA you aren’t activating a location. Op is short for operation, and it’s so convenient that we never use the longer term.

OTA bot

The APRS messaging bot at the center of APRS On The Air. You use the service by sending it APRS messages.

Points

The unit of scoring. Every point comes from a stamp, so nothing else on a contact can earn one. Points are never split or divided: when a QSO earns points, the host and the chaser each add the whole amount to their own total. See Score points for how and when they are awarded.

Q-codes

We use a few Q-codes and other ham abbreviations, which are all listed on their own page

QSO

A completed contact between two operators. QSO is a Q-code that originally meant “I can communicate with”, now used all over ham radio as a noun for a contact both sides confirmed. In APRS OTA a QSO is complete once a chaser has called in and the host has acknowledged with QSL; see Make a contact for the whole sequence. This handbook uses “QSO” and “completed contact” to mean the same thing. Each one is logged, gets a page and a QSL card of its own, and carries its own score.

Score

A total of points. Three things carry one: a QSO scores the sum of its stamps, an op scores the sum of the QSOs made during it, and a callsign carries a callsign total, every point you have earned whether you were the host or the chaser. A QSO’s score is settled the moment the host confirms the contact and is never adjusted afterward.

Stamp

A named fact about one contact that is usually worth points, added the moment the host confirms the contact with QSL. Stamps are the only source of points. Stamps that record a similar kind of fact belong to the same family, like the two water stamps Nessie and Davy Jones. The catalog of every stamp, what it says, and what it is worth is on the stamps and combos page.

Station

A callsign with an SSID, like K7ABC-6: one radio or app of yours on the air. The SSID is the number after the hyphen, and it tells your radios apart. An op is run by one station, and the host’s commands and beacons have to come from that station, not from another SSID of the same callsign. When OTA names the station running an op, it names it with the SSID.