APRS Passcode Generator - Instant Callsign Hash
Generate your APRS-IS passcode securely in your browser. Convert your Amateur Radio Callsign to a valid APRS network key instantly.
Supports standard callsigns with or without SSIDs (e.g., K1ABC-7)
About
This tool calculates the APRS-IS Passcode required to connect amateur radio software to the APRS Internet Service network. The passcode is generated using a standardized hashing algorithm that converts your unique callsign into a 15-bit integer key. This mechanism, while not a high-security cryptographic signature, serves to verify that the station injecting data into the global APRS network holds a valid callsign format.
To use this generator, simply enter your base callsign (e.g., N0CALL). If you use a Secondary Station Identifier (SSID) like -9 or -12, the tool automatically strips it to calculate the passcode for the root callsign, which is standard practice for APRS-IS authentication.
Formulas
The APRS-IS passcode algorithm uses bitwise operations to hash the callsign. The process starts with a constant seed and iterates through the callsign characters.
Step 1: Initialization
H = 0x73e2 (29666)
Step 2: Iteration
For each pair of characters Ci, Ci+1:
H ← H &xor; Ci ≪ 8
H ← H &xor; Ci+1
Step 3: Masking
Passcode = H ∧ 0x7FFF
Where C is the ASCII integer value of the character, &xor; is the Bitwise XOR operator, and ≪ is the Bitwise Left Shift.
Reference Data
| SSID Code | Recommended Usage (APRS Standards) |
|---|---|
| -0 | Primary Station / Home Station (Usually omitted) |
| -5 | Smartphones (Android/iOS apps like APRSdroid) |
| -7 | Handheld Radios (HTs) |
| -9 | Mobile Units (Cars/Trucks) |
| -10 | Internet-only Stations (IGate, Weather Stations) |
| -12 | Trackers / Portable Units |
| -14 | Truckers / Large Vehicles |
| -15 | High Frequency (HF) Gateways |