Position and DF Report Data Formats¶
Position ReportsLat/Long Position Reports are contained in the Information field of an APRS AX.25 frame.
The following diagrams show the permissible formats of these reports, together with some examples. The gray areas indicate optional fields, and the shaded (yellow) characters are literal ASCII characters. In all cases there is a maximum of 43 characters after the Symbol Code.
Why? Where did that 43 character limit come from? Chapter 3 stated that the Information part could be up to 256 characters. In practice, we often see much longer comments. The MIC-E format has ‘n’ for comment length rather than a specific limit.
| Lat/Long Position Report Format — without Timestamp | |||||
|---|---|---|---|---|---|
| ! or = | Lat | Sym Table ID | Long | Symbol Code | Comment (max 43 chars) |
| 1 | 8 | 1 | 9 | 1 | 0-43 |
| Examples !4903.50N/07201.75W-Test 001234 no timestamp, no APRS messaging, with comment. !4903.50N/07201.75W-Test /A=001234 no timestamp, no APRS messaging, altitude = 1234 ft. !49˽˽.˽˽N/072˽˽.˽˽W- no timestamp, no APRS messaging, location to nearest degree. !4903.50N/07201.75Wn no timestamp, no APRS messaging, | |||||
Bytes:
Bytes:
| Lat/Long Position Report Format — with Timestamp | ||||||
|---|---|---|---|---|---|---|
| / or @ | Time DHM / HMS | Lat | Sym Table ID | Long | Symbol Code | Comment (max 43 chars) |
| 1 | 7 | 8 | 1 | 9 | 1 | 0-43 |
| Examples /092345z4903.50N/07201.75W>Test1234 with timestamp, no APRS messaging, zulu time, with comment. @092345/4903.50N/07201.75W>Test1234 with timestamp, with APRS messaging, local time, with comment. |
Bytes:
| Lat/Long Position Report Format — with Data Extension (no Timestamp) | ||||||
|---|---|---|---|---|---|---|
| ! or = | Lat | Sym Table ID | Long | Symbol Code | Course/Speed | Comment (max 36 chars) |
| Power/Height/Gain/Dir | ||||||
| Radio Range | ||||||
| DF Signal Strength | ||||||
| 1 | 8 | 1 | 9 | 1 | 7 | 0-36 |
| Example =4903.50N/07201.75W#PHG5132 no timestamp, with APRS messaging, with PHG. =4903.50N/07201.75W_225/000g000t050r000p001…h00b10138dU2k weather report. |
Bytes:
| Lat/Long Position Report Format — with Data Extension and Timestamp | |||||||
|---|---|---|---|---|---|---|---|
| / or @ | Time DHM / HMS | Lat | Sym Table ID | Long | Symbol Code | Course/Speed | Comment (max 36 chars) |
| Power/Height/Gain/Dir | |||||||
| Radio Range | |||||||
| DF Signal Strength | |||||||
| 1 | 7 | 8 | 1 | 9 | 1 | 7 | 0-36 |
| Examples @092345/4903.50N/07201.75W>088/036 with timestamp, with APRS messaging, local time, course/speed. @234517h4903.50N/07201.75W>PHG5132 with timestamp, APRS messaging, hours/mins/secs time, PHG. @092345z4903.50N/07201.75W>RNG0050 with timestamp, APRS messaging, zulu time, radio range. /234517h4903.50N/07201.75W>DFS2360 with timestamp, hours/mins/secs time, DF, no APRS messaging. @092345z4903.50N/07201.75W_090/000g000t066r000p000…dUII weather report. |
Bytes:
| Maidenhead Locator Beacon | |||
|---|---|---|---|
| [ | Grid Locator | ] | Comment |
| 1 | 4 or 6 | 1 | n |
| Examples [IO91SX] 35 miles NNW of London [IO91] |
Sending raw GPS data is discouraged. This was a hack for early trackers with inadequate computing resources to allow conversion to a proper position report. Symbols had to go in the destination field using names like GPSxxx.
Bytes:
| Raw NMEA Position Report Format | ||
|---|---|---|
| NMEA Received Sentence | ||
| $ | …,…,…,…,…,…,… | |
| 1 | 25-209 | |
| Examples $GPGGA,102705,5157.9762,N,00029.3256,W,1,04,2.0,75.7,M,47.6,M,,*62 $GPGLL,2554.459,N,08020.187,W,154027.281,A $GPRMC,063909,A,3349.4302,N,11700.3721,W,43.022,89.3,291099,13.6,E*52 $GPVTG,318.7,T,,M,35.1,N,65.0,K*69 |
Bytes:
| DF Report Format — without Timestamp | |||||||
|---|---|---|---|---|---|---|---|
| ! or = | Lat | Sym Table ID / | Long | Symbol Code ** | Course/Speed | /BRG/NRQ | Comment (max 28 chars) |
| Power/Height/Gain/Dir | |||||||
| Radio Range | |||||||
| DF Signal Strength | |||||||
| 1 | 8 | 1 | 9 | 1 | 7 | 8 | 0-28 |
| Examples =4903.50N/07201.75W\088/036/270/729 no timestamp, course/speed/ bearing/NRQ, with APRS messaging. DF station moving (CSE is non-zero). =4903.50N/07201.75W*000/036/270/729 Same report, DF station fixed (CSE=000*). |
DF ReportsDF Reports are contained in the Information field of an APRS AX.25 frame. The Bearing and Number/Range/Quality (BRG/NRQ) parameters follow the Data Extension field.
Note: The BRG/NRQ parameters are only meaningful when the report contains the DF symbol (i.e. the Symbol Table ID is / and the Symbol Code is **).
Note: If the DF station is fixed, the Course value is zero. If the station is moving, the Course value is non-zero.
Bytes:
| DF Report Format — with Timestamp | ||||||||
|---|---|---|---|---|---|---|---|---|
| / or @ | Time DHM / HMS | Lat | Sym Table ID / | Long | Symbol Code ** | Course/Speed | /BRG/NRQ | Comment (max 28 chars) |
| Power/Height/Gain/Dir | ||||||||
| Radio Range | ||||||||
| DF Signal Strength | ||||||||
| 1 | 7 | 8 | 1 | 9 | 1 | 7 | 8 | 0-28 |
| Examples @092345z4903.50N/07201.75W\088/036/270/729 with timestamp, course/speed/ bearing/NRQ, with APRS messaging. /092345z4903.50N/07201.75W\000/000/270/729 with timestamp, bearing/NRQ, no course/speed, no APRS messaging. |