Collaboration diagram for RTCM v3:

Functions
static u32	from_lock_ind (u8 lock)
static void	gen_obs_gps (navigation_measurement_t nm, u8 amb, u32 pr, s32 ppr, u8 lock, u8 cnr)
s16	rtcm3_check_frame (u8 *buff)
s8	rtcm3_decode_1002 (u8 buff, u16 id, double tow, u8 n_sat, navigation_measurement_t nm, u8 sync)
u16	rtcm3_encode_1002 (u8 buff, u16 id, gps_time_t t, u8 n_sat, navigation_measurement_t nm, u8 sync)
void	rtcm3_read_header (u8 buff, u16 type, u16 id, double tow, u8 sync, u8 n_sat, u8 div_free, u8 smooth)
s8	rtcm3_write_frame (u16 len, u8 *buff)
void	rtcm3_write_header (u8 *buff, u16 type, u16 id, gps_time_t t, u8 sync, u8 n_sat, u8 div_free, u8 smooth)
static u8	to_lock_ind (u32 time)

Detailed Description

RTCM v3.1 Format message encoding and decoding.

Implements RTCM Standard 10403.1

DFxxx codes indicate a corresponding Data Field as described in RTCM 10403.1 Table 3.4-1.

Function Documentation

static u32 from_lock_ind ( u8 lock ) [static]

Convert a RTCMv3 Lock Time Indicator value into a minimum lock time in seconds. See RTCM 10403.1, Table 3.4-2.

Parameters:

lock	Lock Time Indicator value.

Returns:: Minimum lock time in seconds.

Definition at line 218 of file rtcm3.c.

static void gen_obs_gps	(	navigation_measurement_t *	nm,
		u8 *	amb,
		u32 *	pr,
		s32 *	ppr,
		u8 *	lock,
		u8 *	cnr
	)		`[static]`

Generate RTCMv3 formatted GPS observation fields. Currently L1 only.

Parameters:

nm	Struct containing the observation.
amb	The GPS Integer L1 Pseudorange Modulus Ambiguity (DF014).
pr	The GPS L1 Pseudorange (DF011).
ppr	The GPS L1 PhaseRange – L1 Pseudorange (DF012).
lock	The GPS L1 Lock Time Indicator (DF013).
cnr	The GPS L1 CNR (DF015).

Definition at line 245 of file rtcm3.c.

s16 rtcm3_check_frame ( u8 * buff )

Check RTCM frame header and CRC valid.

Parameters:

buff	A pointer to the RTCM message buffer to check.

Returns:

If valid then return length of the data message in range 0-1023. Returns a negative number if the frame is invalid:

`-1` : Preamble not valid
`-2` : CRC mismatch

Definition at line 46 of file rtcm3.c.

s8 rtcm3_decode_1002	(	u8 *	buff,
		u16 *	id,
		double *	tow,
		u8 *	n_sat,
		navigation_measurement_t *	nm,
		u8 *	sync
	)

Decode an RTCMv3 message type 1002 (Extended L1-Only GPS RTK Observables)

Parameters:

buff	A pointer to the RTCM data message buffer.
id	Reference station ID (DF003).
tow	GPS time of week of epoch (DF004).
n_sat	Number of GPS satellites included in the message (DF006).
nm	Struct containing the observation.
sync	Synchronous GNSS Flag (DF005).

Returns:

If valid then return 0. Returns a negative number if the message is invalid:

`-1` : Message type mismatch
`-2` : Message uses unsupported P(Y) code

Definition at line 337 of file rtcm3.c.

u16 rtcm3_encode_1002	(	u8 *	buff,
		u16	id,
		gps_time_t	t,
		u8	n_sat,
		navigation_measurement_t *	nm,
		u8	sync
	)

Encode an RTCMv3 message type 1002 (Extended L1-Only GPS RTK Observables) Message type 1002 has length `64 + n_sat*74` bits. Returned message length is rounded up to the nearest whole byte.

Parameters:

buff	A pointer to the RTCM data message buffer.
id	Reference station ID (DF003).
t	GPS time of epoch (DF004).
n_sat	Number of GPS satellites included in the message (DF006).
nm	Struct containing the observation.
sync	Synchronous GNSS Flag (DF005).

Returns:: The message length in bytes.

Definition at line 296 of file rtcm3.c.

void rtcm3_read_header	(	u8 *	buff,
		u16 *	type,
		u16 *	id,
		double *	tow,
		u8 *	sync,
		u8 *	n_sat,
		u8 *	div_free,
		u8 *	smooth
	)

Read RTCM header for observation message types 1001..1004.

The data message header will be read starting from byte zero of the buffer. If the buffer also contains a frame header then be sure to pass a pointer to the start of the data message rather than a pointer to the start of the frame buffer. The RTCM observation header is 8 bytes (64 bits) long.

All return values are written into the parameters passed by reference.

Parameters:

buff	A pointer to the RTCM data message buffer.
type	Message type number, i.e. 1001..1004 (DF002).
id	Reference station ID (DF003).
tow	GPS time of week of the epoch (DF004).
sync	Synchronous GNSS Flag (DF005).
n_sat	Number of GPS satellites included in the message (DF006).
div_free	GPS Divergence-free Smoothing Indicator (DF007).
smooth	GPS Smoothing Interval indicator (DF008).

Definition at line 177 of file rtcm3.c.

s8 rtcm3_write_frame	(	u16	len,
		u8 *	buff
	)

Write RTCM frame header and CRC into a buffer.

The buffer should already contain the data message starting at the 4th byte of the buffer, i.e.

data_message = &buff[3]

The buffer must have 3 bytes free at the start to contain the header and must leave 3 bytes past the end free to contain the CRC. The total length of the buffer should be `len+6` bytes.

`len` should be in the range 0-1023 as per the RTCM v3 standard.

Parameters:

len	The length of the data message contained in the buffer.
buff	A pointer to the RTCM message buffer.

Returns:: Zero on success, -1 if `len` is too large.

Definition at line 84 of file rtcm3.c.

void rtcm3_write_header	(	u8 *	buff,
		u16	type,
		u16	id,
		gps_time_t	t,
		u8	sync,
		u8	n_sat,
		u8	div_free,
		u8	smooth
	)

Write RTCM header for observation message types 1001..1004.

The data message header will be written starting from byte zero of the buffer. If the buffer also contains a frame header then be sure to pass a pointer to the start of the data message rather than a pointer to the start of the frame buffer. The RTCM observation header is 8 bytes (64 bits) long.

If the Synchronous GNSS Message Flag is set to `0`, it means that no further GNSS observables referenced to the same Epoch Time will be transmitted. This enables the receiver to begin processing the data immediately after decoding the message. If it is set to `1`, it means that the next message will contain observables of another GNSS source referenced to the same Epoch Time.

Divergence-free Smoothing Indicator values:

Indicator | Meaning --------- | ---------------------------------- 0 | Divergence-free smoothing not used 1 | Divergence-free smoothing used

GPS Smoothing Interval indicator values are listed in RTCM 10403.1 Table 3.4-4, reproduced here:

Indicator | Smoothing Interval --------- | ------------------ 000 (0) | No smoothing 001 (1) | < 30 s 010 (2) | 30-60 s 011 (3) | 1-2 min 100 (4) | 2-4 min 101 (5) | 4-8 min 110 (6) | >8 min 111 (7) | Unlimited

Parameters:

buff	A pointer to the RTCM data message buffer.
type	Message type number, i.e. 1001..1004 (DF002).
id	Reference station ID (DF003).
t	GPS time of epoch (DF004).
sync	Synchronous GNSS Flag (DF005).
n_sat	Number of GPS satellites included in the message (DF006).
div_free	GPS Divergence-free Smoothing Indicator (DF007).
smooth	GPS Smoothing Interval indicator (DF008).

Definition at line 147 of file rtcm3.c.

static u8 to_lock_ind ( u32 time ) [static]

Convert a lock time in seconds into a RTCMv3 Lock Time Indicator value. See RTCM 10403.1, Table 3.4-2.

Parameters:

time	Lock time in seconds.

Returns:: Lock Time Indicator value.

Definition at line 195 of file rtcm3.c.

Functions

Detailed Description

Function Documentation