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V2 reduce rtcm #98

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V2 reduce rtcm #98

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dccb1b9
limit RTCM BW based on GNSS mask
benflyvoly Feb 21, 2022
81ac8a2
Merge branch 'PX4:master' into v2_reduce_rtcm
benflyvoly Feb 21, 2022
4fa7d69
apply PX4 code style rules
JacobCrabill Feb 21, 2022
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46 changes: 34 additions & 12 deletions src/ubx.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -677,7 +677,7 @@ int GPSDriverUBX::configureDevice(const GNSSSystemsMask &gnssSystems)
cfg_valset_msg_size = initCfgValset();
cfgValset<uint8_t>(UBX_CFG_KEY_CFG_UART1OUTPROT_UBX, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_CFG_UART1OUTPROT_RTCM3X, 0, cfg_valset_msg_size);
// heading output period 1 second
// heading output period 1 second (is this once per second or once per nav cycle?)
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1 Hz

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The RTCM messages are being sent at 10Hz (or 8Hz depending on GNSS config) so 8~10Hz heading solution is available. Is there any reason not to increase this to 5 or 10Hz? Would 5/10Hz be better than 4/8Hz for EKF updates?

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Even 1 Hz is enough for ekf, it can go with the gyro alone for quite some time.

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I agree a benefit to 4/5/8/10Hz updates hasn't been demonstrated. A potential downside of 1Hz heading over UAVCAN is that 87.5~90% of the RTCM traffic on the CAN bus doesn't get used for anything.

cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_UBX_NAV_RELPOSNED_UART1, 1, cfg_valset_msg_size);
// enable RTCM input on uart2 + set baudrate
cfgValset<uint8_t>(UBX_CFG_KEY_CFG_UART2_STOPBITS, 1, cfg_valset_msg_size);
Expand Down Expand Up @@ -712,12 +712,24 @@ int GPSDriverUBX::configureDevice(const GNSSSystemsMask &gnssSystems)
cfgValset<uint8_t>(UBX_CFG_KEY_CFG_UART2OUTPROT_RTCM3X, 1, cfg_valset_msg_size);
cfgValset<uint32_t>(UBX_CFG_KEY_CFG_UART2_BAUDRATE, uart2_baudrate, cfg_valset_msg_size);

// Ublox says to match RTCM TYPES MSM4/MSM7on all ports (issue if combining moving with static base)
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issue if combining moving with static base

Can you expand?

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Page 22 of the F9P integration manual has warnings about mixing MSM4 and MSM7 messages on different ports: https://www.u-blox.com/en/docs/UBX-18010802 E.g. The code as is would be using MSM7 from a QGC connected base injected on uart1/I2C and MSM4 over uart2 or uart1 for heading. MSM4 is slightly smaller than MSM7. So I believe it makes sense to use MSM4 for all static and moving baseline corrections. Also, it isn't clear to me that enabling more constellations is helpful for carrier phase based navigation solutions in terms of accuracy or integrity. That was the motivation for wanting to use GNSS mask as a way of enabling GPS only 10Hz rather than the default of 8Hz all constellations enabled.

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From the doc:

If the receiver is configured to output RTCM messages on several ports, they must all have the
same RTCM configuration otherwise the MSM multiple message bit might not be set properly.

This is true in the case of MSM7 output from a GCS receiver and MSM4 output from a heading base, as they are separate receivers. I don't see any problem here.

Using the config to conditionally enable outputs makes sense otherwise.

// Use MSM7 here as that's what's used for static base. MSM4 may have lower bandwidth requirement.
// Turn off Galileo BeiDou to get faster solutions, TBD if GLONASS helps RTK as it lacks common carrier freq.
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE4072_0_UART2, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1230_UART2, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1074_UART2, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1084_UART2, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1094_UART2, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1124_UART2, 1, cfg_valset_msg_size);

if (gnssSystems & GNSSSystemsMask::ENABLE_GLONASS) {
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1230_UART2, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1084_UART2, 1, cfg_valset_msg_size);
}

if (gnssSystems & GNSSSystemsMask::ENABLE_GALILEO) {
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1094_UART2, 1, cfg_valset_msg_size);
}

if (gnssSystems & GNSSSystemsMask::ENABLE_BEIDOU) {
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1124_UART2, 1, cfg_valset_msg_size);
}


if (!sendMessage(UBX_MSG_CFG_VALSET, (uint8_t *)&_buf, cfg_valset_msg_size)) {
Expand All @@ -737,7 +749,7 @@ int GPSDriverUBX::configureDevice(const GNSSSystemsMask &gnssSystems)
cfgValset<uint8_t>(UBX_CFG_KEY_CFG_UART1INPROT_NMEA, 0, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_CFG_UART1OUTPROT_UBX, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_CFG_UART1OUTPROT_RTCM3X, 0, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_UBX_NAV_RELPOSNED_UART1, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_UBX_NAV_RELPOSNED_UART1, 1, cfg_valset_msg_size); // why 1Hz?

if (!sendMessage(UBX_MSG_CFG_VALSET, (uint8_t *)&_buf, cfg_valset_msg_size)) {
return -1;
Expand All @@ -757,15 +769,25 @@ int GPSDriverUBX::configureDevice(const GNSSSystemsMask &gnssSystems)
cfgValset<uint8_t>(UBX_CFG_KEY_CFG_UART1OUTPROT_UBX, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_CFG_UART1OUTPROT_RTCM3X, 1, cfg_valset_msg_size);

// This may have unintended consequences for other moving base applications
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_UBX_NAV_RELPOSNED_UART1, 0, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_UBX_NAV_RELPOSNED_UART2, 0, cfg_valset_msg_size);

cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE4072_0_UART1, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1230_UART1, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1074_UART1, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1084_UART1, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1094_UART1, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1124_UART1, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE4072_0_UART2, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1074_UART2, 1, cfg_valset_msg_size);

if (gnssSystems & GNSSSystemsMask::ENABLE_GLONASS) {
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1230_UART2, 1, cfg_valset_msg_size);
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1084_UART2, 1, cfg_valset_msg_size);
}

if (gnssSystems & GNSSSystemsMask::ENABLE_GALILEO) {
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1094_UART2, 1, cfg_valset_msg_size);
}

if (gnssSystems & GNSSSystemsMask::ENABLE_BEIDOU) {
cfgValset<uint8_t>(UBX_CFG_KEY_MSGOUT_RTCM_3X_TYPE1124_UART2, 1, cfg_valset_msg_size);
}

if (!sendMessage(UBX_MSG_CFG_VALSET, (uint8_t *)&_buf, cfg_valset_msg_size)) {
return -1;
Expand Down