Every fourth altitude value is NaN

[lukehutch]

When using gpsd_client with a u-blox GPS, every fourth altitude value is NaN. This does not happen when using cgps or other gpsd client:

header: 
  seq: 470
  stamp: 
    secs: 1564341473
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519741333
longitude: 6.6806945
altitude: nan
position_covariance: [30.376, 0.0, 0.0, 0.0, 65.352, 0.0, 0.0, 0.0, nan]
position_covariance_type: 2
---
header: 
  seq: 471
  stamp: 
    secs: 1564341473
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519741333
longitude: 6.6806945
altitude: 1699.1
position_covariance: [30.376, 0.0, 0.0, 0.0, 65.352, 0.0, 0.0, 0.0, 90.16]
position_covariance_type: 2
---
header: 
  seq: 472
  stamp: 
    secs: 1564341473
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519741333
longitude: 6.6806945
altitude: 1699.1
position_covariance: [30.376, 0.0, 0.0, 0.0, 65.352, 0.0, 0.0, 0.0, 90.16]
position_covariance_type: 2
---
header: 
  seq: 473
  stamp: 
    secs: 1564341473
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519741333
longitude: 6.6806945
altitude: 1699.1
position_covariance: [30.376, 0.0, 0.0, 0.0, 65.352, 0.0, 0.0, 0.0, 90.16]
position_covariance_type: 2
---
header: 
  seq: 474
  stamp: 
    secs: 1564341474
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.5197375
longitude: 6.680697333
altitude: nan
position_covariance: [30.376, 0.0, 0.0, 0.0, 65.352, 0.0, 0.0, 0.0, nan]
position_covariance_type: 2
---
header: 
  seq: 475
  stamp: 
    secs: 1564341474
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.5197375
longitude: 6.680697333
altitude: 1699.4
position_covariance: [30.376, 0.0, 0.0, 0.0, 65.352, 0.0, 0.0, 0.0, 90.16]
position_covariance_type: 2
---
header: 
  seq: 476
  stamp: 
    secs: 1564341474
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.5197375
longitude: 6.680697333
altitude: 1699.4
position_covariance: [30.376, 0.0, 0.0, 0.0, 65.352, 0.0, 0.0, 0.0, 90.16]
position_covariance_type: 2
---
header: 
  seq: 477
  stamp: 
    secs: 1564341474
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.5197375
longitude: 6.680697333
altitude: 1699.4
position_covariance: [30.376, 0.0, 0.0, 0.0, 65.352, 0.0, 0.0, 0.0, 90.16]
position_covariance_type: 2
---
header: 
  seq: 478
  stamp: 
    secs: 1564341475
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519722833
longitude: 6.680688167
altitude: nan
position_covariance: [47.192, 0.0, 0.0, 0.0, 100.386, 0.0, 0.0, 0.0, nan]
position_covariance_type: 2
---
header: 
  seq: 479
  stamp: 
    secs: 1564341475
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519722833
longitude: 6.680688167
altitude: 1699.7
position_covariance: [47.192, 0.0, 0.0, 0.0, 100.386, 0.0, 0.0, 0.0, 192.05]
position_covariance_type: 2
---
header: 
  seq: 480
  stamp: 
    secs: 1564341475
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519722833
longitude: 6.680688167
altitude: 1699.7
position_covariance: [47.192, 0.0, 0.0, 0.0, 100.386, 0.0, 0.0, 0.0, 192.05]
position_covariance_type: 2
---
header: 
  seq: 481
  stamp: 
    secs: 1564341475
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519722833
longitude: 6.680688167
altitude: 1699.7
position_covariance: [47.192, 0.0, 0.0, 0.0, 100.386, 0.0, 0.0, 0.0, 192.05]
position_covariance_type: 2
---
header: 
  seq: 482
  stamp: 
    secs: 1564341476
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519727
longitude: 6.680691833
altitude: nan
position_covariance: [47.192, 0.0, 0.0, 0.0, 100.386, 0.0, 0.0, 0.0, nan]
position_covariance_type: 2
---
header: 
  seq: 483
  stamp: 
    secs: 1564341476
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519727
longitude: 6.680691833
altitude: 1699.9
position_covariance: [47.192, 0.0, 0.0, 0.0, 100.386, 0.0, 0.0, 0.0, 192.51]
position_covariance_type: 2
---
header: 
  seq: 484
  stamp: 
    secs: 1564341476
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519727
longitude: 6.680691833
altitude: 1699.9
position_covariance: [47.192, 0.0, 0.0, 0.0, 100.386, 0.0, 0.0, 0.0, 192.51]
position_covariance_type: 2
---
header: 
  seq: 485
  stamp: 
    secs: 1564341476
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.519727
longitude: 6.680691833
altitude: 1699.9
position_covariance: [47.192, 0.0, 0.0, 0.0, 100.386, 0.0, 0.0, 0.0, 192.51]
position_covariance_type: 2
---
header: 
  seq: 486
  stamp: 
    secs: 1564341477
    nsecs:         0
  frame_id: "gps"
status: 
  status: 0
  service: 1
latitude: 45.5197065
longitude: 6.6806865
altitude: nan
position_covariance: [47.192, 0.0, 0.0, 0.0, 100.386, 0.0, 0.0, 0.0, nan]
position_covariance_type: 2

[lukehutch]

After a reboot, this seems to have fixed itself -- I am not sure what the issue was.

[lukehutch]

I'm seeing this again. This might be due to the gps_umd driver or gpsd not correctly setting the serial TTY parameters, specifically not disabling echo?