diff options
| -rw-r--r-- | README.md | 3 | ||||
| -rw-r--r-- | lib/postrunner/EPO_Downloader.rb | 25 | ||||
| -rw-r--r-- | lib/postrunner/Main.rb | 8 |
3 files changed, 32 insertions, 4 deletions
@@ -2,7 +2,8 @@ PostRunner is an application to manage FIT files such as those produced by Garmin products like the Forerunner 620 (FR620). It allows you to -import the files from the device and inspect them. +import the files from the device and inspect them. It can also update +satellite orbit prediction data on the device to speed-up fix times. ## Installation diff --git a/lib/postrunner/EPO_Downloader.rb b/lib/postrunner/EPO_Downloader.rb index 30ccd9f..0aa3fd9 100644 --- a/lib/postrunner/EPO_Downloader.rb +++ b/lib/postrunner/EPO_Downloader.rb @@ -79,6 +79,13 @@ module PostRunner epo_fixed = '' 0.upto(27) do |i| offset = i * 2307 + # The fill bytes always seem to be 0. Let's issue a warning in case + # this ever changes. + unless epo[offset].to_i == 0 && + epo[offset + 1].to_i == 0 && + epo[offset + 2].to_i == 0 + Log.warning "EPO fill bytes are not 0 bytes" + end epo_fixed += epo[offset + 3, 2304] end @@ -92,6 +99,9 @@ module PostRunner Log.error "EPO file has wrong length (#{epo.length})" return false end + date_1980_01_01 = Time.parse("1980-01-01T00:00:00+00:00") + now = Time.now + largest_date = nil # Split the EPO data into Arrays of 32 * 72 bytes. epo.each_slice(32 * 72).to_a.each do |epo_set| # For each of the 32 satellites we have 72 bytes of data. @@ -103,8 +113,23 @@ module PostRunner Log.error "Checksum error in EPO file" return false end + # The first 3 bytes of every satellite record look like a timestamp. + # I assume they are hours after January 1st, 1980 UTC. They probably + # indicate the start of the 6 hour window that the data is for. + hours_after_1980_01_01 = sat[0] | (sat[1] << 8) | (sat[2] << 16) + date = date_1980_01_01 + hours_after_1980_01_01 * 60 * 60 + # Either the start point (1980-01-01) is not correct or Garmin is + # publishing data that can be up to 5 days old. We check the date + # with some more relaxed ranges. + if date > now + 8 * 24 * 60 * 60 + Log.warn "EPO timestamp (#{date}) is in the future" + elsif date < now - 8 * 24 * 60 * 60 + Log.warn "EPO timestamp (#{date}) is too old" + end + largest_date = date if largest_date.nil? || date > largest_date end end + Log.info "EPO data is valid until #{largest_date + 6 * 60 * 60}." true end diff --git a/lib/postrunner/Main.rb b/lib/postrunner/Main.rb index ddec18e..1e75767 100644 --- a/lib/postrunner/Main.rb +++ b/lib/postrunner/Main.rb @@ -162,8 +162,8 @@ units <metric | statute> htmldir <directory> Change the output directory for the generated HTML files -update-gps Download the current set of GPS ephemeris data and store them - on the device. +update-gps Download the current set of GPS Extended Prediction Orbit (EPO) + data and store them on the device. <fit file> An absolute or relative name of a .FIT file. @@ -364,7 +364,9 @@ EOT epo_file = File.join(epo_dir, 'EPO.BIN') if !File.exists?(epo_file) || - (File.mtime(epo_file) < Time.now - (24 * 60 * 60)) + (File.mtime(epo_file) < Time.now - (6 * 60 * 60)) + # The EPO file only changes every 6 hours. No need to download it more + # frequently if it already exists. if EPO_Downloader.new.download(epo_file) unless (remotesw_dir = @cfg[:import_dir]) Log.error "No device directory set. Please import an activity " + |