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[gpsd-dev] [PATCH 6/9] Correct definitions of cold start, warm start, et


From: Sanjeev Gupta
Subject: [gpsd-dev] [PATCH 6/9] Correct definitions of cold start, warm start, etc
Date: Fri, 17 Apr 2015 22:54:54 +0800

---
 www/gps-hacking.html | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/www/gps-hacking.html b/www/gps-hacking.html
index bee0274..bba9b1f 100644
--- a/www/gps-hacking.html
+++ b/www/gps-hacking.html
@@ -394,7 +394,7 @@ Of course the quality of signal at your location matters as 
well.</p>
 <p>If a GPS has not been on for several months, then it has no current
 almanac available.  It was to wait to download one before it can
 generate a fix.  This can take just under 15 mins.  This is sometimes
-called an <dfn>autonomous start</dfn>, notably in Garmin's documentation.</p>
+called an <dfn>cold start</dfn>.</p>
 
 <p>While the almanac download takes 15 minutes, you have to be there for the
 start of it, otherwise you have to wait for the next cycle. So if you are
@@ -402,12 +402,11 @@ unlucky and just miss the start of one, it could take 
just under 29 minutes
 to obtain, and on average closer to 22 min.</p>
 
 <p>If a GPS has not been on for a day (four to six hours) then it has
-an almanac but no valid satellite ephemerides, and must download at
-least three before it can generate an accurate fix.  This is sometimes
-called a <dfn>cold start</dfn>.  Each satellite has its own ephemeris that must
-be downloaded if a current copy is not fresh.  It takes about a minute
-per sat to get the ephemeris, or a minute total if your GPS has
-multiple receivers as most do now.</p>
+a valid almanac but no valid satellite ephemerides, and must download at
+least four before it can generate an accurate fix.  This is sometimes
+called a <dfn>warm start</dfn>.  Each satellite has its own ephemeris
+that must be downloaded if a current copy is not fresh.
+</p>
 
 <p>GPSes store ephemerides is non-volatile memory, either internal
 flash storage or battery-backed SRAM.  Thus, a GPS does not need to
@@ -416,14 +415,14 @@ consider old data to be invalid after a while.  In normal 
operation
 the GPS occasionally gets refreshes of ephemeris and almanac data
 from the satellites it's listening to.</p>
 
-<p>For both an autonomous start and a cold start if the sat signal is
-momentarily lost, the process will have to restart and you'll get
+<p>For both an cold start and a warm start, if the sat signal is
+momentarily lost, the process may have to restart and you'll get
 more delay.</p>
 
 <p>If a GPS has been on recently, in the current location, then this
-is sometimes called <dfn>warm start</dfn> or <dfn>hot start</dfn> and
+is sometimes called <dfn>hot start</dfn> and
 an accurate fix can be generated quite quickly.  This will usually be
-under a minute for a modern GPS, perhaps as low as 15 seconds.</p>
+a few seconds for a modern GPS.</p>
 
 <p>Here's <a href="http://gpsinformation.net/main/warmcold.htm";>more
 on this issue</a>.  Details about the satellite signals and there
-- 
2.1.4




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