Missing speed values

[jimbo8]

When I load NMEA data I find that most of the positions have an associated speed, but that for other positions the speed value is missing. It is definitely there on the orginal data.
Can anybody help please?

[routeconverter]

Do you have an example file?

[jimbo8]

Thanks for the reply. I have attached below the results of the list of positions as shown in RouteConverter (1.33), and the NMEA sentances that form the input for this portion. Comparison of the two sets of data shows missing positions (i.e. not consecutive seconds), missing speeds and missing height. Note that the NMEA sentances have been created by me from other data and therefore may not be syntactically correct!
I think that there are 'filters' which eliminate consecutive positions which are within a tolerance?

Code:

1/1/10 1:27:11 PM          -1.676403     55.1630966     99 m
1/1/10 1:27:12 PM          -1.676408     55.1630966     99 m
1/1/10 1:27:15 PM          -1.676471     55.1631049     99 m
1/1/10 1:27:17 PM          -1.676548     55.1631083     99 m
1/1/10 1:27:18 PM          -1.676596     55.1631133     99 m
1/1/10 1:27:20 PM          -1.676711     55.1631233     99 m
1/1/10 1:27:23 PM          -1.676925      55.1631316     99 m
1/1/10 1:27:24 PM    19 Km/h      -1.677004     55.163135     99 m
1/1/10 1:27:25 PM    20 Km/h      -1.677091     55.163135     99 m
1/1/10 1:27:26 PM    21 Km/h      -1.677179     55.16314     
1/1/10 1:27:27 PM    21 Km/h      -1.67727      55.16314     99 m
1/1/10 1:27:28 PM    21 Km/h      -1.677361     55.1631433     99 m
1/1/10 1:27:30 PM    22 Km/h      -1.677549     55.1631466     


$GPGGA,132711,5509.7858,N,00140.5842,W,1,07,1.0,98.9,M,,M,,*72
$GPRMC,132711,A,5509.7858,N,00140.5842,W,0.3,275.6,010110,,*9
$GPGGA,132712,5509.7858,N,00140.5845,W,1,07,1.0,98.9,M,,M,,*76
$GPRMC,132712,A,5509.7858,N,00140.5845,W,1.1,276.9,010110,,*2
$GPGGA,132713,5509.7861,N,00140.5854,W,1,07,1.0,98.9,M,,M,,*7d
$GPRMC,132713,A,5509.7861,N,00140.5854,W,2.1,278.3,010110,,*e
$GPGGA,132714,5509.7861,N,00140.5866,W,1,07,1.0,98.9,M,,M,,*7b
$GPRMC,132714,A,5509.7861,N,00140.5866,W,3.0,277.5,010110,,*1
$GPGGA,132715,5509.7863,N,00140.5883,W,1,07,1.0,98.9,M,,M,,*73
$GPRMC,132715,A,5509.7863,N,00140.5883,W,3.8,275.7,010110,,*1
$GPGGA,132716,5509.7863,N,00140.5904,W,1,07,1.0,98.9,M,,M,,*7e
$GPRMC,132716,A,5509.7863,N,00140.5904,W,4.7,275.9,010110,,*a
$GPGGA,132717,5509.7865,N,00140.5929,W,1,07,1.0,98.9,M,,M,,*76
$GPRMC,132717,A,5509.7865,N,00140.5929,W,5.5,276.9,010110,,*2
$GPGGA,132718,5509.7868,N,00140.5958,W,1,07,1.0,98.8,M,,M,,*73
$GPRMC,132718,A,5509.7868,N,00140.5958,W,6.3,276.7,010110,,*d
$GPGGA,132719,5509.7872,N,00140.5991,W,1,07,1.0,98.8,M,,M,,*7c
$GPRMC,132719,A,5509.7872,N,00140.5991,W,7.1,275.9,010110,,*c
$GPGGA,132720,5509.7874,N,00140.6027,W,1,07,1.0,98.7,M,,M,,*78
$GPRMC,132720,A,5509.7874,N,00140.6027,W,7.7,274.5,010110,,*c
$GPGGA,132721,5509.7877,N,00140.6067,W,1,07,1.0,98.7,M,,M,,*7e
$GPRMC,132721,A,5509.7877,N,00140.6067,W,8.4,275.3,010110,,*1
$GPGGA,132722,5509.7879,N,00140.6109,W,1,07,1.0,98.7,M,,M,,*7a
$GPRMC,132722,A,5509.7879,N,00140.6109,W,9.0,273.1,010110,,*4
$GPGGA,132723,5509.7879,N,00140.6155,W,1,07,1.0,98.6,M,,M,,*73
$GPRMC,132723,A,5509.7879,N,00140.6155,W,9.6,272.8,010110,,*2
$GPGGA,132724,5509.7881,N,00140.6203,W,1,07,1.0,98.6,M,,M,,*73
$GPRMC,132724,A,5509.7881,N,00140.6203,W,10.3,270.2,010110,,*37
$GPGGA,132725,5509.7881,N,00140.6255,W,1,07,1.0,98.6,M,,M,,*71
$GPRMC,132725,A,5509.7881,N,00140.6255,W,10.7,272.9,010110,,*38
$GPGGA,132726,5509.7884,N,00140.6308,W,1,06,1.0,98.6,M,,M,,*7f
$GPRMC,132726,A,5509.7884,N,00140.6308,W,11.1,272.0,010110,,*39
$GPGGA,132727,5509.7884,N,00140.6362,W,1,06,1.0,98.6,M,,M,,*72
$GPRMC,132727,A,5509.7884,N,00140.6362,W,11.2,271.3,010110,,*37
$GPGGA,132728,5509.7886,N,00140.6417,W,1,07,1.0,98.5,M,,M,,*78
$GPRMC,132728,A,5509.7886,N,00140.6417,W,11.4,270.8,010110,,*33
$GPGGA,132729,5509.7886,N,00140.6473,W,1,07,1.0,98.5,M,,M,,*7b
$GPRMC,132729,A,5509.7886,N,00140.6473,W,11.6,271.4,010110,,*3f
$GPGGA,132730,5509.7888,N,00140.6530,W,1,07,1.0,98.4,M,,M,,*7a
$GPRMC,132730,A,5509.7888,N,00140.6530,W,11.8,270.3,010110,,*37

[routeconverter]

Comparison of the two sets of data shows missing positions (i.e. not consecutive seconds), missing speeds and missing height. Note that the NMEA sentances have been created by me from other data and therefore may not be syntactically correct!

Thank you for your explanation. There are two effects that cause this:

Your data contains checksums with lowercase characters like in

$GPGGA,132713,5509.7861,N,00140.5854,W,1,07,1.0,98.9,M,,M,,*7d

which were ignored by RouteConverter. I have created a new prerelease that accepts lowercase characters, so more from your data is read.

Your data contains invalid checksums like in

$GPRMC,132713,A,5509.7861,N,00140.5854,W,2.1,278.3,010110,,*e

which are ignored by RouteConverter.

There background for this decision is here:

There is a provision for a checksum at the end of each sentence which may or may not be checked by the unit that reads the data. The checksum field consists of a '*' and two hex digits representing an 8 bit exclusive OR of all characters between, but not including, the '$' and '*'. A checksum is required on some sentences.

So if you download the latest prerelease and fix the checksums of your NMEA sentences all positions are displayed with speed information.

I think that there are 'filters' which eliminate consecutive positions which are within a tolerance?

Yes, but the tolerance is zero: consecutive NMEA sentences with the same Latitude/Longitude values are joined.