[time-nuts] Leap Second results: cheap GPS/1PPS receivers

[Dave Martindale]

It seems odd that the Garmin receiver got it wrong.  The Garmin GPS-20 and
-25, which I think are both older than the 18x, get it correct.  The GPS-20
is so old it is a single-channel receiver, the GPS-25 is 12-channel but
still 5 V power.

GPS-20, June 1998:
$GPRMC,235959,A,4913.2184,N,12305.9266,W,0.0,199.2,300697,020.3,E*62
$GPGGA,235959,4913.2184,N,12305.9266,W,1,05,2.1,34.3,M,-17.6,M,,*40

$GPRMC,235960,A,4913.2182,N,12305.9267,W,0.0,199.2,300697,020.3,E*6F
$GPGGA,235960,4913.2182,N,12305.9267,W,1,05,2.1,34.2,M,-17.6,M,,*4C

$GPRMC,000000,A,4913.2180,N,12305.9266,W,0.0,199.2,010797,020.3,E*64
$GPGGA,000000,4913.2180,N,12305.9266,W,1,05,2.1,33.7,M,-17.6,M,,*46

GPS-25, December 1999:
$GPRMC,235959,A,4913.2302,N,12305.9332,W,000.0,169.8,311298,019.6,E*6F
$GPGGA,235959,4913.2302,N,12305.9332,W,1,04,2.9,105.0,M,-17.6,M,,*75

$GPRMC,235960,A,4913.2303,N,12305.9333,W,000.0,169.8,311298,019.6,E*65
$GPGGA,235960,4913.2303,N,12305.9333,W,1,04,3.1,105.0,M,-17.6,M,,*76

$GPRMC,000000,A,4913.2304,N,12305.9333,W,000.0,169.8,010199,019.6,E*69
$GPGGA,000000,4913.2304,N,12305.9333,W,1,04,3.1,105.0,M,-17.6,M,,*7A


On Wed, Jul 1, 2015 at 7:34 PM, Kasper Pedersen <time-nuts at kasperkp.dk>
wrote:

> On 07/01/2015 05:23 PM, Tom Van Baak wrote:
> > I logged NMEA from three cheap ($15-$50) GPS/1PPS receivers, the kind
> popular with hobbyists: parallax(good), reyax(good), adafruit(bad).
>
> >
> > 3) Adafruit Ultimate GPS Breakout
> >     http://www.adafruit.com/products/746
>
> >
> > If someone else has data from this model receiver, please let me know.
> >
>
> I have:
>  - MC-1010 (MTK3339, same chipset and code as the adafruit one)
>  - GPS-1513R (Venus 624) <-- FUN!
>  - LTE-Lite
>  - old GPS18x
>
>
> The MTK3339 with the same (standard) firmware is also used in the
> MC-1010. I have output from the 28th and ahead. Same behaviour.
>
> $GPGGA,235958.000,5610.4160,N,00929.5793,E,1,10,0.80,84.8,M,43.3,M,,*5E
> $GPRMC,235958.000,A,5610.4160,N,00929.5793,E,0.01,171.62,300615,,,A*66
>
> $GPGGA,235959.000,5610.4160,N,00929.5793,E,1,10,0.80,84.8,M,43.3,M,,*5F
> $GPRMC,235959.000,A,5610.4160,N,00929.5793,E,0.01,171.62,300615,,,A*67
>
> $GPGGA,235959.000,5610.4160,N,00929.5793,E,1,10,0.80,84.8,M,43.3,M,,*5F
> $GPRMC,235959.000,A,5610.4160,N,00929.5793,E,0.01,171.62,300615,,,A*67
>
> $GPGGA,000000.000,5610.4160,N,00929.5793,E,1,10,0.80,84.8,M,43.3,M,,*5E
> $GPRMC,000000.000,A,5610.4160,N,00929.5793,E,0.02,171.62,010715,,,A*66
>
> $GPGGA,000001.000,5610.4160,N,00929.5793,E,1,10,0.80,84.8,M,43.3,M,,*5F
> $GPRMC,000001.000,A,5610.4160,N,00929.5793,E,0.01,171.62,010715,,,A*64
>
>
>
> But, SkyTraq venus 624 (RF Solutions GPS-1513R) is much more fun. It
> backsteps one minute(!), in addition to the other 'features' it has.
>
> $GPGGA,235958.187,5610.4163,N,00929.5757,E,1,11,0.8,84.6,M,41.0,M,,0000*65
> $GPRMC,235958.187,A,5610.4163,N,00929.5757,E,000.0,308.5,300615,,,A*6F
>
> $GPGGA,235959.187,5610.4163,N,00929.5757,E,1,11,0.8,84.6,M,41.0,M,,0000*64
> $GPRMC,235959.187,A,5610.4163,N,00929.5757,E,000.0,308.5,300615,,,A*6E
>
> $GPGGA,235900.000,5610.4163,N,00929.5757,E,1,11,0.8,84.6,M,41.0,M,,0000*66
> $GPRMC,235900.000,A,5610.4163,N,00929.5757,E,000.0,308.5,300615,,,A*6C
>
> $GPGGA,000000.187,5610.4163,N,00929.5757,E,1,11,0.8,84.5,M,41.0,M,,0000*66
> $GPRMC,000000.187,A,5610.4163,N,00929.5757,E,000.0,308.5,010715,,,A*6C
>
> $GPGGA,000001.187,5610.4163,N,00929.5757,E,1,11,0.8,84.5,M,41.0,M,,0000*67
> $GPRMC,000001.187,A,5610.4163,N,00929.5757,E,000.0,308.5,010715,,,A*6D
>
>
>
> The Venus on the LTE-Lite, with the updated timing firmware, is sane.
> I also have the 20MHz output timestamped every 5ms, nothing odd happened.
>
> $GPGGA,235959.000,5610.4155,N,00929.5739,E,2,09,0.9,85.4,M,41.0,M,,0000*6F
> $GPRMC,235959.000,A,5610.4155,N,00929.5739,E,000.0,000.0,300615,,,D*66
>
> $GPGGA,235960.000,5610.4155,N,00929.5739,E,2,09,0.9,85.4,M,41.0,M,,0000*65
> $GPRMC,235960.000,A,5610.4155,N,00929.5739,E,000.0,000.0,300615,,,D*6C
>
> $GPGGA,000000.000,5610.4155,N,00929.5739,E,2,09,0.9,85.4,M,41.0,M,,0000*6E
> $GPRMC,000000.000,A,5610.4155,N,00929.5739,E,000.0,000.0,010715,,,D*64
>
>
> Old Garmin GPS18x did the same as the MTK3339:
>
> $GPRMC,235958,A,5611.0119,N,00932.1092,E,000.0,136.1,300615,002.0,E,D*10
> $GPGGA,235958,5611.0119,N,00932.1092,E,2,10,0.8,41.5,M,41.7,M,,*72
>
> $GPRMC,235959,A,5611.0119,N,00932.1093,E,000.0,136.1,300615,002.0,E,D*10
> $GPGGA,235959,5611.0119,N,00932.1093,E,2,10,0.8,41.4,M,41.7,M,,*73
>
> $GPRMC,235959,A,5611.0119,N,00932.1094,E,000.0,136.1,300615,002.0,E,D*17
> $GPGGA,235959,5611.0119,N,00932.1094,E,2,10,0.8,41.3,M,41.7,M,,*73
>
> $GPRMC,000000,A,5611.0120,N,00932.1094,E,000.0,136.1,010715,002.0,E,D*1F
> $GPGGA,000000,5611.0120,N,00932.1094,E,2,10,0.8,41.2,M,41.7,M,,*79
>
> $GPRMC,000001,A,5611.0120,N,00932.1094,E,000.0,136.1,010715,002.0,E,D*1E
> $GPGGA,000001,5611.0120,N,00932.1094,E,2,10,0.8,41.2,M,41.7,M,,*78
>
>
> /Kasper Pedersen
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