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

[Kasper Pedersen]

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