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

Tom Van Baak tvb at LeapSecond.com
Wed Jul 1 11:23:43 EDT 2015


I logged NMEA from three cheap ($15-$50) GPS/1PPS receivers, the kind popular with hobbyists: parallax(good), reyax(good), adafruit(bad).



1) Parallax PAM-7Q GPS Module
    https://www.parallax.com/product/28509

When I powered up this board, I see:

$GPTXT,01,01,02,u-blox ag - www.u-blox.com*50
$GPTXT,01,01,02,HW  UBX-G70xx   00070000 EFFFFFFFo*1B
$GPTXT,01,01,02,ROM CORE 1.00 (59842) Jun 27 2012 17:43:52*59
$GPTXT,01,01,02,PROTVER 14.00*1E
$GPTXT,01,01,02,ANTSUPERV=AC SD PDoS SR*20
$GPTXT,01,01,02,ANTSTATUS=DONTKNOW*33
$GPTXT,01,01,02,LLC FFFFFFFF-FFFFFFED-FFFFFFFF-FFFFFFFF-FFFFFF79*21

And it appeared to handle the 2015 leap second perfectly:

$GPRMC,235959.00,A,4733.25270,N,12208.36733,W,0.329,,300615,,,D*65
$GPGGA,235959.00,4733.25270,N,12208.36733,W,2,09,1.01,308.9,M,-18.8,M,,0000*61
$GPGLL,4733.25270,N,12208.36733,W,235959.00,A,D*75

$GPRMC,235960.00,A,4733.25285,N,12208.36731,W,0.181,,300615,,,D*67
$GPGGA,235960.00,4733.25285,N,12208.36731,W,2,09,1.01,308.5,M,-18.8,M,,0000*6F
$GPGLL,4733.25285,N,12208.36731,W,235960.00,A,D*77

$GPRMC,000000.00,A,4733.25301,N,12208.36743,W,0.312,,010715,,,D*6F
$GPGGA,000000.00,4733.25301,N,12208.36743,W,2,09,1.01,308.0,M,-18.8,M,,0000*69
$GPGLL,4733.25301,N,12208.36743,W,000000.00,A,D*74

$GPRMC,000001.00,A,4733.25317,N,12208.36749,W,0.166,,010715,,,D*62
$GPGGA,000001.00,4733.25317,N,12208.36749,W,2,09,1.01,307.6,M,-18.8,M,,0000*6C
$GPGLL,4733.25317,N,12208.36749,W,000001.00,A,D*78



2) Reyax
    as found by multiple sellers on eBay
    http://www.reyax.com/httpdocs/index.files/GPS_Module.htm

When I powered up this board, I see:

$GNTXT,01,01,02,u-blox AG - www.u-blox.com*4E
$GNTXT,01,01,02,HW UBX-M80xx 00080000 *43
$GNTXT,01,01,02,EXT CORE 2.01 (75350) Oct 29 2013 16:15:41*5C
$GNTXT,01,01,02,ROM BASE 2.01 (75331) Oct 29 2013 13:28:17*44
$GNTXT,01,01,02,MOD NEO-M8N-0*7A
$GNTXT,01,01,02,PROTVER 15.00*01
$GNTXT,01,01,02,GNSS OTP:  GPS GLO, SEL:  GPS GLO*67
$GNTXT,01,01,02,ANTSUPERV=AC SD PDoS SR*3E
$GNTXT,01,01,02,ANTSTATUS=DONTKNOW*2D
$GNTXT,01,01,02,FIS 0xEF4015 (73171) found*20
$GNTXT,01,01,02,LLC FFFFFFFF-FFFFFFED-FFFFFFFF-FFFFFFFF-FFFFFF69*3E
$GNTXT,01,01,02,RF0 dev ok*04

It also appeared to handle the 2015 leap second perfectly:

$GNRMC,235959.00,A,4733.25534,N,12208.36945,W,0.052,,300615,,,D*7C
$GNGGA,235959.00,4733.25534,N,12208.36945,W,2,12,1.06,315.5,M,-18.8,M,,0000*7A
$GNGLL,4733.25534,N,12208.36945,W,235959.00,A,D*63

$GNRMC,235960.00,A,4733.25539,N,12208.36940,W,0.076,,300615,,,D*78
$GNGGA,235960.00,4733.25539,N,12208.36940,W,2,08,1.23,315.4,M,-18.8,M,,0000*75
$GNGLL,4733.25539,N,12208.36940,W,235960.00,A,D*61

$GNRMC,000000.00,A,4733.25545,N,12208.36936,W,0.011,,010715,,,D*7B
$GNGGA,000000.00,4733.25545,N,12208.36936,W,2,06,1.59,315.4,M,-18.8,M,,0000*77
$GNGLL,4733.25545,N,12208.36936,W,000000.00,A,D*60

$GNRMC,000001.00,A,4733.25546,N,12208.36933,W,0.181,,010715,,,D*74
$GNGGA,000001.00,4733.25546,N,12208.36933,W,2,06,1.59,315.3,M,-18.8,M,,0000*77
$GNGLL,4733.25546,N,12208.36933,W,000001.00,A,D*67



3) Adafruit Ultimate GPS Breakout
    http://www.adafruit.com/products/746

When I powered up this board I see:

$PGACK,103*40
$PGACK,105*46
$PMTK011,MTKGRS*08
$PMTK010,001*2E
$PMTK010.002*2D

This GPS receiver appeared to mess up the 2015 leap second, with a double 5959 and possible receiver reset:
(I also had serial communications issues with this board today)

$GPGGA,235958.000,t733.2401,N,12208.7780,W,2,7,1.17,257.6,M,-17.3,S000,0000*62
 GPRMC,235958.000,A,4723.2401,N12208.3780,W,0.4x,48.15,300615,,,D*4D

$GPGGA,235959.000,4733.2401,N,52208.3778,W,2,7,1.17,257.6,M,-17.3,M,0000,0000*64
$GQRMC,235959.000,A,47;3.2401,N,12208.3778,W,0.47,48.15,300615,,,D*44

$GPGGA,235959.000,4733.2402,N,12208.3777,W,2,7,1.17,257.6,M,-17.3,M,0000,0000*68-
$GPRMC,235959.00,A,4733.2402,N,12208.3777W,0.46,48.17,300615,,,D*49

$GPRMC,000000000,A,4733.2403,N,12208.3775,W,0.38,4815,010715,,,D*41
$GPGGA,000001.000,4733.2403,N,12208.3773,W,2,7,1.17,257.6,],-17.3,M,0000,0000*6D
$GPRMC,000001.000,A,4733.2403,N,12208.3773,W,0.22,48.15,010715,,,D*4D

If someone else has data from this model receiver, please let me know.

Thanks,
/tvb
www.LeapSecond.com



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