Gary,
Thanks for the reply. As far as I can tell, the GPS device continues to send messages after loss of fix. Here is a sample of the NMEA output
$GPGSV,3,1,11,13,63,127,13,20,61,289,12,29,59,259,14,05,50,049,14*7B
$GPGSV,3,2,11,15,49,191,14,02,31,115,14,21,23,306,14,30,10,064,13*7D
$GPGSV,3,3,11,18,09,258,14,07,02,036,14,26,01,310,15*45
$GPRMC,171144.000,A,3921.2536,N,07701.4957,W,0.28,300.37,151116,,,D*74
$GPZDA,171144.000,15,11,2016,,*51
$GPGGA,171145.000,3921.2537,N,07701.4958,W,2,07,1.31,15.9,M,-33.6,M,0000,0000*63
$GPGSA,A,3,15,02,29,20,13,05,30,,,,,,1.60,1.31,0.92*06
$GPRMC,171145.000,A,3921.2537,N,07701.4958,W,0.28,300.46,151116,,,D*7D
$GPZDA,171145.000,15,11,2016,,*50
$GPGGA,171146.000,3921.2537,N,07701.4958,W,2,07,1.31,15.9,M,-33.6,M,0000,0000*60
$GPGSA,A,3,15,02,29,20,13,05,30,,,,,,1.60,1.31,0.92*06
$GPRMC,171146.000,A,3921.2537,N,07701.4958,W,0.28,300.49,151116,,,D*71
$GPZDA,171146.000,15,11,2016,,*53
$GPGGA,171147.000,3921.2537,N,07701.4959,W,2,06,1.51,15.9,M,-33.6,M,0000,0000*67
$GPGSA,A,3,15,02,29,13,05,30,,,,,,,1.77,1.51,0.92*04
$GPRMC,171147.000,A,3921.2537,N,07701.4959,W,0.28,300.27,151116,,,D*79
$GPZDA,171147.000,15,11,2016,,*52
$GPGGA,171148.000,3921.2538,N,07701.4960,W,2,06,1.51,15.9,M,-33.6,M,0000,0000*6D
$GPGSA,A,3,15,02,29,13,05,30,,,,,,,1.77,1.51,0.92*04
$GPRMC,171148.000,A,3921.2538,N,07701.4960,W,0.28,299.98,151116,,,D*76
$GPZDA,171148.000,15,11,2016,,*5D
$GPGGA,171149.000,3921.2538,N,07701.4961,W,2,05,1.71,15.9,M,-33.6,M,0000,0000*6C
$GPGSA,A,3,02,29,13,05,30,,,,,,,,1.94,1.71,0.93*0E
$GPGSV,3,1,11,13,63,127,16,20,61,289,,29,59,259,13,05,50,049,15*7B
$GPGSV,3,2,11,15,49,191,,02,31,115,13,21,23,306,15,30,10,064,15*78
$GPGSV,3,3,11,18,09,258,13,07,02,036,14,26,01,310,14*43
$GPRMC,171149.000,A,3921.2538,N,07701.4961,W,0.28,299.71,151116,,,D*71
$GPZDA,171149.000,15,11,2016,,*5C
$GPGGA,171150.000,3921.2539,N,07701.4962,W,2,04,1.98,15.9,M,-33.6,M,0000,0000*60
$GPGSA,A,3,02,29,13,05,,,,,,,,,2.21,1.98,0.98*0C
$GPRMC,171150.000,A,3921.2539,N,07701.4962,W,0.28,299.56,151116,,,D*7E
$GPZDA,171150.000,15,11,2016,,*54
$GPGGA,171151.000,3921.2539,N,07701.4963,W,2,04,1.98,15.9,M,-33.6,M,0000,0000*60
$GPGSA,A,3,02,29,13,05,,,,,,,,,2.21,1.98,0.98*0C
$GPRMC,171151.000,A,3921.2539,N,07701.4963,W,0.28,299.26,151116,,,D*79
$GPZDA,171151.000,15,11,2016,,*55
$GPGGA,171152.000,3921.2539,N,07701.4964,W,2,04,1.98,15.9,M,-33.6,M,0000,0000*64
$GPGSA,A,3,02,29,13,05,,,,,,,,,2.21,1.98,0.98*0C
$GPRMC,171152.000,A,3921.2539,N,07701.4964,W,0.28,298.84,151116,,,D*74
$GPZDA,171152.000,15,11,2016,,*56
$GPGGA,171153.000,3921.2540,N,07701.4965,W,2,04,1.98,15.9,M,-33.6,M,0000,0000*6A
$GPGSA,A,3,02,29,13,05,,,,,,,,,2.21,1.98,0.98*0C
$GPRMC,171153.000,A,3921.2540,N,07701.4965,W,0.29,298.22,151116,,,D*77
$GPZDA,171153.000,15,11,2016,,*57
$GPGGA,171154.000,3921.2540,N,07701.4965,W,2,04,1.98,15.9,M,-33.6,M,0000,0000*6D
$GPGSA,A,3,02,29,13,05,,,,,,,,,2.21,1.98,0.98*0C
$GPGSV,3,1,11,13,63,127,14,20,61,289,,29,59,259,13,05,50,049,15*79
$GPGSV,3,2,11,15,49,191,,02,31,115,13,21,23,306,14,30,10,064,*7D
$GPGSV,3,3,11,18,09,258,,07,02,036,,26,01,310,14*44
$GPRMC,171154.000,A,3921.2540,N,07701.4965,W,0.29,297.54,151116,,,D*7E
$GPZDA,171154.000,15,11,2016,,*50
$GPGGA,171155.000,3921.2540,N,07701.4966,W,6,03,99.99,15.9,M,-33.6,M,0000,0000*5C
$GPGSA,A,1,02,29,13,,,,,,,,,,99.99,99.99,0.99*0B
$GPRMC,171155.000,V,,,,,0.29,297.27,151116,,,E*41
$GPZDA,171155.000,15,11,2016,,*51
$GPGGA,171156.000,3921.2541,N,07701.4967,W,6,03,99.99,15.9,M,-33.6,M,0000,0000*5F
$GPGSA,A,1,02,29,13,,,,,,,,,,99.99,99.99,0.99*0B
$GPRMC,171156.000,V,,,,,0.29,296.90,151116,,,E*4F
$GPZDA,171156.000,15,11,2016,,*52
$GPGGA,171157.000,3921.2541,N,07701.4968,W,6,03,99.99,15.9,M,-33.6,M,0000,0000*51
$GPGSA,A,1,02,29,13,,,,,,,,,,99.99,99.99,0.99*0B
$GPRMC,171157.000,V,,,,,0.29,296.43,151116,,,E*40
$GPZDA,171157.000,15,11,2016,,*53
$GPGGA,171158.000,3921.2542,N,07701.4969,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*5D
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPRMC,171158.000,V,,,,,0.30,295.88,151116,,,E*43
$GPZDA,171158.000,15,11,2016,,*5C
$GPGGA,171159.000,3921.2542,N,07701.4970,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*54
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPGSV,3,1,11,13,64,127,14,20,61,289,,29,59,259,12,05,50,049,*7B
$GPGSV,3,2,11,15,50,191,,02,31,115,,21,23,306,13,30,10,064,*70
$GPGSV,3,3,11,18,09,258,,07,02,036,,26,01,310,*41
$GPRMC,171159.000,V,,,,,0.31,295.25,151116,,,E*44
$GPZDA,171159.000,15,11,2016,,*5D
$GPGGA,171200.000,3921.2542,N,07701.4971,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*5A
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPRMC,171200.000,V,,,,,0.32,294.55,151116,,,E*4E
$GPZDA,171200.000,15,11,2016,,*52
$GPGGA,171201.000,3921.2543,N,07701.4972,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*59
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPRMC,171201.000,V,,,,,0.32,293.50,151116,,,E*4D
$GPZDA,171201.000,15,11,2016,,*53
$GPGGA,171202.000,3921.2543,N,07701.4973,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*5B
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPRMC,171202.000,V,,,,,0.32,292.39,151116,,,E*40
$GPZDA,171202.000,15,11,2016,,*50
$GPGGA,171203.000,3921.2543,N,07701.4974,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*5D
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPRMC,171203.000,V,,,,,0.31,291.14,151116,,,E*4E
$GPZDA,171203.000,15,11,2016,,*51
$GPGGA,171204.000,3921.2544,N,07701.4975,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*5C
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPGSV,3,1,11,13,64,127,12,20,61,290,,29,59,259,13,05,50,049,*74
$GPGSV,3,2,11,15,50,191,,02,31,115,,21,24,306,12,30,10,064,*76
$GPGSV,3,3,11,18,09,259,,07,02,036,,26,01,310,*40
$GPRMC,171204.000,V,,,,,0.28,289.67,151116,,,E*4C
$GPZDA,171204.000,15,11,2016,,*56
$GPGGA,171205.000,3921.2544,N,07701.4976,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*5E
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPRMC,171205.000,V,,,,,0.25,287.90,151116,,,E*46
$GPZDA,171205.000,15,11,2016,,*57
$GPGGA,171206.000,3921.2544,N,07701.4976,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*5D
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPRMC,171206.000,V,,,,,0.21,285.78,151116,,,E*45
$GPZDA,171206.000,15,11,2016,,*54
$GPGGA,171207.000,3921.2544,N,07701.4977,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*5D
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPRMC,171207.000,V,,,,,0.18,283.33,151116,,,E*47
$GPZDA,171207.000,15,11,2016,,*55
$GPGGA,171208.000,3921.2544,N,07701.4977,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*52
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPRMC,171208.000,V,,,,,0.15,280.73,151116,,,E*42
$GPZDA,171208.000,15,11,2016,,*5A
$GPGGA,171209.000,3921.2544,N,07701.4978,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*5C
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPGSV,3,1,11,13,64,127,13,20,61,290,,29,59,259,13,05,50,049,*75
$GPGSV,3,2,11,15,50,191,,02,31,115,,21,24,306,14,30,10,064,*70
$GPGSV,3,3,11,18,09,259,,07,02,036,,26,01,310,*40
$GPRMC,171209.000,V,,,,,0.13,278.46,151116,,,E*44
$GPZDA,171209.000,15,11,2016,,*5B
$GPGGA,171210.000,3921.2544,N,07701.4978,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*54
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPRMC,171210.000,V,,,,,0.12,276.67,151116,,,E*40
$GPZDA,171210.000,15,11,2016,,*53
$GPGGA,171211.000,3921.2544,N,07701.4978,W,6,02,99.99,15.9,M,-33.6,M,0000,0000*55
$GPGSA,A,1,29,13,,,,,,,,,,,99.99,99.99,1.00*08
$GPRMC,171211.000,V,,,,,0.11,275.00,151116,,,E*40
$GPZDA,171211.000,15,11,2016,,*52
$GPGGA,171212.000,,,,,0,01,,,M,,M,0000,0000*7F
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,171212.000,V,,,,,0.06,279.77,151116,,,N*42
$GPZDA,171212.000,15,11,2016,,*51
$GPGGA,171213.000,,,,,0,00,,,M,,M,0000,0000*7F
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,171213.000,V,,,,,0.03,279.77,151116,,,N*46
$GPZDA,171213.000,15,11,2016,,*50
$GPGGA,171214.000,,,,,0,00,,,M,,M,0000,0000*78
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,3,1,11,13,64,127,13,20,61,290,,29,59,258,11,05,50,049,*76
$GPGSV,3,2,11,15,50,191,,02,31,115,,21,24,306,13,30,10,064,*77
$GPGSV,3,3,11,18,09,259,,07,02,036,,26,01,310,*40
$GPRMC,171214.000,V,,,,,0.01,279.77,151116,,,N*43
$GPZDA,171214.000,15,11,2016,,*57
$GPGGA,171215.000,,,,,0,00,,,M,,M,0000,0000*79
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,171215.000,V,,,,,0.01,279.77,151116,,,N*42
$GPZDA,171215.000,15,11,2016,,*56
$GPGGA,171216.000,,,,,0,00,,,M,,M,0000,0000*7A
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,171216.000,V,,,,,0.00,279.77,151116,,,N*40
$GPZDA,171216.000,15,11,2016,,*55
$GPGGA,171217.000,,,,,0,00,,,M,,M,0000,0000*7B
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,171217.000,V,,,,,0.00,0.00,151116,,,N*4D
$GPZDA,171217.000,15,11,2016,,*54
$GPGGA,171218.000,,,,,0,00,,,M,,M,0000,0000*74
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,171218.000,V,,,,,0.00,0.00,151116,,,N*42
$GPZDA,171218.000,15,11,2016,,*5B
$GPGGA,171219.000,,,,,0,00,,,M,,M,0000,0000*75
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,3,1,11,13,64,127,11,20,61,290,,29,59,258,,05,50,049,*74
$GPGSV,3,2,11,15,50,191,,02,31,115,,21,24,306,12,30,10,064,*76
$GPGSV,3,3,11,18,09,259,,07,02,036,,26,01,310,*40