GPS RECEIVERS vs 60KFT
Ralph Wallio, WØRPK W0RPK at netINS.net
Updated 07Jun09

The 60kft limit (aka 18km) is one of the three vehicle dynamics limitations placed on GPS receivers for we civilian unwashed, altitude, vehicle velocity and acceleration.  GPS receiver manufacturers are allowed some leeway to juggle the values of these limits to serve their markets so details vary between manufacturers, between models from the same manufacturer and even between software versions in the same model.  The 60kft (18km) upper limit of controlled airspace is the altitude limit most often used.

Amateur high altitude balloonists have discovered a few GPS receivers that allow operation above 60kft and often announce their findings to our small community.  I have yet to hear of balloonists using expensive GPS simulators for this test so this knowledge results from actually flying receivers above 60kft and experiencing the results.  This web page is intended to gather first person information submitted by individuals and groups that have tested receivers.

We will need to be picky about models, software versions and dates so submitted information will need to include:

Manufacturer
Model number (complete)
Software version (often output at power-up)
Individual or group involved in test
Date of test
Test result (Pass or fail)
Other relevant information


RECEIVERS THAT PASS THE 60KFT TEST

MANUFACTURER

MODEL

SOFTWARE

TESTED BY

TEST DATE

DATE POSTED

DeLorme

TripMate

(Rockwell ZODIAC chip set and commands)

TBD

ARSAT (N5SNN)

10Sep05

18Mar06

FASTRAX
See Notes [3] [7]

iTrax02

V 1.11

AMSAT-France
(F6FAO)

15May04

18May04

GARMIN

ETrex

2.11

KMC
(Pioneer Astro)

17Apr02

13Jun02

GARMIN

GEKO 201

V 2.0

TVNSP
(KD7OST)

TV03G 12Jul03

13Jul03

GARMIN

GPS-16-HVS

2.3.0 & 2.9.0

TVNSP

(N7MTZ & W7MJR)

04Jul04

05Jul04

GARMIN [Note 9]

GPS-18-LVC

2.30 & 2.40

 TVNSP
(KC7DBA)

06Nov04

14Nov04

GARMIN [Note 9]

GPS-18X

GPS-18Xvc

3.00

SARA (KØBR)

NTI (N5NTI)

04Apr09

22May09

21Apr09

07Jun09

GARMIN

GPS-25 LP-LVS

GPS 25-LVS V2.5

F1SRX

12Jun2003

30Jan04

GARMIN

 

RINO

TBD

HABITAT SKYLAB

(KAØJLF)

01Aug04

03Aug04

GARMIN

GPS-35HVS

GPS 25-HVS V2.5

WØZC

22Apr01

05May01

GARMIN

GPS-15H

2.70

KB8PVR

09Apr05

19Apr05

INVENTEK [Note 11]

ISMF2-C5.1-V004

C5.1-V004

WB8ELK

17Jan09

20Jan09

MOTOROLA

GT+ ONCORE [5]

NA

KI5CZ

1998

07Dec04

MOTOROLA

M12
P183T12N12

61-G10002A
Ver.1 Rev. 3

ANSR
(KD7LMO)

 

12Jan03

MOTOROLA

M12+
P283T12N15 

61-G10002A
Ver.1 Rev. 8

ANSR
(KD7LMO)

07Dec02

12Dec02

NAVMAN

 

JUPITER 32

(SiRF III chipset)

GSW3.2.4-SDKNM_3.1.00.12-SDK001P1.00a
Jupiter32 v2.1 build 1 (S3)

ANSR

(KD7LMO)

15Dec07

31Dec07

RAND McNALLY

 

Streetfinder GPS for the Palm III

(ROCKWELL ZODIAC)

ZODIAC V1.83

ORB

(KC5TRB)

ORB-5 14Sep03

18Sep03

ROCKWELL
(CONEXANT)

JUPITER
TU30-D140-221/231
[Note 6]

JUP V1.80
CRC:CFB5

EOSS
(W5VSI)

EOSS-39 12Mar00 thru -49 21Apr01

08May01

TRIMBLE

COPERNICUS
(AIR mode)

2.01.1

Meteotek08

28Feb09

21Apr09

TRIMBLE

LASSEN LP GPS P/N 39263-00

7.82

BEAR
(VE6SBS)

BEAR-1 27May00
BEAR-2 05Aug00

23Jun01


RECEIVERS THAT FAIL THE 60KFT TEST

MANUFACTURER

MODEL

SOFTWARE

TESTED BY

TEST DATE

DATE POSTED

 AXIOM

SandPiper

SiRF Star-1 chipset

[1]

 unk

 

BYONICS

GPS2

SiRF-III

Notes [1 & 8]

LASA

24Nov07

27Nov07

 DELUO

(rebranded EVERMORE)

Note [4]

Serial GPS

Unknown

EOSS-83

(KØANI)

08Aug04

09Aug04

 DELUO

 

Lite

Unknown

(Sony chipset)

K5IS

16Apr05

28Apr05

 GARMIN

 

GPS-45

3.05

EOSS
(KCØJHQ, N7QAM)

26Sep01

10Jan02

HOLUX

GM-210 [1]

(SiRF-II chip set)

 $Version 2.3.2-GSW2-2.05.024-C1Prod1.1

$SiRF version : 2.3.2 uservesion : GM210V41

TABEL

KE4PJW/KQ4TV

22Apr06

01Jul06

28Jul06

HOLUX

GR-213

(SiRF-III chip set)

 Also failed

Info pending

TABEL

KE4PJW/KQ4TV

01Jul06

28Jul06

 RADIO SHACK

DigiTraveler

 

Note [2]

 

 

ROCKWELL
(CONEXANT)

 JUPITER
TU30-D140-061
[Note 6]

JUP V1.03

EOSS
(KCØYA)

 

24Jan06

SAN JOSE
NAVIGATION

FV-17
(FURUNO GN-79N)

Unknown

 

Alfred Kastler school
(F5FJA/F6FAO – France)

13May04

02Jun04

 

TELIT

(24km ~80kft  alt limit)

GM862-GPS

(SIRF-III)

Unknown

EDGAR-1

(VA2TCV)

05Apr08

20May08

TRIMBLE

LASSEN SKII

7.74

NSERT (WA8RC)

17Apr09

21Apr09

Note [1]            We now have solid evidence that GPS receivers based on SiRF-I and SiRF-II chip sets all fail at ~60kft.  Some SiRF-III chips sets, receivers that use them and firmware work at high altitude –but- others do not.    

Note [2]            We have a report that a Radio Shack DigiTraveler GPS receiver max’ed-out at 9,999m but continued with reliable 2D navigation.

Note [3]            Warning de F6FAO: To have the GPS working above 18 km, you need to send a command to the GPS. This command is ‘Set Upper Limit’.

Note [4]            The DeLuo Serial GPS receiver is a discontinued product but DeLuo continues to sell a few EverMore GPS receivers.  It appears all EverMore receivers are limited to 18km altitude.  Some other DeLuo GPS receivers are based on either the SiRF Star-I or SiRF Star-II chip sets which are limited to 18km per above.

Note [5]            Motorola GT OnCore receivers in both 6-channel (earlier) and 8-channel (later) versions were successfully flown above 18km by FreeSpace, and HABET (ISGC/ISU).  Model numbers and software versions are no longer available.

Note [6]            From Steve KCØYA of EOSS: Early Rockwell Jupiter boards, serial numbers <300,000 with V1.03 software, have failed above 30km.  Later boards, serial numbers >386,000 with V1.80 software, have repeatedly worked ok.  Contact Steve for more details. 

Note [7]            Gerard Auvray, F6FAO, forwards the following information from FASTRAX support:

De : Fastrax Customer Support [mailto:support@fastrax.fi]
Envoyé : lundi 21 mai 2007 16:33
À : AUVRAY GERARD; Fastrax Customer Support
Objet : RE: Max altitude for GPS

Hello Gerard,

 

The following receivers can be used above 18 km:

 

iTrax03

iTrax03-s

iTrax130

uPatch130 (new receiver, available beginning of Q2)

 

They all work if speed is < 1000 knots

 

http://isuite.fastrax.fi/faq.html#mozTocId469010

 

Other receivers limit the height to either 20 km (uPath101,102) or 60000 feet (All Sirf based receivers like iTrax300, uPatch300) regardless of speed.

 

The only receiver actually tested above 18km in a real application (in a weather balloon) is iTrax03.

 

 Note [8]           Byonics GPS2 cut out when the payload ascended beyond 78,838', and resumed
after burst when it descended below the same level one hour later.  – Rick LASA

Note [9]            On 23Aug08 a new *GPS18xLVC* froze altitude at 60kft.  Garmin development staff found the software problem
which is fixed in software V2.80

                        KØBR reports a successful flight using a Garmin GPS-18X V3.0 to 87lft on 04Apr09.

Following information from W0JRT:

                       There seems to be a lot of confusion about this.  Hopefully this
message will clear things up.  The link that was posted
(http://showcase.netins.net/web/wallio/GPSrcvrsvs60kft.htm) does not
make it entirely clear as it mixes up the "GPS 18-LVC" and "GPS
18x-LVC", or at least lumps them together.  Although they look similar
physically they are two completely different models with completely
different part numbers running completely different software (although
most likely with a lot of shared source.)

The GPS 18-LVC with the 5 meter cable is/was produced under two
different part numbers: 010-00321-06 (non-RoHS) and 010-00321-56
(RoHS).  They are functionally identical and run the same software.
The only difference is that one was built with RoHS-compliant parts
and RoHS-compliant processes.

The GPS 18x-LVC with the 5 meter cable has the part number 010-00321-36.

The latest software (006-B0273-00) for the GPS 18-LVC is v3.20
released in October of 2007.

The latest software (006-B0796-00) for the GPS 18-LVC is v2.70 August
of 2008.

If you have a GPS 18-LVC there is no problem flying it on a balloon.

If you have a GPS 18x-LVC it currently has a limit near 60k feet.
Garmin says this was an oversight and they are working to fix this
since it should meet the same limits at the GPS 18-LVC.

-Jerome

 NOTE [10]        Thomas Scherrer-Tangen, OZ2CPU, provides the following:

                        I have this information directly from Locosys tech department: ALL GPS modules from manufacture Locosys no matter chipset or firmware
or date codes will do this: If the module goes over high or speed limitation it will not longer to provide existing position data and velocity.
It can recover when high or speed is back under limitation.

NOTE [11]         Bill Brown, WB8ELK, provides the following:

  You can officially put the Inventek ISMF2-C5.1-V004 GPS module as "passes" for the "GPS receivers vs. 60k feet" list. It worked great (never lost GPS lock) during my last flight to 110,000 feet.

 

  The module itself is very inexpensive but the eval board that Inventek sells is fairly pricey....they have a reasonably priced USB thumb drive eval board version but it's for the F1 and does not bring out serial port B that has the balloon NMEA data on it....therefore, I'm about done with a PC board design that will allow the balloon community to plug and play the board without having to worry about surface mount soldering....I'll offer the board by itself for those with surface mount assembly experience. I'll have that info posted soon on my website: http://www.wb8elk.com  or http://www.elktronics.com  I should have that done this week.

 

  The V004 version is the custom firmware build that allows the SIRF III chipset to work up to 135,000 feet....Inventek has one of the SIRF software designers on staff according to info I was told when I called them. Here's the ordering link for the high altitude balloon version:...look for the listing that says "GPS custom firmware" and select the C5.1- V004 version that says, "NMEA 4800, ceiling 135000 ft"

 

http://inventeksys.accountsupport.com/store/gps_modules.html

 

  This is a very economical unit,  to the price point of a disposable system....and they don't mind single quantities.

 

I flew it with their equally inexpensive active patch antenna (ACTPAT254-01-IP):

 

http://inventeksys.accountsupport.com/store/gps_antennas.html

 

The active patch has a short coax with a UHL connector that plugs directly into the top of the GPS receiver module...you can also run a short PCB trace out from pin 1 to an SMA connector if so desired.

 

The active patch antenna likes to have a ground plane underneath it for best results...particularly during the acquisition phase....once it's acquired the satellites, it takes a lot less signal to maintain tracking. I put a strip of adhesive metal tape attached to some foam core underneath the patch and it worked great.

 

The smaller patch antennas they offer will also work, but I would recommend the 254 version (about an inch on a side) since that one seems to be the most sensitive.

 

So far, I've seen little or no desense by nearby 70cm transmissions, something that only the long discontinued Motorola VP Oncore can do in my experience. It wasn't affected by the ozonesonde signal on 403.2 MHz at all during this last flight...the Trimble Copernicus was affected however. I will test it in an ATV payload soon.

 

The module operates on 3.3 volts and draws just 25 mA during tracking (add about 10 mA for the active patch)....a big power budget savings over a GPS18 for example...(the GPS18 is 5V at 65 mA). Adding a backup coin cell battery to pin 2 allows you to do incredibly fast hot starts.

 

Photos of the 2m transmitter board with the onboard Inventek GPS module can be seen here...the same board will work on HF as well with different output filter values.

 

http://www.wb8elk.com/oz011709.htm  

 

- Bill WB8ELK

 

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