PLGR GPS Family

©Brooke Clarke, N6GCE

Basics
Applications
    Time
       SINCGARS TOD
       Have Quick TOD
Batteries
Antennas
Computer Interface
Key Load Cable
External Power
Human Factors
What Goes Wrong
Manuals
PLGR II
Other Military GPS Models
Crypto Keys
GPS Patents
Links

PLGR AN/PSN-11

13 Feb 2006 - PLGR taken by the DOD as evidence.  It was stolen.  I'm out what I paid.



Green case PLGR.

Basics

Precision Lightweight GPS Receiver has SPS and PPS capability, made by Rockwell Collins
5 channels C/A, P, Y codes
Baseline II - tan case firmware 613-9854-003 or 613-9854-004  NSN 5825-01-374-6643
Baseline III - green case firmware 613-9854-008 or 613-9854-009
PLGR+96 613-9854-006
(these versions as of Feb 2003)
Brooke's Comment - Although this is a P code capable receiver, since SA was turned off May, 2, 2000 it's questionable how the position accuracy compares to a civilian 12 channel receiver like the Garmin hand held units.  For military operations the Anti Spoof (AS) part of using a key may have an advantage against a sophisticated enemy, it's of little use against a not so sophisticated enemy.  Hopefully the GRAM will be a 12 channel receiver.

Follow-up comment:  This 5 channel GPS receiver is the most sensitive I've worked with.  It will lock up on signals that are right on the horizon whereas the Garmin 12 channel III Plus and the Motorola 8 channel VP Oncore receivers need the sat to be maybe 10 to 15 degrees above the horizon.

Applications

GPS has two classical applications: position and time and the PLGR is used for both of these.

Position

Provides position information using both L1 and L2 with SPS and PPS capability thus will provide position in combat conditions.
Note: The PPS Anti Spoof capability is effective against spoofing, but in my opinion it's more likely the enemy would use a jammer rather than a spoofing transmission.  A jammer will just cause the GPS receiver to not lock hence it will not update the position.

Note 2:  The PLGR seems to choose satellites that are dispersed horizontally, rejecting a satellite that is overhead.  This may be part of the SETUP and depends on what you are trying to learn.  This PLGR mode would be good for Lat & Lon but poor if Elevation was important.

Once the satellite almanac has been loaded and you are in Figure Of Merit (FOM) mode 1 (the best condition) then in SETUP you can change from CONTionious mode to STandBY mode then into AVeraGe mode.  (You can not go directly from CONT to AVG mode, but must first go into STBY mode.  Then in the POSition menus you will find a screen that shows the averaged position.  At my location it shows:
 
 
PLGR
PLGR
UT+ Carrier phase
Surveyor
Lat
N 39:11:24.32
N 39:11:24.53
N 39:11:24.692
N 39:11:24:5833
Lon
W 123:09:49.79
W 123:09:50.18
W 123:09:50.548
W 123:09:50.4842
Elevation meters1
250
273
249.7
280.45
# averages
1510
32400*
na
na
* The averaging function stops at 32400.
Note1 - There appear to be two different elevations (either around 280 or 250 meters), this is probably my error or a difference in the elevation reference.

Time

Modern frequency hopping radios like the SINCGARS VHF low band radio and the "Have Quick" UHF military aircraft radios both depend on very accurate time as part of the frequency hopping scheme.  The PLGR supports both of these radio systems in terms of precise time synchronization.

SINCGARS TOD

The SINCGARS Time Fill cable is the Rockwell p/n 426-0141-070 (NSN 6150-01-375-8666)
It's a 6 contact U-229 on both ends type cable just over 3 meters long indicating that the radio can be left in a vehicle and the PLGR moved to somewhere outside (maybe even on with a man standing on the roof?).

Have Quick TOD

RT-1319 Have Quick Cable

The NSN 6150-01-375-8665 CAGE: 13499, P/N: 4260141040 Cable is for loading the Time Of Day into a Have Quick RT-1319 225 - 400 MHz radio.  This is for the frequency hopping, not the voice crypto.  The radio connector is a Bendix-9137 JMS27467T15B35S  1467830  only sockets 10 and 11 are connected.  The GPS receiver connector is a standard military AUDIO MC329G2 6 pin type.

RT-1319
J____ pin #
PLGR
J1 pin #
Function
10
E
data
11
F
return
The RT-1319 is part of the GRC-206 system which uses the O-1814 Rubidium Frequency Standard to maintain Time Of Day for the Have Quick part of the UHF air band radio.  Pin 11 related to the RT-1219 is ground.

Have Quick comes in a number of flavors.  They all start with the basic Time Of Day data then there are additional data for Day Of Year, and another that adds Time Figure Of Merit after DOY.  SINCGARS has a slightly different way of computing the calendar.  So there are different time fill formats and or signal levels available on the PLGR J1 and J2 connectors.

Batteries

The tan case PLGR draws about 150 mA so you can estimate battery life.  The green case PLGR draws about 75 ma, 1/2 the current of the tan case units.  The OD green case PLGR is supposed to draw maybe 1/2 the current.

Main

This is a plastic cased receiver and they have done the same thing that was done in the SDU-30 marker light.  That is to require a special battery with both contacts on the same end.  By doing this they don't need to use a metal cap and can keep the power circuitry shorter.  But the problem is then placed on the battery vendor to bring both contacts to one end..
6 Volt Lithium Sulfur dioxide BA-5800A/U NSN 6135-01-440-7774. 
The old BA-5800/U NSN 6665-99-760-9742 is obsolete.  Probably because the lack of a charging prevention diode allowed it to explode when using in equipment, like the PLGR, that has provision to charge the battery.

If you use AA-alkaline or AA-lithium (? chemistry) batteries, you'll need eight of them, plus battery holder, NSN 6160-01-3854358.

BA-5800 Battery Adapter holds 8 each AA cells and can be used with either 4 or 8 cells to supply 6 Volts nominal..

Memory

This Hold Up Battery keeps the crypto key alive, almanac, ephemeris and error log.  This AA size 3.6 Volt Lithium battery has conventional construction with positive on one end and negative on the other end.  The battery compartment cap is metal.  Positive in first, negative is cap/spring.
3.6  Volt Lithium  (? chemistry) NSN 6135-01-301-8776
Tadrian TL2100/S
Saft LS-14500
Radio Shack 23-037 (Replaces Types TL-5104 & TL-2100) 3.6V Lithium
Market:
Tadiran
TL-2100
3.6 Volts Lithium

Note

Although this battery is the size of a standard AA cell, a standard AA cell is 1.5 Volts and is way below what a 3.6 Volt cell is even when dead.  Don't bother trying a 1.5 AA cell, it will not work.

SAFETY

Note there are 3 ways a PLGR can be connected to a military vehicle battery system.
(1) connect across both batteries for a 24 volt power source.  This is OK
(2) connect across the 12 volt battery that tied to chassis ground.  This is OK.
(2) DO NOT DO THIS! connect across the 12 volt battery that's not grounded.  This will cause the Memory battery to explode!  DO NOT DO THIS!

Antennas

There is a permanently attached antenna that probably is a quad helix.  In addition you can connect an external antenna to the connector on the back.  Helmet Antenna AS-4334/U and Remote Antenna AS-4333N are made by Spectra Systems, Inc. FL.

Indoor Operation Without the Special Antenna Connector

In order to use my roof mounted house GPS antenna and 4 way power divider to feed the PLGR GPS signals without the special RF PLGR cable, I just used the antenna from my Garmin GPS III Plus.  It looks like a miniature PLGR antenna and even has a flat side just like the PLGR.  By taping the Garmin antenna to the PLGR antenna the PLGR works very well.  In fact the PLGR will lock onto signals that my Motorola VP Oncore receivers can not lock onto.

The connector needed to make up an external antenna is a Combo-D series made by Positronics Industries, model CBD5W1F20 00X with the coax insert FS4202D

AS-4333 Antenna

AS-4333

This is a dual band (L1 and L2) GPS antenna for use with the PLGR.  It's made by MACOM/
NSN 5985-01-375-4660
Antenna p/n 3395-8001-0004
CAGE Code 11556





Helmut AntennaPLGR Helmet AntHelmet Dual Band GPS antenna with special connector for the PLGR.
AeroAntenna Technology, Inc.
NSN 5985-01-374-7757
p/n: AT575-22

This antenna has 22 dB gain and takes 5 Volts on the center conductor at about 50 ma.  So the PLGR could also power most 5 Volt external antennas using an adapter cable to get from the DB-9 shell coax to a standard coax connector.


PLGR Helmet Ant MountHelmet Antenna Mount.

The bag label reads: NSN 5975-01-375-1301, CAGE 13499, p/n 01301928-010, Helmet Antenna Mount, 1 each, F04701-93-D-0001  0015  03/95 Under the flap is: 82820 ASSY SA-????? 
There is a pocket to hole the antenna with a Velcro closure.  Note that the antenna should be installed in the pocket with the active face opposite to the closure so that the metal hooks on the end of the elastic bands will grab the helmet edges without a twist in the elastic band.  The metal clip with square corners has a label "BACK".  The other two metal clips with angles ends have no label.


Computer Interface

The PLGR has a 15 pin "D" series connector that is the same type used on PC video connections.  The digital interface is in RS-422 protocol thus providing greater distance and higher speed than can reliably obtained from RS-232.  There is also a standard RS-232 interface for use with a PC.  There are also timing inputs and outputs to support precision time transfer.

Serial Cable

Serial CableMarked (items shown as <...> are in Hewbrew::
13499ASSY426-0141-090
<5 letters> PLGR <4 letters> <3 letters>
<3 letters> 3 <4 letters> 4263-<2 letters>
3177-00113 <4 letters>

eBay cable is wired as shown below and reported to send NMEA 4800 8N1 data to a PC.
When I run Hyperterminal at 9600 8N1 with no flow control I get gibberish once every second.  At 4800 baud I don't get anything.  This with the PLGR set for Serial: Standard.

This hex taken using LabView looks very much like the Rockwell binary data below.

FF81
0300
3D00
0080
C1FD 7C49 5B8D 56DD
DEE1
A748 3794 ADBA 93C7
0000
0400 2F40 5E1A 09C1 5993
25CB C147 7CCB BCEB 744B
3EAE 8444 7291 7044 10BB
5DBD 6BD4 9ABD D1F1 183C
54C1 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
8F3F 3C2D 851B 1B21 271B


15 Pins (PSN11)                    DB9 connector (PC
 
15   ----------------------------------   3
14   ----------------------------------   2
2     ----------------------------------   5
                                           (1, 4,6,8 linked together on the DB9)
 
(3 and 13 linked together
 on the 15 pins connector on PSN-11 )

Reprogramming Cable

PLGR Prog Cablep/n 9434308-10, CAGE 55928, 09/06/2000 NSN 6150-01-382-1551
This is an octopus type cable with a DB type 15 socket and a 765K plug on one end to attach to the PLGR (no threaded connector for this application) and at the other end there is a standard 9 socket DB serial connector that connects directly to a computer, but in addition there is also a DIN type 5 socket connector that connects to a power supply to power the PLGR so that a battery is not needed on the PLGR, as would be the case when it's returned for reprogramming.






PLGR
15 pin
PLGR
pwr
Computer
DB-9f
Computer
DIN
1 PPS in
1



1 PPS in rtrn
2
Unit Ground

Gnd
5

Gnd
3
Unit Ground



RS-422A out
4



RS-422B out
5



1 PPS out
6



HQ out
7



Rmt not on
8



RS-422 A in
9



RS-422 B in
10



1 PPS out rtn
11



Vprog in
12


3
serial data buffer not enable
13



RS-232 Tx
14

Rx
2x

RS-232 Rx
15

Tx
3


ctr

5
Init Ground
outside

4

By tying the computer DB9 connector pins 1, 4, 6, 7(RTS) and 8(CTS) together the computer thinks is has hardware handshaking (Request To Send from the computer drives the Clear To Send input).   A power supply with a DIN 5 pin plug supplies both power to the PLGR and the 12 Volts needed for the EEPROM programming.  Looking into the end of the DIN connector with the alignment notch at 12:00 o'clock the pins are numbered starting at 3:00 o'clock and going clockwise: 1, 4, 2, 5, 3.

Since the programming voltage ground is completed through the EXT power jack on the PLGR, the external power plug must be installed, even of there is a main battery in the PLGR.

This cable should also work for use with the PC mission planning software.

PLGR - 9600 baud, No Parity, 8 data bits, 1 Stop bit (9600 N,8,1)

LabVIEW

Using a simple LabVIEW program and the above programming cable I can see data coming out of the PLGR.
I used the Collins MicroTracker Designer's Guide binary data format information, which seems to match this data.  I expect that each manufacturer has their own GPS binary data protocol that's used on all their products.  That's the case with Motorola and Trimble.
There is a simple message that is sent out about once every 5 seconds, it is in Collins binary format:
Frame Sync = 81FF hex
Message ID =  0080 hex
Word count = 0001 hex
Flags =           8000 hex
Chk sum =      F8FD hex
message =      0006 hex
msg chk sum = FFAF hex
=========== next frame ==========
FS = 81FF
ID = 00FD
WC = 0000
Flgs = 9000
cs = ED04
no mesage, no message chk sum
=========== next frame ==========
81FF
00FD
0000 another empty frame
9000
ED04
============

Key Load Cable

PLGR Key Load CbleI got this on eBay advertised as a "Rockwell PLGR-II GPS Crypto Adapter Cable".
The unopened plastic bag has a label:  12499ASSY-988-3116-001 REV A (this line is also molded into the DB-15 connector plastic) MFR TSE-J  7-24-98

988-3116-001 is listed on the PLGR-II+ADK Rockwell web page as a "crypto adapter cable", but is not listed on the PLGR+96 web page.

The cable itself has a DB-15(f) connector on one end and a 329G2 6-pin AUDIO connector on the other end.  The AUDIO connector mates with "J1" on top of the PLGR, or with a crypto fill device.

The most likely way this is used is to connect the AUDIO connector to the fill device and the DB connector to the PLGR.

Note that most computers have a DB-9(m) connection and so this cable will not fit.  It will connect to the end of a computer monitor cable, i.e. this is the same connector that's on a computer for the video monitor.

The DB-15(m) connector DOES fit the J2 Data Connector** on the back of the PLGR.

Cable Wiring

AUDIO
Pin #
DB-15m
Pin #
PLGR J2 Function**
A
10
RS-422 A Input
B
9
RS-422 B Input
C
13
Serial Data Port Buffer Not Enable
D
7
Have Quick 1 PPS TTL output
E
8
Remote On when Ground
F
n.c.

n.c.
3, 4*
3 = Ground
n.c. 3, 4*
4 = RS-422 B Output
n.c.
1, 2, 5, 6, 11, 12,14, 15*

* The connection between the DB-15 pins 3 and 4 (and nothing on pins 1, 2, 5, 6, 11, 12,14, 15) may be part of a system of telling the key load equipment (or PLGR) what device is connected to the other end of the cable?

** The J2 connections shown may or may not make sense for a crypto fill connection.  It's common that more than one function is serviced by the same connector.

External Power

Takes 9 to 32 Volts, positive on the center contact. BUT the negative lead must be ground, it can not be higher.  If the "hot" battery in a dual battery system is used for the PLGR  smoke will come out of the wiring.  THe PLGR has an internal switching mode power supply so it's current draw varies with the input voltage.  At 9 Volts in the current is about 200 ma and at 27 VDC in it's about 80 ma, in either case about 1.9 watts.

The manual says the mating connector is a Switchcraft RA-765 which is part of a cord assembly.  The 765K (Red handle) or 760K (Black handle) pug do fit properly.    The "K" suffix means a threaded locking ring, the parts without the locking ring are 765 or 760. 

The Radio Shack 5.5 x 2.5 mm  274-1573 DC Power Plug can be used for external power.  But it does not have the screw down locking collar and so may very well fall out.

The Switchcraft 761K does NOT fit, it's too long.  Switchcraft parts with an "S" prefix have a Small hole and will NOT fit the PLGR.

DC Power Cord
Collins DC Power cord with spade lugs one end and the special PLGR screw lock connector on the other end.  Only one line fused.  I don't know which lead is fused. If it's in the hot (+) lead there's a possible problem connecting the two leads to the "hot" 12 Volt battery in a 24 volt system then connecting something grounded to any ground point on the PLGR.  This lets the smoke out of the PLGR!

WARNING  There are no fuses inside the PLGR so when using external power you should supply a fuse, or better fuse both leads.

SAFETY Do Not connect the external power cable to the top (non grounded) battery in a military vehicle 24 volt system.  Doing so will cause the memory battery to explode.

Hint  When using external power it's good to also have a main battery installed, although not necessary.  The reason is that if you have a power glitch in the external power the receiver shuts down and restarts.  This is very time consuming and annoying but does not happen when you have a main battery to ride out the external power glitch.

External Power Connector , Cigarette Lighter Plug & Power Pole to PLGR cables available.

Carrying Case

P/N: 021-0706-010
NSN: 5895-01-375-7528
- holds PLGR, remote antenna & cables, spare batteries.

Human Factors

A number of problems:

What goes Wrong

Master Reset

If the PLGR fails to turn on, before returning for repair, try a master reset.
Remove both the main and hold up batteries.
Short the external power connector center pin to it's shell for a few seconds.
Install the correct 3.6 volt hold up battery and a main battery, both checked  to be sure they are good.
Press the green ON button.

On the very early versions of the PLGR it's possible that the time displayed is off (in my case by 41 seconds) and every other indication says the receiver is working properly.  This is a large enough error that it would keep frequency hopping radios from working.  By doing a master reset the displayed time because aligned with Zulu (UTC).  This is a serious problem that probably was fixed in later firmware versions.

Oxidized ribbon cables

There are two ribbon cables going from the front panel to the rear printed circuit board.  The white ribbon fits into a socket on both ends and the dark orange ribbon cable fits into a socket on the front panel PCB.

The display was erratic and after a random time the display would change to some pattern or it would break up into gibberish.  The receiver would not run for more than about 10 minutes without display problems.

By using a small philips screw driver to remove the 6 screws on the back and slightly separating the front panel from the back-box you can access the ribbon cables.  They can be removed from the sockets by raising the socket clamp bar about 1/32".  Then the ribbon cable can be slid from the socket.  One side of the ribbon cable has metalized "fingers" that can be cleaned by using a fresh soft pencil eraser and then cleaning the rubber particles with something that will not leave any residue.  DO NOT USE YOUR FINGERS TO CLEAN.  Clean all 3 ribbon ends.

Pressing Up or Down causes the cursor to move Right

This caused by being in Number Lock mode.  To get back into arrow mode press Num Lock so you see "P" in the lower right corner of the display.

Manuals

TM 11-5825-291-10-2
TM 11-5825-291-13 Operation & Maintenance
TO 31R4-2PSN11-1, EE174-AA-OMI-/PSN-11, PCN 6000028200
about an inch thick.
TB 11-5825-291-10 operator check list & menu navigation (on ETM)
TB 11-5825-291-10-2  Soldier's Guide for the PLGR, May 1966. 148+ pages, cartoon style
TB 11-5825-291-10-3 PLGR Made Simple
TB 11-5825-291-30  warranty technical bulletin (on ETM)

PLGR II

This is a12 channel using the NightHawk signal processor and Phoenix RF front end.
With the ADK (Azimuth Determination Kit) add on, angles can be determined to better than 3 mils and with a dual receiver system to better than 1/2 mil.  A mil (1/64000 of a circle)  is about 1 yard at 1,000 yards range.

Other GPS Models

SAASM - Selective Availability and Anti-Spoof Module

Single chip GPS solution

DAGR - Defense Advanced GPS Receiver

Follow on the PLGR National Security Space Road Map
First Article awards Oct 2002
has second PPS frequency, compass and map

GRAM - GPS Receiver Application Module

Standardized military GPS receiver used for embedding into systems.  GRAM is actually a family of products, with varying physical configurations and functionality.  Current planning calls for a minimum of three configurations VME bus and SEM-E for avionics applications, and PCMCIA for ground-based vehicle applications. This form is likely to be the most commonly-used for Army customers.

SLGR AN/PSN-10 "Slugger" & SAGR

Moved to the Trimble Trimpack web page.

AN/PSN-8

Manpack, an Army developed 17-pound GPS receiver

AN/ASN-149 aka R-2400, aka Rcvr UH

AN/GSN-13 high precision survey GPS system

AEGR Army Embedded GPS Receiver

 M1A2 Abrams

Aircraft GPS

 
Aircraft
Model
Description
UH-60A/L
Blackhawk
AN/ASN-128B Doppler GPS Navigation Set (DGNS)
CH-47D
Chinook
"
"
EH-60A
EW UH-60
AN/ASN-163 Miniaturized Airborne GPS Receiver (MAGR)
AH-64A/D
Apache

Embedded GPS - Inertial Navigation System (EGI) 
OH-58D
Kiowa Warrior
"
"
OH-58A/C
StandAlone Airborne GPS Receiver (SAGR)
AH-1F 
Cobra gunship
"
"
UH-1H/V
Huey utility helicopter

Cargo utility GPS Receiver (CUGR),
RC-12
fixed wing
AN/ASN-149

Crypto Keys

Common GPS key types are:
Group Unique Variable (GUV) good for one year
Crypto Variable Weekly (CVW) good for 6 weeks
Can be loaded by the KYK-13, KOI-18 or AN/CYZ-10.
When the AN/CYZ-10 is used the menu choices are: Radio/COMSEC/LD/TEK/(GPS model#)/QUIT  note the key is loaded as soon as the PLGR is connected to the loader.
"Check GUV Issue Number" - is the error message when the key expires.

Links

GPS Patents

Army Product Manager - Global Positioning System - Pathfinder Magazine - PLGR Made Simple -
2 May 2000:  SA TURNED OFF -
PS Magazine - All About PLGR Batteries -
External Protection Module - spike protection on the data lines, reverse polarity on the external power lines and built in serial self test.
Integrated Test System - B -

SUBJECT:  AVIATION SAFETY ACTION MESSAGE (ASAM)

4.  SUMMARY OF PROBLEM -
     A. THE GLOBAL POSITIONING SYSTEM (GPS) JOINT PROGRAM OFFICE (JPO) HAS REPORTED THAT C-17, VH-60, AND HH-60 AIRCREWS HAVE REPORTED ERRORS WITH THE NAVIGATION SOLUTION IN THE RECEIVER 3A.  THE FAILURE MANIFESTS ITSELF AS A GRADUAL NAVIGATION POSITION SOLUTION RUN-OFF (AS GREAT AS 20-40 NM) WITH NO WARNING TO THE OPERATOR.  THE RECEIVER WILL CONTINUE TO INDICATE A FIGURE OF MERIT (FOM) OF 1 DURING THE RUN-OFF.  THIS OCCURRED DURING THE FIRST MISSION AFTER CRYPTO KEYS WERE LOADED TO ACTIVATE THE RECEIVER'S SELECTIVE AVAILABILITY/ANTI SPOOF (SA/AS) FEATURES.  ALTHOUGH THE REPORTED ANOMALIES HAVE OCCURRED WITH THE RECEIVER 3A, THE FAILURE MODE IS COMMON TO OTHER RECEIVERS INCLUDING THE 3S, UH, OH, C4, AND MANPACK RECEIVERS USED IN THE V1, V2, AND V3 CONFIGURATIONS OF AN/ASN-149 GPS SETS.  THE PROBLEM IS CAUSED BY CORRUPTED DATA IN THE RECEIVER AND CAN OCCUR WHEN THE RECEIVER BECOMES AUTHORIZED TO OPERATE IN ENCRYPTED (P(Y)CODE) MODE.  AUTHORIZATION OCCURS WHEN A PREVIOUSLY-LOADED GUV OR CVW KEY IS VERIFIED BY THE RECEIVER.  GUV KEYED RECEIVERS RE-VERIFY THEIR KEY EACH ZULU DAY.  CVW KEYED RECEIVERS ARE VERIFIED FOR THE DURATION OF THE CVW KEY.

AVIACONVERSIA GPS Jammer

Robbins PLGR web page -PLGR Accessories -

PLGR Notes -

Performance Testing of the Rockwell PLGR+ 96 P/Y Code GPS receiver -

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