Ashtech Z-sensor Manual do Utilizador descarregar pdf (Página 3)

Presented at ION-GPS 97, Kansas City, MO. ÒNew Product DescriptionsÓ Session.

RT K st ands for Ò Real T ime KinematicÓ, but it means

real-time-centimeters. A brief dig through the layers of

GPS history uncovers the origins of the terminology.

The first use of GPS for centimeter position relied on

static receivers which collected only carrier data, hours

of data, to be processed later on desktop computers.

T h is was called Ò staticÓ surveying. T he technique

evolved till minutes, not hours, of data was enough,

Ò rapid-staticÓ. Later techniques required only one

static initialization of the receiver. From then on, as

long as the receiver maintained phase-lock, it could be

moved and t he dat a would st ill yield cent imet er

accuracy when processed back in the office. This was

ÒkinematicÓ surveying. With faster and smaller

computers, the desktop processing moved into the GPS

receiver itself, providing results in the field, in real-

time. Hence ÒReal Time KinematicÓ.

There used to be a distinction between RTK with static

initialization and RTK on-the-fly, but any modern

RT K receiver that cannot do on-the-fly initialization

is not worth bothering about.

THE PRODUCTS

Both product s are available in t wo st andard

configurat ions: Base and Remot e. Remote unit s have

RT K capability, standard. Base units can provide

Differential corrections and RTK data, at the same

time, so you can operate DGPS and RTK remote units

simultaneously with the same base st ation.

Both product s conform to t he RT CM st andard for

Differential and RTK data. So any other receiver

(from any manufacturer) that also conforms to the

RT CM standard can be used compatibly as a Base or

Remote unit wit h an Ashtech Remote or Base,

respectively, as long as it tracks the correct signal (dual

frequency GPS, compatible with Z, or single frequency

GP S+GLONASS, co m p at ible wit h GG-RT K) .

The Z Sensor also supports a more concise RTK

format, as an alternative to RTCM, to reduce

bandwidth requirements for RTK. The GG-RTK

receiver achieves low bandwidth requirements, using

the standard RTCM format, thanks to the low drift

rate of GLONASS errors, and the fact that it is a single

frequency receiver.

Both receivers provide high rate RTK updates with no

extrapolation of old positions. Every position is based

o n a fresh set of range measurem en t s at t h e Remot e

receiver.

Z Se n s or

Specification hilites:

· 12-channel, all-in-view, full wave length code

and carrier phase on L1 and L2

· Z-tracking (all observables, even with A-S on)

· Horizontal accuracy (1s) 1cm.

· Vertical accuracy (1s) 2cm.

· 10 Hz RTK position output

· Less than 30ms latency

· RTK on-the-fly initialization: > 99.9%

reliability

· RTCM messages: 1, 2, 3, 6, 16, 18, 19, 22

· Power Consumption 7.5W

Form Factors:

Z-Surveyor: Injected molded plastic housing,

including display, integral battery, removeable PC-

Memory Card, and optional internal radio.

Z-Surveyor FX: Metal waterproof housing including

display, internal PC-Memory Card, and optional

internal radio.

Z-Sensor: Metal housing, no display, no memory,

optional internal radio.

OEM Boards: The Z-Sensor is based on a single-

board design. The boards are available for OEM

purchase. Contact Ashtech for details.

For full specifications see product data sheets.

GG-RTK

Specification hilites:

· 12 channels GPS, L1 code and carrier

· 12 channels GLONASS, L1 code and carrier

· Horizontal accuracy (1s) 1cm.

· Vertical accuracy (1s) 1cm.

· 5 Hz RTK position output

· Less than 100ms latency

· RTK on-the-fly initialization: > 99.9%

reliability

· RTCM: 1, 2, 3, 9, 16, 18, 19, 22, 31, 32, 34

· Power Consumption 2.6W (Sensor) 1.8W

(Board)

Form Factors:

GG-Surveyor: Metal housing, no display, internal

PC-Memory Card, optional internal radio.

GG-RTK Sensor: Metal housing, no display, no

memory, optional internal radio.

GG RTK OEM Board: Eurocard format.

Any existing GG24 receiver can be upgraded to a GG-

RT K wit h n o har dware chan ges.

For full specifications see product data sheets.

RTK PERFORMANCE

RT K is a special form of Differential GPS. It is

differes from conventional DGPS in three major

r e sp e ct s:

1 2 3 4 5 6

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