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Help Sheet: Using the Built-In Attenuator in GSS6400 RPS

Help Sheet 1The first in a series of Spirent Help Sheets, containing hints and tips for using Spirent’s GSS6400 Record Playback Systems for GPS and/or GLONASS signals.

This Help Sheet contains practical examples of how to attenuate the stored signal to test GPS and/or GLONASS receivers. Enter your details to download it.

PLUS: Check out the other help sheets in the series

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Spirent has been the global leader in GNSS testing for near 30 years. Spirent delivers navigation and positioning test equipment and services to governmental agencies, major manufacturers, integrators, test facilities and space agencies worldwide.

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    This help sheet explains the use of the built-in attenuator in the GSS6400 Record Playback Systems. The sheet covers both: GSS6400 GPS and GSS6400 GPS/GLONASS systems. ‘nullonulltonull help sheet null SP nullnullT nullnull Snullnull S H ow to... This help sheet explains the use of the built-in attenuator in the GSS6400 Record Playback Systems. This help sheet covers both: GSS6400 GPS and GSS6400 GPS/GLONASS systems. GPS System The GSS6400 has an innullnulllt attennulltor capable onullnullnullincreases onullattennulltion null to a manullmnull onullnulldnull The attennulltion is set nullinnull the nullont panel nullysnullor the nullebserver applicationnulland is nulllly described in the mannulll. nullonullever it is nullrth considerinnull honullthe system nullrnull as addinnull nulldnullattennulltion nullom the nullont panel or nullebserver may not mean an enullct decrease in the observed nullo as calcnullated by an attached receivernullonullnulldnull nullinullre null SP nullnullT nullnull Snullnull S H ow to... Panull nullSPnullnullT nullelp tonull nullLP Snullnull null Panull nullSPnullnullT nullelp tonull nullLP Snullnull null The system operates as nullllonull. nulleal linull spectrnull nullinullals and noisenull are stored on the hard drive onullthe GSS6400 nullS. nullen the system plays bacnullnullth no attennulltion at all nulldnull on the nullanullsnullthe spectrnull is played bacnullnullth aronulld nulldnullnullinnullas shonull in area A onullnullinullre null nullecanulle nullTnull the sinullal and the noise are played bacnullhinull an attached receivernulls AGnull nullll compensate nullr this and modinull its thresholds accordinnullynullpreservinnull the orinullnal sinullal to noise ratio. nullonullnullll also appreciate there is then an additional noise nullnulle to tanull into acconullt nullen played bacnullinto an attached GPS receivernulls null nullont end. nully playinnullbacnullnullotnull yonullrednulle the enullnullct onullthe receivers null noise nullnulle. nullonullever in storinnullthe sinullalsnulldnull to the nullantisation onullthe datanullthere is a small loss in sinullal onullaronulld nullnull null bitsnullnullich cannot be nullined bacnull nullatever yonulldo. So a sinullal recorded at nulldnullnullnulld theoretically pay bacnull at nulldnull As soon as yonulladd nullnullonull attennulltion the GSS6400 actnulllly drops the sinullal levels by aronulld nulldnull and the system no lonnullr rnulls nullotnull Anullin the AGnullin the GPS receiver shonulld compensate nullr thisnulland a sinullal recorded at nulldnull nullll nonullplay bacnullat aronulld 4nullnull shonullnnullone dnullonullattennulltion over the playbacnullnullth 0dnullonullattennulltion. Thereanuller a nullnullinpnull attennulltion rednulles the sinullal onullpnull by nullnullas shonull in area nullin the nullnulle null Theoretically therenullre a sinullal recorded at a nullo onullnull dnull nullth no attennulltion added nullll be played bacnullat nulldnulldespite the nullct that the spectrnull is beinnullplayed bacnullnull dnull hot. The nulldnullloss is the nullantisation loss. nullith nullnullonullattennulltion the onullpnull sinullals nullll be seen as 4nullnull nulln reality there are some error sonullces nullich modinull the pernullrmance slinulltlynull as shonull in nullinullre null nullinullre null SP nullnullT nullnull Snullnull S H ow to... Panull 4SPnullnullT nullelp tonull nullLP Snullnull null nullnsider nullstly the renullon A nullere the one adds nullst nullnullonullattennulltion nullom the nullont panel or nullebservernull bnull the system lonullers the sinullal by nulldnull nullependinnullon the AGnullonullthe receiver vienullnnullthe drop and the null pernullrmance onullthe receiver nullder test there nullll be a marnulln onullerrornulland a nullo drop nullich in onull theoretical case onullnullinullre nullnulls nulldnullmay be seen by the receiver as a drop onullnull or nulldnull Secondly the area nullmay not be enullctly linearnullbnull typically nullnulld be in a rannull onullnullnullnulldnullattennulltion nullr a nominal inpnull attennulltion onullnull dnull nullepresented by the blacnulllinesnull GPSnullnullnullnullS System nullirstly the arnullments nulled above nullr the GPS system hold pernullctly nullell nullr the GPS/GLONASS system nullth some additional considerations nullinullre null. nullinullre null SP nullnullT nullnull Snullnull S H ow to... Panull nullSPnullnullT nullelp tonull nullLP Snullnull null The lenull hand nullaph is the GPS attennulltion nullaphnulland the rinullt hand that nullr GLONASS. A sinnulle attennulltor attennulltes the sinullal on nullTnullthe GPS and GLONASS sinullals. The theoretical GLONASS nullaph is very similar to that nullr the GPS enullcept nullr the nullllonullnnull null The nullantisation onull the GLONASS is nullnulllly nullbitnullcompared to nullbit nullr the GPS. This nullves aronulld nullnull onullsinullal loss. Therenullre nullth no attennulltion the sinullal plays bacnull nullnulllonuller than the enullivalent strennullh sinullal on the GPS null in nullinullre null. null The slope onullthe attennulltion cnullve is not linear nullot nullnullnullrather it is aronulld a drop onull0.nulldnullper nulldnull onullattennulltion. So tanullnnullthe enullmple onullthe previonull section nullth no attennulltion and an inpnull sinullal onullnulldnullon both GPS and GLONASS the GPS nullll playbacnullat nulldnull nullile the GLONASS nullll only be 4nullnull nulln order to minimise these enullnullcts the system is set so that nullen null dnullonull attennulltion is added as an inpnull the onullpnull is balanced to nullve a drop onull nulldnullon the GPSnullbnull only nullon the GLONASS. This means that inullnulle start nullth nulldnullsinullals beinnullrecorded on both GPS and GLONASS addinnullnull dnullonull attennulltion nullll nullve an onullpnull sinullal as vienulled by the GNSS receiver onull40dnullnullr both the GPS and the GLONASS. This is shonull as the nullnullalisation point in nullinullre null nulle have honullever seen mnullh more variation in honullGNSS receivers calcnullate their noise nullornulland honullthe AGnullnullrnullnullthan nullth GPS receivers. This manulls the nulle onullthe attennulltion table more variable. nullnclusion The nulle onullthe attennulltor in the GSS6400 has been describednulland nullves a simple nully to attennullte the stored sinullals. nullonulls vienulled on an attached GNSS receiver may honullever not be enullctly commensnullate nullth the inpnull attennulltion becanulle onullthe nully that the GNSS receiver calcnullates its nullonulland adnullsts it AGnull That beinnullsaid nullr a nullven GNSS receiver the resnullts nullinnullthe innull bnulllt attennulltor nullll be repeatable. Therenullre the nuller shonulld be able to dranullnull a simple table nullr a particnullar receiver onullinpnull attennulltion anullinst that onullpnull and measnulled nullinnullan attached GNSS receiver. SP nullnullT nullnull Snullnull S H ow to... Spirent nullmmunications null4 null0nullnull6nullnull nullobalsalesnullpirent.com nullnull.spirent.com/positioninnull Spirent nullederal Systems null null4 6null 6nullnull innullnullpirentnullderal.com nullnull.spirentnullderal.com nully not share this documentnull Got a smartphonenull If you have a smartphone download a QR Code reader and then point your phone camera at the QR Code to read the graphic. nullf you found this article of interest nullnull.spirent.com/positioninnull nullisit the Spirent GnullS blonull nullnull.spirent.com/nulllonullPositioninnullaspnull nulleed more informationnull nullssnullolnullionsnullpirent.com nullnull0null6 nullssnull null0null SP nullnullT nullnull Snullnull S H ow to... nullaceboonull Linnulldnulln Tnulltter Technorati Goonulle nullnullnull nullinull nullelicionull nulleddit Stnullblenullon