Callsing and squawk appears ONLY on west side of the contry..

[CRJ08]

Hi, goos day people, a serious question here, well, in Venezuela most of receivers are on a VRS server, so we can help to improve each other coverage, in VRS callsigns for Conviasa V0/VCV an others B735 General aviation LJ45, appears only with receivers from the west of the cuntry, considering SVMI/CCS is almost on the middle, e.g when and E190 departs from SVMG/PMV (EAST) to SVMC/MAR (WEST) they don't show callsign, not on VRS nor FR24, when appears with MLAT, but when they have passed SMVI and enter on coverage from some receivers in the western side of Venezuela, the callsign suddenly appears from nothing on VRS, most of them with the mark (*) and moments later that callsign shows on the FR24 site aswell, so WHAT IS HAPPENING, why some receivers gets callsign and others are not, what format are they transmitting? because non of the eastern receivers are reciving callsign, even if and aircraft departs west, eastbound, with callsign showing on that receivers whe arrives east the callsign is not there, (on the site stills that info), AAAAAAAAAAAAAND the same exact thing with SQUAWK!!!! I think all your receivers are the same, with same info and same format, or not???? greetings...

[Mike]

And ADS-B transponder is transmitting most of the data by itself. For an ModeS transponder some of the data needs to be requested from ground, for example callsign. In Europe there are ground stations requesting this data so most MLAT aircraft have a callsign in Europe. In USA callsign is rarely requested from ground, so there are much more flights without a callsign. I guess the same apply in different regions of Venezula.

[CRJ08]

Hello, here, callsign is not requested because our radar system(obsolete and some times not working) works only with mode A and C, pilots input callsign by themselves, Aeropostal has MD with ADS-B and they put callsign almost always, Conviasa also input callsign and only appears on that side, others aircraft, LJ45 B350, B735, AN12, C500, all of them shows callsign always when on the Western side of the country, so MUST be something on the receiver, when they take off from East the already have the callsign but only appears when reach Western receivers... It's weird but is like that, no one on ground request callsign

[Mike]

I'm not talking about Mode A and C. For ModeS transponder the Callsign is only transmitted if requested from a ground station so it's regional. Eurocontrol in Europe is requesting so in Europe most MLAT flights have callsign. Iceland is not requesting and most MLAT flights have "no callsign". USA was not requesting 12 months ago and all MLAT flights were "no callsign". Now FAA request and MLAT flights have callsign. In Brazil callsign is not requested and most MLAT flights have "No callsign". So it has nothing to do with ModeA/C or the receiver, just ground stations requesting data.

[CRJ08]

Well I repeat, Venezuelan facilities of Radar system does not require callsign because our radars are not for Mode S, only old radar for A/C so, should be Curacao FIR sending request for all mode S transponders on its range?? Because Venezuela is not requesting callsign, but Curacao is on the West of Venezuela, and has modern technology and their ATC and radar system probably is requesting callsign to all transponders on its range, or is this request aircraft selected?