Tomtom heeft een aantal generaties de sirf3 gebruikt (vanaf de one v2 dacht ik) (die komt door folie heen), in de meest recente modellen zit weer een ander model gps chip, de global locate van broadcom.
Ik haal de volgende info vh net:
I’m an electrical engineer that has been using GPS for many years. I have owned more units than I can count and have “grown up” with the technology. I do not work in GPS receiver or systems design, and I am not an expert in the field. I study the subject just enough to settle my curiosities and to make educated buying decisions. The key is not the chip manufacture or the number of channels (once you get to 12-channel receivers), it’s the number of correlators. GPS satellites transmit with very low power and they are very distant. In addition, they all transmit on the same frequency. The correlators find the very weak signal among the noise and confusion. As a result, the receiver technology, along with the map accuracy/currency, seems like a major purchasing decision to me. I don’t care how clever the style, packaging, or user interface is if the unit can’t get a fix when I need it and if the maps are not accurate. The key aspect of the SiRFStar III chipset is a design feature referred to as massively parallel correlators. This is what enables the receiver to have the ability to receive very weak signals. I would not buy a GPS navigator that doesn’t use this technology. In fact, I own 4 GPS receivers at any one time (two for cars and two for hiking) and I have revamped my entire set with units that utilize this technology. Anyone that has been frustrated by the lack of a fix when hiking in canyons, or hiking in deep cover, or driving in cities with tall buildings will appreciate this recent improvement in receiver technology. This technology also has the ability to improve a phenomenon called multi-path (where the receiver sees more than one signal because it is being bounced off objects or structures). This is counter intuitive to some, because the technology can make the problem worse due to it’s inherent design. The Motorola Instant GPS, the SiRFStar III, and Global Locate’s chips all have designs that incorporate massively parallel receivers. To my knowledge, Magellan has not incorporated this technology into their chips yet, Garmin is hit and miss so read the specs, and TomTom is pretty committed. I agree with the author in that I would not buy units that only use the SiRFStar III chips. Instead, I look at the receiver sensitivity. For example, the SiRFStar III advertises a sensitivity of -159 dBm. The Global Locate Hammerhead is -160 dBm. The Motorola Instant GPS was part of a SiRF acquisition of the Motorola GPS line. The SiRF Instant GSCi-5000 is -142 dBm. The larger (more negative) the number the better.
Dus dat lijkt OK , ook de nieuwe chpset is high sensitivity.
Wel hebben ze de externe antenne aansluiting laten vervallen. Dus alternatieven heb je niet. Je oude tomtom heeft dat wel nl. Op een tomtomt forum als Webloq kun je vinden hoe je je oude tomtom kunt upgraden naar de firmware van de recente modellen (op eigen risico)
Ligt dat overigens aan die SiRF3 chipset? TT vermeldt helaas niet expliciet dat de TT 1000 daar ook van is voorzien...
