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Rosum TV-GPS
The limitations of GPS and A-GPS
GPS signals were designed for accurate tracking and location in open outdoor areas; however, indoors and in urban areas, the technology is not reliable. Assisted GPS (A-GPS) helps the GPS receiver by providing an alternate source of the fragile navigation message and helping the receiver average for extended periods of time. However, even A-GPS is unreliable indoors due to the fundamental physics of GPS satellite signals.
Rosum's TV Advantage
In contrast, television signals were designed for indoor reception. Rosum TV-GPS uses commercial broadcast TV signals to provide reliable positioning indoors and in urban environments. By combining TV signals with GPS signals, Rosum can provide seamless indoor/outdoor coverage across all environments.
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| METRIC | EFFECT | TV-GPS | A-GPS | GPS |
| Power | Stronger signals are more widely detectable. The greater the signal level, the faster the position fix. | Typically 1000 KW or more, broadcast within 50 miles of commercial and population centers. | 500W, from 12,500 miles above the Earth's surface. | 500W, from 12,500 miles above the Earth's surface. |
| Frequency | Lower frequencies penetrate buildings more easily. | 300-750 MHz. Good indoor coverage. | 1,512 MHz. Poor indoor coverage. | 1,512 MHz. Very poor indoor coverage. |
| Bandwidth | Wider signal bandwidth means more accurate positions. | 6 MHz | 1 MHz | 1 MHz |
| Frequency Diversity / Clear Channels | Ensures coverage in difficult environments. Clear channels speed signal acquisition by increasing Signal-to-Noise ratios. | Every building has slightly different signal attenuation across the broadcast TV spectrum. Since each TV tower typically broadcasts more than one channel, the Rosum receiver will have a better chance of acquiring a signal given that these channels are broadcast at different frequencies. Rosum can choose the best channels from each tower to compute the user's location. | All channels use the same frequency. One channel's signal is another channel's noise. | All channels use the same frequency. One channel's signal is another channel's noise. |
Rosum. For enterprises and government entities that suffer from the limits of GPS, we provide a seamless indoor/outdoor location technology that is rapid, available, and accurate.
Read about Rosum TV-GPS components.
How Rosum TV-GPS Works
The illustration below depicts how Rosum TV-GPS works.
Note that location could be determined autonomously at the RTMM under the following situations:
- TV signals were all synchronized to a common clock
- Timing information for the TV clocks could be provided
over-the-air as a part of the TV signal.