Laptop phone promises speedier transmission


By Barry Fox A SATELLITE communications system due for launch in August may spell further trouble for Iridium, the global satellite telephone company which has been struggling to attract subscribers since its launch last year. Inmarsat, the maritime satellite communications organisation, is to launch a laptop-style satellite phone unit that can send or receive data at ISDN speeds—64 kilobits per second—from anywhere in the world except the polar icecaps. This compares with the 2.4K data rate possible with the Iridium phone network. When Iridium was conceived by Motorola in 1987, PC modems were just reaching 2.4K speeds, so Iridium’s data speed was set at that level. But with modems now routinely handling up to 56K, 2.4K is painfully slow and one quarter the speed of a GSM cellphone. A spokeswoman says Iridium has “no plans” to redesign the system to handle a higher data rate. Iridium’s hand-held receiver works like a cellphone, continually switching from one low Earth orbit satellite to another as they come over the horizon and pass overhead. The company’s $2 billion satellite service was ready by November 1998, but has been slow to take off, with only around 10 000 subscribers worldwide. In the US, Iridium is already promising swingeing price cuts. But unlike Iridium’s phone, which looks and handles like a large cellphone, Inmarsat’s Global Area Network terminal has to be pointed at a geostationary satellite using a compass built into the laptop. Inmarsat says it will be fast enough to send and receive videophone pictures. High-quality video can be transmitted slowly,
  • 首页
  • 游艇租赁
  • 电话
  • 关于我们