Posts by Little Fishie

Virgin Media to push out nimble new broadband speeds

"I have the 50mbit service from them, and i can download at around 10-20mbit max from several colocated servers i have (all on gigabit links)..."

Main reason for this is Latency

It doesnt matter how much bandwidth you throw at it the maximum throughput will be dependent on the latency. (torrents get round this by setting up multiple sessions)

Even on corperate private networks latency is the main issue

100mb lines topping out at 10-20mb per session when latency starts going over 20ms.

with internet latency going into the 100's for long hauls this has a major impact.

US spy drone hijacked with GPS spoof hack, report says

GPS is triangulation based on distance from the satalite (time delay of the signal)

Jam the originals and retransmit the the original signals with the required timedelay to indicate the new triangulation point (The GPS itself does not know the time it just determins position based on the diferential timestamps on the signal) . unless the drone has an onboard atomic clock you can drift the time signals forward the miniscule amount away from real time to allow for not being able to transmit a signal in the past.

No decription required

the complexity is the timing in the retransmission of the signals

Voyager 2 finally agrees to a long hard thrust

A Little out of date but gives the details

Power was provided to the spacecraft systems and instruments through the use of three radioisotope thermoelectric generators. The RTG's were assembled in tandem on a deployable boom hinged on an outrigger arrangement of struts attached to the basic structure.

Each RTG unit, contained in a beryllium outer case, was 40.6 cm in diameter, 50.8 cm in length, and weighed 39 kg. The RTG's used a radioactive source (Plutonium-238 in the form of plutonium oxide, or PuO2, in this case) which, as it decayed, gave off heat. A bi-metallic thermoelectric device was used to convert the heat to electric power for the spacecraft. The total output of RTG's slowly decreases with time as the radioactive material is expended. Therefore, although the initial output of the RTG's on Voyager was approximately 470 W of 30 V DC power at launch, it had fallen off to approximately 335 W by the beginning of 1997 (about 19.5 years post-launch). As power continues to decrease, power loads on the spacecraft must also decrease. Current estimates (1998) are that increasingly limited instrument operations can be carried out at least until 2020.