[time-nuts] Did the FCC put LightSquared on ice?

[Magnus Danielson]

On 11/08/11 08:03, Chuck Forsberg WA7KGX N2469R wrote:
> The FCC has decided GPS is worth saving ... but not necessarily all
> current GPS receivers.
>
> http://www.aero-news.net/index.cfm?do=main.textpost&id=1c898613-45b1-48a0-9d86-a767db2b017d

Root cause for interference is significantly changed dynamics 
requirements on the GPS receivers, as side-bands would become stronger.

The dynamics has allowed for simple 1-bit or 1.5 bit receivers, where 
1.5 bit receivers with separate level detection for AGC steering has 
better supression of CW signal than straight 1-bit. Much work went into 
few-bit ADC analysis in the early days, so the use is widespread. Using 
say 8-bit ADC would allow for the C/A code to de-correlate the signal 
further 30 dB down rather than letting the AGC be captured. That and 
filtering.

One has to realize that the relative low interference have allowed many 
small and cheap designs to evolve, for the benefit of mobile phone use, 
tracking devices on packages etc. etc.

Reducing civilian receivers resistance to jamming would also potentially 
reduce the effect of intentional jamming. Still, modern jamming 
techniques should not see much of such effect, so I don't think the 
green guys worry too much.

Cheers,
Magnus