[time-nuts] how good an oscillator do you need for a GPS simulator

Jim Lux jimlux at earthlink.net
Sat Dec 17 15:57:55 EST 2011

On 12/17/11 9:01 AM, Magnus Danielson wrote:
> On 12/17/2011 05:10 PM, Jim Lux wrote:
>> On 12/17/11 6:58 AM, Azelio Boriani wrote:
>>> Correct: I was thinking how to simulate an only bird. The RACAL GPS101
>>> is a
>>> single channel simulator and maybe made that way. Then it is possible to
>>> place a number of 1 channel simulators at a distance...
>> I was thinking more along the lines of how would one do a indoor test
>> setup. Magnus's comment was a good one.. if you want to simulate
>> multiple channels, you'd probably want some sort of resistive combiner.
> Yes, but if you have them all in the same sample clock, adding them
> together you can do a smaller resistor chain DAC. Three or four bits can
> be done without much performance setback.
> Jim, would you be satisfied with L1 C/A only or do you need L1/L2 P-code
> or even pseudo-P(Y)?

L1 C/A

But the real question isn't how to generate the signals (that's straight 
forward).. it's "how good does the oscillator have to be" to effectively 
test the receiver, in the sense of measuring it's timing performance.

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