[time-nuts] Checking the Frequency of a Rubidium Oscillator

[Lux, James P]

> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Brucekareen at aol.com
> Sent: Tuesday, November 11, 2008 9:28 AM
> To: time-nuts at febo.com
> Subject: [time-nuts] Checking the Frequency of a Rubidium Oscillator
>
>
> I  have an EIP Model 548 counter with a YIG-tuned front end
> that can be programmed  to scan over narrow frequency ranges.
>  By feeding the rubidium oscillator under test into the 10
> MHz clock input  of the counter, is there any reasonably
> simple way to directly measure the  frequency of a GPS
> satellite transmission so as to ascertain the accuracy of the
>  rubidium source?

Not a chance.. The signal is a PN code at about 1 Megachip/second, and the power spectral density is probably comparable to the thermal noise floor of the receiver.


 The counter has an  input sensitivity in
> the order of about -25 dBm -- not sufficient to measure
> directly from an amplified antenna, but perhaps through an
> amplifier.  I am not sure whether the input YIG  tuner
> selectivity is sufficient to separate transmissions from the
> various  satellite's (or are they TDMS?).  What do you think?

All the satellites are at the same frequency, and they are CDMA (each satellite has a different PN sequence on its signal)