[time-nuts] Ublox neo-7M GPS

Said Jackson saidjack at aol.com
Tue Aug 19 12:44:26 EDT 2014


Graham,

Those are not GPSDO's by definition.

They are based on NCO technology.

The difference being many orders of magnitude higher phase noise and ADEV noise.

We tried to measure their phase noise and our TSC5125A could not even lock on  to the 10MHz - they were so noisy.

You can make a GPSDO out of them if you use a post filter oscillator loop locked with sufficient time constant (>>10s).. 

Sent From iPhone

> On Aug 19, 2014, at 9:20, "Collins, Graham" <CollinG at navcanada.ca> wrote:
> 
> Good day all,
> 
> On another list to which I subscribe, there has been chatter about the Ublox neo-7M GPS receiver. It seems that the device's configurable timepulse output is configurable from 0.25hz to 10 MHz as well as it's duty cycle and can also be set to be one condition when the GPS is not locked and a different condition when locked (i.e. 1 PPS if not locked, 10KHz when locked).
> 
> This seems all too good to be true. Sounds like a very simple self-contained GPSDO.
> 
> I don't know anything more about the device. I have just downloaded the documents and will be spending some time reading them.
> 
> I am curious if any other list members were aware of this feature of this device and have had any first hand experiences with it.
> 
> There is another model, the 7N. the 7M uses a simple crystal clock, the 7N a TXCO.
> 
> Cheers, Graham ve3gtc
> 
> 
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