pseudo-range estimation error

0 votes

I work on LEA6T0. For my project, I need the pseudo-range estimation error due to the receiver noise. I want to report it in my project presentation,

Thank you.
by amirtaba asked Sep 26, 2017
by clive1 edited Sep 27, 2017
0 votes
I don't believe that value has been documented anywhere in u-blox literature since it is not an unique need-to-know value for user assessmemt of navigation quality.

However, I have seen docs on the internet that describe all the error components of receiving a GPS signal, and I believe the contribution of thermal and equipmemt noise against signal power (resulting in C/N0 value) has been documented thoroughly for its effect on position accuracy.
As a start, look for graphs showing increase in position uncertainty against C/N0 value.
by grampy answered Sep 27, 2017
It's one of those hard to answer questions.

On the one hand, I can contain the phase of the carrier to below 1mm on a 19 cm wave, on the other there are GPS docs/specs that suggest dozens of metres of error, and on the third hand it is demonstrable that you can output an answer that's a metre or so from a truth position, and 3-5m CEP95.

The performance of the constellation is well above that originally conceived*, but clearly lacking updates from the ground for 90-120 days things would like degrade somewhat.

Also there were some expectations about the cost of accurate clocks, one mindset had them needing to be very accurate, OCXO or better implementations (ppt short term), but another school of thought is that you need to know what your clock performance actually is and work back the maths on the carrier and code generation.

*They may have hoped for such performance, but things worked out really well, and perhaps were more cautious in selling the technology lest it run into difficulties. Also I'm not sure anyone really expected the kind of gate count available from an SoC vs 70's era 7400 series logic chips, and the doors that would open to processing/modelling the signal.
0 votes
Isn't it a carrier based receiver?

Local copies of the code/phase will be taken at the measurement epoch (instant), so any timing/distance error will be across all satellite measurements.

You can pull pseudo-range residuals from NAV-SVINFO

You can pull local time error estimates from NAV-CLOCK
by clive1 answered Sep 27, 2017
Agreed. I was assessing the question literally ---- of all the error components, what is the pseudorange error attributed specifically to thermal noise plus receiver equipment noise (hence manifest as C/N0).
I decided that quoting a magic number would be unhelpful. I'm sure it's broken down in text books, but the numbers I remember seem to be far larger than what's actually attainable. The quoted accuracy is only going to afford a couple of metres of error

Yes, I'd agree that phase noise (ie a situation where the clock gets faster or slower due to thermal or whatever) would tend spread the signal across multiple correlator bins, and thus drop the CNO from those considered "on-time". Thermal shock to the local oscillator beyond the receivers ability to track/flow would look like massive acceleration/deceleration, and loss of lock.
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