Mapping sampling methods and feature requests

Hi,

Just a quick question on Spike and the new mapping capability, which appears to be very useful.

I wish to use it for narrowband measurement so I set the GPS measurement delta to conform to the Lee method with the hope that the power relates to the whole distance interval. Can you explain what the power measured is, for example is it the median of many samples taken over the distance interval, or is it just a single sample taken when the delta distance criterion is met? If the power is related to the statistics of many samples, it would be good to know the number of samples achieved. With the mapping, it would be lovely if the software could just download OpenStreet maps or at least read georeferencing metadata in simple file export like PGW world headers allied to a PNG. Finally regards GPS, it would be very useful to be able to specify an IP source rather than a COM port, so that you can use the sophisticated positioning on a modern phone (for example using GPS2IP app as a source).

Regards,

Cyprien

Cyprien,

We appreciate some of your ideas and suggestions.

Regarding the power measurement. It is a channel power measurement using the user defined settings in the sweep settings control panel. The channel power result is what is plotted on the map. The channel power measurement is made in the frequency domain, not the time domain, so it may not be accurate for very short duration pulsed signals.

The GPS min delta and meas speed control how often the GPS is sampled. It can prevent you from taking measurements too often or too close together. If the meas speed interval has passed and the GPS reports a distance at least minimum distance from the last point, then a new point is plotted on the map using the most recent channel power reading.

I hope this helps. Let us know if you have follow up questions. There is some short descriptions of the controls in the Spike user manual as well.

Andrew

Hi Andrew,

To explain why I ask, I am attempting to conduct a CW signal survey. My understanding is that in a mobile environment a narrowband signal may suffer significant fading which will cause quite some variation in the net signal over very short distances as the scattered vectors interfere. To measure the coverage it is desirable to remove the fast fading by gathering an adequate number of samples over a distance of typically 20-40 wavelengths. These samples can then be used to estimate the local mean to a given confidence interval. This general principle is known as the Lee Method.

In a test survey I can observe the deep fades, but the values I measure today are hard to reconcile because I am unsure how to setup, so any advice on how to achieve the above would be great.

Regards,

Cyprien

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