Am I correct that you need an internet connection to setup the NEO-D9S, but once it’s connected, you are able to connect to the PointPerfect network via L-band? No internet connection needed in the field?
The u-blox NEO-D9S is designed to receive correction data via the L-band satellite signal for the PointPerfect service. Once it is set up and configured, it does not require an active internet connection in the field to access the PointPerfect network.
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Hi @KnightHawk ,
The GPS/GNSS forum is the best place to ask questions like this.
The PointPerfect encryption keys are updated (usually) every 28 days. The current and next key can be obtained from PointPerfect over the Internet. Worst case, you get ~29 days worth of keys. Best case, you get ~56 days.
The NEO-D9S doesn’t need to know the keys. It only needs the L-Band frequency for your geographical area (plus some other set-and-forget settings). But the (e.g.) ZED-F9P does need the keys so it can decrypt the PMP (SPARTN) data output by the NEO-D9S.
Hope this helps,
Paul
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Key distribution is the issue here, and there’s probably a lot of different ways to do that.
The key isn’t unduly large, it can be typed by hand, or delivered by some low bandwidth method, like say an SMS message, which might work better on the “outer reaches” where cellular can’t support voice or internet, as SMS get’s queued, and doesn’t have to occur in real-time.
Most of the SPARTN keys have had a 4-week life, had a couple of occasions with 5-weeks, and you can get them in a pair, ie current and next.
They could honestly deliver new keys over the L-Band channel itself, with a user identification number, and a unique customer specific crypto key. Like old cable boxes, or XM-Radio.