smart meter musings...

[James Sentman]

The way that most such devices work is that they make a long ON pulse of RF energy which lets any receiver setup it’s ACG and get ready to receive data. (and when I say long I mean some number of milliseconds) Once the receiver software sees such a long “sync” pulse it starts recording from the radio into it’s pulse chain buffer. Which is just a list of the timings of every pulse it receives thereafter. Once it receives a second sync pulse of approximately the same duration meaning there is about to be a repeat itr will try to process the data it has saved into some useful message, 

Mostly every time it sees a long pulse beyond a certain arbitrary length it starts back at the beginning of that pulse chain memory buffer. If no second sync pulse is received before you run out of pulse chain buffer then you get that error. That would mean that it is either receiving a real message that is too long to fit in it’s buffer size, which is possible but unlikely, or more likely that it’s just all noise but that happened to have a long pulse of something high energy a while ago. Might also be that the transmitter it is receiving is so far away or slightly mistuned so that it’s not getting it all or any number of reasons, but not necessarily a real signal that is just too big, most likely is just noise with some tiny bits of real signal mixed in.

> On May 26, 2021, at 1:26 PM, KC Hundere <khundere at gmail.com> wrote:
> 
> I've been playing around with a radio tuned to 345MHZ, and every time I enable the interface, I get 3 or 4 
> 
> pulse_FSK_detect(): Maximum number of pulses reached!
> 
> in the log.  Could this be from local meters?
> 

Thanks,
 James


James Sentman                       http://www.PlanetaryGear.org		http://MacHomeAutomation.com




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