[TangerineSDR] SAE J2497

[David G. McGaw]

On the Zoom call this evening, Jay WB8SBI brought to our attention a 12V 
power-line signalling standard used by heavy trucks, SAE standard J2497, 
which can potentially radiate RF outside of a vehicle.  It probably is 
not of much concern.  While I cannot read the actual standard without 
paying for it, I was able to find a datasheet on a chip designed to 
implement the standard: 
<https://www.digchip.com/datasheets/parts/datasheet/228/SSCP485-pdf.php>. 
It is a spread spectrum protocol using chirped signals swept between 
100kHz and 400kHz.  It may interfere with radio services in this range, 
mostly navigation beacons, but I notice that signals in the AM Broadcast 
Band are spec'ed to be -60dB below the signaling level (1.5mVrms max vs 
4Vpp max).  There is a 400kHz low-pass filter on the signal transmitter 
to limit the emissions so ham-band levels would presumably be even less.

Interesting, though.  I do know my car has things that can interfere 
with FM Broadcast and 2M Amateur radios.

73,

David N1HAC

P.S.  Happy Summer Solstice!