FCC Part 15.249
FCC Part 15.249
(OP)
Hi,
I would appreciate helping me with interpretation of the FCC Part 15.249 regulations.
Section 249 allows for low power (EM field less than 50 mV/m) devices to operate with a fixed carrier - no spread spectrum. That section points specifically to “fixed” entities.
So, the question is …
Is a hand-held unit, with a capability to transmit a signal, in the “fixed” device category, Section 249 talks about? What if I move my sniffer arround? What if I mount my sniffer onto a truck, and I interrogate slave devices while I drive? I need to transmit short radio packets to do that.
I don’t see any reference, in the section 249, preventing moving my transmitting entity to different locations?
Is this the right way to interpret the section 15.249?
Would my sniffer need to comply with any other FCC regulations?
Thanks,
rfeng1
I would appreciate helping me with interpretation of the FCC Part 15.249 regulations.
Section 249 allows for low power (EM field less than 50 mV/m) devices to operate with a fixed carrier - no spread spectrum. That section points specifically to “fixed” entities.
So, the question is …
Is a hand-held unit, with a capability to transmit a signal, in the “fixed” device category, Section 249 talks about? What if I move my sniffer arround? What if I mount my sniffer onto a truck, and I interrogate slave devices while I drive? I need to transmit short radio packets to do that.
I don’t see any reference, in the section 249, preventing moving my transmitting entity to different locations?
Is this the right way to interpret the section 15.249?
Would my sniffer need to comply with any other FCC regulations?
Thanks,
rfeng1





RE: FCC Part 15.249
You'll also need to read through sub-part B (15.107 and 15.109 come to mind) to check for unintentional emissions.
RE: FCC Part 15.249
RE: FCC Part 15.249
Operating below 50 mV/m allows fixed carrier (at a chosen frequency), with "old" FM-like modulation (FM, FSK, PSK, ..., also AM, OOK, ...). To generate 500 mV/m a spread spectrum is needed, complicating the transmit/receive circuit. The spread spectrum usually is FHSS or DSSS, with a number of modulation techniques allowed. Spread spectrum needs extra time to lock and synchronize the receiver.
A simplified system (with a fixed carrier) can work below 50 mV/m within tens/hundreds feet of the range, but it is more sensitive to interference, and can be killed if a strong interfering harmonics (or a carrier) accidentally sits at the frequency of operation.
Regards,
RFENG1
RE: FCC Part 15.249
The FCC has set up mailboxes (oetinfo@fcc.gov, htt
Check out http://www.fcc.gov/oet/faqs/ for more info.
Good luck.