About adaptation device to FCC15.247(CC1200)

CC1200 supports wideband digital modulation under 15.247. Check out the attached presentation with two alternatives (200kbps GFSK, +-180kHz dev and 200kbit/s GFSK on the air with 4 bit processing (50 kbps throughput), +-180kHz dev).

To increase output power above +14 dBm you need CC1190. That said, the PSD requirement of +8 dBm/3 kHz limits the output power to roughly +14 dBm (if the PSD is 8 dBm/3 kHz across the TX bandwidth of 500 kHz wide you can transmit at 1 W)

CC1200 supports wideband digital modulation under 15.247. Check out the attached presentation with two alternatives (200kbps GFSK, +-180kHz dev and 200kbit/s GFSK on the air with 4 bit processing (50 kbps throughput), +-180kHz dev).

To increase output power above +14 dBm you need CC1190. That said, the PSD requirement of +8 dBm/3 kHz limits the output power to roughly +14 dBm (if the PSD is 8 dBm/3 kHz across the TX bandwidth of 500 kHz wide you can transmit at 1 W)

6840.CC1200_Wideband_Digital_Modualtion.pptx

Sverre-san

Thanks for your quick reply and accurate information.
I have another question.

Can your explanation adapt to CC1120?

Best regards,

Manabu

I'm trying to figure out FCC 15.247 (or .249 for that matter). We have close to no data rate requirement and a very short range. I keep seeing this DN006 referenced, and I also keep seeing people talking about the 4 bits of processing gain available with the CC1200.

So yeah, if you follow DN006 you end up meeting some bandwidth and emissions limits in 15.247, but I'm reading other requirements that are not met, specifically 15.247e "The processing gain of a direct sequence system shall be 10dB." You're getting zero processing gain with the DN006 recommendations, and only a few dB using the 4 bits of spreading with the CC1200.

I just can't read 15.247 and get DN006 to fit in there, and I see it being quoted an awful lot on this forum. Am I missing something with my reading of the regs?

I really am looking for a solution though, we don't need to go far, or fast, I was hoping to get away with 15.249 which doesn't REQUIRE a spread spectrum technique, but less than 50mV/m, or ~-1dBm. I understand however that you need to use a reflective groundplane in this test and account for antenna gain, so you might hit that 50mV/m at more like -6dbm.

But I'm new to FCC regs and really don't know what I'm talking about. Any advice/corrections is appreciated.

Thanks,

Jon

I could not find the quote about the 10 dB coding gain here: www.ecfr.gov/.../text-idx . Am I looking the wrong place?

If range is not an issue you should target compliance with 15.249 as you then don't have to do FHSS or use wide band digital modulation. The output power is limited to approx -1.25 dBm under 15.249.

When selecting the data rate: Higher data rates means less time in active mode and hence lower average current consumption. Higher data rate gives less sensitivity so range is reduced.

Interesting. I found it here, part e) at the bottom of page 734. Your reference says it is current, perhaps mine is not. They removed the processing gain requirement? That would make it easier.
www.gpo.gov/.../CFR-2001-title47-vol1-sec15-247.pdf

Thanks,
Jon

Thanks.
It looks like the standard has changed, see www.ecfr.gov/.../text-idx

I would click verify answer if I knew how to do that. Where is this supposed verify answer button?

When you are logged in it's a green button next to the replay button.