In the FCC, there technically aren't any parts of the spectrum that are not "in the plan". Every frequency is governed by something under the FCC's Part 15 rules<http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&SID=3ad5847adc442ba7c9e0c9ed27f0c59c&n=47y1.0.1.1.16&r=PART&ty=HTML>. There are some underlying "baseline" or "default" emission rules, and then there are some specific carve-outs or overrides that apply to specific devices or sub-bands. TV white space is defined as specialized overrides within the context of the Part 15 rules (specifically, sections 15.701 thru 15.717<http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&SID=3ad5847adc442ba7c9e0c9ed27f0c59c&n=47y1.0.1.1.16&r=PART&ty=HTML#47:1.0.1.1.16.8> ).
In other words, sections 15.701 thru 15.717 can grant higher emissions limits on some frequencies, and impose additional limits on others, but anything else not specifically called out would fall to some other default rule within the Part 15 rules (e.g., section 15.109<http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&SID=3ad5847adc442ba7c9e0c9ed27f0c59c&n=47y1.0.1.1.16&r=PART&ty=HTML#47:1.0.1.1.16.2.236.6>). Part 15 rules define the upper bound of what a device is allowed to radiate. Any device that exceeds these limits will fail the FCC certification tests. In addition to the hard limits defined by Part 15, devices are encouraged to lower their emissions as much as possible, as a general "politeness protocol". For example, section 15.709<http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&SID=c66e2da386cac159cb62df35b2090f07&n=47y1.0.1.1.16&r=PART&ty=HTML#47:1.0.1.1.16.8.237.6>(a)(5) talks about white space in-band emission limits and section 15.709(c)(1) talks about emission limits on the first-adjacent channel to a TV broadcast. The rules are silent on what happens for second-adjacent channels, and channels that are further out, so one should assume that the the "default" rules then apply. Another example is section 15.709(c)(4), where there are special emission constraints around TV channel 37. It gives specific power spectral density limits for frequencies around channel 37 as illustrated in the following ASCII diagram. Field strength numbers have been converted to dBm values for convenience. -63.19 dBm -- + + \ / \ / -65.22 dBm -- +--+ +--+ | | | | ch36 | ch37 | ch38 | | | | -75.23 dBm -- +--------+ | | | | | | 602 607 608 614 615 620 MHz This example also illustrates a case where the emission profile has a non-zero slope for some frequency ranges (i.e., 602-607 and 615-620 MHz have sloped psd profiles). Andy Lee | Google Inc. | [email protected] | 408-230-0522 On Fri, Sep 13, 2013 at 9:00 AM, Vincent Chen <[email protected]> wrote: > Ray, > > Sorry for the delay in response. > > >> My point about being able to represent discontinuities in the frequency >> range still appears to stand, however. >> > > I see. Television channels do not occupy a contiguous range of > frequencies. In the US, > > - [54MHz, 72MHz] Channel 2-4 > - [76MHz, 88MHz] Channels 5-6 > - [174MHz, 216MHz] Channels 7-13 > - [470MHz, 698MHz] Channels 14-51 > > So the response given by the database should not include any frequencies > not in the plan. > > That means a "spectrum profile" should be encoded as a list of "array" of > (frequency, power) points. > - Each array represents a "profile" for a contiguous range of frequencies > - The range of frequencies within a list of profiles MUST be disjoint and > SHOULD be sorted > - The entire set of frequency bands defined by the regulatory domain MUST > be represented by a single list of "profiles" > (rather than split them across multiple lists) > > That last point is to remove ambiguity and, thus, variations in database > implementation, to simplify logic on devices. > > Example: > > "spectra": [ > { > "bandwidth": 6e6, > "profiles": [ > [ > { "freqHz": 5.4e7, "maxPsdDbmPerBw": -56.8 }, > { "freqHz": 7.2e7, "maxPsdDbmPerBw": -56.8 }, > ], > [ > { "freqHz": 7.6e7, "maxPsdDbmPerBw": -56.8 }, > { "freqHz": 8.8e7, "maxPsdDbmPerBw": -56.8 }, > ], > [ > { "freqHz": 1.74e8, "maxPsdDbmPerBw": -56.8 }, > { "freqHz": 2.16e8, "maxPsdDbmPerBw": -56.8 }, > ], > [ > { "freqHz": 4.70e8, "maxPsdDbmPerBw": -56.8 }, > { "freqHz": 5.18e8, "maxPsdDbmPerBw": -56.8 }, > { "freqHz": 5.18e8, "maxPsdDbmPerBw": 30.0 }, > { "freqHz": 5.24e8, "maxPsdDbmPerBw": 30.0 }, > { "freqHz": 5.24e8, "maxPsdDbmPerBw": 36.0 }, > { "freqHz": 5.30e8, "maxPsdDbmPerBw": 36.0 }, > { "freqHz": 5.30e8, "maxPsdDbmPerBw": -56.8 }, > { "freqHz": 6.98e8, "maxPsdDbmPerBw": -56.8 } > ] > ] > }, > { > "bandwidth": 1e5, > "profiles": [ > [ > { "freqHz": 5.4e7, "maxPsdDbmPerBw": -74.58 }, > { "freqHz": 7.2e7, "maxPsdDbmPerBw": -74.58 }, > ], > [ > { "freqHz": 7.6e7, "maxPsdDbmPerBw": -74.58 }, > { "freqHz": 8.8e7, "maxPsdDbmPerBw": -74.58 }, > ], > [ > { "freqHz": 1.74e8, "maxPsdDbmPerBw": -74.58 }, > { "freqHz": 2.16e8, "maxPsdDbmPerBw": -74.58 }, > ], > [ > { "freqHz": 4.70e8, "maxPsdDbmPerBw": -74.58 }, > { "freqHz": 5.18e8, "maxPsdDbmPerBw": -74.58}, > { "freqHz": 5.18e8, "maxPsdDbmPerBw": 27.0 }, > { "freqHz": 5.24e8, "maxPsdDbmPerBw": 27.0 }, > { "freqHz": 5.24e8, "maxPsdDbmPerBw": 33.0 }, > { "freqHz": 5.30e8, "maxPsdDbmPerBw": 33.0 }, > { "freqHz": 5.30e8, "maxPsdDbmPerBw": -74.58 }, > { "freqHz": 6.98e8, "maxPsdDbmPerBw": -74.58 } > ] > ] > } > ] > > Does that address your concern? > > -- > -vince >
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