Amateur Radio Allocations and Overlapping Part 15 Bands - An Overview
And a Part 97 versus Part 15 and Permissible Power Comparison

One of the main advantages to reclassifying your operations to Part 97 is interference protection from unlicensed operations (see Sec. 15.5) Licensed services have priority over unlicensed operations.

Reclassifying under Part 97 also provides a way around the Part 15 certification/authorization problem. (see Sec. 15.204) Which states in short that an authorized system includes its marketed antenna and other components and must always be used in its original configuration in which it was authorized, and should not be modified. Amateur equipment does not require certification / authorization, and hams may use equipment that has been certified for another service on amateur frequencies. [Sec. 97.315] Under Part 97 you can legally modify these devices, using (homebrew) pre-amps, RF amplifiers, and high gain antennas.

Another fairly big advantage is the amount of achievable radiated power under Part 97.   As you may know Part 15 operation has effective radiated power (ERP) limits. It also has different (lower) limits for omni-directional antennas.

Amateur Radio has never had or has any type of ERP limits. The wording of Part 97.311(d) which regulates Amateur Spread Spectrum uses the words "transmitter power" which imply peak envelope power (PEP) or carrier power (CP) not effective radiated power (ERP). (If it said radiated power then ERP would be implied). Non-Spread Spectrum modes such as 802.11a or 802.11g have the 1500 Watt PEP limit. Note there are no ERP / EIRP limits for Part 97 operation. There is also no difference for omni-directional or directional setups. The directional antennas sited in the table below are for example purposes. And the EIRP's listed below are only limited by the gain of your antenna.

In late 2011 Doodle Labs made the first Atheros based transceiver specially optimized for the Amateur Band.  The DL-435.

Since the band is unshared by Part 15 there may be some advantages to this, such as fighting interference and to keep out Part 15.    Also 70 cm is not line of site, compare to 2.4 GHz.

Our amateur allocations on this band overlap the Part 15 band exactly.  Most equipment you will find is FHSS, with slower speeds and generally older such as the Lucent/NCR WaveLAN and Metricom Ricochet wireless data radios.  Other options include the FreeWave modem, Aerocomm ConnexLink radios.  And now due to the modular architecture of the Atheros chipset, the Ubiquiti XR9.  (The XR9 is 802.11g OFDM/ 802.11b DSSS)

Ubiquiti XR9

			20 MHz channel width @ 54 Mbps		10 MHz channel width @ 27 Mbps		5 MHz channel width @ 13.5 Mbps
802.11g Channel	2.4 GHz center reference	900 MHz Center  Freq (MHz)	Lower Freq (MHz)	Upper  Freq (MHz)	Lower Freq (MHz)	Upper  Freq (MHz)	Lower Freq (MHz)	Upper Freq (MHz)
3	2.422	922	912	932	917	927	919.5	924.5
4	2.427	917	907	927	912	922	914.5	919.5
5	2.432	912	902	922	907	917	909.5	914.5
6	2.437	907	897	917	902	912	904.5	909.5

 

Achievable under Part 97:	Max. PEP RF power	Ant. gain	EIRP
900 MHz (spread spectrum)	10 watts (per 97.313)	14 dBd yagi	411.9 watts
900 MHz (non spread spectrum i.e 802.11g)	1500 watts  (per 97.313)	14 dBd yagi	37.8 Kilo-watts
Permissible under Part 15:	Max. Transmitter RF power	Ant. gain (dBi)	EIRP (W)
900 MHz	30 dBm (1 W)	6	3.98

	US Amateur Band Allocations
13 Centimeters
2300 - 2305 MHz	Secondary - No primary
2305 - 2310 MHz	Secondary to fixed, mobile and radiolocation services
2390 - 2400 MHz	Primary
2400 - 2402 MHz	Secondary - No primary amateur service
2402 - 2417 MHz	Primary
2417 - 2450 MHz	Co-secondary with government radiolocation (industrial, scientific and medical are primary)
	US Part 15 Band
2400 - 2483.5 MHz	may not cause interference to other services, and  must accept interference that may cause undesired operation

On this band our amateur allocations do not overlap the Part 15 band entirely.  However many 802.11 systems can be user set for frequencies centered below 2.45. 

 802.11g Orthogonal Frequency Division Multiplexing (OFDM) Channel to Frequency Mapping 

802.11g uses the same 2.4 GHz channels as 802.11b but enables speeds up-to 54 Mbps. (Actual occupied bandwidth at 11/54 Mbps is about 16.6 MHz.)  It can co-exist and maintain backwards compatibility with 802.11b. It should be noted that OFDM is Not a Spread Spectrum mode per FCC definition and thus the special spread spectrum Part 97.311 rules need not apply.

 

		20 MHz channel width @ 54 Mbps		10 MHz channel width @ 27 Mbps		5 MHz channel width @ 13.5 Mbps
802.11g Channel	Center Freq (GHz)	Lower Freq (GHz)	Upper Freq (GHz)	Lower Freq (GHz)	Upper Freq (GHz)	Lower Freq (GHz)	Upper Freq (GHz)
-3**	2.392	2.382	2.402	2.387	2.397	2.3895	2.3945
	2.394	2.384	2.404	2.389	2.399	2.3915	2.3965
-2**	2.397	2.387	2.407	2.392	2.402	2.3945	2.3995
	2.399	2.389	2.409	2.394	2.404	2.3965	2.4015
-1**	2.402	2.392	2.412	2.397	2.407	2.3995	2.4045
	2.404	2.394	2.414	2.399	2.409	2.4015	2.4065
0**	2.407	2.397	2.417	2.402	2.412	2.4045	2.4095
	2.409	2.399	2.419	2.404	2.414	2.4065	2.4115
1	2.412	2.402	2.422	2.407	2.417	2.4095	2.4145
	2.414	2.404	2.424	2.409	2.419	2.4115	2.4165
2	2.417	2.405	2.427	2.412	2.422	2.4145	2.4195
	2.419	2.409	2.429	2.414	2.424	2.4165	2.4215
3	2.422	2.412	2.432	2.417	2.427	2.4195	2.4245
	2.424	2.414	2.434	2.419	2.429	2.4215	2.4265
4	2.427	2.417	2.437	2.422	2.432	2.4245	2.4295
	2.429	2.419	2.439	2.424	2.434	2.4265	2.4315
5	2.432	2.422	2.442	2.427	2.437	2.4295	2.4345
	2.434	2.424	2.444	2.429	2.439	2.4315	2.4365
6	2.437	2.427	2.447	2.432	2.442	2.4345	2.4395
	2.439	2.429	2.449	2.434	2.444	2.4365	2.4415
7	2.442	2.432	2.452	2.437	2.447	2.4395	2.4445
	2.444	2.434	2.454	2.439	2.449	2.4415	2.4465
8	2.447	2.437	2.457	2.442	2.452	2.4445	2.4495
	2.449	2.439	2.459	2.444	2.454	2.4465	2.4515
9	2.452	2.442	2.462	2.447	2.457	2.4495	2.4545
	2.454	2.444	2.464	2.449	2.459	2.4515	2.4565
10	2.457	2.447	2.467	2.452	2.462	2.4545	2.4595
	2.459	2.449	2.469	2.454	2.464	2.4565	2.4615
11	2.462	2.452	2.472	2.457	2.467	2.4595	2.4645
	2.464	2.454	2.474	2.459	2.469	2.4615	2.4665

*Europe allows channels 12 & 13. Japan allows channels 12, 13, & 14.
**Channels unassigned but supported by IEEE , and  available in Atheros chipset.  This chipset is used by over 30 different wireless device manufacturers, including Netgear, D-Link and Linksys.  StarOS software by Valemount Networks generally supports the additional features of the Atheros Chipset, along with other driver vendors.  One of these settings is the country code.  Changing the country code to that of a country where the Part 15 bands are different than ours may create a convenient incompatible fork.  For ham radio use this may keep nosey Part15 users out, and/or provide channels that do not overlap the Part 15 channels in the USA.  All of the below country codes (including XX or ## which have been used for "without regulatory constraints") are part of the driver, or "hardware abstraction layer" (HAL).   These are the secrets to unlock all channels supported by the Atheros hardware (2312-2732, 4920-6100 MHz). It is up to the end user to ensure they stay within their region's regulatory channel ranges.  (While IEEE has not assigned channels to these frequencies, however they would equate to 0, -1, -2, etc.)

On this band there are no current adjacent Part 15 allocations.  However, a chunk that doesn't appear to overlap our allocations has been proposed. It is possible with transverters to take consumer off the shelf 2.4 GHz 802.11 hardware and have it operate on this ham band.  Ubiquiti Networks has a device for this band too that is compatible with the 802.11 Atheros chipset.  Since the band is unshared by Part 15 there may be some advantages to this, such as fighting interference and to keep out Part 15.  

There are three different Ubiquiti XR3 frequency ranges that are version dependant (hardware limited ranges): XR3-2.8 (2.70-2.90 GHz), XR3-3.5 (3.40-3.70 GHz), and XR3-3.7 (3.65-3.70 GHz-Part90Y)

Once again, on this band our amateur allocations do not overlap the Part 15 band entirely.  However many 802.11 systems can be user set for frequencies that overlap.

There are a number of channels allocated.  It depends on your region and the equipment what channels will be user settable.  Most are non-overlapping channels. Channels are 20 MHz wide with speeds up-to 54 Mbps. (A little space is left on either side of each channel) The first two operate on the (U-NII) Unlicensed - National Information Infrastructure band segments. The first is for indoor applications only and must have integrated antennas. U-NII-2 allows outdoor operations but also has a corresponding low ERP limit. The third segment has complete amateur overlap. It also overlaps the ISM band. This segment is intended for outdoor applications with higher ERP limits under Part 15.247, however if the equipment is only 15.407 (U-NII) certified, a lower ERP limit applies. Not all 802.11a gear is capable of all three segments or all channels listed. It should be noted that OFDM is Not a Spread Spectrum mode per FCC definition and thus the special spread spectrum Part 97.311 rules need not apply.   Channels 132, 136, 140, & 165 are also inaccessible to unlicensed (Part 15) users inside the United States adding inherent security to these channels.

**ETSI Channels allowed in Europe

**Operating as a Part 15.247 device this is an estimated maximum achievable EIRP, you are allowed unlimited antenna gain for point to point. Under Part 15.407 (U-NII) it is 32dBi EIRP. Check your devices classification.

You may need to use directional antennas to avoid interfering with any primary occupants such as government use. (Note: It's technically impossible to interfere with ISM devices as they utilize RF energy for non-communicative purposes.)  As a secondary service you you may not cause harmful interference to primary service stations that may exist in your area, nor may you claim protection from harmful interference from primary stations. Unlicensed Part 15 users may not cause harmful interference to primary or secondary services and also may not claim protection from either.

Reclassifying under Part 97, imposes the standard amateur restrictions. Obviously the communications you make under Part 97 must be to and from licensed amateurs. These communications cannot be made with a pecuniary interest and may not be obscene or indecent. Other misc. Part 97 clarifications