Part 97 versus Part 15 and Permissible Power Comparison

[carter1945]

I was made aware from another thread in this forum that the 2.4 Ghz frequency is also shared by Amateur Radio.

I have posted this thread to see what others might know, understand, or want to discuss the issues that a high power Amateur Radio site might have on the lower power users.

The following is from http://www.qsl.net/kb9mwr/projects/wireless/pwr.html

Currently unlicensed users operate under FCC Part 15 - Under part 15 operation has effective radiated power (ERP) limits. It also has different (lower) limits for omni-directional antennas.

Amateur Radio operating under Part 97 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.

As I read the information on the web, I can just see some amateur spread spectrum user transmitting 100Watts and blanking everyone in the aera out.

I can also see 2.4 Ghz phones ringing for no reason day or night or microwaves set on defrost and cooking the frozed roast in 10 minutes.

I am asking here for thoughts, feedback and ideas. I do not want to get the Part 15 users and the Part 97 users in a fire fight, so lets all keep our heads on.

[JoeTampa]

Just some general notes:


1. Amateur Radio is protected from interference from Part 15 devices. If your 802.11 gear under Part 15 causes interference to Amateur communications, you are primarily responsible to resolve the interference. This could be to non-802.11 Amateur communications as well.

2. All Amateur Radio operators are limited at max to 1500 watts PEP. However, we are also limited to the "maximum power required to reasonably facilitate communications". Therefore, if it takes 5 watts to communicate to the desired station(s), 100 watts may not be used. This would also effect ERP, since the increased gain would make lower PEP possible.


Hope this helps.

[carter1945]

Joe,

I agree with you and thanks for your reply.

I appreciate your detailed explanation. From you said the 802.11 Part 15 guys could be in a big lot of trouble both by causing interference and by having their signals “jammed” by “extra PEP” allowed under Part 97.

What if both parties were broadcasting on the same channel at the same time and power settings. Would the Part 15 operator have to back down and change channels to accommodate the Part 97 operator?

While this may not be a problem today, I am sure given six months it might be a battle of the Hatfield’s and McCoy’s.

Will be interesting to watch.

[JoeTampa]

Precisely.


Remember, Part 15 devices of every size, shape, and flavor are ALWAYS the burdened device in interference issues. Read the manual of EVERY Part 15 device and you will see a statement mandated to be included by the FCC which says:

"This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:

1. This device may not cause harmful interference.

2. This device must accept any interference received, including interference that may cause undesired operation."



So it's not even a "Hatfield and McCoy" issue - the Part 15 device operator is always General Lee at Appomattox and must surrender. This would be not only to Part 97 operators, but to any other licensed services, such as the Government Radiolocation service, which is primary on a small segment of the affected spectrum.


Here's the relevant section of Part 97, so you can see that even those users have their restrictions:

(i) The 2300-2305 MHz segment is allocated to the amateur service on
a secondary basis. (Currently the 2300-2305 MHz segment is not allocated
to any service on a primary basis.);
(ii) The 2305-2310 MHz segment is allocated to the amateur service
on a secondary basis to the fixed, mobile, and radiolocation services;
(iii) The 2390-2400 MHz segment is allocated to the amateur service
on a primary basis; and
(iv) The 2400-2402 MHz segment is allocated to the amateur service
on a secondary basis. (Currently the 2400-2402 MHz segment is not
allocated to any service on a primary basis.) The 2402-2417 MHz segment
is allocated to the amateur service on a primary basis. The 2417-2450
MHz segment is allocated to the amateur service on a co-secondary basis
with the Government radiolocation service. Amateur stations operating
within the 2400-2450 MHz segment must accept harmful interference that
may be caused by the proper operation of industrial, scientific, and
medical devices operating within the band.