League Requests Rule Change to Ease Spread Spectrum Operation:
from
The ARRL Letter, Vol 25, No 12
on
March 24, 2006
Website:
http://www.arrl.org/
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League Requests Rule Change to Ease Spread Spectrum Operation:
The ARRL has asked the FCC to modify one of its rules governing spread
spectrum (SS) operation on Amateur Radio frequencies. The League has
petitioned the Commission to drop all but the first sentence of §97.311(d),
which now requires the use of automatic power control (APC) for SS stations
running more than 1 W. The ARRL request would retain the 100 W overall power
limitation for SS.
"The effect of the rule change would be to eliminate an automatic power
control provision that has proven over time to be impractical" in terms of
compliance, the League said in its Petition for Rule Making filed March 13
http://www.arrl.org/announce/regulatory/SS-Rulemaking-Petition.pdf. It
also conceded that the provision--one the League had proposed and supported
more than 10 years ago--was unnecessary to protect the operations of other
licensees and had "unfortunately served as an unintended but effective
deterrent to spread spectrum experimentation" on ham radio.
Since the FCC first approved the use of spread spectrum techniques for
Amateur Radio in 1985 on bands above 225 MHz and at power levels up to 100
W, there's been limited--but never widespread--experimental amateur
operation. More recently, the FCC has made the SS rules less restrictive in
response to League showings that the rules were hampering SS experimentation
and that interference has not proven to be an issue.
The ARRL says it now agrees with those who opposed the automatic power
control provision in WT Docket 97-12, concluded in 1999. Those changes not
only relaxed rules governing the use of spread spectrum techniques by radio
amateurs but opened the door to the possibility of international spread
spectrum communication.
"Now seven years later, it is apparent to ARRL that the rules requiring APC
indeed have proven to be difficult to implement, unnecessary and something
of a barrier to SS experimentation," the ARRL said in its latest rule making
petition. "Section 97.311(d) can be greatly simplified without increasing
the risk of intra-service or inter-service harmful interference."
The ARRL said keeping the maximum power at 100 W limits the power spectral
density of an SS emission, contributing to compatibility between Amateur
Radio SS and narrowband modes in the same allocations. The rules already in
place make spread spectrum "essentially secondary to any amateur narrowband
emission modes," the League pointed out, and make the APC requirement
unnecessary to avoid interference to other users of the same spectrum.
In any event, the League concluded, radio amateurs employing SS modes would
remain obliged to comply with the rule requiring use of "the minimum
transmitter power necessary to carry out the desired communication." That
was a primary reason the ARRL asked for the APC provision in the first
place.
The FCC has not yet assigned a rule making (RM) petition number to the
ARRL's petition nor invited comments.
In its Notice of Proposed Rule Making (NPRM) WT Docket 04-140, the FCC, in
response to another ARRL petition, proposed extending the bands available
for spread spectrum to include 222-225 MHz. On its own initiative, the
Commission also recommended permitting SS operation on 6 and 2 meters, a
move the ARRL opposes. In its comments, the League cited concerns about
raising the noise floor on 6 meters and the fact that both bands already
support substantial narrowband and weak-signal work, meaning "fewer
opportunities for frequency reuse in those allocations."
The Commission is expected to conclude WT Docket 04-140 this year. The FCC
suggested that restrictions on spread spectrum already in place should be
sufficient to prevent any adverse impact of SS operation to other users of 6
and 2 meters.
Source:
The ARRL Letter
Vol. 25, No. 12
March 24, 2006
This article has expired. No more comments may be added.
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League Requests Rule Change to Ease Spread Spectru
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by KE7MBL on March 25, 2006
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I for one have no comment on the subject.
Besides I enjoy using single sideband on
6 and 2 meters.
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RE: League Requests Rule Change to Ease Spread Spe
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by N5PVL on March 26, 2006
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Utilization of SS on 2 and 6 meters will elevate the noise floor as demonstrated by Ed Hare of the ARRL over a decade ago, when TAPR was wanting to intrioduce SS operation on HF. This will eliminate mnost weak signal operation on VHF/UHF if it goes through, making it a thing of the past.
Once again, the ARRL was astoundingly stupid in making this proposal, as they have been with almost all of thier proposals over thge last decade.
They just withdrew a particularly stupid one that called for the introduction of encrypted communications on the ham bands. That boner was Jim Haynie's parting gift to the hobby.
Hopefully this load of thoughtless crap will be shot down too.
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RE: League Requests Rule Change to Ease Spread Spe
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by W1RFI on March 26, 2006
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>> Utilization of SS on 2 and 6 meters will elevate the
>> noise floor as demonstrated by Ed Hare of the ARRL
>> over a decade ago, when TAPR was wanting to
>> intrioduce SS operation on HF. This will eliminate
>> mnost weak signal operation on VHF/UHF if it goes
>> through, making it a thing of the past.
>> Once again, the ARRL was astoundingly stupid in
>> making this proposal, as they have been with almost
>> all of thier proposals over thge last decade.
> On its own initiative, the Commission also
> recommended permitting SS operation on 6 and 2
> meters, a move the ARRL opposes. In its comments,
> the League cited concerns about raising the noise
> floor on 6 meters and the fact that both bands
> already support substantial narrowband and weak-
> signal work, meaning "fewer opportunities for
> frequency reuse in those allocations."
ARRL opposes any use of spread spectrum on 6 and 2 meters. Those bands are too heavily used to rely on the "SS can't cause harmful interference" provisions in the spread spectrum rules.
Ed, W1RFI
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RE: League Requests Rule Change to Ease Spread Spe
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by N5GLR on March 27, 2006
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Some "dumb questions" from a Spread Spectrum dummy ...
What will prevent Spread Spectrum use on 2 and 6 meter or other bands that are ... "too heavily used to rely on the "SS can't cause harmful interference" ... provisions in the spread spectrum rules."
Why are cell phones companies, WIFI, and other spread spectrum users able to comply and "experimenters" not?
What sort of experimentation is this requirement restricting?
Garry
N5GLR
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RE: League Requests Rule Change to Ease Spread Spe
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by W1RFI on March 28, 2006
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> What will prevent Spread Spectrum use on 2 and 6
> meter or other bands that are ... "too heavily used
> to rely on the "SS can't cause harmful
> interference" ... provisions in the spread spectrum
> rules."
When it was seeking spectrum, spread-spectrum advocates put forth the premise that because SS systems spread energy out over bandwidth, it would be much weaker to a narrowband user, and thus could operate on the same spectrum as other users.
That can be the case, but spreading is no panacea for preventing interference. The near-far problem is as much an issue for narrowand users as it between spread-spectrum users.
Let's take an example. If a 10-watt spread spectrum station were located 1 km away from a narrowband user, good line of site, and it were spread across the full 4 MHz of 6 meters, for example, in the 15 kHz bandwidth of an FM receiver, the tranmsmitter would have an equivalent average power of 37.5 milliwatts. An SS station transmitting 37.5 milliwatt transmitter itno a narrowband user's bandwidth at a distance of 1 km away would result in an S9+20 dB signal to the narrowband user, assuming isotropic sourceson both ends. If that narrowband user had an S9+40 dB signal from a nearby repeater or other narrowband user, it would not interfere, but only the very strongest of desired signals would be usable, even on FM. This would be a 60-70 dB increase in the local noise levels.
> Why are cell phones companies, WIFI, and other
> spread spectrum users able to comply
> and "experimenters" not?
Cell phones operate in a controlled environment. There are no other users other than other SS users, and they use things like automatic power control to ensure that all signals are of equal amplitude at the cell-tower receiver. Their spread spectrum has process gain to offer some rejection of other spread-spectrum users. It only needs to operate over short ranges. The type of spread-spectrum used by most cell-phone systems could work for Amateur Radio, too, if we all scrapped our existing rigs and put Amateur cell towers up all over town like the cell companies do. Our transmitters and receivers would only have a range of about a mile or so, though.
WiFi and other spread spectrum users do NOT avoid interfering with each other. To the contrary, mutual interference is the justification that the industry is using to ask the FCC for more spectrum. The process gain used by 802.11 SS does not, in practice, allow multiple SS users to share the same channel over different networks. As I have seen at a number of large meetings, if too many users try to share the same channel even through the same access point, the system grinds to a complete halt.
> What sort of experimentation is this requirement
> restricting?
IMHO, none. Those that want to experiment with spread spectrum have plenty of spectrum available to do it, on frequencies where they will have sufficient bandwidth to really see some speed.
Ed Hare, W1RFI
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RE: League Requests Rule Change to Ease Spread Spe
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by N5GLR on March 28, 2006
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Thanks Ed, I appreciate the education and your time to provide it.
"> What sort of experimentation is this requirement
> restricting?"
"IMHO, none. Those that want to experiment with spread spectrum have plenty of spectrum available to do it, on frequencies where they will have sufficient bandwidth to really see some speed."
It appears that you don't agree with the league's latest petition when they state that the current requirement is a "...deterrent to spread spectrum experimentation." ?
Garry
N5GLR
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RE: League Requests Rule Change to Ease Spread Spe
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by W1RFI on March 28, 2006
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> It appears that you don't agree with the league's
> latest petition when they state that the current
> requirement is a "...deterrent to spread spectrum
> experimentation." ?
I had taken the question in the wrong context. I took it to ask what experimentation would be prevented by keeping spread spectrum off of six and two meters.
The present rules for automatic power control have had the effect of essentially limting Amateur experiementation to 10 watts. In some of the work being done, looking to do high-speed digital communication over longer paths, more than 10 watts is needed to achieve good reliability at full speed.
I had always thought that the automatic power-control rules were not needed. Point-to-multipoint work will not require high power - that is essentially local in nature. For point-to-point links, it is easy enough to cacluated the necessary power for a given desired bit-error-rate, so that would serve as well, IMHO, as automatic power control.
I am not an expert in this area, but I have learned enough to be dangerous. :-)
Ed
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RE: League Requests Rule Change to Ease Spread Spe
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by KG4RUL on April 4, 2006
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I guess I am having a hard time with this topic.
I hear the ARRL say that BPL spectrum pollution, at Part 15 power levels is bad. Then I hear the ARRL say that SS operation at power levels up to 100W is a good thing.
Is not spectrum pollution, regardless of the mode, a very bad thing?
Dennnis KG4RUL
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RE: League Requests Rule Change to Ease Spread Spe
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by AB0WR on April 4, 2006
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W1RFI:
The present rules for automatic power control have had the effect of essentially limting Amateur experiementation to 10 watts. In some of the work being done, looking to do high-speed digital communication over longer paths, more than 10 watts is needed to achieve good reliability at full speed.
I had always thought that the automatic power-control rules were not needed. Point-to-multipoint work will not require high power - that is essentially local in nature. For point-to-point links, it is easy enough to cacluated the necessary power for a given desired bit-error-rate, so that would serve as well, IMHO, as automatic power control.
I am not an expert in this area, but I have learned enough to be dangerous. :-)
*****************************************************************
SS is supposed to be a secondary user of the amateur spectrum and is not supposed to cause interference to any other mode.
In your earlier message you showed just how badly a spread spectrum station could raise the noise floor for "near" station.
Yet in this message you are speaking as if the SS stations are *primary* users and the only consideration is the power needed to overcome path loss on a "longer" connection.
This seems to be at odds with the secondary status of SS and the restriction that it not interfere with other users. As you raise the power in order to communicate over longer distances you will certainly be raising the noise floor even higher for other users, especially close-in ones.
How do you propose reconciling the two issues?
You speak of point-to-multipoint operation not requiring higher power yet the ARRL petition, as filed, specfically mentions the difficulty of decreasing power during point-to-multipoint operation as a reason for allowing high power to be used with no APC functionality required.
You seem to be at odds with the petition on this point. Or am I misunderstanding something?
tim ab0wr
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RE: League Requests Rule Change to Ease Spread Spe
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by W1RFI on April 7, 2006
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> Yet in this message you are speaking as if the SS
> stations are *primary* users and the only
> consideration is the power needed to overcome path
> loss on a "longer" connection.
I'm not sure what in my post implies that SS stations are not secondary users, but you are, of course, correct: Under the rules, Amateur SS stations are unconditionally responsible for not causing harmful interference to other Part 97 users.
> As you raise the power in order to communicate over
> longer distances you will certainly be raising the
> noise floor even higher for other users, especially
> close-in ones.
> How do you propose reconciling the two issues?
The issues are not reconciled any better with automatic power control than they are with manual power control. The only reconciliation of the requirement not to cause harmful interference is that operators need to be responsible for their operation.
Under Part 97, Amateurs have a similar responsibility not to cause harmful interference to ongoing communications. They also have a requirement to use the minimum necessary power. They manage to reconcile both, at least most of the time, without the need for automatic power control. There will always be glitches, and the near/far problem exists on HF, with skip zones and receive-only stations complicating the mix, but hams have worked it out reasonably well.
I would expect the same of SS operators. And automatic power control does not address the requirement to not cause interference any better than manual power control by the operator would. APC addresses only the SS level at the distant station that is part of a 2-way QSO. It does not adjust power for the levels at receievers at unknown locations. With or without APC, that still needs to be addressed by other means.
Keeping in mind that SS would operate on 222-225 MHz and 902 MHz and up, and that by band plan, it avoids the weak-signal parts of the band, the net effect of all of this may be to have hams making better use of spectrum that is at, this juncture, lightly used at best.
> You speak of point-to-multipoint operation not
> requiring higher power yet the ARRL petition, as
> filed, specfically mentions the difficulty of
> decreasing power during point-to-multipoint
> operation as a reason for allowing high power to be
> used with no APC functionality required.
My comment about point-to-multipoint was intended as a general statement. I still agree with myself that virtually all point-to-multipoint operation will be better served with low power, not with 100-watt class stations. Having said that, however, I think that Amateur Radio is better served by the rules that require the minimum necessary power and the rules that SS stations must not cause harmful interference than by also adding a requirement for automatic power control that really doesn't protect other users anyway. All in all, the more flexibile our rules, the more flexibility we have in using them. IMHO, the unconditional non-interference rule best serves the purpose, leaving discretion to the individual operator on how to use it.
On HF, usage is much higher than on microwave and propagation is much more variable, yet narrow-band users manage to sort it out through the existing rules. I think that getting as close as possible to those rules for SS operation will be appropriate.
Just one ham's view. I am not involved in the policy-level decisions that went into ARRL's petition.
Ed, W1RFI
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RE: League Requests Rule Change to Ease Spread Spe
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by W1RFI on April 7, 2006
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> I hear the ARRL say that BPL spectrum pollution, at
> Part 15 power levels is bad. Then I hear the ARRL
> say that SS operation at power levels up to 100W is
> a good thing.
>
> Is not spectrum pollution, regardless of the mode, a
> very bad thing?
I think there is a big difference between licensed Part 97 use of the band and spectrum pollution. BPL, for example, does not intentionally emit anything; none of its emissions are necessary to its fundamental purpose.
Part 97 SS would be no more spectrum pollution than my narrowband CW signal is on 20 meters. It could be harmful interference to other users, and under the rules, SS must unconditionally give up its use of spectrum in deference to other Part 97 (or other primary) use of the bands.
On bands where SS is permitted, Amateur Radio operators are secondary to other users. We must unconditionally give way to their operation. To them, we are spectrum pollution of a sort. They could share some of the same concerns about our presence on the band. We would not feel it a fair solution to require that we not access the bands. In reality, secondary users do have a right to access the spectrum they are allocated, and, for the most part, that works out well. I think that we can expect that Part 97 secondary use will work out at least as well as the requirement all hams share in not interfering with primary users.
Ed, W1RFI
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RE: League Requests Rule Change to Ease Spread Spe
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by AB0WR on April 7, 2006
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vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
W0RFI:
> Yet in this message you are speaking as if the SS
> stations are *primary* users and the only
> consideration is the power needed to overcome path
> loss on a "longer" connection.
I'm not sure what in my post implies that SS stations are not secondary users, but you are, of course, correct: Under the rules, Amateur SS stations are unconditionally responsible for not causing harmful interference to other Part 97 users.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Determining Eb and No is easy, Ed. Passing it from the receiving end to the transmitting end is easy. Pactor does it every hour of every day to negotiate speed and the number of tones. PIII even negotiates power level by passing control data from the received end to the transmitting end.
The hard part is how the SS stations are going to determine they are causing harmful interference to other Part 97 users.
If you can't determine Io in order to use it in an automatic mode, how will the SS stations determine it in order to use it with manual power control?
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
> As you raise the power in order to communicate over
> longer distances you will certainly be raising the
> noise floor even higher for other users, especially
> close-in ones.
> How do you propose reconciling the two issues?
The issues are not reconciled any better with automatic power control than they are with manual power control. The only reconciliation of the requirement not to cause harmful interference is that operators need to be responsible for their operation.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
I'm sorry. You haven't provided an answer. If they can't do it with automatic control how will they do it with manual control?
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Under Part 97, Amateurs have a similar responsibility not to cause harmful interference to ongoing communications. They also have a requirement to use the minimum necessary power. They manage to reconcile both, at least most of the time, without the need for automatic power control. There will always be glitches, and the near/far problem exists on HF, with skip zones and receive-only stations complicating the mix, but hams have worked it out reasonably well.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Ed, in the case of compatible narrow-band operations you have users who can hear the interfering signals and can either coordinate with the other stations to share the frequency or who can move to a clear adjacent frequency. This is for *primary* users of the spectrum. In the case of SS signals, there is no way to coordinate between the narrow-band operator and the SS operator and there is no where to move to avoid the wideband noise being generated by the SS opertor.
As you should already know from the comments associated with the ARRL bandwidth regulation, the exact situation already exists on HF with the Pactor mode and other modes. Less than 1% of the amateur community uses Pactor. The other 99% of the amateur community has no way to communicate to hams using Pactor that they are interfering with ongoing communications. Since Pactor statons will not recognize the other modes (i.e. no calculation of Io) and most Pactor operators apparently don't listen to the data stream continuously (i.e. no manual Io calculation) the only answer when a Pactor station fires up on your frequency is to move or QRT.
What you are advocating here is the same thing for SS. Even though it is a *secondary* operation, it will take on more than primary consideration because it is NOT interfered with by narrow-band modes but can interfere heavily *with* narrow-band modes. Since the SS operator will have no way to listen to the entire bandwidth to tell if a narrow-band mode is being interfered with and the narrow-band operator will have no way to communicate with the SS operator - the only alternative will be for the narrow-band operator to QRT. There won't *be* anyplace to move to!
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
I would expect the same of SS operators.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Expectations aren't enough. You should expect Pactor station operators to not interfere with other modes already in communication but they do.
Before turning the SS operators loose with 100watt bricks on their store-bought SS routers, there should be SOMEWAY specified for the SS operators to determine when they are interfering.
Otherwise you are tacitly approving of their status being promoted to at least *primary user* of the spectrum if not more.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
And automatic power control does not address the requirement to not cause interference any better than manual power control by the operator would. APC addresses only the SS level at the distant station that is part of a 2-way QSO. It does not adjust power for the levels at receievers at unknown locations. With or without APC, that still needs to be addressed by other means.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Frankly, this is not an answer either. This is the type of logic that would justify always running maximum power so that you can always be received at the maximum possible distance.
Once again, this is the type of operation you would expect from a primary use station, not a secondary use station trying to avoid inteference with primary users.
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Keeping in mind that SS would operate on 222-225 MHz and 902 MHz and up, and that by band plan, it avoids the weak-signal parts of the band, the net effect of all of this may be to have hams making better use of spectrum that is at, this juncture, lightly used at best.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Wait a minute. Is that why a STA application has been made to run SS on 6meters?
Frankly, I'm rather disappointed in the support given in the ARRL petition as well here for getting rid of the power restrictions. The logic that automatic power control is hard to accomplish so it should be abandoned is not acceptable. The hard piece of doing automatic power control is Io and that can't be done any easier by manual control than automatic control. Trying to tell me that it can be is just insulting my intelligence.
tim ab0wr
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