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I am not sure how it is a conflict. The HFT proposal doesn’t reallocate the amateur HF frequencies but uses other frequencies. They propose using really high po

I am not sure how it is a conflict. The HFT proposal doesn’t reallocate the amateur HF frequencies but uses other frequencies. They propose using really high power which could cause interference but interference is illegal. I think the danger is that HFT will make HF bands valuable and there will be push to acquire the amateur bands.

lightlyused 3y ago
And certain people would gladly sell a public resource for private profit because you know lobbyist dollars and billionaire hush payments would go to those that would make that decision.
thenobsta 3y ago
Agreed, the precedent set, if goes through, seems fraught and ripe for attempts at expanding the spectrum usage.
cma 3y ago
It adds no value and shouldn't waste this resource. Latency arbitragers get rewarded based on beating the next best: they get the same reward for beating next-best by 100ms as for beating by 1us. There is no net value to society for the difference, but lots of resources wasted in achieving it once competition has reached that level, squandering most of the reward on in the forms of data center waste heat, spectrum waste, and soon probably rocket exhaust.
StingyJelly 3y ago
I'm not ham operator so I'm just guessing here, but they may be talking about interference at the receiver. The new signal may be so strong and near enough ham band, that even after attenuation by typical band-pass filter it's still the strongest component and will overwhelm input stage amplifier. Trivial solution for that would be adding a band-stop filter tuned for the frequencies used for HFT but that again may add noise and attenuate nearby frequencies.
- wbl 3y ago
  In HF the limiting noise is not receiver generated unlike in microwaves and (ideal) capacitors and inductors don't generate noise: resistors and active components do. However a sharp notch is a real pain to make in analogue domain. Lots of stages, temperature changes the component values, and things get bulky.
dbcurtis 3y ago
> They propose using really high power which could cause interference but interference is illegal. Let me be a little bit pedantic here. High power itself does not cause interference, assuming that the unwanted sidebands are sufficiently suppressed. That is an engineering challenge, because modulation of any sort creates sidebands that put power on either side of the carrier. Higher modulation rates lead to more power in the sidebands. Secondly, any non-linearities in the power amplifier chain will also cause unwanted sideband emissions. That said, keeping your unwanted emissions outside of your allocated spectrum down to legal levels is "only" an engineering challenge. So the question to ask here is at the power levels they are asking for, is it practical to construct a transmitter that will keep unwanted sideband power down to acceptable levels? A second issue is on the receiving side. And this gets challenging to explain easily -- but there is a concept in receiver design called "dynamic range", which is the difference in received signal strength between "minimum detectable signal" and the point where a strong signal causes 3dB of gain compression to set in at the first receive amplifier. A second concept is reciprocal mixing and 3rd-order-intercept, but I won't try to explain -- the bottom line is all receivers have a limit to how much undesired signal they can reject before the receiver front-end becomes non-linear and starts creating undesired mixing products. The undesired signal transmitter may be perfectly clean and legal, but the receiver on the other end just collapses like a gym bro that tried to bench too much. Part of the FCC's mandate is to make sure that users of other spectrum, using reasonably-well engineered receivers, can survive in the RF environment created by transmitters in unrelated spectrum. To put into other words, transmitting a perfectly clean signal that is so strong that it is impractical that, say, a consumer-price-point broadcast radio receiver has no chance of surviving should not be allowed, and certainly the commercial broadcasters are going to object.
- ShadowBanThis01 3y ago
  And how demanding will any FCC analysis of receiver interference be? These guys are trying to tune in distant signals from around the world. So yeah if they're getting blasted by super-high-power "clean" signals, their receivers might "work" for less-demanding conditions but will they be deprived of a large portion of the edge cases that they could once resolve enough to communicate?
dist-epoch 3y ago
This is for inter-continental short-wave. There is very little bandwidth available in that frequency range. And short-wave is less directional.
pc486 3y ago
To add onto some of the great replies, one aspect of the proposal is much higher power with less harmonic attenuation. 23 db less attenuation with a 20x power increase is going to cause interference in the adjacent ham bands. As a practical matter, interference complaints from hams are not easily or quickly resolved. Interference from power companies is difficult enough, and they want to know when their equipment is throwing sparks!

lightlyused 3y ago

And certain people would gladly sell a public resource for private profit because you know lobbyist dollars and billionaire hush payments would go to those that would make that decision.

thenobsta 3y ago

Agreed, the precedent set, if goes through, seems fraught and ripe for attempts at expanding the spectrum usage.

cma 3y ago

It adds no value and shouldn't waste this resource. Latency arbitragers get rewarded based on beating the next best: they get the same reward for beating next-best by 100ms as for beating by 1us. There is no net value to society for the difference, but lots of resources wasted in achieving it once competition has reached that level, squandering most of the reward on in the forms of data center waste heat, spectrum waste, and soon probably rocket exhaust.

StingyJelly 3y ago

I'm not ham operator so I'm just guessing here, but they may be talking about interference at the receiver. The new signal may be so strong and near enough ham band, that even after attenuation by typical band-pass filter it's still the strongest component and will overwhelm input stage amplifier. Trivial solution for that would be adding a band-stop filter tuned for the frequencies used for HFT but that again may add noise and attenuate nearby frequencies.

wbl 3y ago
In HF the limiting noise is not receiver generated unlike in microwaves and (ideal) capacitors and inductors don't generate noise: resistors and active components do. However a sharp notch is a real pain to make in analogue domain. Lots of stages, temperature changes the component values, and things get bulky.

dbcurtis 3y ago

> They propose using really high power which could cause interference but interference is illegal. Let me be a little bit pedantic here. High power itself does not cause interference, assuming that the unwanted sidebands are sufficiently suppressed. That is an engineering challenge, because modulation of any sort creates sidebands that put power on either side of the carrier. Higher modulation rates lead to more power in the sidebands. Secondly, any non-linearities in the power amplifier chain will also cause unwanted sideband emissions. That said, keeping your unwanted emissions outside of your allocated spectrum down to legal levels is "only" an engineering challenge. So the question to ask here is at the power levels they are asking for, is it practical to construct a transmitter that will keep unwanted sideband power down to acceptable levels? A second issue is on the receiving side. And this gets challenging to explain easily -- but there is a concept in receiver design called "dynamic range", which is the difference in received signal strength between "minimum detectable signal" and the point where a strong signal causes 3dB of gain compression to set in at the first receive amplifier. A second concept is reciprocal mixing and 3rd-order-intercept, but I won't try to explain -- the bottom line is all receivers have a limit to how much undesired signal they can reject before the receiver front-end becomes non-linear and starts creating undesired mixing products. The undesired signal transmitter may be perfectly clean and legal, but the receiver on the other end just collapses like a gym bro that tried to bench too much. Part of the FCC's mandate is to make sure that users of other spectrum, using reasonably-well engineered receivers, can survive in the RF environment created by transmitters in unrelated spectrum. To put into other words, transmitting a perfectly clean signal that is so strong that it is impractical that, say, a consumer-price-point broadcast radio receiver has no chance of surviving should not be allowed, and certainly the commercial broadcasters are going to object.

ShadowBanThis01 3y ago
And how demanding will any FCC analysis of receiver interference be? These guys are trying to tune in distant signals from around the world. So yeah if they're getting blasted by super-high-power "clean" signals, their receivers might "work" for less-demanding conditions but will they be deprived of a large portion of the edge cases that they could once resolve enough to communicate?

dist-epoch 3y ago

This is for inter-continental short-wave. There is very little bandwidth available in that frequency range. And short-wave is less directional.

pc486 3y ago

To add onto some of the great replies, one aspect of the proposal is much higher power with less harmonic attenuation. 23 db less attenuation with a 20x power increase is going to cause interference in the adjacent ham bands. As a practical matter, interference complaints from hams are not easily or quickly resolved. Interference from power companies is difficult enough, and they want to know when their equipment is throwing sparks!