FCC looking for comments on 3.8-4.5 MHz waiver

[speedway_navigator]

https://docs.fcc.gov/public/attachments/DA-25-630A1.pdf

The PR department got involved from the looks of this statement.

Hitachi claims its upgraded system will allow BART to safely operate trains on tighter schedules and at more closely spaced intervals, significantly
increasing the throughput and passenger capacity all without introducing risk of causing harmful interference.

They make it sound like BART has cars, operators and passengers standing by just waiting for waiver.
I can imagine a descendant of admiral Farragut as an engineer saying
"damn the spacing, full speed ahead!"

'Damn the Torpedoes'

Rear Admiral David Glasgow Farragut’s timeless words echo down the corridors of naval history—but just what exactly were those words?

www.usni.org

 

[kc2asb]

Interesting It looks like this will primarily operate in the maritime mobile band, but it mentions operating across the "3.8 - 4.5 MHz band". That does put it into the 80 meter amateur and 75 meter broadcast bands.

Section 15.205(a) of the Commission’s rules does not permit intentional radiators to be operated
in the 4.125-4.128 MHz, 4.17725-4.17775 MHz, and 4.20725-4.20775 MHz bands.9 The rules only
permit spurious emissions in these bands to protect maritime safety-of-life related operations in the
bands.10 Hitachi claims that its system will not present a significant risk of harmful interference given the
very limited space and time in which the transponder transmits.11 Additionally, Hitachi states that
interference will not occur because none of the protected maritime licensees could operate at locations
within a few meters of any BART track with a moving train.12 Hitachi seeks a waiver to permit its system
to operate as an intentional radiator across the 3.8-4.5 MHz band

 

[EAFrizzle]

BART has absolutely no need for HF frequencies. Whatever they're trying to do can be done elsewhere in the spectrum.

 

[mmckenna]

BART has absolutely no need for HF frequencies. Whatever they're trying to do can be done elsewhere in the spectrum.

These are very low power proximity systems. Very commonly used for card reader badges, theft prevention, etc.

Yes, they may need to pick another slice of spectrum, but these systems are -extremely- low powered an only useable within inches/feet at the most. Pretty much any office building in the world has similar systems running on 13.56MHz.

I'm sure the ARRL is warming up their "panic" buttons over this. Hopefully people think about this/read up on it before reacting.

 

[kc2asb]

These are very low power proximity systems. Very commonly used for card reader badges, theft prevention, etc.

Yes, they may need to pick another slice of spectrum, but these systems are -extremely- low powered an only useable within inches/feet at the most. Pretty much any office building in the world has similar systems running on 13.56MHz.

I'm sure the ARRL is warming up their "panic" buttons over this. Hopefully people think about this/read up on it before reacting.

Good to know and excellent points. There are other examples of low-power devices sharing spectrum with few, if any, issues, such as the old 46 MHz cordless phones.

There is nothing wrong with vigilance on the part of the ARRL and amateur operators. Something like this could be seen as testing the waters. If it's met with indifference, perhaps a more significant intrusion into the amateur band(s) will be proposed next. The FCC has been all too happy to auction off slices of the spectrum in the past.

 

[mmckenna]

There is nothing wrong with vigilance on the part of the ARRL and amateur operators.

The ARRL has cried wolf too many times to get much space in my brain. They often take things like this and tag their "spectrum defense fund" onto the end. They lose credibility when they turn non-issues like this into fund raising campaigns. Us hams could spend that money better elsewhere.

 

[W8KIC]

These are very low power proximity systems. Very commonly used for card reader badges, theft prevention, etc.

Yes, they may need to pick another slice of spectrum, but these systems are -extremely- low powered an only useable within inches/feet at the most. Pretty much any office building in the world has similar systems running on 13.56MHz.

I'm sure the ARRL is warming up their "panic" buttons over this. Hopefully people think about this/read up on it before reacting.

As someone who spends well over 95% of their time on CW, the possible "loss" of 75 meters is not something I'd lose much sleep over. The conversations that take place there are pretty much unlike anything else you'll run across on 40, 20, 17, 15, 12 or 10 meter SSB. Let's just say that "etiquette" is a bit of a foreign concept. Lol! Having said that, I realize that numerous hams enjoy operating phone and one less "privilege" is just that. It'll be intriguing to see how the league frames the argument in defense of the 75 meter amateur band and of course, how receptive that argument goes over with the powers that be in Hell's kitchen.

 

[speedway_navigator]

The ARRL has cried wolf too many times to get much space in my brain. They often take things like this and tag their "spectrum defense fund" onto the end. They lose credibility when they turn non-issues like this into fund raising campaigns. Us hams could spend that money better elsewhere.

In my opinion APCO has done the same. Maybe some of what you felt as an earthquake was an actual 'the sky is falling incident'...

The system uses a passive transponder on the track that only radiates when the train passes over it. The report indicates the signal cannot be measured over 3.5m from the track so no co-channel RFI should be seen. The transponder is below the top of the rails by about 2" so lateral radiation is greatly reduced.

The uplink power is about 16.5 dBm / 45 mW.

https://www.fcc.gov/ecfs/search/search-filings/filing/1051405095037

 

[mmckenna]

In my opinion APCO has done the same.

That they do.

 

[mmckenna]

Wait until the CB crowd sees that they want to use some space between channel 11 and 12.

 

[AM909]

I'd worry more about incoming interference, like when the tracks run past the guy with the giant antenna farm and surplus maritime multi-kilowatt transmitter on 75 or 11 meters.

 

[kc2asb]

Wait until the CB crowd sees that they want to use some space between channel 11 and 12.

Should be all good, unless the Ch 6 Super Bowl dudes decide to hold a key down contest track side.

 

[mmckenna]

Should be all good, unless the Ch 6 Super Bowl dudes decide to hold a key down contest track side.

The 27MHz signal is used to excite the transponder, looked like in tests it was 10 watts. Someone on a CB nearby would only cause the transponder to send out its ID.

Wouldn't harm CB'ers, unless one had a really out of tune radio.

 

[kc2asb]

The 27MHz signal is used to excite the transponder, looked like in tests it was 10 watts. Someone on a CB nearby would only cause the transponder to send out its ID.

Wouldn't harm CB'ers, unless one had a really out of tune radio.

CB'ers cause more harm to each other with splatter box radios and amps than this piddly 10w signal ever could.

 

[speedway_navigator]

I tell folks I've been on social media since the 'breaker one nine' days

 

[Golay]

The ARRL has cried wolf too many times to get much space in my brain. They often take things like this and tag their "spectrum defense fund" onto the end. They lose credibility when they turn non-issues like this into fund raising campaigns. Us hams could spend that money better elsewhere.

I can agree. They put up a big fight for 3 GHz saying amateurs use it for satellites.
Yet on AMSAT's website, they don't list a ham bird on those frequencies anywhere in the world.

 

[kc2asb]

I can agree. They put up a big fight for 3 GHz saying amateurs use it for satellites.
Yet on AMSAT's website, they don't list a ham bird on those frequencies anywhere in the world.

Hopefully, the ARRL's response to this is not hysterical. Clearly, it does not pose any dire threat to the 80 meter band. The ARRL is not perfect, but it's really the only organized advocate for the interests of amateur radio operators.