FCC Narrowbanding Update

Thanks for all the good info Shelby. If you don't mind my asking, who is your license consultant?

TIA,

Doug

I am using these guys, they are actually affiliated with Day Wireless and I think do all of the licensing for Day. I don't know if Day has offices up you way or not, BUT they have a number of locations in Oregon.

SHG

Thanks Shelby. Day does have a shop nearby (relatively).

I have a question about RTK Base Radios. We have on of the OLD Pac Crest 35 Watt PDL Base Stations. One day, it started only working for about 600 feet, on low or high power, even with an open line of site. Has anyone experienced this. I think it has been discussed before on some other message board.

Becasue of the Narrowbanding issue, we ordered a new base station. It has been about 6 weeks and still no joy. Do we have any other choices than Pac Crest, without changing out all 3 rover radios? Part of the problem might be that Pac Crest is owned by Trimble, and we do not use Trimble GPS.

We did all the normal trouble shooting stuff like checking the antenna cable, and trying a different battery.

I would look at replacing the antenna and antenna cable if you didn't do that with the new radio.

There are other choices, Satel is a menu pick in Leica receivers and Intuicom is a license free radio, BUT typically shorter range than a 35W UHF radio, although I recently heard they were coming out with a longer range radio. That said, Pac Crest is still by far the most common in North America and the PDL product was good as I suspect the ADL product would be, the stuff prior to maybe 2000 gave me a lot of issues, BUT that was a long time ago.

SHG

These radios speak PDL and Trimble and connect to all the GPS receivers. They are typically a stock item.

About the licensing... a 25 kHz radio cannot be used at any speed or power next year without an extension fromt he FCC. It is a metter of the bandwidth occupied. The radio frequency modulation fills in the entire bandwidth.

Most newer radios have selectable bandwidth. Older radios can usually be sent in to the manufacturer to have the bandwidth modified for a price (less than a new radio).

The license modification can be done online.

Data operations on channels greater than 12.5 KHz must employ data rates greater than 4.8 kbps per 6.25 kHz channel, such as 19.2 kbps per 25 kHz channel

What does that mean?

I just went through narrow banding my license and when it came back, ALL of my UHF data frequencies have an emissions designator indicating 19.6 KHz bandwidth (19K6F1D). When I questioned my licensing consultant about that he stated that data radios "may" be exempt depending on the FCC ID number, I am having him verify that I truly am OK prior to the deadline.

After talking to him, I went to the FCC web site where the red quoted info came from, that to me does indicate that if I transmit at 19,200 over the air on my licensed frequencies that in fact does meet the FCC narrow banding rules.

I am surveyor, not a radio expert, so I might be proven wrong on this, in fact I was surprised to discover this only this week after thinking I would have to junk my perfectly fine PDL radio.

FYI, Pac Crest has told me they WILL NO LONGER upgrade PDL radios, so a new ADL or other brand of new radio will be required if my information above turns out to be incorrect.

SHG

The quoted text from the FCCis an efficiency standard that typically only applies to voice radios. Basically it is stating that the 25 kHz channel may be split into 2 separate frequencies "one voice path per 12.5 kHz". It doesn't apply to any "F1D" emissions designators.

The emissions designator 19K6F1D translates technically to a transmitter using "19"."6" "k"Hz bandwidth for "F" Fixed frequency transmission, on "1" single, "D" Data channel.

The designator must have "12K5" or smaller, such as "11K0", "8K3", "6K0", etc...

- It is too bad Pac Crest won't upgrade thier older radios anymore. There are a lot more base station radio choices to use with Pac Crest and Trimble rovers than there used to be.

Thanks for the info, since I just renewed my FCC license AND did the narrow banding as part of that process, it seems odd that the FCC would of approved with that emissions designator if not true, however I am still looking into this, there may need to be some rework of the new license based on your information! I also licensed two voice frequencies in the VHF band AND those DO HAVE a 12.5 emissions designator! The whole process seems a bit confusing to the guy who doesn't do this everyday, more like every 10 years, I guess that is why there are entire companies set up to do the process for a fee, one would hope they actually know what they are doing.

SHG

Would you mind shooting me an e-mail, I would like to discuss Satel radio options vs. Pacific Crest assuming I need to ditch my PDL by year end.

sgriggs@orbitechinc.com

SHG

You know the FCC is confusing because there are "FCC Lawyers" just to help with paperwork and disagreements in text.
The FCC granted 12.5 kHz bandwidth to use. The individual who processed the modification (yes, they are hand processed) may not have noticed or cared what the emission designation was.
I wouldn't go through the effort of a license modification simply to update the emissions designation. If there are ever any repercussions with the FCC they would come from causing interference to somebody else regardless of the designator.

From my radio licensing consultant this morning:

Sorry all for the delay in responding. I wanted to confer with our lab

before responding. Based on my discussions with them, it would appear

that this use would be compliant with the narrowband equivalent

efficiency. Specifically, the data efficiency requirement is 4800 bps

per 6.25 kHz channel. He's using a 25 kHz channel which requires a

minimum of 19200 bps (4800 *4).

I am going with my old PDL set to 19200 as meeting FCC narrowbanding rules.

As they say on Myth Busters, CONFIRMED

SHG

Good news! :good: Thanks for sharing Shelby.

Doug

Just got off the phone with Kuker Ranken, they have independently got an answer in the form of an e-mail from someone at the FCC also confirming this, NOW, they are trying to find out if you can actually transmit over the air RTK correctors at 19,200 since that is faster than what has historically been used. It may depend on the format being used, hopefully have an answer on that soon. I seem to vaguely remember that prior to RTCM 3.x it wasn't possible to transmit faster than 9600 baud due to data packets colliding, I am hopeful that it can now be done.

SHG

It may not really solve your problems

Back in 2001 a well-known manufacturer of GPStuff for whom I was a dealer introduced a new radio modem that would broadcast at 19200 bps over-the-air in 25-kHz channel spacing.

It worked, but not nearly as well as 9600 bps, and every time one of our customers tried 19200 bps they were disappointed in the coverage area and radio-link reliability.

Anything to do with radio modems is definitely YMMV territory with two zillion variables, but after we and our customers wasted considerable time attempting to use 19200 bps we gave up and never tried it again. Simply not worth the trouble, especially when 9600 bps worked so well.

19200 bps may work better in this new decade, but I would not bet the farm on it.

My dos centavos, amigo!

GB

It may not really solve your problems

Glen, I may very well find that to be true, although I am hoping maybe the newer data formats will allow this to work, if not, I buy the new radio, but I am not ready to toss a perfectly good radio without trying first!

SHG

It may not really solve your problems

between lightsquared and narrowband mandate, my head hurts 😛
As I'm trying to learn the narrowbanding, here's what we have:
trimble R8-GNSS model 2 receivers,and HPB450 radios. the HPB450 radio data sheet has this info: 4800,9600 + 19,200 over-the-air baud rates. "the 19,200 requires HPB450 or PDL450 at both base and receiver". we're using the radios and antennas, am I missing something, or will be be able to continue to use this equipment if we set it up for 19,200? frequency controls: synthesized 12.5kHz resolution.
I'm checking into our FCC license, from what I remember, we got this latest license in 2008 when we bought the R8's, and I thought the license was good for 10 years.
Can someone please help?

It may not really solve your problems

> trimble R8-GNSS model 2 receivers and HPB450 radios.

Is that HPB450 a yellow Pac Crest PDL?

Anyway, as I understand it, 19,200 baud data meets narrowbanding requirements.

The question Glen brings up AND which I am still working on is this; will the RTK data stream work at that rate, if not, 19,200 is a moot point and buying new radios that have 12.5 kHz channel spacing will be the only solution and then continue to transmit at a lower baud rate.

My understanding is that you still have to have your license narrowband compliant, BUT yours may already be. If not, you would still have to do that EVEN if retaining your current hardware.

Best advice I can give on the FCC license is to consult with a person or firm that is well versed in what is required. That cost should be a few hundred dollars depending on what is needed, I renewed my license because the 10 years was up, did the narrowbanding, changed one voice channel and added a second one for $650, but as you can see there was quite a bit of extra stuff that you may not need to do.

SHG

It may not really solve your problems - FCC Narrowbanding

Shelby,
thanks for your reply and I apologize for this reply being so tardy. I have been told by one of our Trimble suppliers that our one license can apply to multiple radios, and that we are basically "grandfathered in". I need to call FCC and talk with them directly to confirm his message to me,and also if that will require us to move to a 19,200 baud rate at 12.5kHz. This is still over my head as to the technical aspects, so I'll continue to look for answers and solutions here and anywhere else I can find info. thanks again, I'll post to this topic again once I learn more or have new questions.