AshGPS: Firmware, Software Update Notification

Tuesday 28 February 2012

 

This document concerns RTK data radios in use in the USA. If you are not using RTK GPS in the United States, then you don’t need to read this.

 

Also, if you are a US Government user, your radios are most likely already narrowband 12.5 KHz radios and this document does not apply to you.

 

By:    Mark Silver, ms@igage.com, +1 801-412-0011

 

Date: 28 February 2012           Rev: C

 

I suspect that you are already worried about narrow-banding your GPS data radios (Pacific Crest PDL radios).

 

You have already probably received a few unsolicited pieces of mail offering to narrowband your license.

 

Let me take a few moments to help you out with these questions:

 

          Why has the FCC has made this change?

          When must changes be made by?

          What are your options?

          What license and equipment recommendations do I have?

 

Most current radios use 25 kHz bandwidth. If your current base radio looks like these:

 or  

then you may have 25 KHz radios. (Check the nameplate to be sure.)

 

New ‘narrow banded’ radios use 12.5 kHz bandwidth. After everyone switches to narrow band radios twice as many users can use the same spectrum at the same time.

 

For example, in the frequency range 461.000 to 461.100 with 25KHz bandwidth there are four possible channels (shown in red):

 

 

With 12.5KHz bandwidth there are eight possible channels (shown in blue).

Narrow-banding doubles the number of simultaneous users of the limited available spectrum.

 

 

License: Your existing 25 KHz FCC license (for baud rates less than 19,200) will terminate January 1 2013 (the end of this year.) Narrow-band modifications are currently taking the FCC 90-days to complete, however you may assume that your request has been granted 10-working days after filing if you don’t hear otherwise. It takes about 1-week to process your application through a license facilitator.

Thus you must have your narrow-banding request filed with the FCC 21-days before the end of 2012.

 

To be safe, file for a license modification as soon as possible (see the links at the end of this document). If you want to live on the edge wait until December 7, 2012.

 

Hardware: Replacement transmitters are currently available from stock. Since every single PDL user in the United States will have to replace every single transmitter prior to the end of the year, it is a safe bet that equipment will be allocated by the end of this year.

 

To be safe, order your replacement transmitters before August 1 2012.

 

If your equipment is mission critical, order replacements now so you have plenty of time to verify range, settings and procedures.

 

Can I use a new 12.5 KHz Base with my existing 25 KHz License?:

 

Yes. Until the end of 2012. Thus, you can purchase a new radio, convert to narrow band operation and then get a narrow band license at a later date (before the end of the year of course).

 

There is no problem using a new 12.5 KHz base with your existing 25 KHz license up to the last day of 2012. After that, if you have not filed to modify your license, it may terminate in which case you will need to apply for a new license ($600!)

 

 

Well, the cowboy life is not always the easiest path...

 

First, if you don’t narrowband your license by the end of 2012, your existing license may terminate at the end of the year. So you will be operating without a license. It will be easy to spot you as your radio will be sending your old FCC call sign out in Morse code every 10 minutes. Anyone with an internet connection will be able to track your old call sign to your business address.

 

I suspect you would lose your equipment (the radio and anything connected by a cable to it) and get a substantial fine (~$4,000 is my guess.) And you will have to apply for a new license ($600 instead of $110).

 

If you operate a 25-KHz bandwidth radio after the first of the year, your risk of being caught by a newly licensed user in an adjacent 12.5 KHz channel will increase as time passes and more licenses in adjacent channels are issued.

 

If you are in Los Angeles CA then your chances of getting caught is really high. If you are in Dutch John UT, probably not so much.

 

But again, the cost of complying is not that high. And the updated radio has value.

 

 

Retuning Your Existing Radio:

 

 

Last year it may have been possible to return later model base radios to Pacific Crest and have them re-tuned to 12.5 KHz for ~$500. This is no longer an option.

 

 

Replace Your Existing Base Radio:

 

The Pacific Crest Vantage Pro radio is an excellent replacement for the HPB because the cables are interchangable.

 

          Vantage Pro Datasheet: Data Sheet
          Vantage Pro FAQ: FAQ
          Vantage Pro User Manual: User Manual

 

The Pacific Crest ADL Vantage Pro radio is the preferred replacement for PDL HPB base radios:

HPB  is replaced by Vantage Pro

 

The Vantage Pro uses the same programming and data cables as the HPB. (An adapter may be required for the antenna connector.)

 

The Pacific Crest ADL Vantage radio is a replacement for PDL LPB radios:

 

LPB  is replaced by Vantage+

 

The Vantage uses the same programming and data cables as the HPB (not the LPB), so you will need to purchase a new data cable, a new programming cable and an antenna cable.

 

You may also choose to replace your LPB with the Vantage Pro:

 

LPB  is replaced by Vantage Pro

 

This too requires a new data cable, a new programming cable and an antenna cable; but results in higher power for better range.

 

The high power Vantage Pro (2 – 35 watts) costs $545 more than the low power Vantage (0.1 – 4 watts).

 

 

Good question! Your existing rover radio is receive only, thus it will continue be legal to operate after the first of the year.

 

In my testing, I can not discern any difference in range using a 25 KHz receive radio with a 12.5 KHz transmit radio. (Eventually there may be voice users transmitting in the newly opened adjacent channels. They won’t be bothered by your 12.5 KHz base, but they may impact your rover’s ability to receive distant transmissions.)

 

One caveat is the new base radio will not transmit 9600-baud over-the-air with 12.5 KHz bandwidth. You will need to configure the over-the-air baud rate to 4800 for both rover and base. (This is true for Trimmark II, Trimtalk 450S, Transparent EOT and Transparent EOC protocols.)

 

The new base radios have some new protocols that will transmit at 9600-baud, but you would have to purchase new rover radios to utilize these new protocols.

 

At 4800-baud, the base can transmit ~450 characters per second.

For a base transmitting GPS and GLONASS corrections for 20 SV’s (12 US + 8 GLONASS) we expect these throughputs:

 

 

For legacy GPS only equipment (Z Surveyor, Z Extreme, Z Max) only 12 US SV’s can be tracked, thus RTCM 3, CMR+ and ATOM will all be just fine.

 

On modern Ashtech equipment (ProMark 500, ProMark 800, ProFlex 500, ProMark 200) the default base setting is to only broadcast corrections for the best 14 satellites. With this default setting, there will always be plenty of time to broadcast corrections with RTCM3, CMR+ or ATOM formats. Even with SVM (max # of SV’s) set to 26, it is still possible to utilize ATOM Compact format at all times.

 

Another strategy for reducing required throughput is to lengthen the time between transmissions to 2 to 3 seconds. This will not affect rover performance in non-machine control applications.

 

2. Power requirements for the Base radio:

 

Since the base radio takes twice as long to broadcast the same data at 4,800-baud as it does at 9,600-baud the amount of battery power required is double.

 

Power consumption is best mitigated by configuring the broadcast rate to 1 correction every 2 or 3 seconds.

 

3. Heat / thermal considerations:

 

The amount of heat generated will also be double. (The new radios automatically reduce power when the case gets (really) hot so range may be impacted.)

 

Reducing the broadcast rate to 1 correction every 2 seconds will halve the generated heat.

 

Also, clipping on a box fan will greatly assist in cooling the transmitter.

 

4. Repeater Operation:

 

At 4800-baud, cross-frequency repeaters will probably only repeat every other message unless the broadcast rate is adjusted to 1 correction every 2 or 3 seconds.

 

Same frequency repeaters will require some strategy (reduced rate, compact message) so the message length is less than ½ the broadcast rate.

 

 

 

While you could fill out the FCC application yourself, it is doubtful you can do it properly. I have arranged for a third party licensing company to complete your narrow banding application for $110.

 

Business Radio Licensing (BRL)
30251 Golden Lantern, Suite E #501
Laguna Niguel, CA 92677-5993
Toll Free: 800-783-9006

 

BRL has an ‘A+’ rating with the BBB (see BBB ), they are nice people and their prices are as reasonable as I have found.

 

To get started, download this combined FCC 601 / Request Form:

 

 

fill it out and fax the completed form to +1 949-348-8514, BRL will contact you to arrange for billing. The cost for narrow banding should be $110, the cost for a new license is $600.

 

2. Order new base radios before August 1, 2012.

If you currently have a HPB (the 35-watt Brick) order these items:

 

          PN 87400; ADL Vantage Pro, 430-470 MHz, MSRP $2,195
          PN 242148; BNC Female to TNC Male Adapter, MSRP $15.80

 

We (Igage) are offering an upgrade kit including these two items for $2,085 until July 15^th 2012.

 

Provide us your current authorized channel list or your FCC Call Sign so we can pre-program the channel list for you. Also, provide us with your current protocol, interface baud rate, FEC and Scrambling settings and we will configure your radio to work out of the box.

 

You will be able to change all settings (protocol, FEC, Scrambling, interface baud rate) except for the frequencies and bandwidth from the device front panel.

 

Your existing cables will work with the new radio.

 

If you currently have a LPB (Low Power Base - the Tube with antenna on top)

 

Decide if you want to upgrade to a high powered base (or not) and call me. Once we figure out what antenna, and GPS cables you currently have we can provide a written quotation.

 

Hopefully, we will all recover from narrow banding and none of us will risk being fined by the FCC. If you have any additional questions, please drop me a note at ms@igage.com. I will try to get you answers and add them to this document.

 

iGage Mapping Corporation, 1545 S 1100 E, Salt Lake City UTAH USA
www.igage.com