[time-nuts] Re: Question about Trimble NetR9 receiver options

[Bob Camp]

Hi

With the Trimble gear, it’s not just about bandwidth. They have always run with high
gain antennas. Their antennas have > 50 db of gain. Your typical telecom gps
antenna might be down at 20 db. A lot of survey antennas are in the 30 to 40
db range. 

The quoted “gain margin” on the NetR9 is 13 db. That would suggest that with no
cable loss, you would be ok at 37 db of gain. From what I’ve seen the R8 and R9
do better than the spec. The NetRS generation does indeed need the higher gain. 

Another antenna fun rabbit hole is having one that is in the database. The correction
services have been getting a bit more picky about wanting a proper antenna description
( = an ID from the database) before they will process the files. Your typical sub 
$100 Chinese survey antenna probably isn’t in that database. 

The various generations of gear feed the antennas at a range of voltages. Best to 
get one that is happy with > 5V, or use a DC block and feed it with your own supply.

Fun 

Bob

> On Mar 28, 2023, at 10:27 AM, paul swed <paulswedb at gmail.com> wrote:
> 
> Also a note you should check that your antenna is useful for the other frequencies. I needed to buy a newer multi-band antenna. Works great out the window but somehow has not made it to the 90' level on the tower yet. Spring is in the air.
> Good luck
> Paul
> WB8TSL
> 
> On Tue, Mar 28, 2023 at 9:40 AM Bob Camp via time-nuts <time-nuts at lists.febo.com <mailto:time-nuts at lists.febo.com>> wrote:
>> Hi
>> 
>> The NetR9 comes in a somewhat bewildering range of sub models. The Ti-1 has
>> pretty much everything turned on from scratch. The Ti-2 can be upgraded, it comes 
>> with just Glonass and GPS. These and the TI-3 are all identifiable by the -10, -20 
>> or -30 at the end of the model number. (Ti-1 = -10 and so on ).
>> 
>> Can the -30 be upgraded? I’ve never played with one. Can the “other” version be
>> upgraded ( not listed above)? Apparently not based on internet comments. Maybe
>> so if you actually talk to a dealer.
>> 
>> Cost wise, the upgrades are in the “forget about it” range. Last time I checked on
>> doing a Galilleo upgrade, it was in the $10,000 range. What else that might have
>> gotten you … who knows. I can buy one with all the systems enabled on eBay
>> for about $2K delivered.
>> 
>> Adding more systems means more sats go into the mix. Errors go down baed
>> on the number of sats. How much they go down is very much a “that depends”
>> sort of thing.
>> 
>> Most precision timing relies on some sort of correction process. The easy / lazy
>> approach is to send things off to NRCan or Opus or something similar. If you wait
>> a few weeks ( 3 to 4) NRCan will give you a nice “.clk” file with lots of digits in 
>> the estimate. Most of the time, a week long file seems to be ok to about 0.1 ns.
>> There can be 1 to 2 ns bumps in some files. 
>> 
>> Keep in mind that all this is simply going back to GPS time and without some
>> further work, you don’t have a full link to BIH. 
>> 
>> If you sit down over a beer and taco’s with the folks who designed the NetR9,
>> they are very much focused on survey applications. They made a business 
>> decision to leave the timing market to somebody else on this sort of hardware. 
>> Just why is a somewhat long and convoluted story. 
>> 
>> The net result is that even with “everything right” there is a time offset between
>> the NetR9 (or NetR8 or NetRS or …) clock and GPS. It is measured in hundreds
>> of microseconds. Power cycle the device and it will come up with another 
>> random clock offset. There are commands to read out this offset. 
>> 
>> The PPS in and PPS out are a bit coarse on these boxes. The magic readout
>> commands do not tell you the offset of the PPS out of the device. (or if they
>> do, they aren’t doing a very good job of it). 
>> 
>> The R8 / R9 / NetRS devices all lock up nicely to an external 10 MHz input. 
>> Turn off clock steering and enable the input. They should lock up and tell you
>> they are locked. 
>> 
>> The R8/R9 generation will do L1/L2/L5 measurements. As far as I know, the
>> world of free correction services has not caught on to L5 yet. There also 
>> don’t seem to be any obvious candidates for correcting anything other than
>> GPS / Glonass. I keep hoping somebody will chime in with a correction to 
>> this part of it. 
>> 
>> Like all devices that write to flash memory, there’s only just so long that will
>> keep working. Eventually they will die. When they go bonkers, a firmware
>> reload *might* fix the problem. How long it stays fixed … who knows. A
>> full up firmware upgrade and repair contract from your local dealer is about
>> $1,250 or so per year. 
>> 
>> With the NetR8 selling for the same price as the NetR9, I’d ignore the R8.
>> In some cases NetRS boxes are listed for more, those people are a bit 
>> crazy. There also are sellers with upgraded Ti-2’s calling them Ti-1’s, 
>> welcome to eBay. ( The Ti-1 has 8 GB internal storage, an upgraded Ti-2
>> still only has 4GB). 
>> 
>> This sort of makes it sound like the NetRS is pretty much the same thing
>> as the NetR9. The R9 does do a better job. Is it enough better? That
>> depends a lot on how much you paid for each of them. A Mosaic-T will 
>> beat either one ….. ( just not in the area of packaging / ruggedness )
>> 
>> If you need more info, feel free to ask ….
>> 
>> Bob
>> 
>> 
>> > On Mar 26, 2023, at 9:26 PM, Stan via time-nuts <time-nuts at lists.febo.com <mailto:time-nuts at lists.febo.com>> wrote:
>> > 
>> > I just got a Trimble NetR9, which I hope to ultimately use to make some high
>> > precision timing measurements. I've updated to the latest firmware and it's
>> > happily ticking along right now.
>> > 
>> > 
>> > 
>> > Questions: 
>> > 
>> > 
>> > 
>> > 1.    The NetR9 spec sheet says it's capable of receiving the GPS,
>> > GLONASS, Galileo, and BeiDou constellations. My receiver is currently
>> > receiving just the GPS and GLONASS birds, with the options for Galileo and
>> > BeiDou not enabled. Is it possible to enable them with a license key, and if
>> > so, what is involved in getting that key?
>> > 2.    If it is possible to enable them, is it worth it to do so in order
>> > to (significantly) enhance the precision of positioning and timing?
>> > 
>> > 
>> > 
>> > Thanks,
>> > Stan 
>> > 
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