At the end of last month, I posted a topic inquiring about dual frequency receivers https://surveyorconnect.com/index.php?mode=thread&id=83789. I'm been reading and re-reading that post, gleaning the wisdom offered. Thanks to all who posted!
Bottom line is that I've decided that buying a dual frequency receiver is a good idea, and I'd like to follow up by asking for recommendations of which receiver/antenna combinations have been the best value for other users.
I realize that existing equipment/software can play a role in whether new equipment turns out to be a good value, so I will list my existing major equipment/software here for reference:
A pair of Ashtech ProMark3 GPS L1 receivers/antennas
Sokkia SRX3 Robotic Total Station
(w/ non-OP tribrachs and AP41 rotating tribrach adapters for glass or GPS antennas)
GNSS Solutions (without L2 key)
AutoCAD Land Desktop 3
Regarding the purchase of a dual frequency receiver, I am inclined to prefer to go with an Ashtech receiver, though would consider another brand if there was a good reason to go that way. I am working on a limited budget, and I would say I don't really want to spend more than $3K on this. Because of the wooded landscape here in western MA, I not envisioning that this tool would be used on a daily basis, but would nonetheless like to add it to my toolbox, as I do see it having some applications for certain types of jobs.
Are there particular models that you would recommend at less than $3K? I understand that in this price range I'll be buying old equipment, with typically higher battery draws, heavier equipment, with more cables, etc. As for models, I have been looking consthe Ashtech Z-12, Z-sensor, and MicroZ, Ashtech Z-extreme, Trimble 4000 SSI and 5700, and Topcon GP-DX1.
Any thoughts?
We have six Trimble 4000 SSI receivers. They are workhorses. Like you said, lots of cables and such, but workhorses nonetheless.
> As for models, I have been looking consthe Ashtech Z-12, Z-sensor, and MicroZ, Ashtech Z-extreme, Trimble 4000 SSI and 5700, and Topcon GP-DX1.
The Z-Sensor has no on-board storage, so you'd have to stream the data to a laptop or other logging device. It'd be a slightly clunky setup, but workable, especially for drive-to stations.
Topcon DX1s are hard to come by -- I see very few on eBay. A colleague bought a pair of them new and still uses them. I believe they're Trimble 4700 boards in a Topcon package.
I'm partial to the Trimble 4000SSi and SSe, but that's mostly due to familiarity. The bare boxes have been going for under $1k on eBay lately.
Don't overlook the Trimble 4400. Like the Z-Sensor, it has no onboard storage. However, a TSC1 will capture the data and is a pretty robust package. No laptop required.
Good luck!
Al, I'd go ahead and have the little breakdown, and buy a set of RTK stuff, and data collector. Used, you would be out 8-12000, ready to work. But, you would not look back.
Let me explain.
Using RTK for stakeout, in the woods, is STILL better than the old way. So what if all you can muster is a FLOAT solution. It STILL gets you within 15' (Typicaly within 4-6 feet)of what you are looking for. So, now you can search with metal detectors, and shovels. IF you do not find it, then you know WHERE to set up your control, and shoot it in with Total station.
So, My advice: find a friendly EXPERIENCED USER of RTK, and spend a day in the field with him.
It will change your life.
N
Thanks Jim. Some time ago you had suggested looking carefully at the Z-12 and 4000 series, and I have been studying these especially since.
I'm aware of the Z-sensor not having on-board storage. One option for logging the data is to use a CE device and VirtualGPSCE as software. Have you used this or know anyone that has? This would be a pretty inexpensive option.
I've also been seeing the 4000SSI bare boxes for sale on eBay. Then, would still have to find an antenna and cables and batteries, separately. The antenna for these units looks rather large, although I understand where multipath is not a concern, the outer part of the antenna can be removed. Also, I understand that one has to be concerned not just with buying a 4000 SSI, but also knowledgeable about which options are installed, i.e. RTK, OTF, etc. Any suggestions in this respect would be appreciated.
The Topcon DX1 I read only has 9 channels so maybe doesn't log all the data that is available. Not sure if this presents much of a detriment, though.
> > As for models, I have been looking consthe Ashtech Z-12, Z-sensor, and MicroZ, Ashtech Z-extreme, Trimble 4000 SSI and 5700, and Topcon GP-DX1.
>
> The Z-Sensor has no on-board storage, so you'd have to stream the data to a laptop or other logging device. It'd be a slightly clunky setup, but workable, especially for drive-to stations.
>
> Topcon DX1s are hard to come by -- I see very few on eBay. A colleague bought a pair of them new and still uses them. I believe they're Trimble 4700 boards in a Topcon package.
>
> I'm partial to the Trimble 4000SSi and SSe, but that's mostly due to familiarity. The bare boxes have been going for under $1k on eBay lately.
>
> Don't overlook the Trimble 4400. Like the Z-Sensor, it has no onboard storage. However, a TSC1 will capture the data and is a pretty robust package. No laptop required.
>
> Good luck!
Something like this,
But I'd be sure it has 35 watt base radio.
That unit above is 16k. Well, still, you would not look back. UNLESS you did not learn how to utilize what it can really do.
N
You got $3,000 budget. You can buy an old system which may or may not last long. Work horses do not live for ever, even the once that are genetically superior.
It's a gamble, a $3,000 gamble.
And remember, those 35-watt radios wear out with time regardless if they are busy in the field or collecting dust on the shelf. There's an aging crystal inside the unit (as told once by tech support).
Personally, unless you are doing this for training / development purposes and consider this cost as a way to advance your knowledge, I'd say go for it. If you are planning to buy for many years of service, I would say, postpone, raise your budget to $12-15,000 then revisit your dual frequency receiver purchase options.
I would have to agree. If you can hold off and raise capital, wait. There are several options out there in the +-12K range.
Most of the older units have firmware that is outdated and cant be upgraded anymore. Trimble released the last version of firmware for the 4000's sometime ago.
I can get within 3' using autonomous single frequency receivers. You need a geodetic search coordinate though which can be gotten in any number of ways.
I've used a handheld backpacker unit and gotten within 15' of a good coordinate.
For search there are cheaper options without all the time overhead of setting up a base station.
I dunno...tough call.
I would hate to sell someone one of my OLD (all at least 10 years old) receivers (that worked fine last time I used them), and then have it crap out on them next week (or even next year). I don't know WHEN one of these (9) receivers will fail (for whatever reason, fixable or TOAST), but they all work right now (I think), and they are all paid for!
That said, I would be very hesitant to spend more than about a grand on an old L1/L2 receiver at this point (with all accessories including antenna). At a grand, you will get your money's worth [back] pretty fast! If it craps out after a year...well that's the breaks, but you are not out all that much, and you are probably ahead of the game (even if it can't be fixed).
Also bear in mind, that a 10-15k system that is only a few years old can crap out at anytime TOO! Of course you would probably have better luck getting it FIXED than an old [way past] EOL unit.
Loyal
Thanks. Interesting dichotomy between spending more for something better vs. spending less for something that may have limitations. I've heard again and again from surveyors in these heavily wooded parts that GPS is good for some jobs, but isn't something that you want to take in the woods. You're right though: spending a day in the field with an experienced RTK GPS user is a good idea.
One question though: what are the key things that spending $12K is going to get me? Many of the older units 4000 etc. also do RTK. Ability to upgrade firmware? Better integration with software? Glonass? Longer life? Faster, lighter, less clunky? I suppose it's all of these. Still this is partly a training/development issue for me. I want to test out what GPS can do before investing big $$ in it.
> Most of the older units have firmware that is outdated and cant be upgraded anymore. Trimble released the last version of firmware for the 4000's sometime ago.
I'm trying to think of a reason for wanting to upgrade the firmware in a 4000SS receiver, but I'm not coming up with any. I only use mine for static/fast-static, though, so maybe it's an RTK thing.
Big Al, call me if ya want to.
870-356-3797
N
Jim it's not so much a reason why. It just happens to be that when upgrades to firmware are ended that those units are near the end of their expected life cycle.
I would see if I could get a Trimble 4700 base station (lots of memory) with a micro-centered antenna. You don't need a TSC1 but the controller will put meta-data into the file such as ARP height, point name and code.
It can just be turned on and it will automatically start a file. You need to write down good notes and I include the start and stop times so you can sort out the files later.
Al
skip that one. its a hiper light.
short range
N
> Jim it's not so much a reason why. It just happens to be that when upgrades to firmware are ended that those units are near the end of their expected life cycle.
Those units hit their expected life cycle about 10 years ago. I have 6 of them (plus a 4400), and aside from having to replace some of the internal batteries, all are still chuggin' along fine, outdated firmware and all.
Al, I'm in SW, N.H. and have all Ashtech gear,
My opinion, the old aluminum blue box, FX model is the winner.
Oh yeah they are still working great here too, all six of them. It's just that when they do go, they are gone. And yeah, the firmware updates are more important when you are using them for RTK.
