Survey Party 'A' is doing a GPS survey.
Half a mile away Survey Party 'B' is doing their own GPS survey.
Questions: is it possible for one party's transmissions to interfere with the other's?
If yes, under what conditions?
How can such interference be detected?

Yes

If they are using the same type of equipment on same radio freq. MOst of the new gps equipment will take care of this by setting the ids on the base and the rover.

C.O.

I disagree with CO Surveyor's statement slightly.

If surveyor A is using RTK GPS on frequency 464.5500 and half a mile away surveyor B is using RTK GPS equipment on frequency 464.5500, they will both have problems.

Setting the IDs on the base and rover will not eliminate interference, imho.

One surveyor will have to switch to another frequency.

Running a scanner before you set your broadcasting RTK base up is the simplest way to avoid this problem. The radios hold 16 frequencies, and it is generally no problem to find an open frequency.

During the RTK Base Station Set-up, while connected to the RTK Base Receiver, the controller (Ranger CE) will display the position being used by the RTK Base receiver (Position being TX'd). Obtained from the "GET" position when selecting the "Localization w/Control Points" method, or from the NADCON rotation when selecting the "Mapping Plane" method.
When selecting Localization Calculator, the WGS84 Lat/Long/Ellip Ht is manually entered. (NOTE THIS POSITION).

On the RTK Rover, Keep an eye on your RTK Base Station Position. Your known RTK Base Station position should be displayed through the RTK Rover display menu on the controller. If you note the rec'd Base Station Position differs from what you know it to be, you may be listening to someone else's RTK Base Station. The RTK Rover compares the incomming data from the RTK Base station, if the Delta Position is greater than 500 Meters, the RTK Rover should display "Bad Base Coordinates" message.

If the RTK Rover looses FIX & has a hard time re-Fixing, double check the Rec'd RTK Base position. If the RTK Rover is getting "Stepped-On", you'll need to change Radio Freq's on the RTK Base & RTK Rover.

Even with unique ID's for your base and rover, the signal is on the same wavelength so it should cause interference. While your unit shouldn't 'use' the wrong RTK solution, it will be much noisier than expected because of the additional data in the air..
On our radios, you can monitor the frequency before you start your base. This won't help if it's clean, you start your base, and then another company starts their's an hour later. You'll just notice the hard time getting solutions when they start..

I would also think that radio waves are propogated on the square of the distance, so it will be more pronounced if the triangulation of the units is close in proximity.

We generally have 2-3 RTK crews (different companies) working on projects in our town at one time (not a large town), but none have had any particular problems..Of course they are all on HARN derived monuments, so even if they used the wrong base, then they'd still have a good solution...

Sorry..Rambling on, when I should be heading to work..Another fine day of inverting sewer manholes...

DP Anybody work in the large municipal areas where lots' of RTK bases are going and have some experience with this?

RECENTLY GOT FED UP WITH ALL THE PROBLEMS ASSOCIATED WITH A BLUE RADIO AND SWITCHED TO A COMPANY CALLED TELEDESIGN, THEY USE A SIMULTANEOUS BROADCASTING OF 4 FREQUENCIES, AND ROTATES THEM AND USES ONLY THE STRONGEST ONE, IF IT DETECTS ONE OF THE 4 COMING FROM AN OUTSIDE SOURCE IT DROPS IT FROM THE LINEUP AND ADDS ANOTHER ONE FROM YOUR LICENSED 12,
SINCE SWITCHING TO THIS COMPANY WE HAVE VIRTUALY ELMIMINATED THE RADIO PROBLEMS.

P.S. IT ALSO COSTS LESS THEN OUR ORIGINAL RADIO SYSTEM, AND OUR BASE BATTERY IS 2 YEARS OLD AND WE CHARGE IT EVERY DAY.