No RTCM data being passed from Base to Rover (via UHF radio)

[AndrewW]

Hi,

I'm trying to set up Base - Rover using JAVAD 2xTriumph 2s, UHF radio and Victor LS.
Having read and followed the manuals, it all makes sense, but I have run into two snags:
1. The Triumph 2 base (hitched to a HPT435BT radio) is not passing RTCM 3 data to the Victor LS (screenshot 1)
2. The Triumph 2 rover behaves strangely with the Victor LS, and randomly (it seems) does not pass data to the Victor LS (screenshot 2) - it was working great - recognizing and passing satellite data to the Victor, and then stopped (having set up the sat selection in the General Group).

I have been just trying to get the system 'nearly working' with everything pretty much next to each before stretching its legs and separating base and rover by a 4-5km minimum (or using beast mode). The data should still be passed regardless (obviously without getting the requisite accuracy etc)? (Note I set the radio power way low to avoid it overwhelming the Victor LS at short range).

To be honest, I've kind of stumbled around trying to figure out what's going on, but if some kind soul can suggest what might be causing either or both issues, that would save me hours of time that I don't have.

Cheers,

Andrew W

 

[Matt Johnson]

Looking at your screenshots, the problem appears to be that the rover receiver is not communicating with the Victor-LS. If the rover receiver is connected to the Victor-LS and the Bluetooth connection is lost, either by unintentional disconnect or powering off the reciever, the Victor-LS will need to be rebooted for the communications to work properly again.

 

[Daryl L.]

I had the exact same issue yesterday. I updated my LS on Thursday afternoon and this was the first trip out after the update. I had solid signal from the base via UHF (-88dbm), but it would not get RTK. The engines showed "no data". After I added the external antenna on a 15' cable and extended the antenna up high on a pole, the signal strength increased to -79dbm, everything started working. The signal had to be blasting into the LS for it to begin collecting with RTK.

 

[Adam]

I had the exact same issue yesterday. I updated my LS on Thursday afternoon and this was the first trip out after the update. I had solid signal from the base via UHF (-88dbm), but it would not get RTK. The engines showed "no data". After I added the external antenna on a 15' cable and extended the antenna up high on a pole, the signal strength increased to -79dbm, everything started working. The signal had to be blasting into the LS for it to begin collecting with RTK.

Make sure the constellations are checked on. I have seen a few LS's have glonass or gps or both unchecked after updating. Your issue doesn't sound like radio problem to me.

 

[AndrewW]

Thanks very much guyz - I think the loss of BT signal between T2 & LS accounts for the Rover issue (the constellations were checked on - I kept checking) - as Matt suggests. I haven't updated my LS recently - but will check to see if the firmware is the most recent. I still can't account for the Base radio RTK issue - because connectivity was excellent, and the radio and T2 seemed to be definitely talking to each other over BT and transmitting (I checked the pairing). As Adam suggests, it must be something else...

 

[Daryl L.]

Checked that first thing. That wasn't the issue. In terms of signal strength the radio was definitely not the problem. I was suspecting something in the demodulater section of the LS radio. I'll be out trying a few things with it today. I sure do miss the days before I upgraded to the Linux operating system. My LS just has not gotten up to the level of performance that I had before I made the switch.

 

[Matt Johnson]

Daryl, your issue is likely completely different that the problem Le scruf is asking about with a Victor-LS and Triumph-2 rover which has a known issue that requires the Victor-LS be rebooted if the Bluetooth connection is disconnected between the Victor-LS and Triumph-2. If the problem is demodulating the signal then you should see a bit error ratio (BER) > 0, otherwise, if the RSSI is good then make sure the RX mode is set to Auto Detect and that the Base ID for the base and rover are identical.

 

[Daryl L.]

I'll be heading out in a few and I'll look into that when I get set up. Thanks for the response.

 

[AndrewW]

Hi Matt and others, thanks - problems pretty much all resolved as far as I can see. Apologies for the delay in getting back. Rebooting the Victor LS seems to cure the bluetooth disconnectivity issue, particularly if you keep the T2 and Victor LS turned on for the rest of the time you're on survey. Matt, a quick Q, I'm using an aerial (5/8, 5dBd gain, NMO) for HPT435BT which is tuned for 450-470MHz but it turns out we need to operate in the 430-450MHz range (in Uganda) so as not to stray where we shouldn't. If I set the radio frequency at e.g. 449,500KHz using the aerial (i.e. just below its tuned range) - how much loss in range and optimality is that likely to result in? Significant or not? We are operating on 35W often at the margins of reception. Cheers.

 

[Matt Johnson]

I'm using an aerial (5/8, 5dBd gain, NMO) for HPT435BT which is tuned for 450-470MHz but it turns out we need to operate in the 430-450MHz range (in Uganda) so as not to stray where we shouldn't. If I set the radio frequency at e.g. 449,500KHz using the aerial (i.e. just below its tuned range) - how much loss in range and optimality is that likely to result in?

This antenna comes from the factory tuned to 450 Mhz so it will work well if you are using 449.5 MHz. For higher frequencies it must be cut shorter. Here is the datasheet and whip cutting insturctions for reference: http://www.javad.com/downloads/javadgnss/sheets/UHF_Whip_Antenna_5dB_NMO_Datasheet.pdf

 

[AndrewW]

Hi Matt, thanks for the speedy feedback. That data sheet is rather handy! Cheers for now, Andrew W

 

[AndrewW]

Hi Matt, so a new issue has crept in - which is on starting base, the radio connects to the Victor LS fine, but it keeps waiting and waiting for the RTCM correction to come through. Last night it worked fine (with 2 'OK's' on the connection) with great accuracy, but previously that day the Victor LS had been problematic and kept waiting for the RTCM signal 'waiting'. The radio signal seems to be working great. The base and controller settings are identical - and nothing was changed since last night to cause the RTCM signal not to be passed. The T2 base is showing green on all lights that need to be green. OAF is up to date. Restarting base doesn't seem to work. We can't figure out what's going on.

 

[Matt Johnson]

Did you restart the Victor-LS?

 

[AndrewW]

Hi yes - we've done that several times. We were starting the system with base first, but then the Victor-LS started treating the T2 base as a rover (which is why it wasn't connecting as base). So we connect to the T2 Rover first, and then once that's good, we start-up the base T2 & radio which then connects very reliably to the Victor-LS. However on starting the base (using the base-rover start-up page on the Victor LS), we are are not getting the corrections being passed through.

 

[Matt Johnson]

Does the TX light flash on the HPT435BT? What does the UHF status screen show?

 

[AndrewW]

So the TX is flashing ok - and the UHF screen (from memory - apologies the equipment is locked up in the office) shows that the signal is excellent, but there are no correction packets (or equivalent) being sent - and base distance isn't recognised (i.e. it just seems no RTCM data is being sent through). I can't explain why it would work great and then previously not before (the problem just started suddenly), and thereafter not again - with no changes to the settings... Victor LS is updated to latest JField and GeoData. T2s running on latest stable firmware, OAFs are permanent. One thing we did notice, when we connected to JMT to see if there was a problem with the T2 base recognising sats, was that many sats were 'user-deselected' but going to the sats option in JMT, we would select all useable sats, and that wouldn't help. If we looked at the base T2 using Netview Hub or Netview Modem, everything seemed to be fine with all useable sats in view recognised and seemingly being used. Not sure if that's significant. In the Victor LS under the 'Group' option where the sats can be selected, they are all checked on (but I assume this only pertains to the T2 Rover?).

 

[Matt Johnson]

It sounds like the same problem you had before with the T2 rover not communicating with the Victor-LS. Does the satellite status screen show satellites being tracked or not?

 

[Shawn Billings]

How are the deltas on the base position. What you describe will occur if the base position is not valid.

 

[AndrewW]

The T2 rover is working fine. It's the base that is behaving oddly... I will check the deltas tomorrow - but we are on the same line of thinking in that regard... more tomorrow. Thks.

 

[AndrewW]

Hi Matt and Shawn, so I swapped the T2s - by unpairing and repairing with the radio using NetHub... and that sorted the issue immediately. The base-rover machine seems now to be connecting reliably. One question though - is that I have flashing red/green bluetooth symbol on the base-rover connect screen on the Victor-LS - what does that mean? Thx! Andrew W