rtknavi_qt : slip detected doppler / ambiguity validation failed

[hans-mayer]

Dear All,

I try to get an accurate position point with rtknavi_qt

My environment: I have an U-blox ZED-F9P-02B as GNSS receiver connected to RaspberryPi with Debian 11.11 .
The F9P has FWVER=HPG 1.51 and PROTVER=27.50
Attached is an antenna HAB-ANN-MB-00-00 at the top of the roof of my house.
On F9P I enabled BINARY , RAWX and SFRBX

Below you can find my config ( username/pwd is fake )

rtknavi_static_TRF200AUTO_fake_user.conf.gz

In an earlier different setup I feed the ntrip source directly to the F9P when starting gpsd as argument. In this previous situation I got positions points within a field of 2 times 2 cm. So I can say that the ntrip mountpoint works for me if it's even 40 km away.
Now I try to use rtknavi_qt. I switched off "gpsd" and configured rtknavi_qt to use the serial interface.

When I press the start button I get after a while solution "FLOAT" but never "FIX"
The value for Ratio is almost 1.0 sometimes 1.1 and I have seen for very short time the value 6 ( but only once )

When I open the monitor looking for errors I the following messages are permanently running over the screen.

110 19:22:51.00: slip detected doppler (sat=61 rcv=1 dL1=-0.306 off=-0.053 tt=1.00)
111 19:22:51.00: slip detected doppler (sat=61 rcv=1 dL2=-0.340 off=-0.053 tt=1.00)
112 19:22:51.00: slip detected doppler (sat=63 rcv=1 dL1=-0.316 off=-0,053 tt=1.00)
113 19:22:51.00: slip detected doppler (sat=63 rcv=1 dL2=-0.335 off=-0.053 tt=1.00)
114 19:22:51.00: slip detected doppler (sat=65 rcv=1 dL2=-0,255 off=-0,053 tt=1.00)
115 19:22:51.00: slip detected doppler (sat=68 rcv=1 dL2=-0.258 off=-0.053 tt=1.00)
116 19:22:51.00: slip detected doppler (sat=69 rcv=1 dL1=-0.246 off=-0.053 tt=1.00)
117 19:22:51.00: slip detected doppler (sat=69 rcv=1 dL2=-0.277 off=-0.053 tt=1.00)
118 19:22:51.00: slip detected doppler (sat=70 rcv=1 dL1=-0.373 off=-0.053 tt=1.00)
119 19:22:51.00: slip detected doppler (sat=70 rcv=1 dL2=-0.252 off=-0.053 tt=1.00)
120 19:22:51.00: slip detected doppler (sat=71 rcv=1 dL1=-0.838 off=-0.053 tt=1.00)
121 19:22:51.00: slip detected doppler (sat=78 rcv=1 dL1=-0.277 off=-0.053 tt=1.00)
122 19:22:51.00: slip detected doppler (sat=78 rcv=1 dL2=-0.215 off=-0.053 tt=1.00)
123 19:22:51.00: slip detected doppler (sat=95 rcv=1 dL1=-0.092 off=-0.053 tt=1.00)
124 19:22:51.00: slip detected doppler (sat=95 rcv=1 dL2=0.081 off=-0.053 tt=1.00)
125 19:22:51.00: slip detected forward (sat=17 rcv=1 F=2 LLI-1)
126 19:22:51.00: ambiguity validation failed (nb=31 ratio-1.00 thresh=99.99 s=0.04/0.04)

sometimes there is also rcv=2
Of course I tried also a different ntrip caster.

Obviously I miss some important settings, either for rtknavi_qt or for ZED-F9P
I looked around since several days and tried different settings. But till now without success.
I can't believe that no one tried such a setup or can't be solved.

Maybe there is someone out there who can check my config or can submit his setup for rtknavi_qt and for ZED-F9P

Kind regards
Hans

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[rtklibexplorer]

The doppler detected cycle slip error checking can be disabled by setting the doppler slip threshold (pos2-dopthres) to zero. Zero is supposed to be the default value, so not sure if you set this accidently, or there is an issue with the default value. I'm also not sure if these errors are the reason you are not getting a fix, but I would at least start by disabling them.

[hans-mayer]

Hi Tim,
many thanks for your swift answer.
The default value is
pos2-dopthres =0.05 # (m)
So I changed this value now to 0 but there is no change. I have still a ratio of 1.0 more or less constant, sometimes up to 1.3 but not more.

Are there maybe any other parameters which should be adapted. Actually I didn't change many, I tried some changes but in general I have the defaults for pos2. This is the settings.

pos2-armode        =continuous # (0:off,1:continuous,2:instantaneous,3:fix-and-hold)
pos2-gloarmode     =off        # (0:off,1:on,2:autocal,3:fix-and-hold)
pos2-bdsarmode     =off        # (0:off,1:on)
pos2-arfilter      =on         # (0:off,1:on)
pos2-arthres       =99.99
pos2-arthresmin    =99.99
pos2-arthresmax    =99.99
pos2-arthres1      =99.99
pos2-arthres2      =99.99
pos2-arthres3      =1e-09
pos2-arthres4      =1e-05
pos2-varholdamb    =0.1        # (cyc^2)
pos2-gainholdamb   =0.01
pos2-arlockcnt     =0
pos2-minfixsats    =4
pos2-minholdsats   =5
pos2-mindropsats   =10
pos2-arelmask      =0          # (deg)
pos2-arminfix      =10
pos2-armaxiter     =1
pos2-elmaskhold    =0          # (deg)
pos2-aroutcnt      =5
pos2-maxage        =30         # (s)
pos2-syncsol       =off        # (0:off,1:on)
pos2-slipthres     =0.05       # (m)
pos2-dopthres      =0          # (m)
pos2-rejionno      =30         # (m)
pos2-rejcode       =30         # (m)
pos2-niter         =1
pos2-baselen       =0          # (m)
pos2-basesig       =0          # (m)

Kind regards
Hans

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