Questions tagged [gnss]
The gnss tag has no usage guidance.
53
questions
1
vote
0
answers
38
views
Switch Mode Power Supply / GPS - Filtering+Shielding
I'm working on my first RF PCB, for GPS/ GNSS and am particularly concerned about Noise/ Interference. Hopefully someone can shed some light, or point me toward a similar thread?
It's worth noting ...
2
votes
2
answers
131
views
Can you do without a base station for RTK GPS if only relative positioning is needed?
I am trying to take two drones in an open field and have them know precise and accurate relative positioning of each other. I don't need them to actually know where they are. My plan is to use some ...
- 29
0
votes
0
answers
19
views
Using Here3+ for GNSS information, missing documentation?
The Here3+ is a GNSS receiver often used by drones, specifically the pixhawk. I wanted to use this receiver in my own project for geopositioning, I am however completely unable to find any ...
0
votes
0
answers
70
views
GPS/GNSS standard active antenna voltage and current draw
I'm designing a GNSS receiver that I'd like to be compatible with a variety of different active antennas. What antenna voltages are possible, and is there any (unofficial) standardization of this? I'...
- 1,033
0
votes
0
answers
18
views
Do all u-blox ZED-F9T input pins have internal pull-up resistors?
The ZED-F9T datasheet says in section 5 Communications Interfaces:
All the inputs have internal pull-up resistors in normal operation and can be left open if not used.
This statement on its own ...
- 1,033
0
votes
1
answer
39
views
What's the purpose of VCC_RF for u-blox ZED-F9T GNSS receiver?
The ZED-F9T, and presumably other u-blox GNSS receivers, can power an active antenna with a VCC_RF pin. The VCC_RF voltage is specified as being essentially the same as the module voltage (VCC) (...
- 1,033
1
vote
0
answers
44
views
Why isn't my Teseo-LIV3FL's CEP value within the datasheet specifications?
Context: CEP is defined as the radius of a circle, centered on the mean, whose perimeter is expected to include the landing points of 50% of the rounds (Wikipedia.)
According to the Teseo's datasheet, ...
- 121
1
vote
0
answers
81
views
GNSS module Allystar TAU1302 has fix but does not output PPS
I have a microcontroller board Datagnss Tiny EVK with an integrated chip TAU1302 (Allystar). I can get a fix with expensive Tallysman antennas in a rural area, with over 30 satellites and SNRs ...
2
votes
2
answers
99
views
Why are there LC filters on the UART line to the M20050-1 GPS module?
I am designing an IoT device.
In first version, I forgot to put the LC filters as in the datasheet.
I found it after I get the prototyping board on my hands, but I thought it would be fine without ...
- 1,469
0
votes
1
answer
94
views
Using an active GPS antenna in the SIM868 module
Is it better to connect to VBAT or to VDD_EXT in the SIM868 module to supply the active GPS antenna voltage?
- 1
0
votes
1
answer
146
views
GPS antenna not working
We are developing a GPS+LTE project based on the LE910S1-EAG module. We use a GPS LNA NJG1159PHH and an ACAG0301-1575 GPS antenna.
In this module GNSS_LNA_EN is left open and GNSS_ANT_RF_OUT is ...
0
votes
1
answer
67
views
What are this components on uBlox EVA M8M GPS?
I am designing my own pcb board based on a Sodaq One V3 (I built my prototype with a Sodaq One V3 and a MAX30102) and I am currently integrating both devices in KiCAD but I have a doubt with the GPS ...
- 411
0
votes
0
answers
65
views
Why do some GPS modules in smartphones have two or more antennas?
Some GPS modules have only one antenna, but some of them have two and more. For what? Are they made for different frequencies and ranges?
2
votes
3
answers
559
views
Proper PCB layout for GNSS ceramic patch antenna
I am designing a PCB that will require a GNSS antenna. The antenna will feed directly into a GNSS module located on the same board. It seems a popular antenna choice for this is a ceramic patch ...
- 199
2
votes
1
answer
119
views
Noise factor in homemade software-defined GPS receiver
I'm building a homemade software-defined GPS receiver. I'm currently at a point where I can acquire and track strong signals but struggle to even detect weak signals.
I've ruled out problems with my ...
- 133
2
votes
1
answer
161
views
Microcontroller GNSS time synchronization
I'm interested in having a Microcontroller trigger a device within a 1ms time of GNSS time every 100ms GNNS time.
What is the best approach to this problem?
Edit: I understand that GNSS may update at ...
- 670
0
votes
1
answer
112
views
GPS patch antenna feeding line layout issue
When I tried to put Molex GPS ceramic patch antenna 2042860001 on two-layer PCB, I found it's impossible to connect the feed pin to the RF trace on the two-layer PCB if following the recommended ...
- 562
1
vote
0
answers
48
views
Is there an advantage to cover all bands of GNSS constellations when selecting an antenna?
I am shopping for shark-style (or aerodynamic low-profile) antennas to make the most of my GNSS receiver (a Septentrio Mosaic X5). Is there any advantage to cover all bands (i.e. ~1.1GHz to 1.6GHz) of ...
- 9,777
15
votes
1
answer
2k
views
How do receivers decode multiple GPS signals on the same carrier frequency?
I'm currently researching GPS signals and am trying to fully understand the path of a signal from satellite to receiver.
I understand that mixed into the GPS signal is a C/A code as well as a PRN ...
- 153
1
vote
0
answers
71
views
Multiple GNSS receivers on a tiny PCB - layout advices
I am designing a board where I want to have 2 receivers using different constellations.
Due to space constraints, I have the idea to put the two receivers on the same PCB (one on the top layer and one ...
0
votes
1
answer
140
views
Polarity of inductor in GNSS antenna design
I was assembling a PCB today which had a circuit to connect the main module to an active GNSS antenna. I noticed that the inductor, a 47nH datasheet, had polarity markings on it, but I was unsure the ...
- 1,233
0
votes
1
answer
43
views
Connecting Ashtech antenna to mobile device [closed]
Just recently I got my hands on some old GNSS survey equipment from Ashtech, which was originally brought to the market around 2010.
It consists of two ASH111660 antennas with corresponding two ...
- 3
1
vote
0
answers
338
views
Why is a low resolution ADC (e.g. 4-bits) a bad idea for a Zero-IF GPS/GNSS RF front-end?
This is another follow-up from this fascinating question (the other follow-up question is here) for the design of an RF front-end for a GPS/GNSS SDR receiver.
In a comment to the accepted answer, it ...
- 1,504
0
votes
0
answers
204
views
How do I choose IF for a GPS/GNSS RF Front-end?
This is a follow-on from this fascinating question on selecting a TCXO (or entire frequency plan) for a GNSS SDR RF front-end. (I also have another follow-up question here).
The MAX2769 and MAX2771 ...
- 1,504
0
votes
1
answer
82
views
PCB GNSS module with RPi
I am trying to get a GNSS module to communicate with a raspberry pi serially. I was attempting to set this up with an ESP module but I don't think it will work, or at least I am missing something. In ...
- 1,233
-4
votes
1
answer
46
views
choise ic gnss for drone [closed]
I found a company that produces GNSS IC . I can't choose between 1065 https://ntlab.lt/product/nt1065/ 1066 https://ntlab.lt/product/nt1066/ I want to build a navigation system for a drone"
- 3
1
vote
1
answer
583
views
RF via impedance calculation with NFP removal
I'm trying to match the impedance of a RF via from bottom layer to top layer in a 6-layer PCB design. GNSS signal. Unused pad (NFP) removal activated.
The selected via size is 0.9mm pad and 0.5mm ...
- 21
0
votes
1
answer
72
views
GNSS antenna properties
GPS has three seperate frequency bands which are L1, L2 and L5 while Glonass has two seperate frequency bands including L1 and L2. Also Galileo has three frequency bands named as E1, E6 and E5.
I ...
- 145
0
votes
1
answer
1k
views
Help with calculating frequency offset
A 10 MHz TXCO is driving a receiver’s front end and has a frequency deviation of 10 ppm. It drives a direct downconversion RF front-end mixing the L5 frequency. What is the frequency offset at ...
- 3
0
votes
0
answers
48
views
What are the important values of GNSS antennas
I want to compare different GNSS antennas, but I don't really know what values to compare.
How can I compare them with datasheets looking like this?
Edit:
The antenne will be used on a rover that will ...
- 101
12
votes
2
answers
4k
views
GPS taking long time to fix out in the open
I am trying to use a ORG-1411 GPS (https://origingps.com/products/hornet-org1411/) to get location and UTC fix, using the breakout from Mikroe (https://www.mikroe.com/nano-gps-click). To parse the ...
- 157
0
votes
3
answers
392
views
GPS relative positioning
I have a set of 4 rovers crawling on the ground, each of them equipped with a standard GPS positioning system. The rovers start together from a known position. Each rover is locating itself via GPS.
...
- 5
0
votes
0
answers
192
views
SIM868 breakout board does not accept GNSS/GPS AT commands
I bought SIM868 breakout board with GNSS support. https://www.aliexpress.com/item/33013782111.html
However, I can’t get coordinates using standard at-command AT+CGNSPWR=1, AT+CGNSTST=1, etc. I get “+...
- 121
0
votes
2
answers
321
views
coplanar waveguide vs microstrip for gnss and cellular?
coplanar waveguide vs microstrip for gnss and cellular?
I read on internet microstrip is better for signals <30Ghz but some gps manufacturer (Delorme) said that coplanar is most efficient so it's ...
- 45
1
vote
0
answers
503
views
Elevation accuracy of dual band RTK GNSS module? (ZED-F9P)
Does anyone know the accuracy of height given from the ublox F9P dual band GNSS module in RTK mode? Or any dual band RTK GNSS module in general?
The website says up to 1 cm accuracy but I don't know ...
- 185
1
vote
2
answers
72
views
assited gps vs differential gnss [closed]
i am writing as essay evaulating accuracy of smart phone gnsss for GIS data collection
for part of the essay i thougt it appropriate to mention DGNSS and Assisted GNSS. So far i understand Assited ...
- 23
1
vote
1
answer
1k
views
Through Hole (Vertically Mounted) SMA Connector on PCB - Feasible for GNSS Application?
Due to space constraints on a board I am designing, it is ideal to have the GNSS cable connecting vertically onto the top of the board. I haven't been able to find any edge-mounted connectors that go ...
- 43
6
votes
1
answer
204
views
GPS L5C Differential? Max Update Rate(bits/s|Hz)?
The differential GPS chips use L1 and L2C to calculate the ionospheric interference.
With the new GPS satellites, the new band L5C is being deployed, and I am wondering about the following things:
...
0
votes
1
answer
240
views
Board requirements for a chip PCB antenna?
TL;DR: What are the requirements of chip antennas like this one (without LNA) or this one (with LNA)? I see PCB size specs in the PDF, but I am not sure I understand how the rest has to look.Does this ...
- 185
1
vote
1
answer
791
views
What kind of GNSS antenna is this?
I would like to know what types of GNSS antennas are on the images below (patch etc.) and also which one is better from the two (if any). They are being sold as "high precision" survey grade antennas.
...
- 471
0
votes
1
answer
444
views
Can every L1 GPS/GLONASS/BeiDou GNSS antenna receive E1 Galileo too?
I want to buy a survey grade single frequency L1 GPS/GLONASS/BeiDou/Galileo GNSS antenna (survey antennas have a ground plane built in). I found a product that specifies it is a GPS/GLONASS/BeiDou ...
- 471
1
vote
1
answer
72
views
FPGA Frequency Domain Based Beidou-3 B2a Coarse Acquisition Processor Using FFT
I'm using an ARM+FPGA platform to capture B2a (BeiDou or COMPASS) signals and determine the user position, velocity and precise time (PVT). The C/A frequency of B2a is 10.23MHz. If my sample rate is ...
- 11
3
votes
0
answers
131
views
Running Application on SIM808 GNSS module beside it's internal firmware
I'm trying to load my written program to SIM808 and the module will be responsible for running my program and also its internal firmware.
SIMCOM has a document about doing this in SIM800 module but ...
2
votes
1
answer
696
views
High precision distance between two GPS devices (may be GNSS-SDR)
I wish to get to high precision distance between 2 not moving points.
e.g. 1 cm accuracy for distance 1 km
I think if I will catch same GPS signal in two points then distance between resulting ...
- 121
1
vote
1
answer
71
views
I'm comparing a couple of GNSS front-end modules. Is a lower In-band IIP3 point better or worse than a higher one?
I would typically compare the small signal gain and noise figure first. One of the FEMs requires an external matching component but other that they are very similar in terms of cost and foot-print ...
- 912
0
votes
1
answer
449
views
SIM808 GNSS location update
I'm working on a project in which I have to get the current location every 10 s. I've used a SIM808 (GSM/GPRS & GNSS) on which I execute the AT+CGNSINF command ...
14
votes
2
answers
14k
views
What is the highest achievable update rate for a civilian GPS receiver?
I'm interested in knowing the maximum achievable update rate for a civilian GPS receiver. Specifically
Receivers that depend exclusively on GPS satellites (e.g. not including IMU-based movement ...
user139772
0
votes
2
answers
195
views
Do I need a dummy load for a GPS satellite signal generator?
I'm in the process of applying for an FCC experimental certificate so I can be legal when I purchase a satellite generator.
I found a used (calibrated) generator on eBay and want to know if I need a ...
- 912
1
vote
0
answers
232
views
Obtaining GPS Pseudoranges from Code Phase
After the tracking process in a Software GPS receiver, I need to compute the pseudoranges between the receiver and the satellite (without having in mind the clock corrections). In the tracking process ...
- 11
2
votes
2
answers
394
views
How does RF Coax cable impedance + Microstrip impedance mismatch affect power transfer
I have a passive GNSS antenna with a 6" 1.13mm shielded coaxial cable that connects to a u.FL connector. From the u.FL connector I have a 2" microstrip transmission line to the RF input of my GPS ...
- 912