Simple GPS/GNSS module + antenna for inside - Page 1
Forum section: electronics / projects

author: PinheadBE
author_rank: Regular Contributor
timestamp: October 01, 2023, 10:40:31 pm
content: Hi,I am looking for a simple GPS module and a suitable antenna for inside.My project is very simple: getting a simple frequency reference, configurable from 1 Hz to 10 MHz.I don't care about the jitter due to the internal 48 MHz oscillator division.I also don't care for the precision of the location and altitude. As far as the module gets in sync with satellites within 1 or 2 minutes, it's okI just need a reference of a module with a pulse output that is configurable through serial commands, and the reference of a suitable antenna.Until now, I was thinking about the mikroe-3922 equipped with a u-blox NEO 9 M module, but I do not know which antenna to use with that....

author: RoGeorge
author_rank: Super Contributor
timestamp: October 02, 2023, 05:45:07 am
content: AFAIK the signal is too weak, GPS does not work indoors. In fact, even outdoors it's a miracle that it works.There are GPS antennas made for exterior, with a long cable and a weather resistant enclosure, made to mount on the wall of a building with direct view to the sky, or on an outdoor pole.

author: rdl
author_rank: Super Contributor
timestamp: October 02, 2023, 07:23:59 am
content: I bought a u-blox module a few years ago. It's a Neo M8. The antenna I used was nothing special. It works pretty good indoors, but I live on the upper floor of an apartment building, so there's not much between it and the sky. This is the antenna:https://www.amazon.com/gp/product/B083D59N55/The board was an "Acxico NEO-8M GPS Module Development Board". I don't think the exact board is still available.

author: Bicurico
author_rank: Super Contributor
timestamp: October 02, 2023, 08:53:57 am
content: This is more about luck than anything else.Any cheap GPS receiver module might work or not, depending on your building. I have several cheap GPS receivers and one is permanently connected to my PC just for the fun of it and to check the time. I work on the last floor of our house. The roof is concrete and then the usual roof tiles.This will NOT allow for any GPS reception. But I happen to have big windows and if I place the GPS module (with built-in antenna) close enough to the window (0.5-1.0 meter), I get a fairly good reception on the USB devices.I own two Garmin handheld devices and those need to be placed right next to the window to get a reception.

author: croma641
author_rank: Regular Contributor
timestamp: October 02, 2023, 03:03:59 pm
content: For a reliable GPSDO signal reception (and OCXO stabilization) You must install outside Your antenna, with a good line of sight, minimizing all possible loss of signalhttps://en.wikipedia.org/wiki/Holdover_in_synchronization_applications

author: tszaboo
author_rank: Super Contributor
timestamp: October 02, 2023, 07:35:57 pm
content: Quote from: Bicurico on October 02, 2023, 08:53:57 amHonestly, I think this is probably the decades of experience with older technologies, and the hoard of badly designed or used boards. I also tried GPS a few years ago with a chinese chipset. Evaluation board, with SMA connector, and proper dedicated GPS antenna. Had to put the antenna outside the window to get anything.A few weeks ago we made a frankenreceiver, with two boards hacked together with a coax, a 1cm large FR4 antenna, and a west made receiver, and got like 20 satellites on my desk.One is integrated into a modem, doesn't have a LNA and a SAW filter onboard (LNA in the antenna), probably lies about the performance.The other was a state of the art receiver.And then you get all the chinese boards, with some decade old chipset, with bad RF design, matching circuit completely missing or replaced with some random components along the way, patch antennas without ground plane or RF randomly routed to two different connectors. I don't think I need to tell you guys why they don't work optimal.