WiGLE.net

Looking good! You decided you could do without the realtime clock module? Ive been debating whether or not to add it to my new pi 4-based rig.

Honestly, I never even thought about it, lol. Half my bag of phones are starting to battery bloat really bad, need something to replace them soon, wanted to do it on the cheap. Buddy gave me the pi, had a battery, figured I'd grab the most common gps dongle and see what happens. Turns out, I may need to think about a clock of some sort. Went for a run with it, got back a couple log outputs that converted and uploaded, but no luck with it finding new APs. Each log seemed to only show 45 found APs, none new, and in a fairly untouched area. So I guess I have a few things to work out:

-I've never gone stumbling in my wife's car, which seems to be a heck of a faraday cage. Even my phones seemed to come back with less than expected for an untouched area. The pi was just laying on the passenger seat.
-The sd card in the pi is about as fast as you can get, so that shouldn't be an issue.
-The pi should have had correct time when I pulled the wired connection to go for the run, how much would not having a clock affect scans?
-The pi4's wifi seems to be pretty flaky, saw a number of failures kismet had to recover from. Is it commonly bad?
-Which overpriced external alfa card do I need to blow money on?

I just want the most dots on maps for the least amount of money

no concrete answers (building a similar rig myself right now, so I'll post here as I learn things), but:

1. if you're ntp sync'd when you start, I would think that should be fine. I was specifically worried about GPS accuracy, which is what led me to add a hardware clock module. I probably over-thought things, but at least before COVID I was a frequent traveler, and desire to just be able to boot-and-go was a design constraint. In this vein, do you know the number of networks vs. networks-with-location in your run database? (I believe but have not verified that the kismet WiGLE export script only exports nets with location)

2. I've noticed the internal wireless is flaky, too, but maybe there's a driver fix? I'm using a pair of Pandas radios on my rig, will report back.

-ark

I remember writing a janky script to do time syncs with my VK-162 GPS too.

I wrote a WiFi suggestion in another thread, I'll quote it.

For radio, get stuff from the MediaTek MT76 driver family. The most common chipset is the MT7612U. Trust me, own at least one of them. You can pick up a generic MT7612U adapter for about $15:
https://smile.amazon.com/dp/B086L3D3NB/
If you want something brand name the Alfa AWUS036ACM is about $40.

Realtek solutions can be enticing when you look at the price but it's not worth it. The drivers available often behave in mysterious ways.

Note: Some Terow AC1200M adapters will have automation issues in Windows because it presents a fake CD drive with drivers. You need to eject the fake drive (or blacklist it somehow) before Windows can use the adapter for WiFi. This isn't an issue in Linux distros like Kali.

Edit: You want the CD Driver version, you can tell because it has a CD in the box.

The Alfa seems slightly higher quality but for the price of one Alfa you can buy 2-3 Terows. The Terow is <$15 with a business account. There shouldn't be a huge difference in performance since they're the same chipset. If there is, it's probably in the antennas which are swappable anyways.

no concrete answers (building a similar rig myself right now, so I'll post here as I learn things), but:

1. if you're ntp sync'd when you start, I would think that should be fine. I was specifically worried about GPS accuracy, which is what led me to add a hardware clock module. I probably over-thought things, but at least before COVID I was a frequent traveler, and desire to just be able to boot-and-go was a design constraint. In this vein, do you know the number of networks vs. networks-with-location in your run database? (I believe but have not verified that the kismet WiGLE export script only exports nets with location)

2. I've noticed the internal wireless is flaky, too, but maybe there's a driver fix? I'm using a pair of Pandas radios on my rig, will report back.

-ark

To follow up on this, for anyone reading, the on-board pi4 wifi with nexmon drivers is useless. It will just stall out and never recover, always. Got the recommended alfa radio plugged in today, and it flies, works flawlessly. Now I just need to get out of this damn home office so I can get back to the WWWD competition

godspeed and good hunting!

@arkasha you could update the system clock from the gps one it has a fix. So you don't need a RTC clock.

I failed to set it up with ntpd so I am using chrony instead. It is jsut a simple line to add to the config file

nice - I did that with my pi w zero rig!

The thing I'm not clear on is whether GPS fix time is chicken/egg with the clock

The main issue is the gps taking a long time for a first fix on cold boot. Could take 10 minutes with a clear sky.

Your VK-172 seems like it has a u-blox (7?) chipset. You can warm start the GPS by getting assist data from the internet, it's saved in storage. The company offers a Windows-only software called "U-Center" for GPS management.

1. Get a token here: https://www.u-blox.com/en/assistnow-ser ... quest-form
2. Plug your GPS into a computer and start U-Center
3. Receiver > Connection > Select ComX (your GPS)
4. Tools > AssistNow Online > AssistNow Online, GPS Only (u-blox 5 - 7)

Put the token you got in "Server Token." Most of the fields are self-explanatory. Click "Download & Transfer Now" when you're done. Now you can unplug your GPS and put it back into your rig.

@arshasa no the gps does not depend on the system clock time. From what I have understood, but it may differ from device to device, may be ?

I had problem with u-blox 7 based mouse usb gps, and I had to use A-gps, and finally sometimes not working
so I bought on ebay a new one with ublox-8 chip called BN-808. It's cheap but it took a long time to come from china.

Now, with that new gps, no more worries, and it has a fix in a minute (or less) without even needing a-gps.

@SkywardLark I have forked a github project to get A-GPS data in linux with a simple python script: it's there https://github.com/solsticedhiver/ublox-agps
yes. solsTicedhiver that's me too

And the wooden box was too heavy to carry so now I am using a mask box, the one very popular now during covid times.