Sponsored Links

Accuracy of coverage checkers?

JSHarris

Super Pro Member
I've wasted hours trying to find out why I can't get any signal at all from the provider with supposedly the best coverage here, to the extent that I've gone so far as to wander around the area with three devices doing an ad hoc survey (tablet with a 3 SIM, two phones, one with an O2 SIM, other with a Vodafone SIM).

The results are surprising. For example, the provider with the very best apparent signal here (according to their coverage checker) is 3. Their prediction for my post code is:

1694853619763.webp

In reality there is no signal at all from 3 here. I've even climbed up to the top of a ladder at the gable end of our house to see if there's any signal at height and there's nothing at all from 3.

EE is much the same. Their coverage checker has this to say about our location:
1694853894384.webp

Again, there is no EE signal at all here, even at the top of the ladder, so the EE checker is also wrong.

O2 and Vodafone seem to be pretty much spot on. They both predict the signal here is good enough for calls and 4G when outdoors, which it is (if stood on the top of a ladder).

All four providers use the same mast, all four have sector antennas facing us that are about the same beam width and all four are using Band 20. I'm struggling to get my head around the reasons for the EE and 3 coverage checkers being so wrong, wildly so for the 3 checker (so wrong as to make it completely useless).

Anyone have any idea why things on the ground are nothing like the predictions from the providers?

It's annoying, as I've wasted time and a bit of cash on getting a SIM for what I assumed would be the best provider for our area, only to find that in reality they are the worst.
 
Different devices can behave differently. So you need to switch SIMs between them so that a particular network can be compared. Internal antenna design, modem chip and SIM plan can obscure the true picture. e.g an iPhone 13 is faster on EE than an Android.

Coverage maps are theoretical and they don't always include holes due to terrain. In addition there may be power lines or some other interference between the particular mast and your location. Mast are also shared.

If you are limited to a particular then you need a device that can capture that most effectively and provide WIFI to other devices. I find phones only a general tool (and better monitoring) so prefer an unlocked MIFI on a 6m telescopic pole for testing speeds on poor 4G.

I also use https://bidb.uk/ so the coverage maps are all in the same place. If you look at the coverage you can often see the epicentre (hence direction) which may or not align with Cellmapper. Tricky thing RF as you have found.
 
Thanks. Been playing around a bit more, with two iPhones and the old Sony tablet. I can't swap the sims around unfortunately, as the 3 SIM isn't pre-cut down to nano, and so will only physically fit into the tablet. I've just tried slotting the Vodafone SIM into a micro holder and putting it into the tablet as a cross check and the signal and performance seems much the same as when it's in an iPhone (accepting that there will always be small variations).

I'm now pretty much convinced that 3 aren't actually using the B20 sector antenna that points in our direction. I can't seem to get anything resembling a usable signal, even on high ground that should be LoS to the mast.

I've dug out my HackRF One connected it to a fairly broadband omni antenna and am trying to get to grips with a spectrum analyser app. So far I've managed to just about see the EE 1846.7MHz B3 downlink, although the signal is way down in the noise. Can't see any of the B20 signals though, there seems to be a lot of other stuff in that band. Might be interference, and if so that may explain some of the things I've been seeing.

This afternoon's exercise is to try and see if I can get a HackRF One app to run on my Macbook (I've beenb using it with a Windows desktop this morning), so I can go roaming around the local area to get a better idea of the raw downlink RF from the various providers. My gut feeling is that the provider with the strongest signal has to be a good candidate.
 
Sponsored Links
Got the HackRF One spectrum analyser app working on an old Windows laptop and sorted out some finger trouble when adjusting the settings. Because the downlink signal is wideband I had to turn on a waterfall display to see them clearly.

Having done that I can clearly see the O2 downlink on 816MHz and also the Vodafone downlink on 806MHz. No sign of the 3 downlink that's supposed to be on 793.5MHz though. That does explain why I couldn't get a 3 SIM to work, though!

Looking at the spectrum analyser display the O2 signal is noticeably better than the Vodafone signal, so I'm tempted to try an O2 SIM in the router and see how that goes. The router will get a fair bit stronger signal, as I've got a couple of 12dBi gain directional antennas connected to it, pointed at the mast that's about 2.5km away.
 
At my location in Wales, according to Ofcom outdoors I am supposed to have OK 4G on EE, 3 and O2. Vodafone is supposed to be Good.

They are all undetectable on any phone or tablet I have used. To get a usable connection on Vodafone, I need this…

isp02low-jpg.4478
 
Seems the coverage checkers are pretty pointless, then, really just a way to sucker people into buying. All told it's a bit annoying to find this out now, after I've wasted time with something that won't work here.

Been playing around a bit more with the HackRF One spectrum analyser. Got some narrow band interference artefacts, look to be clock harmonics from the laptop, I think, but the Vodafone and O2 downlinks are just about detectable. Hard to be sure whether O2 or Vodafone is the better of the two, as the nature of the beast means that the apparent signal on a waterfall display varies a great deal depending on the data the mast is handling at any instant.

This screen print shows Vodafone as being slightly better, but also shows the complete absence of any signal from 3:

1694869887332.jpeg
 
Mystery of the missing 3 signal perhaps resolved!

I've looked at the Cellmapper data more closely and there's an anomaly with the sector direction for the 3 mast antenna I need to connect to. The sector map shows the coverage for this antenna centred on around 085°T, fine for us as our house bears 074°T from the mast. The cell info on Cellmapper shows this sector antenna as being centred on 352°T! That would explain why I can't find it.

Looks like some sort of glitch in the Cellmapper data, I think. For comparison the O2 sector antenna is centred on 064°T and the Vodafone sector antenna is centred on 106°T, so we're well within the ~ 75° wide beam width from either of them, which fits with the signal strength from them that I'm seeing.
 
  • Like
Reactions: bon
Sponsored Links
Mystery of the missing 3 signal perhaps resolved!

I've looked at the Cellmapper data more closely and there's an anomaly with the sector direction for the 3 mast antenna I need to connect to. The sector map shows the coverage for this antenna centred on around 085°T, fine for us as our house bears 074°T from the mast. The cell info on Cellmapper shows this sector antenna as being centred on 352°T! That would explain why I can't find it.

Looks like some sort of glitch in the Cellmapper data, I think. For comparison the O2 sector antenna is centred on 064°T and the Vodafone sector antenna is centred on 106°T, so we're well within the ~ 75° wide beam width from either of them, which fits with the signal strength from them that I'm seeing.
Just a word of warning as you are putting a lot of effort into this and I would hate you to finally get the signal and then be unimpressed with the results but…..

If you’re replacing a landline with this solution, what is the landline currently capable of?

On Vodafone and O2 4G (800Mhz) you’re unlikely to see anything over 40Mbps. Certainly nothing north of 100Mbps.
 
Just a word of warning as you are putting a lot of effort into this and I would hate you to finally get the signal and then be unimpressed with the results but…..

If you’re replacing a landline with this solution, what is the landline currently capable of?

On Vodafone and O2 4G (800Mhz) you’re unlikely to see anything over 40Mbps. Certainly nothing north of 100Mbps.

Best we get from our FTTC is about 18Mb/s down and we're unlikely to ever get FTTP here, so anything that matches that would be fine. Just as well, as we can only connect on B20, with 10MHz bandwidth, so we're not going to get lightning fast speeds!
 
Best we get from our FTTC is about 18Mb/s down and we're unlikely to ever get FTTP here, so anything that matches that would be fine. Just as well, as we can only connect on B20, with 10MHz bandwidth, so we're not going to get lightning fast speeds!
In that case it makes sense for you to pursue it then.
 
I've changed the outdoor antenna for an EAD LCO7270 2dBi omni that I had lying around. made a substantial difference and confirmed that the directional antennas I bought second hand were absolute pants. Here's a waterfall plot covering the bit of B20 that my local mast uses (annotated to show the operators):

1695047883566.webp


Massive improvement in SNR, and the downlinks for all four operators are very clear. Discovered that EE also have 5MHz of B20 bandwidth centred on 798.5MHz, and the weak 3 signal (also 5MHz BW) centred on 793.5MHz is now detectable (before it wasn't).

O2 and Vodafone have 10MHz bandwidth, with nothing much to choose between them in terms of signal (the second-by-second changes in a waterfall plot mostly show the traffic density). Vodafone has the edge in terms of signal strength (from the top spectral plot), but only by a couple of dB.

In the light of this data I've bitten the bullet and ordered a Mikrotik LHG LTE6. That has a gain of around 4 to 5dB at 800MHz, plus maybe another 2dB from having no cable loss, so compared with my test set up (2dBi antenna, ~2.3dB cable loss) that should give a signal boost of around 5dB or so.

Interesting exercise finding out what's really available at the point where I will be locating the Mikrotik. If nothing else it's confirmed which operator to use and that there is no other mast covering this area. Also been fun getting to grips with the spectrum analyser app for the HackRF One. Not used it like this before, I've only used the Hack RF One for pen testing car security systems until now.
 
Sponsored Links
Top
Cheap BIG ISPs for 100Mbps+
Community Fibre UK ISP Logo
150Mbps
Gift: None
Virgin Media UK ISP Logo
Virgin Media £22.99
132Mbps
Gift: None
Vodafone UK ISP Logo
Vodafone £24.00 - 26.00
150Mbps
Gift: None
NOW UK ISP Logo
NOW £24.00
100Mbps
Gift: None
Plusnet UK ISP Logo
Plusnet £25.99
145Mbps
Gift: £50 Reward Card
Large Availability | View All
Cheapest ISPs for 100Mbps+
Gigaclear UK ISP Logo
Gigaclear £17.00
200Mbps
Gift: None
Community Fibre UK ISP Logo
150Mbps
Gift: None
Virgin Media UK ISP Logo
Virgin Media £22.99
132Mbps
Gift: None
Hey! Broadband UK ISP Logo
150Mbps
Gift: None
Youfibre UK ISP Logo
Youfibre £23.99
150Mbps
Gift: None
Large Availability | View All
Sponsored Links
The Top 15 Category Tags
  1. FTTP (6027)
  2. BT (3639)
  3. Politics (2721)
  4. Business (2440)
  5. Openreach (2405)
  6. Building Digital UK (2330)
  7. Mobile Broadband (2146)
  8. FTTC (2083)
  9. Statistics (1901)
  10. 4G (1816)
  11. Virgin Media (1764)
  12. Ofcom Regulation (1582)
  13. Fibre Optic (1467)
  14. Wireless Internet (1462)
  15. 5G (1407)
Sponsored

Copyright © 1999 to Present - ISPreview.co.uk - All Rights Reserved - Terms  ,  Privacy and Cookie Policy  ,  Links  ,  Website Rules